Viral Mechanisms and Pathogenesis
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Viral Mechanisms and Pathogenesis

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Questions and Answers

What mechanism involves the fusion of infected cells into larger structures that can lead to cell death?

  • Induction of cell fusion into multinucleated giant cells (correct)
  • Immune-mediated cytotoxicity
  • Inhibition of cellular protein synthesis
  • Accumulation of toxic viral proteins

    • Which of the following contributes to the symptoms of viral respiratory disease?

  • Decreased breathing rate
  • Direct bacterial colonization
  • Cellular replication without effects
  • Inflammatory response to viral infection (correct)

    • What is a common consequence of viral infection in respiratory epithelial cells?

  • Increased mucus production without cell damage
  • Rapid cell proliferation in the respiratory tract
  • Triggering of an inflammatory response leading to cell death (correct)
  • Enhanced oxygen absorption by lung tissue

    • What role do secondary bacterial infections play in viral respiratory diseases?

    <p>They can exacerbate the already existing disease</p> Signup and view all the answers

    Which of the following is NOT a mechanism by which viruses kill cells?

    <p>Enhanced cellular respiration</p> Signup and view all the answers

    How do early virus-coded proteins contribute to cell death during viral replication?

    <p>By interfering with the host cell's protein synthesis</p> Signup and view all the answers

    What is the primary function of viral capsid proteins in infected cells?

    <p>To accumulate and cause cellular dysfunction</p> Signup and view all the answers

    What are inclusion bodies and their role in viral infections?

    <p>Crystalline aggregates indicating viral replication</p> Signup and view all the answers

    Which of the following best describes the relationship between viral proteins and host cell functions?

    <p>Viral proteins inhibit cellular functions necessary for survival</p> Signup and view all the answers

    What effect do inclusion bodies have on cellular structures during a viral infection?

    <p>They distort and disrupt normal cellular structures</p> Signup and view all the answers

    What is one consequence of cell fusion in viral infections?

    <p>Multinucleated giant cells are formed.</p> Signup and view all the answers

    What process describes the self-digestion of virus-infected cells?

    <p>Autolysis</p> Signup and view all the answers

    How does immune-mediated cytotoxicity contribute to cell death during viral infections?

    <p>It marks infected cells for destruction by immune cells.</p> Signup and view all the answers

    What effect can viral infections have on cellular membranes?

    <p>They can cause disintegration of the cell membrane.</p> Signup and view all the answers

    Which of the following best describes a potential outcome of the formation of multinucleated giant cells?

    <p>Increased susceptibility to cell death.</p> Signup and view all the answers

    How does the death of respiratory epithelial cells due to viral infection impact mucociliary clearance?

    <p>It disrupts mucociliary clearance, increasing infection risk.</p> Signup and view all the answers

    Which inflammatory response is NOT typically triggered by viral respiratory infections?

    <p>Neutrophil apoptosis</p> Signup and view all the answers

    What symptom would you most likely expect from a viral infection located in the nasal passages?

    <p>Sneezing</p> Signup and view all the answers

    What is a consequence of viral infections in the terminal airways and alveoli?

    <p>Severe symptoms such as dyspnea and cyanosis</p> Signup and view all the answers

    Which of the following best describes the overall effect of the inflammatory response during a viral respiratory infection?

    <p>It leads to symptoms like coughing and nasal discharge.</p> Signup and view all the answers

    What is typically restored following the resolution of uncomplicated viral respiratory infections?

    <p>Normal architecture of respiratory tissues</p> Signup and view all the answers

    Which major family of viruses is NOT associated with respiratory disease in veterinary patients?

    <p>Bacillus</p> Signup and view all the answers

    What impact do secondary bacterial infections have on viral respiratory diseases?

    <p>Exacerbate tissue damage</p> Signup and view all the answers

    How does the immune system primarily clear uncomplicated viral infections?

    <p>Via both cellular and humoral immune responses</p> Signup and view all the answers

    What mechanism is primarily responsible for the complications arising from secondary bacterial infections during viral respiratory diseases?

    <p>Impaired mucociliary clearance</p> Signup and view all the answers

    Which respiratory disease is specifically caused by Herpesvirus in horses?

    <p>Equine rhinopneumonitis</p> Signup and view all the answers

    What is a common symptom associated with respiratory diseases caused by Herpesviruses?

    <p>Nasal discharge</p> Signup and view all the answers

    How do Herpetoviridae viruses affect respiratory epithelial cells?

    <p>They lead to intranuclear inclusion bodies and cell death.</p> Signup and view all the answers

    Which of the following is NOT a characteristic of the Poxviridae family regarding respiratory disease?

    <p>Primarily respiratory pathogens</p> Signup and view all the answers

    What potential consequence can occur due to the latency of Herpesviruses in the host?

    <p>Reactivation under stress</p> Signup and view all the answers

    What respiratory condition is associated with Canine Adenovirus Type 2 in dogs?

    <p>Kennel cough</p> Signup and view all the answers

    Which family of viruses is known for causing antigenic shift and drift, leading to new strains in animals?

    <p>Orthomyxoviridae</p> Signup and view all the answers

    Severe respiratory diseases in animals due to Paramyxoviridae can lead to the formation of what type of cells?

    <p>Multinucleated giant cells</p> Signup and view all the answers

    What type of respiratory disease is associated with swine influenza?

    <p>Respiratory illness in pigs</p> Signup and view all the answers

    Which virus is notably recognized for causing severe respiratory morbidity in canine patients?

    <p>Canine Distemper Virus</p> Signup and view all the answers

    What is the primary respiratory disease caused by Bovine Herpesvirus-1 in cattle?

    <p>Infectious bovine rhinotracheitis</p> Signup and view all the answers

    Which of the following clinical signs is NOT typically associated with equine rhinopneumonitis caused by Equine Herpesvirus-1?

    <p>Ulcerative lesions</p> Signup and view all the answers

    What severe outcome can Equine Herpesvirus-1 lead to in pregnant mares?

    <p>Abortion</p> Signup and view all the answers

    Which virus is known to cause tracheobronchitis and pneumonia in animals?

    <p>SARS-CoV-2</p> Signup and view all the answers

    What is a common clinical sign of infectious bovine rhinotracheitis caused by Bovine Herpesvirus-1?

    <p>Mucopurulent nasal discharge</p> Signup and view all the answers

    What are the primary symptoms of Feline Herpesvirus-1 in cats?

    <p>Sneezing and coughing</p> Signup and view all the answers

    Which respiratory disease is caused by a herpesvirus in chickens?

    <p>Avian Laryngotracheitis</p> Signup and view all the answers

    What is a significant effect of Herpesvirus suis (SuHV-1) in pigs?

    <p>Leads to mild respiratory symptoms in adults</p> Signup and view all the answers

    What are the clinical signs of Avian Laryngotracheitis in chickens?

    <p>Nasal discharge and gasping</p> Signup and view all the answers

    How does Herpesvirus suis affect other species like cattle and dogs?

    <p>Can lead to fatal neurological disease</p> Signup and view all the answers

    What is the primary mechanism through which herpesviruses establish persistence in the host?

    <p>Latency in neurons</p> Signup and view all the answers

    Which of the following viruses is associated with respiratory disease in horses?

    <p>Hendra Virus</p> Signup and view all the answers

    What type of disease does Paramyxoviridae cause in dogs?

    <p>Severe pneumonia and immunosuppression</p> Signup and view all the answers

    What is a common cellular effect caused by Paramyxoviridae infections?

    <p>Formation of multinucleated giant cells</p> Signup and view all the answers

    What triggers the reactivation of herpesvirus latency in a host?

    <p>Physical stress</p> Signup and view all the answers

    What is the primary cause of Jaagsiekte in sheep?

    <p>A betaretrovirus</p> Signup and view all the answers

    What type of cell proliferation is primarily associated with Jaagsiekte?

    <p>Type II pneumocytes</p> Signup and view all the answers

    How does Visna-Maedi primarily affect the lungs of sheep?

    <p>By causing fibrosis and restrictive lung disease</p> Signup and view all the answers

    Which secondary bacterial infection is commonly associated with Canine Distemper Virus pneumonia?

    <p>Bordetella bronchiseptica</p> Signup and view all the answers

    What role does Parainfluenza-3 play in the shipping fever complex in cattle?

    <p>It promotes mild respiratory symptoms but exacerbates underlying bacterial infections.</p> Signup and view all the answers

    What is a characteristic clinical sign of Newcastle Disease Virus in poultry?

    <p>Laryngeal inflammation</p> Signup and view all the answers

    Which statement best describes the impact of Hendra virus on horses?

    <p>It can cause acute pulmonary edema and rapid deterioration.</p> Signup and view all the answers

    What role do multinucleated giant cells play in Paramyxoviridae infections?

    <p>They indicate viral replication and tissue damage.</p> Signup and view all the answers

    Which of the following is a potential consequence in poultry infected with Newcastle Disease Virus?

    <p>Fatal systemic disease in severe cases</p> Signup and view all the answers

    What common symptom might indicate Hendra virus infection in horses?

    <p>Severe respiratory distress</p> Signup and view all the answers

    What is the primary cause of Jaagsiekte in sheep?

    <p>Betaretrovirus</p> Signup and view all the answers

    Which of the following best describes the lung condition caused by Visna-Maedi?

    <p>Chronic interstitial pneumonia</p> Signup and view all the answers

    How does the progression of Jaagsiekte differ from that of Visna-Maedi?

    <p>Jaagsiekte involves the formation of lung tumors, while Visna-Maedi leads to fibrosis.</p> Signup and view all the answers

    What pathological change occurs in the lungs due to Jaagsiekte?

    <p>Proliferation of Type II pneumocytes</p> Signup and view all the answers

    What additional effect can be expected from the fibrosis caused by Visna-Maedi?

    <p>Obliteration of alveolar spaces</p> Signup and view all the answers

    Which cells are primarily affected by Jaagsiekte?

    <p>Type II pneumocytes</p> Signup and view all the answers

    What is a significant difference between the causes of Jaagsiekte and Visna-Maedi?

    <p>Jaagsiekte leads to lung tumors, while Visna-Maedi causes chronic interstitial inflammation.</p> Signup and view all the answers

    Which type of pneumonia is primarily associated with Visna-Maedi?

    <p>Chronic interstitial pneumonia</p> Signup and view all the answers

    How are viruses that cause primary respiratory disease usually transmitted?

    <p>By aerosols from coughs, sneezes, or sniffing</p> Signup and view all the answers

    What is a consequence of the chronic interstitial inflammation caused by Visna-Maedi?

    <p>Induction of restrictive lung disease</p> Signup and view all the answers

    What contributes to the transmission of infected aerosols among animals?

    <p>Grouping animals into herds or flocks</p> Signup and view all the answers

    Where are particles smaller than 3 microns primarily deposited in the respiratory tract?

    <p>Terminal airways and alveoli</p> Signup and view all the answers

    Why do rhinoviruses prefer to replicate in the nasal passages rather than deeper in the lungs?

    <p>Cooler temperature of nasal passages</p> Signup and view all the answers

    What type of particles is primarily deposited on the mucosa of the nasal cavity and upper airways?

    <p>Particles larger than 10 microns</p> Signup and view all the answers

    Which viruses are known to have a predilection for causing infections in the upper respiratory tract?

    <p>Rhinoviruses and herpesviruses</p> Signup and view all the answers

    What role do Toll-like receptors play in response to viral exposure in the respiratory tract?

    <p>They recognize pathogen-associated molecular patterns and trigger an immune response.</p> Signup and view all the answers

    What is the initial consequence when a pathogenic virus enters the respiratory tract?

    <p>Selective entry into specific cells for replication.</p> Signup and view all the answers

    How do alveolar macrophages respond to viral infections in the respiratory tract?

    <p>They engulf the virus and transport it to lymph nodes.</p> Signup and view all the answers

    What triggers the release of cytokines and chemokines during a viral infection in the respiratory tract?

    <p>Recognition of viral components by Toll-like receptors.</p> Signup and view all the answers

    Why do viruses selectively enter certain respiratory cells?

    <p>Specific viral receptors are present on those cell types.</p> Signup and view all the answers

    What is the net effect of viral invasion of respiratory epithelial cells?

    <p>Cell death resulting from viral cytolysis</p> Signup and view all the answers

    How do early virus-coded proteins affect host cells during viral replication?

    <p>They inhibit host cell protein and RNA synthesis.</p> Signup and view all the answers

    Which cells play a crucial role in the initial immune response to viral infections?

    <p>Natural killer cells and neutrophils</p> Signup and view all the answers

    What function do dendritic cells serve in the immune response to respiratory viral infections?

    <p>They take up antigens and interact with T cells.</p> Signup and view all the answers

    What is a common outcome of viral cytolysis in respiratory epithelial cells?

    <p>Cell death and necrosis</p> Signup and view all the answers

    Which factors are primarily responsible for whether an infected animal shows clinical signs of respiratory disease?

    <p>The amount and location of tissue destruction</p> Signup and view all the answers

    What are the three key characteristics of the inflammatory reaction during viral respiratory disease?

    <p>Hyperemia, vascular leakage, and extravasation of leukocytes</p> Signup and view all the answers

    What clinical signs are most commonly associated with inflammation in the nasal mucosa?

    <p>Serous or purulent nasal discharge and sneezing</p> Signup and view all the answers

    What causes ocular discharge during a viral respiratory infection?

    <p>Inflammation of the nasolacrimal duct tissues</p> Signup and view all the answers

    Which of the following does NOT contribute to the inflammatory exudate during viral respiratory disease?

    <p>Production of antibodies</p> Signup and view all the answers

    What is the primary clinical sign associated with lesions in the trachea and bronchi?

    <p>Coughing</p> Signup and view all the answers

    What distinguishes a productive cough from a non-productive cough in viral respiratory disease?

    <p>Presence of mucus</p> Signup and view all the answers

    What clinical manifestation occurs with minor epithelial damage in the terminal airways and alveoli?

    <p>Pneumonitis</p> Signup and view all the answers

    How does viral infection create a conducive environment for secondary bacterial infections?

    <p>Loss of epithelial cells and mucociliary activity</p> Signup and view all the answers

    What severe consequence can occur if epithelial damage in alveoli is extensive?

    <p>Severe dyspnea and cyanosis</p> Signup and view all the answers

    What is the primary outcome of uncomplicated viral respiratory infections?

    <p>Complete recovery with no respiratory function loss</p> Signup and view all the answers

    Which of the following viruses is known to predispose dogs to secondary bacterial infections?

    <p>Canine distemper virus</p> Signup and view all the answers

    What result may occur due to secondary bacterial infections following viral infections?

    <p>Extensive tissue destruction and potential severe scarring</p> Signup and view all the answers

    How do the immune responses contribute to the resolution of uncomplicated viral infections?

    <p>Through the destruction of viral particles and re-epithelialization</p> Signup and view all the answers

    What potential complications are associated with secondary bacterial infections following respiratory viral infections?

    <p>Severe scarring and functional loss of lung tissue</p> Signup and view all the answers

    Which of the following respiratory viruses is associated with secondary bacterial infections in cats?

    <p>Feline herpesvirus</p> Signup and view all the answers

    Identify the respiratory virus in cattle that is linked to secondary bacterial infections.

    <p>Bovine respiratory syncytial virus</p> Signup and view all the answers

    Which virus is a known cause of respiratory infections in pigs that predisposes them to secondary bacterial infections?

    <p>Swine influenza virus</p> Signup and view all the answers

    Among the following viruses, which one is recognized for its role in respiratory disease in horses that can lead to secondary infections?

    <p>Equine herpesvirus-1</p> Signup and view all the answers

    What is an example of a viral respiratory pathogen in cattle that can lead to secondary bacterial infections?

    <p>Infectious Bovine Rhinotracheitis</p> Signup and view all the answers

    Which of the following viral families is less commonly involved in respiratory disease?

    <p>Poxviridae</p> Signup and view all the answers

    How many viral families are known to cause respiratory tract lesions in domestic and laboratory animals?

    <p>Ten</p> Signup and view all the answers

    Which of the following is NOT one of the commonly seen viral families in veterinary patients?

    <p>Rhabdoviridae</p> Signup and view all the answers

    Which of the following respiratory viruses in birds predisposes to secondary bacterial infections?

    <p>Avian influenza virus</p> Signup and view all the answers

    Which of the following viral families includes viruses that primarily affect the respiratory system in veterinary patients?

    <p>Orthomyxoviridae</p> Signup and view all the answers

    What type of lesions are typically caused by viruses in the Poxviridae family?

    <p>Proliferative and necrotizing lesions</p> Signup and view all the answers

    Which of the following subfamilies of Herpetoviridae is considered to have minor importance regarding respiratory disease?

    <p>Beta-herpesviruses</p> Signup and view all the answers

    Are Poxviruses considered primary pathogens of the respiratory tract?

    <p>No, they are not regarded as primary pathogens</p> Signup and view all the answers

    What is the general size classification of viruses in the Poxviridae family?

    <p>Largest and most complex viruses</p> Signup and view all the answers

    Which of the following characteristics is NOT associated with viruses in the Poxviridae family?

    <p>They primarily affect the respiratory tract</p> Signup and view all the answers

    What percentage of cats infected with Feline Herpesvirus-1 are known to harbor latent virus?

    <p>80%</p> Signup and view all the answers

    Which of the following is a trigger for herpesvirus reactivation?

    <p>Stress</p> Signup and view all the answers

    Where do herpesviruses primarily establish latency in the host's body?

    <p>Neurons</p> Signup and view all the answers

    What is the main mechanism through which herpesviruses cause cell death in respiratory epithelial cells?

    <p>Blocking of cellular DNA synthesis</p> Signup and view all the answers

    Which immune response is essential for controlling herpesvirus infections in the body?

    <p>Innate and specific immune systems</p> Signup and view all the answers

    Which disease is specifically associated with Equine Herpesvirus I (EHV-1)?

    <p>Equine viral abortion</p> Signup and view all the answers

    What are common clinical signs of feline viral rhinotracheitis (FVR)?

    <p>Sneezing and coughing</p> Signup and view all the answers

    What type of signs typically manifest in horses suffering from equine rhinopneumonitis?

    <p>Mild upper respiratory symptoms</p> Signup and view all the answers

    Which of the following diseases is caused by Bovine Herpesvirus I (BHV-1)?

    <p>Infectious pustular vulvovaginitis</p> Signup and view all the answers

    What severe outcome can occur due to Equine Herpesvirus I (EHV-1) in pregnant mares?

    <p>Fetal death and late gestational abortion</p> Signup and view all the answers

    What is the primary response of adult swine infected with SuHV-1?

    <p>Mild, inapparent infection</p> Signup and view all the answers

    Which condition is specifically associated with Herpesvirus canis (CHV) in puppies?

    <p>Infectious tracheobronchitis</p> Signup and view all the answers

    What clinical symptom is associated with infection from the Avian Laryngotracheitis Virus in chickens?

    <p>Nasal discharge and gasping</p> Signup and view all the answers

    What type of infection do adenoviruses typically cause in animals?

    <p>Mild upper respiratory infections</p> Signup and view all the answers

    Which age group of dogs is most significantly impacted by Herpesvirus canis (CHV)?

    <p>Young puppies under 2 weeks of age</p> Signup and view all the answers

    Which species is NOT commonly affected by minor respiratory diseases caused by adenoviruses?

    <p>Dogs</p> Signup and view all the answers

    What is a key symptom of the mild upper respiratory disease caused by Canine Adenovirus II?

    <p>Pharyngitis</p> Signup and view all the answers

    What type of vaccine is available for Canine Adenovirus II?

    <p>Live attenuated vaccine</p> Signup and view all the answers

    What respiratory disease is caused by Feline Calicivirus?

    <p>Feline respiratory disease</p> Signup and view all the answers

    Which clinical sign is associated with feline respiratory disease caused by Feline Calicivirus?

    <p>Ulcerations in the nose</p> Signup and view all the answers

    What is a primary reason swine are significant in influenza virus reassortment?

    <p>Their respiratory tract cells have receptors for both avian and human influenza viruses.</p> Signup and view all the answers

    Which strain is currently associated with canine influenza?

    <p>H3N2</p> Signup and view all the answers

    What type of disease does Equine Influenza Virus (H3N8) typically cause in horses?

    <p>A highly contagious respiratory disease</p> Signup and view all the answers

    Which clinical sign is NOT typically associated with equine influenza?

    <p>Seizures</p> Signup and view all the answers

    Which of the following viruses represents an example of antigenic shift?

    <p>H5N1 avian influenza virus in pigs</p> Signup and view all the answers

    What primary mechanism is involved in the disease caused by Feline Calicivirus?

    <p>Direct viral invasion and host immune response</p> Signup and view all the answers

    How is African Horse Sickness Virus predominantly transmitted?

    <p>Via insect vectors</p> Signup and view all the answers

    What is the typical shedding duration for Feline Calicivirus after infection?

    <p>2-3 weeks</p> Signup and view all the answers

    What are the primary clinical signs associated with African Horse Sickness?

    <p>Pulmonary edema and cardiac failure</p> Signup and view all the answers

    Which natural reservoir is associated with Influenza A viruses?

    <p>Wild waterfowl and shorebirds</p> Signup and view all the answers

    How do Influenza viruses primarily evade host immunity?

    <p>Through antigenic shift and drift</p> Signup and view all the answers

    What role do Type II epithelial cells play in recovery from Feline Calicivirus infection?

    <p>They replace desquamated Type I cells</p> Signup and view all the answers

    What characteristic is true about the Orthomyxoviridae family?

    <p>It is exclusively composed of one genus, Influenzavirus</p> Signup and view all the answers

    What is a potential consequence of secondary bacterial infections in equine influenza?

    <p>Bronchopneumonia</p> Signup and view all the answers

    Which of the following describes a method by which swine influenza is transmitted?

    <p>Infected aerosols or via lungworm</p> Signup and view all the answers

    What is a common lung lesion associated with swine influenza?

    <p>Focal necrosis of upper airway mucosa</p> Signup and view all the answers

    What type of vaccine is available for equine influenza?

    <p>Commercially available vaccines</p> Signup and view all the answers

    Which virus is responsible for causing swine influenza?

    <p>Swine Influenza Virus</p> Signup and view all the answers

    What is the secondary bacterial infection that complicates swine influenza?

    <p>Hemophilus suis</p> Signup and view all the answers

    Canine Influenza (CIV) is linked to which virus transmitted from horses?

    <p>H3N8 virus</p> Signup and view all the answers

    Which hemagglutinin subtypes are most frequently involved in avian influenza?

    <p>H5 and H7</p> Signup and view all the answers

    What clinical signs are commonly associated with Canine Influenza?

    <p>Cough and nasal discharge</p> Signup and view all the answers

    Which animal serves as the major reservoir for avian influenza viruses?

    <p>Waterfowl</p> Signup and view all the answers

    What is a major concern associated with antigenic shift in avian influenza viruses?

    <p>It results in new strains without population immunity.</p> Signup and view all the answers

    What is H7N9 avian influenza virus known for?

    <p>Its high zoonotic potential and human cases.</p> Signup and view all the answers

    What characteristic cytopathic effect is often associated with Paramyxoviridae?

    <p>Formation of multinucleate, syncytial giant cells.</p> Signup and view all the answers

    How do Paramyxoviridae affect cellular protein synthesis?

    <p>They do not cause immediate cessation but lead to cell death when synthesis stops.</p> Signup and view all the answers

    What notable risk is posed by the H7N9 avian influenza virus?

    <p>It often leads to severe disease in humans after exposure.</p> Signup and view all the answers

    Which clinical features are associated with Canine Distemper Virus infection?

    <p>Pneumonia and encephalomyelitis</p> Signup and view all the answers

    How does Canine Distemper Virus spread throughout the body?

    <p>By airway macrophages to the tonsils</p> Signup and view all the answers

    What secondary infection is commonly associated with Canine Distemper Virus?

    <p>Bordetella bronchiseptica</p> Signup and view all the answers

    Which species are primarily affected by Canine Distemper Virus?

    <p>Dogs, wolves, and raccoons</p> Signup and view all the answers

    What vaccine is available that targets Canine Distemper Virus?

    <p>Commercial vaccines for CDV and Bordetella</p> Signup and view all the answers

    What is the primary method of transmission for the Measles Virus?

    <p>Aerosols</p> Signup and view all the answers

    What cellular effect does the Measles Virus cause in the respiratory system?

    <p>Extensive necrosis</p> Signup and view all the answers

    Is there a vaccine available for the Measles Virus?

    <p>Yes, vaccines are commercially available</p> Signup and view all the answers

    What disease is caused by Rinderpest Virus?

    <p>An acute disease in cattle and sheep</p> Signup and view all the answers

    How does the Measles Virus replicate in the body after transmission?

    <p>In the respiratory mucosa, transported by macrophages</p> Signup and view all the answers

    In which regions was Rinderpest Virus primarily found before its eradication?

    <p>Africa, the Middle East, and Asia</p> Signup and view all the answers

    What type of disease does Parainfluenza-1 (Sendai Virus) cause in rodents?

    <p>Mild respiratory disease</p> Signup and view all the answers

    Canine Parainfluenza-2 is most commonly associated with which condition in dogs?

    <p>Infectious tracheobronchitis (kennel cough)</p> Signup and view all the answers

    How does stress affect the susceptibility of cattle to PI-3 infection?

    <p>It decreases resistance to infections</p> Signup and view all the answers

    What disease is associated with Parainfluenza-3 (PI-3) in cattle?

    <p>Shipping fever complex</p> Signup and view all the answers

    What disease is caused by Newcastle Disease Virus in poultry?

    <p>Avian Pneumoencephalitis</p> Signup and view all the answers

    How many genera are found in the Coronaviridae family?

    <p>One</p> Signup and view all the answers

    How were coronaviruses previously viewed in terms of their role in respiratory diseases?

    <p>Not significant contributors</p> Signup and view all the answers

    What was the cause of the 2003 SARS epidemic?

    <p>A novel member of the Coronavirus genus</p> Signup and view all the answers

    Which statement about coronaviruses and respiratory disease is accurate?

    <p>They were historically underestimated in their impact.</p> Signup and view all the answers

    What effect does the PRRS Virus have on newborn piglets?

    <p>Causes widespread deaths among them</p> Signup and view all the answers

    What is the incubation period for Maedi/Visna Virus?

    <p>2-3 years</p> Signup and view all the answers

    How is Maedi/Visna Virus primarily transmitted?

    <p>Via infected aerosols or colostrum</p> Signup and view all the answers

    What diseases are associated with Maedi/Visna Virus in sheep?

    <p>Maedi and ovine progressive pneumonia</p> Signup and view all the answers

    What type of virus is responsible for respiratory disease in sows?

    <p>Porcine Reproductive and Respiratory Syndrome Virus</p> Signup and view all the answers

    Which animal is identified as a model for studying SARS coronavirus?

    <p>Ferret</p> Signup and view all the answers

    What receptor does SARS-CoV-2 utilize to enter host cells?

    <p>ACE-2</p> Signup and view all the answers

    What demonstrates the understanding of viral disease during the COVID-19 pandemic?

    <p>Rapid development of therapies</p> Signup and view all the answers

    How many strains of coronavirus are known to have zoonotic potential?

    <p>Seven</p> Signup and view all the answers

    In terms of viral replication, how does low vaccination affect virus variants?

    <p>Increases chances of new variants</p> Signup and view all the answers

    What disease does Infectious Bronchitis Virus cause in chickens?

    <p>Serous tracheobronchitis</p> Signup and view all the answers

    Which animal species has NOT been infected by SARS-CoV-2?

    <p>Penguins</p> Signup and view all the answers

    What disease is caused by Equine Arteritis Virus (EAV) in horses?

    <p>Respiratory disease</p> Signup and view all the answers

    What is a significant feature of the Maedi/Visna Virus's impact on lung tissue?

    <p>Obliteration of alveolar spaces</p> Signup and view all the answers

    Jaagsiekte, caused by Betaretrovirus, primarily leads to the proliferation of which type of cells?

    <p>Type II pneumocytes</p> Signup and view all the answers

    Which of the following viruses from the Retroviridae family is known to cause respiratory disease in sheep?

    <p>Maedi/Visna Virus</p> Signup and view all the answers

    What are the two main Arteriviruses recognized in veterinary medicine?

    <p>Equine Arteritis Virus and Porcine Reproductive and Respiratory Syndrome Virus</p> Signup and view all the answers

    Which condition is associated with the progressive replacement of lung tissue in sheep due to the Betaretrovirus?

    <p>Jaagsiekte or pulmonary adenomatosis</p> Signup and view all the answers

    Study Notes

    Mechanisms of Cell Killing by Viruses

    • Viruses inhibit cellular protein synthesis, halting essential functions necessary for cell survival.
    • Toxic viral proteins accumulate within infected cells, contributing to cellular damage and death.
    • Inclusion bodies form within cells as a result of viral replication, disrupting normal cell structure and function.
    • Viral infections can induce cell fusion, creating multinucleated giant cells, which are nonfunctional and lead to cell death.
    • Leakage of lysosomal enzymes can result in autolysis, damaging the cell from within.
    • Immune-mediated cytotoxicity occurs when the immune system targets and kills infected cells due to viral presence.

    Pathogenesis of Viral Respiratory Disease

    • Viral infection begins with entry into and replication within respiratory epithelial cells, instigating cell death.
    • Infected cells trigger an inflammatory response, activating immune cells and releasing cytokines.
    • Common symptoms of viral respiratory disease include nasal discharge, coughing, and dyspnea due to inflammation and cellular damage.
    • The severity of respiratory symptoms correlates with the amount of tissue damage and the specific area of the respiratory tract affected.
    • Secondary bacterial infections can occur following the initial viral infection, often worsening the existing disease and symptoms.

    Viral Inhibition of Protein Synthesis

    • Early viral proteins disrupt host cell protein and RNA synthesis.
    • This disruption is critical, leading to essential cellular function failure and resulting in cell death.

    Toxic Viral Proteins

    • High concentrations of viral capsid proteins accumulate during replication.
    • These proteins are toxic to host cells, contributing to dysfunction and promoting cell death.

    Inclusion Bodies in Viral Cytopathology

    • Inclusion bodies are crystalline aggregates of viral proteins and developing virions.
    • These structures form within the nucleus or cytoplasm of infected cells.
    • Inclusion bodies can distort cellular structures and serve as markers of viral infection, detectable under a microscope.

    Cell Fusion and Viral Infections

    • Some viruses induce infected cells to fuse, resulting in multinucleated giant cells.
    • These giant cells exhibit dysfunction due to disruption of normal cellular architecture.
    • The abnormal structure of giant cells makes them more susceptible to death.

    Autolysis in Virus-Infected Cells

    • Viral infections can increase cellular membrane permeability.
    • This permeability change allows lysosomal enzymes to leak and digest the cell.
    • The process called autolysis leads to rapid cell death as the cell undergoes self-digestion.

    Immune-Mediated Cytotoxicity

    • Viral antigens can be integrated into the host cell membrane, signaling for immune attack.
    • Cytotoxic T cells and natural killer cells identify and destroy these infected cells.
    • This immune response significantly contributes to the overall cytopathic effects caused by the virus.

    Viral Entry and Replication in Respiratory Epithelial Cells

    • Viral entry into respiratory epithelial cells initiates replication, leading to cell death.
    • Loss of epithelial cells disrupts mucociliary clearance, increasing susceptibility to infections.
    • Disruption allows inflammatory processes to initiate and escalate.

    Key Inflammatory Responses to Viral Respiratory Infections

    • Inflammatory response includes hyperemia (increased blood flow) and vascular leakage of plasma proteins.
    • Recruitment of leukocytes occurs at the infection site, amplifying the immune response.
    • Production of inflammatory exudates results in symptoms like nasal discharge, coughing, and increased respiratory effort.

    Influence of Viral Infection Locations on Symptoms

    • Viral infections in the nasal passages lead to sneezing and nasal discharge.
    • Infections in the trachea and bronchi primarily cause coughing.
    • Severe symptoms like dyspnea (difficulty breathing) and cyanosis (bluish skin due to lack of oxygen) occur with involvement of terminal airways and alveoli, impairing gas exchange.

    Role of Secondary Bacterial Infections in Viral Respiratory Disease

    • Secondary bacterial infections can arise when mucociliary clearance is compromised.
    • Viral infections damage the epithelial barrier, increasing vulnerability to bacterial invasion.
    • These infections may worsen tissue damage and inflammation, resulting in severe respiratory complications.

    Immune System Response to Uncomplicated Viral Respiratory Infections

    • The immune system employs both cellular and humoral responses to tackle uncomplicated viral infections.
    • Viral clearance restores the normal respiratory tissue architecture through re-epithelialization.
    • Typically, absence of secondary bacterial infections prevents permanent loss of respiratory function.

    Major Virus Families Causing Respiratory Disease in Veterinary Patients

    • Significant virus families include:
      • Poxviridae
      • Herpetoviridae
      • Adenoviridae
      • Picornaviridae
      • Caliciviridae
      • Reoviridae
      • Orthomyxoviridae
      • Paramyxoviridae
      • Coronaviridae
      • Retroviridae
    • These viruses differ in pathogenicity and species affected, contributing to respiratory diseases in various animals.

    Respiratory Diseases Caused by Herpesvirus

    • Herpesviruses are responsible for several significant respiratory diseases in various animal species.
    • Equine Rhinopneumonitis: Affects horses, characterized by upper respiratory symptoms such as coughing and nasal discharge.
    • Infectious Bovine Rhinotracheitis: Occurs in cattle, leading to similar respiratory signs and complications.
    • Feline Viral Rhinotracheitis: Affects cats, causing coughing, nasal discharge, and potentially ulcerative lesions.
    • Infectious Laryngotracheitis: Primarily seen in chickens, causing respiratory distress and lesions.
    • Common symptoms across these infections include nasal discharge, coughing, and ulcerative lesions in the upper respiratory tract.
    • Herpesviruses establish latency within the host, with the potential to reactivate during periods of stress or immune suppression.

    Key Characteristics of the Poxviridae Family

    • Poxviridae comprises large, complex viruses known for causing proliferative and necrotizing lesions primarily in the skin and oral mucous membranes.
    • Although not primarily associated with respiratory disease, some Poxviridae members can induce lesions that impact respiratory function.
    • Their mechanism often involves tissue damage rather than direct respiratory infection.

    Herpetoviridae Viruses and Respiratory Disease in Veterinary Patients

    • Herpetoviridae viruses, especially alpha-herpesviruses, target the respiratory epithelium.
    • They lead to significant cellular damage, characterized by the formation of intranuclear inclusion bodies and cell death.
    • Resultant symptoms often include ulcerative lesions in the respiratory tract.
    • These viruses are key contributors to upper respiratory diseases across various animal species, highlighting their veterinary significance.

    Respiratory Diseases Associated with Adenoviridae

    • Adenoviridae primarily lead to mild upper respiratory infections in healthy animals.
    • In immunocompromised animals, these viruses can cause severe pneumonia.
    • Canine Adenovirus Type 2 is associated with kennel cough, a highly contagious respiratory disease in dogs.

    Contribution of Orthomyxoviridae to Respiratory Disease

    • Orthomyxoviridae encompasses the Influenza viruses.
    • Influenza impacts various animals: equine influenza in horses, swine influenza in pigs, and avian influenza in birds.
    • These viruses can experience antigenic shift and drift, producing new strains.
    • Potential for zoonotic transmission exists, allowing viruses to jump from animals to humans.

    Respiratory Impacts of Paramyxoviridae

    • The Paramyxoviridae family includes Canine Distemper Virus and Parainfluenza-3.
    • These viruses are responsible for severe respiratory diseases in various animal populations.
    • Infections can lead to the formation of multinucleated giant cells.
    • Conditions such as bronchopneumonia are significant contributors to respiratory morbidity in veterinary patients.

    Coronaviridae Viruses and Respiratory System in Animals

    • Coronaviridae includes notable viruses such as SARS-CoV-2 and Infectious Bronchitis Virus (IBV).
    • These viruses cause respiratory diseases characterized by symptoms like tracheobronchitis and pneumonia.
    • Severe outbreaks can occur, impacting animal populations significantly.
    • These viruses have zoonotic potential, meaning they can be transmitted between animals and humans.

    Equine Herpesvirus in Horses

    • Equine Herpesvirus-1 (EHV-1) is responsible for equine rhinopneumonitis, a highly contagious upper respiratory disease in horses.
    • Common clinical signs include nasal discharge, coughing, and fever, especially in younger horses.
    • EHV-1 can lead to severe complications such as abortion in pregnant mares and equine myeloencephalopathy in critical cases.

    Bovine Herpesvirus-1 in Cattle

    • Bovine Herpesvirus-1 (BHV-1) causes infectious bovine rhinotracheitis (IBR), a highly contagious respiratory disease in cattle.
    • Clinical signs of IBR include mucopurulent nasal discharge, persistent coughing, and ulcerative lesions in the upper respiratory tract.
    • BHV-1 is also linked to infectious pustular vulvovaginitis (IPV) in cattle, presenting additional health concerns.

    Feline Herpesvirus-1 in Cats

    • Feline Herpesvirus-1 (FHV-1) leads to feline viral rhinotracheitis (FVR), affecting the upper respiratory tract.
    • Common symptoms include sneezing and coughing, indicating respiratory distress.
    • Nasal discharge is prevalent, often causing discomfort and indicating infection.
    • Ulcerative lesions may form in nasal passages and conjunctiva, leading to further complications.

    Herpesvirus in Chickens

    • Avian Laryngotracheitis, caused by a herpesvirus, is a serious respiratory disease in chickens.
    • Key clinical signs include nasal discharge and gasping, signifying severe respiratory distress.
    • Dyspnea, or difficulty breathing, can occur, indicating blocked airways.
    • Severe cases may result in death, often due to superadded bacterial infections.

    Herpesvirus suis (SuHV-1) in Pigs and Other Species

    • Herpesvirus suis (SuHV-1) causes pseudorabies, also known as Aujeszky's disease, primarily affecting pigs.
    • Adult pigs often experience mild respiratory symptoms, while piglets may suffer severe, fatal disease.
    • This virus has the potential to cause fatal neurological diseases in other species, including cattle, dogs, and cats, highlighting its cross-species impact.

    Role of Latency in Herpesvirus Infections

    • Herpesviruses can establish latency primarily in neurons, allowing long-term survival in the host without active virus replication.
    • Latency enables the virus to evade the host's immune system, maintaining a dormant state.
    • Stressful conditions can trigger reactivation of the virus, resulting in recurrent infections and associated symptoms in the host.

    Respiratory Diseases Caused by Paramyxoviridae

    • Paramyxoviridae family viruses are responsible for various respiratory diseases in multiple species.
    • Canine Distemper Virus (CDV) affects dogs, characterized by severe pneumonia and immunosuppression, leading to increased susceptibility to secondary infections.
    • Bovine Parainfluenza Virus-3 is significant in cattle, contributing to the "shipping fever complex," a severe respiratory illness that can occur during transportation.
    • Newcastle Disease Virus primarily impacts poultry, causing both respiratory and systemic illnesses, often resulting in high mortality rates.
    • Hendra Virus is pathogenic to horses, causing severe respiratory distress and neurological symptoms, with potential zoonotic implications.
    • Paramyxoviridae infections commonly result in the formation of multinucleated giant cells and intracytoplasmic inclusion bodies, indicators of viral infection, which significantly contribute to respiratory morbidity.

    Jaagsiekte vs. Visna-Maedi

    • Jaagsiekte is caused by a betaretrovirus.
    • Leads to pulmonary adenomatosis in sheep, characterized by the proliferation of Type II pneumocytes.
    • Results in slowly progressive lung tumors.
    • Visna-Maedi is caused by a lentivirus.
    • Affects sheep, resulting in chronic interstitial pneumonia.
    • Causes gradual thickening of alveolar walls and infiltration of mononuclear cells.
    • Progression of Jaagsiekte includes tumor formation, while Visna-Maedi leads to fibrosis and restrictive lung disease.

    Canine Distemper Virus

    • Canine Distemper Virus (Morbillivirus canis) causes a severe and often fatal disease in dogs.
    • Symptoms include pneumonia, encephalomyelitis, and immunosuppression.
    • The virus infects airway macrophages and spreads to lymph nodes, causing severe viremia.
    • In the respiratory tract, it causes necrosis of the trachea, bronchi, and alveolar epithelial cells.
    • Secondary bacterial infections, such as Bordetella bronchiseptica, complicate the disease, leading to bronchopneumonia.

    Parainfluenza-3 in Cattle

    • Parainfluenza-3 (PI-3) contributes to "shipping fever complex," a multifactorial respiratory disease in cattle.
    • Often exacerbated by stress, it leads to mild respiratory symptoms.
    • When combined with secondary bacterial infections (e.g., Pasteurella or Mannheimia hemolytica), it can result in severe bronchopneumonia.
    • PI-3 may alone cause rhinitis, tracheitis, and sometimes bronchopneumonia, but clinical signs are aggravated by concurrent bacterial infections.

    Newcastle Disease Virus in Poultry

    • Newcastle Disease Virus (NDV) is highly contagious, affecting birds primarily through respiratory symptoms.
    • Lentogenic strains cause mild symptoms such as nasal discharge and laryngeal inflammation.
    • Velogenic strains lead to severe systemic disease, often resulting in fatal outcomes.
    • Common clinical signs include respiratory distress and coughing.
    • Severe cases may exhibit neurological symptoms due to virus spread throughout the body.

    Hendra Virus in Horses

    • Hendra virus causes significant respiratory and neurological diseases in horses.
    • Clinical manifestations include acute pulmonary edema, hemorrhage, and pneumonia.
    • Symptoms observed include fever, nasal discharge, and respiratory distress, leading to rapid health deterioration.
    • The virus has zoonotic potential, presenting risks for human health.

    Significance of Multinucleated Giant Cells and Inclusion Bodies in Paramyxoviridae Infections

    • Paramyxoviridae infections are characterized by the formation of multinucleated giant cells.
    • Eosinophilic intracytoplasmic and intranuclear inclusion bodies are also typically observed in infected tissues.
    • These changes indicate viral replication and cellular fusion, contributing to extensive tissue damage, particularly in the respiratory tract.

    Jaagsiekte

    • Caused by a betaretrovirus, resulting in ovine pulmonary adenomatosis.
    • Leads to proliferation of Type II pneumocytes in the lungs; tumor formation occurs.
    • Tumors replace normal lung tissue, causing respiratory distress.
    • Compromised lung function can lead to death.

    Visna-Maedi

    • Caused by a lentivirus, resulting in chronic interstitial pneumonia in sheep.
    • Characterized by thickening of alveolar walls due to mononuclear phagocytic cell proliferation and infiltration.
    • Leads to fibrosis and obliteration of alveolar spaces.
    • Results in restrictive lung disease, significantly impairing respiratory function.

    Comparison of Progression

    • Jaagsiekte progresses through tumor formation, gradually replacing functional lung tissue.
    • Typically has a slow progression but ultimately causes significant respiratory impairment.
    • Visna-Maedi progresses through chronic inflammation and fibrosis, leading to restrictive lung disease without tumor formation.
    • Both conditions are slowly progressive but affect lung functionality through different mechanisms.

    Jaagsiekte

    • Primarily affects Type II pneumocytes, leading to their proliferation.
    • Result in pulmonary tumors within the lungs.
    • Caused by a betaretrovirus, specifically linked to tumor formation.

    Visna-Maedi

    • Affects the alveolar walls through infiltration of mononuclear phagocytic cells.
    • Leads to chronic interstitial pneumonia and fibrosis.
    • Induced by a lentivirus, causing inflammation and restrictive lung disease without tumor development.

    Transmission of Respiratory Diseases

    • Primarily transmitted through aerosols from infected animals.
    • Generated by actions such as coughing, sneezing, or sniffing.

    Transmission of Infected Aerosols in Animals

    • Grouping animals in herds, flocks, or kennels enhances the transmission of infected aerosols due to close contact with uninfected individuals.
    • Animal hospitals are also environments conducive to the spread of infections among animals.

    Aerosol Particle Deposition in the Respiratory Tract

    • Particles larger than 10 microns are deposited in the nasal cavity and upper airways.
    • Particles ranging from 3 to 10 microns are primarily deposited in the trachea and bronchi.
    • Smaller aerosol particles reach the terminal airways and alveoli.

    Deposition of Inspired Viral Particles

    • Inspired viral particles typically settle in smaller bronchioles, where ciliated cells have a protective protein layer rich in lysozyme and immunoglobulins, secreted by Club cells.
    • Viral particles may also be deposited in the alveoli, interacting directly with Type I epithelial cells and macrophages, further influencing immune response.

    Viruses in the Upper Respiratory Tract

    • Rhinoviruses and herpesviruses particularly target the upper respiratory tract, causing damage to nasal passages, trachea, and bronchi.

    Rhinovirus Replication Preference

    • Rhinoviruses thrive at lower temperatures, replicating more efficiently at 33°C, which aligns with their preference for the cooler environment found in the nasal passages.

    Viral Entry into Respiratory Cells

    • Specific viral receptors on respiratory tract cell types allow selective entry of viruses.
    • Viruses exploit the unique receptor profiles of respiratory epithelial cells to bind and enter.

    Pathogenic Virus Entry and Effects

    • Upon entering the respiratory tract, pathogenic viruses can directly infect specific cells.
    • Viruses may replicate within infected cells, leading to cell death.
    • Some viruses are taken up by alveolar macrophages, facilitating transport to regional lymph nodes.
    • Following replication in lymph nodes, viruses can cause viremia, spreading throughout the body.
    • Eventually, viruses invade respiratory epithelial cells as part of the infection process.

    Immune Response Activation

    • Viral exposure activates innate immune recognition through Toll-like receptors present on pulmonary cells.
    • Toll-like receptors detect pathogen-associated molecular patterns, triggering a rapid immune response.
    • This activation leads to the release of cytokines and chemokines, which recruit immune cells to the site of infection.

    Viral Invasion of Respiratory Epithelial Cells

    • Viral invasion leads to cell death through necrosis resulting from viral cytolysis.
    • This cell death can occur via direct invasion or through viremia.

    Mechanisms of Cell Death

    • Respiratory viruses are classified as cytocidal, meaning they cause cell death.
    • Lethal effects stem from products of the viral genome targeting host cellular structures and functions.

    Host Cell Protein and RNA Synthesis

    • Early viral proteins synthesize during infection inhibit the host's protein and RNA synthesis.
    • This suppression contributes to ultimately causing cell death.

    Initial Immune Response

    • The body's initial defense against viral infection is mediated by natural killer (NK) cells and neutrophils.
    • These immune cells play a crucial role in recognizing and responding to the viral threat.

    Role of Dendritic Cells

    • Dendritic cells capture antigens from viruses and migrate to drainage lymph nodes.
    • They interact with T cells, promoting the activation of effector T cells, which help lyse infected host cells.

    Factors Influencing Clinical Signs of Respiratory Disease

    • Development of clinical signs depends on the extent and location of tissue damage.
    • Tissue destruction and resultant inflammation are critical determinants of disease manifestation.

    Characteristics of Inflammatory Reaction in Viral Respiratory Disease

    • Hyperemia: Increased blood flow to affected tissues, contributing to redness and warmth.
    • Vascular leakage: Plasma proteins leak from blood vessels, leading to swelling and edema.
    • Leukocyte extravasation: White blood cells migrate to the site of infection, resulting in inflammatory exudate formation.

    Common Clinical Signs of Nasal Mucosa Inflammation

    • Nasal discharge: Can be serous (clear fluid) or purulent (containing pus), influenced by leukocyte presence.
    • Sneezing: A frequent clinical sign indicating irritation of the nasal mucosa.

    Causes of Tearing or Ocular Discharge in Viral Infections

    • Inflammation of tissues surrounding the nasolacrimal duct can lead to excessive tearing.
    • Ocular discharge may occur due to disruptions in normal drainage pathways caused by inflammation.

    Coughing and Respiratory Lesions

    • Coughing occurs due to lesions in the trachea and bronchi caused by irritation of the respiratory mucosa.

    Productive vs Non-Productive Cough

    • A non-productive (dry) cough arises with no inflammatory exudate present in viral respiratory disease.
    • A productive cough is characterized by the expulsion of mucopurulent exudates, indicating inflammation.

    Inflammatory Reactions in Airways and Alveoli

    • Minor epithelial damage leads to pneumonitis, thickening of alveolar septa, impaired gas exchange, hyperpnea, and increased respiratory effort.
    • Severe epithelial damage results in alveoli filled with plasma proteins and inflammatory cells, leading to compromised gas exchange, dyspnea, and risk of cyanosis.

    Viral Infection and Secondary Bacterial Infections

    • Viral infections promote secondary bacterial infections by causing loss of epithelial cells and impairing mucociliary activity.
    • The condition allows plasma proteins to extravasate into air spaces, creating an environment conducive for opportunistic bacterial pathogens.

    Role of Secondary Bacterial Infections

    • Secondary bacterial infections can result in more significant tissue destruction compared to the initial viral infection.
    • Extensive tissue damage from secondary infections may lead to complications and impact recovery.

    Resolution of Uncomplicated Viral Respiratory Infections

    • Uncomplicated viral respiratory infections resolve largely through:
      • Viral destruction facilitated by both cellular and humoral immune responses.
      • Re-epithelialization of affected tissues, restoring normal structure.
    • Typically, there is no lasting impairment of respiratory function or tissue after recovery.

    Impact of Secondary Bacterial Infections

    • In cases of secondary bacterial infections, extensive tissue destruction may lead to:
      • Severe scarring of lung tissue.
      • Considerable loss of lung function, which can hinder respiratory capabilities.

    Respiratory Viruses in Dogs

    • Certain respiratory viruses in dogs can predispose them to secondary bacterial infections, including:
      • Canine parainfluenza virus
      • Canine adenovirus type-2
      • Canine distemper virus
    • Awareness of these viral agents is crucial for understanding potential complications in canine respiratory health.

    Respiratory Viruses in Cats

    • Feline herpesvirus (FVR): Common in cats, can lead to severe respiratory symptoms and facilitate bacterial infections.
    • Feline calicivirus: Another prevalent virus in cats that causes respiratory illness and increases susceptibility to secondary bacterial infections.

    Respiratory Viruses in Cattle

    • Parainfluenza-3: A viral agent that contributes to respiratory disease in cattle, predisposing them to bacterial complications.
    • Infectious Bovine Rhinotracheitis (IBR): Caused by Bovine herpesvirus-1, it leads to severe respiratory issues and opens pathways for bacterial infections.
    • Bovine respiratory syncytial virus (BRSV): A major respiratory pathogen in cattle, known for its role in exacerbating secondary bacterial infections.

    Respiratory Viruses in Horses

    • Equine herpesvirus-1 (Equine rhinopneumonitis): A significant viral respiratory disease in horses that can trigger bacterial infections as a secondary condition.
    • Equine type A influenza virus: Has high impact on equine respiratory health, often leading to bacterial infections following initial viral activity.

    Respiratory Viruses in Pigs

    • Porcine circovirus type 2: Associated with respiratory illnesses in pigs and has been linked to increased risk of bacterial infections.
    • Porcine respiratory coronavirus: Contributes to respiratory distress in pigs and serves as a precursor to potential bacterial infections.
    • Swine influenza virus (H1N1, H3N2): Known to cause respiratory diseases in pigs, raises the likelihood of subsequent bacterial infections.

    Respiratory Viruses in Birds

    • Avian influenza virus is known to predispose birds to secondary bacterial infections.
    • Avian herpesvirus can also lead to respiratory complications in birds.
    • Newcastle disease virus is another respiratory virus affecting avian species.

    Viral Families Causing Respiratory Tract Lesions

    • Ten viral families are identified as causes of respiratory tract lesions in domestic and laboratory animals.

    Common Viral Families in Veterinary Patients

    • Herpetoviridae is frequently observed in veterinary cases.
    • Adenoviridae is another common family affecting animals.
    • Picornaviridae, known for a variety of species infections, is also prevalent.
    • Caliciviridae affects numerous domestic animals in clinical settings.
    • Reoviridae, which includes various animal pathogens, is commonly seen in practice.
    • Orthomyxoviridae, associated with influenza viruses, is regularly encountered.
    • Paramyxoviridae causes infections in several species, including birds.
    • Coronaviridae includes major pathogens that impact respiratory systems in animals.
    • Retroviridae, while typically associated with other conditions, is also seen in veterinary patients.

    Less Commonly Involved Viral Family

    • Poxviridae is recognized as less frequently involved in respiratory diseases across animal species.

    Characteristics of Poxviridae Family

    • Includes some of the largest and most complex viruses known.
    • Viruses in this family possess a unique double-stranded DNA structure.
    • Exhibit a wide range of host species, affecting both animals and humans.

    Pathogenicity of Poxviruses

    • Not considered primary pathogens of the respiratory tract.
    • Their main transmission occurs through direct contact, rather than inhalation.

    Lesions Associated with Poxviruses

    • Typically cause proliferative and necrotizing lesions.
    • Affected areas include the epidermis, dermis, and oral mucous membranes.
    • Lesions can manifest as pock-like formations on the skin.
    • Alpha-herpesviruses are significantly associated with respiratory infections.
    • Beta-herpesviruses also relate to respiratory disease but are of minor importance.

    Affinity of Herpesviruses

    • Herpesviruses specifically target respiratory epithelium, affecting the nasal passages, trachea, and bronchi.

    Mechanism of Cell Death

    • Viral proteins inhibit cellular DNA synthesis.
    • This inhibition leads to eosinophilic intranuclear inclusion bodies, which cause the death of respiratory epithelial cells.

    Latency Establishment

    • Herpesviruses can establish latency predominantly in neuronal cells.
    • In latently infected neurons, viral DNA persists in the nucleus without active viral replication.

    Reactivation Triggers

    • Reactivation of herpesviruses is often triggered by stress, resulting in renewed viral replication.

    Prevalence in Feline Herpesvirus-1

    • Approximately 80% of cats infected with Feline Herpesvirus-1 harbor a latent form of the virus.
    • These cats can shed the virus under periods of stress.

    Immune Response to Infection

    • Control of herpesvirus infection relies on both the innate and specific immune systems.
    • Successful herpesvirus infection necessitates evasion of both types of host immune responses.

    Equine Herpesvirus I (EHV-1)

    • Causes equine rhinopneumonitis and equine viral abortion.
    • Associated with equine myeloencephalopathy, which can lead to neurological issues.
    • Significant risk during pregnancy, as it can lead to fetal death and late gestational abortion.

    Clinical Signs of Equine Rhinopneumonitis

    • Considered a mild upper respiratory disease primarily affecting young horses.
    • Common signs include persistent coughing, along with nasal discharge.

    Bovine Herpesvirus I (BHV-1)

    • Responsible for infectious bovine rhinotracheitis (IBR) and infectious pustular vulvovaginitis (IPV).
    • Affects the respiratory tract and reproductive health of cattle.

    Clinical Signs of Infectious Bovine Rhinotracheitis (IBR)

    • Characterized by mucopurulent nasal discharge.
    • Other signs include coughing and ulcerative lesions on mucous membranes.

    Feline Herpesvirus-1 (FHV-1)

    • Causes feline viral rhinotracheitis (FVR), a highly contagious illness in cats.
    • Primarily impacts the upper respiratory system.

    Clinical Signs of Feline Viral Rhinotracheitis (FVR)

    • Sneezing and coughing are common symptoms.
    • Also present with nasal discharge, leading to respiratory discomfort.

    Herpesvirus Suis (SuHV-1)

    • Causes pseudorabies, known as Aujeszky's disease.
    • Affects a variety of species including cattle, swine, sheep, dogs, cats, and rats.

    SuHV-1 Infection in Swine

    • Adult swine typically experience a mild, often unnoticed infection.
    • Young piglets can develop a severe, generalized disease that may result in death.

    Herpesvirus canis (CHV)

    • CHV is linked to infectious tracheobronchitis, commonly known as kennel cough.
    • This virus is a significant contributor to neonatal fatalities in puppies younger than 2 weeks.

    Avian Laryngotracheitis Virus

    • Causes a highly contagious illness specifically in chickens.
    • Symptoms include nasal discharge, gasping for breath, and dyspnea (difficulty breathing).

    Clinical Significance of Adenoviruses in Animals

    • Adenoviruses mainly result in mild upper respiratory infections.
    • In animals with compromised immune systems, they can lead to severe pneumonia.

    Adenoviruses and Affected Species

    • Commonly affected species include swine, cattle, horses, and poultry.
    • These animals experience clinically minor respiratory diseases due to adenoviruses.

    Canine Adenovirus II (CAV-II)

    • CAV-II is responsible for mild upper respiratory conditions in dogs.
    • Clinical manifestations include tonsillitis, pharyngitis, and potentially tracheobronchitis (kennel cough).
    • Vaccines are commercially available for CAV-II, providing preventative measures for dog owners.

    Feline Calicivirus

    • Feline Calicivirus leads to feline respiratory disease.
    • Symptoms include rhinitis (inflammation of the nasal lining), conjunctivitis (eye inflammation), palatine and glossal ulcerations, and bronchopneumonia.

    Feline Calicivirus

    • Direct viral invasion targets epithelial and endothelial cells, leading to disease.
    • Secondary immune response results in cell desquamation and plasma protein leakage into alveolar spaces.
    • Viral shedding occurs for 2-3 weeks in respiratory secretions; transmission via air, saliva, or fomites.
    • Recovery involves replacement of desquamated Type I epithelial cells by Type II epithelial cells.
    • Commercial vaccines are available to protect against Feline Calicivirus.

    African Horse Sickness Virus

    • Causes peracute, systemic disease with high mortality in Equidae (horses and related species).
    • Found in Africa and the Middle East, transmitted by insect vectors.
    • Clinical signs include pulmonary edema, severe myocarditis, and cardiac failure.

    Orthomyxoviridae Family

    • Contains one genus: Influenzavirus, which has A-C subtypes.
    • Influenza A viruses are classified based on hemagglutinin (HA) and neuraminidase (NA) surface glycoproteins.
    • Natural reservoirs include wild waterfowl, gulls, and shorebirds.

    Influenza Virus Immunity and Host Infectivity

    • Antigenic shift occurs with new HA or NA protein combinations.
    • Antigenic drift happens due to mutations in surface glycoproteins during replication.
    • High mutation rate is due to the RNA polymerase complex lacking proofreading activity.

    Emergence of New Influenza Strains

    • New strains arise from antigenic shift when two influenza viruses infect the same cell, leading to gene segment reassortment.
    • Swine are significant in reassortment because their cells can bind both avian and human influenza viruses.

    Recent Antigenic Shift Examples

    • H3N8 equine influenza virus transmitted to dogs.
    • H5N1 avian influenza virus has been transmitted to dogs, exotic felids, and humans.

    Current Influenza Strains

    • Avian influenza strains include H5N2.
    • Canine influenza is associated with strain H3N2.

    Equine Influenza Virus (H3N8)

    • Causes a highly contagious respiratory disease in horses, typically non-fatal.
    • Clinical signs featured are nasal discharge, cough, dyspnea, fever, and depression.

    Effects of Secondary Bacterial Infection in Equine Influenza

    • Secondary bacterial infections can lead to bronchopneumonia, a serious complication following equine influenza.
    • This condition enhances respiratory distress, potentially leading to severe outcomes in affected horses.

    Vaccination for Equine Influenza

    • Commercial vaccines are available to prevent equine influenza.
    • Vaccination is critical in reducing the incidence and severity of outbreaks in equine populations.

    Swine Influenza Virus (SIV)

    • Swine Influenza Virus causes swine influenza, a highly contagious respiratory disease affecting pigs.
    • Symptoms may include coughing, fever, and respiratory distress, significantly impacting swine health and farming productivity.

    Transmission of Swine Influenza

    • SIV spreads primarily through infected aerosols emitted by infected pigs.
    • The virus can also be transmitted via the porcine lungworm (Metastrongylus sp.), which acts as a vector, facilitating the spread of the disease.

    Common Lung Lesions in Swine Influenza

    • Lesions typically observed in swine influenza include focal areas of necrosis in the upper airway mucosa.
    • Other significant findings are the presence of hyaline membranes and desquamated pneumocytes, indicating severe lung damage.

    Swine Influenza Complications

    • Infection with Hemophilus suis can complicate swine influenza, leading to bronchopneumonia.

    Canine Influenza

    • Canine Influenza (CIV) is a highly contagious respiratory infection in dogs, linked to the H3N8 virus originally transmitted from horses.
    • Clinical signs of canine influenza include:
      • Cough
      • Nasal discharge
      • Secondary bacterial infections may lead to pneumonia.

    Avian Influenza Reservoirs

    • Waterfowl serve as the major reservoir for all avian influenza A viruses, including highly pathogenic strains such as H5N1 and H5N2.

    Hemagglutinin Subtypes in Avian Influenza

    • The hemagglutinin subtypes most frequently associated with avian influenza are H5 and H7.

    Antigenic Shift in Avian Influenza Viruses

    • Antigenic shift alters the infectivity of avian influenza viruses.
    • Results in new virus strains to which populations have no prior immunity, posing public health risks.

    H7N9 Avian Influenza Virus

    • H7N9 is a newly identified avian influenza virus with zoonotic potential.
    • It has led to hundreds of human cases, primarily in China and Vietnam.
    • The virus spread through live poultry markets, highlighting transmission dynamics.

    Cytopathic Effects of Paramyxoviridae

    • Paramyxoviridae often cause the fusion of infected cells, resulting in multinucleate syncytial giant cells.
    • Characteristic effects include the formation of eosinophilic intracytoplasmic or intranuclear inclusion bodies.

    Impact of Paramyxoviridae on Cellular Protein Synthesis

    • These viruses do not abruptly stop cellular macromolecular synthesis.
    • However, once cellular protein synthesis is halted, it inevitably leads to cell death.

    Canine Distemper Virus (CDV)

    • Affects multiple species, including dogs, wolves, ferrets, mink, otters, and raccoons.
    • Clinical features include pneumonia, encephalomyelitis, and significant lymphocytic depletion causing immunosuppression.
    • CDV spreads via airway macrophages to the tonsils and bronchial lymph nodes, leading to replication and severe viremia, which results in invasion of the respiratory mucosa.
    • Common complications involve secondary bacterial infections, particularly with Bordetella bronchiseptica, often resulting in severe bronchopneumonia.
    • Vaccines are commercially available to protect against both Canine Distemper and Bordetella bronchiseptica infections.

    Measles Virus

    • Primarily affects young children and various species of nonhuman primates.
    • A notable respiratory complication is giant cell pneumonia, though most patients recover from this condition.

    Measles Virus: Spread and Replication

    • Measles virus spreads through aerosols, allowing transmission in crowded environments.
    • The virus replicates in the respiratory mucosa before moving into the bloodstream.
    • Macrophages transport the virus to regional lymph nodes, leading to viremia, which facilitates widespread infection.

    Respiratory Effects of Measles Virus

    • Causes extensive necrosis of respiratory epithelial cells.
    • Formation of syncytial giant cells results from viral fusion processes.
    • Infected cells desquamate into alveolar spaces, contributing to respiratory complications.

    Measles Vaccine

    • Vaccines are commercially available to prevent Measles Virus infection.
    • The vaccine is typically administered during childhood as part of routine immunizations.

    Rinderpest Virus

    • Rinderpest virus leads to an acute, highly contagious disease primarily affecting cattle and sheep.
    • It has significant implications for livestock health and agricultural economies.

    Rinderpest Virus

    • Rinderpest virus was primarily found in Africa, the Middle East, and Asia.
    • The virus has been successfully eradicated from the global population.

    Parainfluenza-1 (Sendai Virus)

    • Parainfluenza-1 leads to mild respiratory disease in rodents.
    • Symptoms include rhinitis, tracheitis, and occasionally bronchopneumonia.

    Canine Parainfluenza-2

    • Canine Parainfluenza-2 is a key agent in infectious tracheobronchitis, commonly known as kennel cough, in dogs.

    Parainfluenza-3 (PI-3) in Cattle

    • PI-3 is associated with the shipping fever complex, a condition in cattle characterized by multiple contributing factors.
    • This syndrome is often exacerbated by secondary bacterial infections, particularly with Pasteurella species.

    Impact of Stress on PI-3 Infection in Cattle

    • Stress is a significant factor that increases susceptibility in cattle to both viral and bacterial respiratory infections.

    Newcastle Disease

    • Caused by Newcastle Disease Virus (NDV).
    • Results in a highly contagious disease in poultry known as Newcastle Disease or Avian Pneumoencephalitis.

    Coronaviridae Family

    • Contains only one genus: Coronavirus.
    • Characterized by a viral structure that includes a single-stranded RNA genome.

    Evolution of Understanding Coronaviruses

    • Historically, coronaviruses were not seen as significant causes of respiratory diseases in humans or animals.
    • Recent outbreaks have dramatically changed this perception, leading to increased recognition of their potential impact.

    2003 SARS Epidemic

    • Emerged in March 2003, caused by a novel member of the Coronavirus genus.
    • Resulted in Severe Acute Respiratory Syndrome (SARS), a highly contagious and potentially fatal respiratory illness.

    SARS Coronavirus and Animal Models

    • Bats serve as the natural reservoir for SARS coronavirus.
    • Ferrets are recognized as an effective animal model to study SARS coronavirus.

    Role of SARS-CoV-2 in the Pandemic

    • SARS-CoV-2 emerged in early 2020, triggering the global COVID-19 pandemic.

    Entry Mechanism of SARS-CoV-2

    • SARS-CoV-2 utilizes the ACE-2 receptor for entry into host cells, prevalent on various cell types.

    Rapid Response to COVID-19

    • The swift development of COVID-19 therapies and vaccines illustrates advanced comprehension of viral mechanisms and vaccine technology.

    Antigenic Drift Similarities

    • Coronaviruses, like influenza viruses, are RNA viruses that experience antigenic drift during replication, facilitating genetic variability.

    Impact of Low Vaccination Rates

    • Low vaccination rates correlate with heightened viral replication, increasing the risk of emerging variants such as Delta and Omicron.

    Zoonotic Potential of Coronaviruses

    • Seven strains of coronaviruses are identified to have zoonotic potential.

    SARS-CoV-2 Transmission in Animals

    • SARS-CoV-2 has infected various animal species, including:
      • Domestic animals: Cats, dogs, mink, otters, pet ferrets
      • Wild animals: Lions, tigers, pumas, snow leopards, gorillas
      • Deer species: White-tailed deer

    Transmission Among Cats

    • Cats can efficiently replicate and transmit SARS-CoV-2 to one another through respiratory droplets.

    Infectious Bronchitis Virus in Chickens

    • Infectious Bronchitis Virus causes serous tracheobronchitis, a respiratory illness, in chickens.

    Equine Arteritis Virus Clinical Impact

    • Equine Arteritis Virus (EAV) induces respiratory disease in horses, exhibiting symptoms like fever, nasal discharge, and limb swelling.
    • EAV enters through the respiratory tract and can circulate in the bloodstream, leading to viremia.

    PRRS Virus Effects on Pigs

    • Porcine Reproductive and Respiratory Syndrome (PRRS) Virus results in respiratory illnesses in sows and significant mortality in newborn piglets.

    Maedi/Visna Virus Diseases

    • Maedi/Visna Virus causes:
      • Maedi and ovine progressive pneumonia in sheep.
      • A neurological disorder known as visna.

    Transmission and Incubation of Maedi/Visna Virus

    • The virus transmits through aerosols or colostrum on farms with endemic infection.
    • Incubation period is typically 2-3 years, consistent with characteristics of lentiviruses.

    Effects of Maedi/Visna Virus on the Lungs

    • Causes gradual thickening of alveolar walls, leading to reduced lung function.
    • Results in obliteration of alveolar spaces, disrupting normal gas exchange.
    • Associated with chronic interstitial pneumonia, characterized by inflammation in lung tissue.
    • Induces fibrosis, contributing to scarring and stiffness in lung tissues.
    • BALT hyperplasia occurs, indicating proliferation of bronchial-associated lymphoid tissue in response to infection.

    Disease Caused by Betaretrovirus in Sheep

    • Jaagsiekte, also known as pulmonary adenomatosis, is a contagious neoplastic disease.
    • It is specifically caused by the Betaretrovirus in sheep.

    Characteristics of Jaagsiekte

    • Features progressive proliferation of Type II pneumocytes, which can replace functional lung tissue.
    • Some lesions may exhibit the potential to regress over time, suggesting variability in disease progression.

    Main Arteriviruses in Veterinary Medicine

    • Equine Arteritis Virus (EAV) is one of the primary Arteriviruses affecting horses.
    • Porcine Reproductive and Respiratory Syndrome (PRRS) Virus is significant in pig populations.

    Retroviridae Viruses Causing Respiratory Disease

    • Maedi/Visna Virus is linked to chronic respiratory disease in sheep.
    • Betaretrovirus, responsible for Jaagsiekte, also contributes to respiratory complications in the same host.

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    This quiz explores the mechanisms by which viruses kill cells and the pathogenesis of viral respiratory diseases. Understand how viral infections disrupt normal cellular functions and the impact on host health. Test your knowledge on these crucial aspects of virology.

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