Viral Disease Pathogenic Mechanisms Quiz
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Questions and Answers

What is the process by which an infection leads to disease called?

  • Host immunity
  • Viral shedding
  • Viral replication
  • Pathogenesis (correct)

    • What are the pathogenic mechanisms of viral disease?

  • Implantation of virus at the portal of entry (correct)
  • Bacterial replication
  • Protein synthesis in host cells
  • Virus susceptibility to host defenses

    • What factors affect the pathogenic mechanisms of viral disease?

  • Temperature of the environment
  • Accessibility of virus to tissue, cell (correct)
  • pH of the body fluids
  • Blood pressure regulation

    • What does natural selection favor in terms of virus strains?

    <p>Low-virulence virus strains</p> Signup and view all the answers

    What happens when several viruses infect the same type of tissue?

    <p>They usually cause the same type of disease</p> Signup and view all the answers

    What is the percentage of subclinical viral infections, suggesting that body defenses arrest most infections before disease symptoms become manifest?

    <p>90%</p> Signup and view all the answers

    How can viral pathogenesis be viewed on two distinct levels?

    <p>Cellular and tissue/systemic pathogenesis</p> Signup and view all the answers

    What is the hallmark of viral infection of the cell?

    <p>Rounding and darkening of the cell</p> Signup and view all the answers

    Which effect of virus infection on the cell is characterized by prolonged survival and unrestrained growth?

    <p>Malignant transformation</p> Signup and view all the answers

    What is a common result of direct cell damage and death from viral infection?

    <p>Competition of viral mRNA for cellular ribosomes</p> Signup and view all the answers

    What is a hallmark of viral infection of the cell that aids in the clinical diagnosis of herpesvirus skin infections?

    <p>Multinucleated giant cells with eosinophilic intranuclear inclusions</p> Signup and view all the answers

    What can result from integration of the viral genome into the host genome?

    <p>Malignant transformation</p> Signup and view all the answers

    What method is frequently used for quantifying the amount of virus in a sample based on the appearance of cytopathic effect (CPE) in cell culture?

    <p>Plaque assay</p> Signup and view all the answers

    What happens during the incubation period of a typical viral infection?

    <p>Local multiplication and spread occur</p> Signup and view all the answers

    What is a common indirect result of virus infection on cells?

    <p>Induction of inflammation</p> Signup and view all the answers

    What is a common outcome when infected cells contain inclusion bodies?

    <p>Death of the infected cells</p> Signup and view all the answers

    What is a characteristic of viral infection accompanied by virus production but without morphologic or gross functional changes?

    <p>Focal areas of rounded, piled-up cells</p> Signup and view all the answers

    Which stage of a typical viral infection involves nonspecific symptoms?

    <p>Prodromal period</p> Signup and view all the answers

    What are the four main effects of virus infection on the cell?

    <p>Death, fusion of cells to form multinucleated cells, malignant transformation, no apparent morphologic or functional change</p> Signup and view all the answers

    How do most virus types spread among cells?

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

    What is the most common route of systemic spread from the portal of entry?

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

    How may the virus enter the target organs from the capillaries?

    <p>All of the above</p> Signup and view all the answers

    What is dissemination via nerves usually associated with?

    <p>All of the above</p> Signup and view all the answers

    What determines the final outcome of infection?

    <p>Virus dose and location, as well as its infectivity and virulence</p> Signup and view all the answers

    In which route can viruses implant onto living cells?

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

    What may lead to localized disease and localized shedding of virus?

    <p>Local replication and local spread</p> Signup and view all the answers

    Where does multiplication in the target organ occur?

    <p>In endothelial cells or fixed macrophages</p> Signup and view all the answers

    Which factor determines the viral affinity for specific body tissues?

    <p>Local temperature and oxygen tension</p> Signup and view all the answers

    What refers to people who produce virus for long periods of time and can serve as a source of infection for others?

    <p>Persistent viral infections</p> Signup and view all the answers

    What characteristic is associated with latent infections?

    <p>Not producing virus at the present time but can be reactivated at a subsequent time</p> Signup and view all the answers

    What is one of the barriers that the virus must traverse when infecting the fetus?

    <p>Developing first-trimester fetal organs</p> Signup and view all the answers

    What is the medically important example associated with slow virus infections?

    <p>HIV infection</p> Signup and view all the answers

    Which stage of a typical viral infection involves nonspecific symptoms?

    <p>Incubation period</p> Signup and view all the answers

    What are the characteristics of slow virus infections?

    <p>Long incubation period, often measured in years</p> Signup and view all the answers

    What does carrier state refer to in the context of viral infections?

    <p>&quot;People who produce virus for long periods of time and can serve as a source of infection for others&quot;</p> Signup and view all the answers

    Which of the following viruses is associated with cancer of the cervix?

    <p>Epstein Barrvirus (EBV)</p> Signup and view all the answers

    Which virus is known to cause liver cancer?

    <p>Hepatitis B virus (HBV)</p> Signup and view all the answers

    Which RNA virus causes liver cancer?

    <p>Hepatitis C virus</p> Signup and view all the answers

    Which type of virus is associated with Burkitt’s lymphoma and nasopharyngeal carcinoma?

    <p>Epstein Barrvirus (EBV)</p> Signup and view all the answers

    What is the known viral agent of cancers associated with nasopharyngeal carcinoma?

    <p>Epstein Barrvirus (EBV)</p> Signup and view all the answers

    Which virus is associated with Adult T-cell lymphocytic leukaemia?

    <p>Human T-cell leukaemia virus type 1</p> Signup and view all the answers

    Which of the following viruses is NOT associated with cancer?

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

    Which type of immunity is present in all normal individuals and does not discriminate amongst microorganisms?

    <p>Innate immunity</p> Signup and view all the answers

    Which components are part of the innate resistance in the immune system?

    <p>Physical barriers, Phagocytic cells, Proteins, and Antibodies</p> Signup and view all the answers

    Which activity is NOT a major activity of the immune response?

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

    What type of immunity is acquired through immunization or clinical/subclinical infection?

    <p>Active immunity</p> Signup and view all the answers

    Which physiological conditions regulate innate immunity?

    <p>Nutrition, Age, Hormones</p> Signup and view all the answers

    Which cells are part of the innate immune system's phagocytic cells?

    <p>Neutrophils, Macrophages, Natural Killer cells</p> Signup and view all the answers

    Which type of infection involves immunization with live or killed infectious agents or their antigens?

    <p>Acquired immunity</p> Signup and view all the answers

    Which proteins are part of innate resistance in the immune system?

    <p>Complement, Lysozyme, Interferon</p> Signup and view all the answers

    Which type of infection involves transfer of antibodies from another individual?

    <p>Passive immunity</p> Signup and view all the answers

    Study Notes

    Infection and Disease Process

    • The process by which infection leads to disease is termed pathogenesis.
    • Pathogenic mechanisms of viral disease include direct cytopathic effects, immune response modulation, oncogenesis, and persistence in the host.
    • Factors affecting viral pathogenesis include viral strain, host genetics, immune status, and environmental influences.

    Viral Strains and Infections

    • Natural selection favors virus strains that efficiently replicate and spread while evading the immune response.
    • Co-infection occurs when multiple viruses infect the same tissue, potentially leading to recombination or interference.

    Subclinical Viral Infections

    • Approximately 80% of viral infections are subclinical, indicating that most infections are contained by the body’s defenses before symptoms arise.

    Levels of Viral Pathogenesis

    • Viral pathogenesis can be viewed at cellular and organismal levels, encompassing both direct viral effects and secondary consequences on host physiology.

    Hallmarks of Viral Infection

    • A hallmark of viral infection is the induction of cytopathic effects (CPE) in infected cells.
    • Prolonged survival with unrestrained growth characterizes transformation effects of certain viruses on cells, like oncogenesis.
    • Direct cell damage from viral infection often results in apoptosis or necrosis of infected cells.

    Clinical Diagnosis and Inclusion Bodies

    • Inclusion bodies, which are aggregates of viral proteins or genomes, often serve as diagnostic markers in herpesvirus infections.
    • Integration of the viral genome into the host genome can lead to latency or transformation.

    Quantification and Incubation

    • The cytopathic effect (CPE) method is used to quantify viruses in a sample based on visible effects on cultured cells.
    • During the incubation period, the virus replicates silently without producing symptoms.

    Indirect Effects and Symptoms

    • Common indirect effects on cells infected by viruses include immune-mediated damage and inflammation.
    • Inclusion bodies indicate viral replication and can signal potential cell death.

    Immune Response and Viral Spread

    • A characteristic of viral infection can be presence of virus without observable morphological changes in host cells.
    • Prodromal stage of infection typically brings nonspecific symptoms such as fever and malaise.
    • Main effects of viral infection on cells include lysis, transformation, induction of inclusion bodies, and apoptosis.

    Routes of Viral Dissemination

    • Most viruses spread through intercellular diffusion, with systemic spread commonly occurring through blood.
    • Viruses may enter target organs directly from capillary circulation.
    • Nervous system dissemination is often linked to neurotropic viruses.

    Infection Outcomes and Viral Affinities

    • The final outcome of infection is determined by host immune response, viral factors, and environmental conditions.
    • Viruses can attach and penetrate living cells via specific receptors recognized by viral proteins.

    Localized Infections

    • Localized disease may occur due to restricted viral spread or specific host responses, leading to localized shedding.
    • Target organ multiplication occurs post-invasion, where viruses replicate extensively.

    Viral Persistence and Latency

    • Viral affinity for tissues is primarily determined by host receptor availability and tissue tropism.
    • Persistent infections refer to individuals who harbor the virus for extended periods, potentially acting as reservoirs for transmission.

    Vertical Transmission

    • Viruses must overcome barriers such as the placenta during fetal infection.
    • Slow virus infections, exemplified by certain prion diseases, exhibit prolonged incubation and gradual progression.

    Carrier States and Cancer Associations

    • The carrier state is characterized by chronic viral presence without immediate disease manifestation.
    • Human Papillomavirus (HPV) is notably associated with cervical cancer.
    • Hepatitis B and C viruses are linked to liver cancer, with Hepatitis C being an RNA virus specifically implicated.
    • Epstein-Barr virus is connected to Burkitt’s lymphoma and nasopharyngeal carcinoma.
    • Human T-cell lymphotropic virus (HTLV) is associated with Adult T-cell leukemia.

    Immune Response

    • Innate immunity is present in all individuals, providing non-specific resistance against pathogens.
    • Components of innate immunity include physical barriers, cellular defenses (e.g., macrophages, neutrophils), and antimicrobial proteins.
    • Acquired immunity develops through exposure to antigens via immunization or prior infections.
    • Regulatory factors for innate immunity involve physiological conditions such as hormonal levels and age.

    Immunological Factors

    • Types of immunization include active (via vaccines) and passive (transfer of antibodies).
    • Innate immune proteins include complement proteins and defensins, crucial for early pathogen recognition and response.

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    Description

    Test your knowledge of the pathogenic mechanisms of viral diseases with this quiz. Explore topics such as implantation of the virus, local replication, evasion of host immunity, and spread to target organs and shedding sites. Also, learn about the factors that affect pathogenic mechanisms and natural selection.

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