Podcast
Questions and Answers
What contributes to the risk of developing herpes zoster in individuals?
What contributes to the risk of developing herpes zoster in individuals?
Which age group is most likely to show mild classic disease when infected with VZV?
Which age group is most likely to show mild classic disease when infected with VZV?
How is varicella (chickenpox) primarily spread?
How is varicella (chickenpox) primarily spread?
What percentage of individuals experience reactivation of varicella leading to shingles after initial infection?
What percentage of individuals experience reactivation of varicella leading to shingles after initial infection?
Signup and view all the answers
Which of the following groups is at greater risk for life-threatening complications from varicella?
Which of the following groups is at greater risk for life-threatening complications from varicella?
Signup and view all the answers
What is a common reactivation of the Varicella zoster virus?
What is a common reactivation of the Varicella zoster virus?
Signup and view all the answers
Which type of immunity is crucial for controlling herpesvirus infections?
Which type of immunity is crucial for controlling herpesvirus infections?
Signup and view all the answers
How can herpes simplex viruses be distinguished from each other?
How can herpes simplex viruses be distinguished from each other?
Signup and view all the answers
Which characteristic is NOT shared by both HSV-1 and HSV-2?
Which characteristic is NOT shared by both HSV-1 and HSV-2?
Signup and view all the answers
Which of the following diseases can herpes simplex viruses cause?
Which of the following diseases can herpes simplex viruses cause?
Signup and view all the answers
What does the term 'latent infection' imply about herpes simplex viruses?
What does the term 'latent infection' imply about herpes simplex viruses?
Signup and view all the answers
What is the primary method of transmission for HSV-1?
What is the primary method of transmission for HSV-1?
Signup and view all the answers
What aspect of herpesviruses allows them to persist in the host indefinitely?
What aspect of herpesviruses allows them to persist in the host indefinitely?
Signup and view all the answers
What is the drug of choice for most herpes simplex virus (HSV) infections?
What is the drug of choice for most herpes simplex virus (HSV) infections?
Signup and view all the answers
Which condition is not a specific indication for antiviral chemotherapy?
Which condition is not a specific indication for antiviral chemotherapy?
Signup and view all the answers
What type of immunity is crucial in controlling Varicella-Zoster virus (VZV) infections?
What type of immunity is crucial in controlling Varicella-Zoster virus (VZV) infections?
Signup and view all the answers
In which part of the body does Varicella-Zoster virus establish a latent infection?
In which part of the body does Varicella-Zoster virus establish a latent infection?
Signup and view all the answers
Which antiviral drug is typically more expensive than acyclovir?
Which antiviral drug is typically more expensive than acyclovir?
Signup and view all the answers
What is a primary route of spread for Varicella-Zoster virus (VZV)?
What is a primary route of spread for Varicella-Zoster virus (VZV)?
Signup and view all the answers
What is the recommended use of older antiviral agents like idoxuridine?
What is the recommended use of older antiviral agents like idoxuridine?
Signup and view all the answers
What characteristic is shared between herpes simplex virus (HSV) and Varicella-Zoster virus (VZV)?
What characteristic is shared between herpes simplex virus (HSV) and Varicella-Zoster virus (VZV)?
Signup and view all the answers
What is the most common outcome of congenital CMV infection?
What is the most common outcome of congenital CMV infection?
Signup and view all the answers
What type of infection can neonates acquire through maternal milk?
What type of infection can neonates acquire through maternal milk?
Signup and view all the answers
In the context of AIDS patients, what is one of the most common manifestations of CMV disease?
In the context of AIDS patients, what is one of the most common manifestations of CMV disease?
Signup and view all the answers
How can a fetus become infected with CMV during pregnancy?
How can a fetus become infected with CMV during pregnancy?
Signup and view all the answers
Which of the following symptoms is NOT associated with perinatal CMV infection?
Which of the following symptoms is NOT associated with perinatal CMV infection?
Signup and view all the answers
What is a potential consequence of VZV infection in immunocompromised patients?
What is a potential consequence of VZV infection in immunocompromised patients?
Signup and view all the answers
Which laboratory method is effective for detecting VZV infection?
Which laboratory method is effective for detecting VZV infection?
Signup and view all the answers
What treatments are approved for VZV infections in adults and immunocompromised patients?
What treatments are approved for VZV infections in adults and immunocompromised patients?
Signup and view all the answers
What characteristic effects are associated with cytomegalovirus (CMV) infection?
What characteristic effects are associated with cytomegalovirus (CMV) infection?
Signup and view all the answers
Which of the following describes the type of infections caused by cytomegalovirus (CMV)?
Which of the following describes the type of infections caused by cytomegalovirus (CMV)?
Signup and view all the answers
What is a primary method of acquiring CMV infection?
What is a primary method of acquiring CMV infection?
Signup and view all the answers
How does CMV differ from other viruses in terms of its genetic composition?
How does CMV differ from other viruses in terms of its genetic composition?
Signup and view all the answers
What is required for the resolution of CMV infections?
What is required for the resolution of CMV infections?
Signup and view all the answers
Which immune condition significantly increases the risk of symptomatic CMV infection?
Which immune condition significantly increases the risk of symptomatic CMV infection?
Signup and view all the answers
What typically occurs with CMV infections in normal individuals?
What typically occurs with CMV infections in normal individuals?
Signup and view all the answers
Which demographic is considered at higher risk for severe symptomatic CMV disease?
Which demographic is considered at higher risk for severe symptomatic CMV disease?
Signup and view all the answers
Which of the following is NOT a common clinical manifestation of CMV?
Which of the following is NOT a common clinical manifestation of CMV?
Signup and view all the answers
In organ transplant recipients, which of the following is true regarding CMV infections?
In organ transplant recipients, which of the following is true regarding CMV infections?
Signup and view all the answers
Which transmission route of CMV is associated with congenital infections?
Which transmission route of CMV is associated with congenital infections?
Signup and view all the answers
Which clinical manifestation carries an 85% mortality rate in the absence of treatment for CMV?
Which clinical manifestation carries an 85% mortality rate in the absence of treatment for CMV?
Signup and view all the answers
When does CMV typically establish latency within the host?
When does CMV typically establish latency within the host?
Signup and view all the answers
Study Notes
Herpes Viruses
- The herpes viruses are a group of large, DNA-enveloped viruses.
- Features of herpes viruses include virion morphology, basic replication, and the ability to cause latent and recurrent infections.
- Human herpes viruses are categorized into three subfamilies (alpha, beta, and gamma) based on viral characteristics (genome, tissue tropism, etc.).
Classification of Human Herpesviruses
- The Herpesviridae family includes Herpesvirinae subfamily.
- Various subfamilies and genera of Human Herpesviruses are classified.
- Official names for each genus and subfamily are listed alongside common names.
Subfamily Alpha herpes virinae
- Viruses in this subfamily primarily infect mucoepithelial cells and neurons .
- Transmission through close contact is common.
- Some viruses are sexually transmitted.
Subfamily Beta herpes virinae
- These viruses primarily infect monocyte, lymphocyte, and epithelial cells.
- Transmission through close contact, blood transfusions, and tissue transplants is common.
Subfamily Gamma herpes virinae
- These viruses mainly infect B cells and epithelial cells.
- Spread through saliva and close contact are typical transmission modes.
Herpesviruses' Viral Replication and Persistence
- Herpesviruses encode enzymes (DNA polymerase) promoting viral DNA replication.
- They are easily targeted by antiviral drugs.
- Release mechanisms include exocytosis, cell lysis, and cell-cell bridges.
- Herpesviruses can persist in host cells indefinitely, typically in the nucleus.
- Varicella-zoster and herpes simplex viruses establish latent infections in neurons.
- Herpes zoster (shingles) is a common reactivation of varicella-zoster virus.
Herpes Simplex Viruses (HSV) 1 & 2
- HSV is the first human herpesvirus recognized, derived from the Greek word "herpes" meaning to creep.
- It is extremely widespread in humans.
- It has a broad host range, replicating in numerous cell types and infecting various animals.
- HSV grows rapidly and is highly cytolytic, responsible for a spectrum of diseases, from gingivostomatitis to keratoconjunctivitis and encephalitis.
- HSV-1 is usually associated with infections above the waist, while HSV-2 is associated with infections below the waist.
- HSV-1 and HSV-2 significantly differ in their growth characteristics and antigenicity as well as their modes of transmission.
- HSV-1 is generally spread by saliva, and HSV-2 is typically transmitted sexually.
Herpes Simplex Virus Pathogenesis
- HSV causes lytic infections in most cells, persistent infections in lymphocytes/macrophages, and latent infections in neurons.
- Lesions in skin and mucous membranes caused by HSV-1 and HSV-2 are similar.
- The changes caused during primary and recurrent infection are also similar.
- Characteristic histopathologic changes include ballooning of infected cells and Cowdry type A intranuclear inclusion production.
- HSV can escape host defenses via formation of multinucleated giant cells and syncytia (fusion of cells).
Herpes Simplex Virus (HSV) Laboratory Diagnosis
- Cytology reveals characteristic CPEs (cytopathogenic effects).
- Tzank smears, Pap smears, or biopsy specimens are useful for cytology analysis.
- Giemsa staining can also be used to visualize CPEs (e.g., syncytia and Cowdry type A intranuclear inclusions).
- Methods like electron microscopy, immunofluorescence, PCR are available for diagnosing HSV infections.
Varicella-Zoster Virus (VZV)
- VZV causes chickenpox (varicella) and shingles (herpes zoster) which is the reactivation of latent VZV
- VZV is easily spread via respiration
- VZV replicates initially in the respiratory tract, then spreads to the skin causing crops of lesions
- VZV is susceptible to antiviral drugs similar to HSV.
Varicella-Zoster Virus (VZV): Pathogenesis
- VZV replicates in the respiratory tract, infecting epithelial cells, fibroblasts, T cells, and neurons.
- VZV creates syncytia (cell fusion) allowing for cell-to-cell spread.
- VZV spread can occur through viremia, causing crops of skin lesions.
- Cell-mediated immunity is crucial for VZV infection.
Varicella-Zoster Virus (VZV): Epidemiology
- VZV is extremely contagious, affecting >90% of susceptible persons.
- Transmission occurs primarily through respiratory droplets and skin vesicle contact.
- Risk groups include children (ages 5-9), teenagers/adults (more severe cases), immunocompromised individuals (disseminated disease), and newborns, who are at risk for serious infection.
Varicella-Zoster Virus (VZV): Clinical Features
- Varicella (chickenpox): acute, mostly symptomatic disease in children, with a typical maculopapular rash.
- Chicken pox-neonatal: occurs during maternal pregnancy, possible severe disease and high mortality
- Chicken pox-adults: more severe in adults. Interstitial pneumonia is the most common complication.
Varicella-Zoster Virus (VZV): Herpes Zoster (Shingles)
- Shingles (herpes zoster) is caused by reactivation of latent VZV.
- Occurs in 10-20% of infected individuals usually after the fourth decade of life.
- Unilateral vesicular eruption within a dermatome, often associated with severe pain.
- Reactivation can occur in immunocompromised individuals at any age.
Cytomegalovirus (CMV):
- CMV is part of the Beta-herpesvirinae subfamily.
- Lymphotropic
- Has the largest genome among human herpesviruses.
- The name comes from the cytomegalic cells (enlarged infected cells) observed during infection.
- Viral mRNAs are delivered directly into the cell to facilitate infection.
- CMV replicates only in human cells, very species-specific and cell-type-specific.
- CMV establishes latent infection.
- CMV generally causes subclinical infection in normal immunocompetent hosts.
- CMV infections usually become symptomatic only in immunocompromised individuals (e.g., AIDS patients).
- The condition may be severe and even life-threatening in immunodeficient individuals, pregnant women, and infants.
CMV: Pathogenesis
- CMV primarily replicates in epithelial and other cells.
- Latency occurs in T cells, macrophages, and other cells.
- Cell-mediated immunity plays a role in resolving/limiting/preventing acute infection.
- Antibody response is limited; immune compromise allows recurrence/severe presentation.
CMV: Epidemiology
- CMV transmission occurs through blood, organ transplants, secretions (urine, saliva, semen), and breast milk.
- Risk factors include newborns (through mother), organ transplant recipients, and immunocompromised individuals (e.g., AIDS patients) showing life-threatening disease
CMV: Diagnosis and Treatment:
- Characteristic cytomegalic cells (enlarged cells with an "owl's eye" intranuclear inclusion) and/or specific antibodies are used for diagnosis.
- Ganciclovir, foscarnet, cidofovir, and fomivirsen are used in treatments
Epstein-Barr Virus (EBV)
- EBV is a member of the Gamma herpes virinae subfamily.
- Hosts include both humans and some New World monkeys.
- EBV preferentially infects B cells, sometimes replicating in them, and some epithelial cells.
- EBV establishes latency in B cells.
- B cells are activated to enter the cell cycle, and a limited range of EBV genes are expressed.
- EBV causes heterophile antibody-positive infectious mononucleosis.
- EBV is associated with various cancers, including nasopharyngeal carcinoma and Burkitt's lymphoma (in immunocompromised individuals, young individuals living in malaria regions).
- EBV may also induce a variety of other benign to malignant tissue changes depending on infection and host status.
EBV: Epidemiology
- Transmission occurs via saliva.
- Risk includes children (asymptomatic), adolescents and adults (infectious mononucleosis in susceptible), immunocompromised (high risk for life-threatening neoplastic disease)
EBV: Pathogenesis
- Virus in saliva infects oral epithelia and spreads to B cells.
- Productive infection occurs in epithelial cells and B cells.
- EBV promotes B cell growth and immortalization.
- T cells limit B cell proliferation.
- Antibody plays a limited role in controlling infection.
- EBV latency occurs in memory B cells and reactivated after cell activation.
EBV: Infectious Mononucleosis
- Typical symptoms include enlarged lymph nodes and/or spleen as well as fever and sore throat .
- Atypical T cells (Downey cells) are visible.
- Diagnosis is via heterophile antibody testing, EBV IgM.
EBV: Burkitt Lymphoma
- BL is a jaw tumor, often associated with, though not always, infections in children who live in malaria endemic areas
- Frequent EBV presence.
EBV: Nasopharyngeal Carcinoma (NPC)
- Malignant tumor of squamous epithelium, most frequent in Southern China..
- EBV is strongly linked to NPC development.
EBV: Treatment and Prevention
- No established EBV vaccine yet available
- Treatment generally focuses on treating symptoms.
- Supportive care may be needed for some symptomatic diseases associated with EBV such as infectious mononucleosis.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Explore the diverse world of herpes viruses, focusing on their classification into subfamilies. This quiz covers the morphological features, replication processes, and transmission methods of alpha and beta herpesvirinae. Test your knowledge on the unique characteristics of these significant pathogens!
