DNA Viruses and Herpesviridae Overview

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the approximate global prevalence rate of congenital cytomegalovirus (CMV) infection in newborns?

0.64% (correct)

0.3 - 2%

17 - 20%

0.03 - 0.2%

If a child is infected with congenital CMV, what is the estimated chance of experiencing significant long-term effects?

2-5%

10-15%

5-10%

17-20% (correct)

When does the risk of symptomatic congenital cytomegalovirus infection become the highest in pregnancy?

Immediately before birth

Third trimester

First trimester (correct)

Second trimester

Which of these is a neurological sign of congenital cytomegalovirus infection?

Hypotonia Signup and view all the answers

Which of these conditions can be caused by cytomegalovirus (CMV) in immunocompromised patients?

Meningoencephalitis Signup and view all the answers

What is the typical progression of skin lesions in varicella?

Vesicles → pustules → crusts Signup and view all the answers

What is the primary risk factor for VZV reactivation leading to herpes zoster?

Decline in VZV-specific cell-mediated immunity Signup and view all the answers

What percentage of the population infected with VZV will develop herpes zoster?

10-20% Signup and view all the answers

Which of the following is NOT a characteristic of herpes zoster?

The infection is localized to the skin level Signup and view all the answers

What is the correlation between VZV cell-mediated immunity at the onset of a herpes zoster rash and the severity of the condition?

Robust cell-mediated immunity is correlated with reduced severity of disease and less risk of postherpetic neuralgia Signup and view all the answers

Which of the following antiviral medications is NOT typically used for treating VZV infections?

Ganciclovir Signup and view all the answers

What is the primary mechanism by which the VZV vaccine provides protection?

Inducing production of protective antibody and cell-mediated immunity Signup and view all the answers

What is a known limitation in the treatment of VZV infections, according to the information provided?

Absence of good treatment for postherpetic neuralgia Signup and view all the answers

Which of these cells is NOT mentioned as being permissive for CMV replication?

Neurons Signup and view all the answers

In CMV infections, what percentage of CD4+ and CD8+ memory cells are typically involved in the T cell response?

Approximately 10% Signup and view all the answers

In which location was the highest seroprevalence of CMV found in the seroprevalence studies?

Bologna, Italy Signup and view all the answers

Which of the following statements is TRUE regarding CMV infection?

It can cause severe disease in those with immature immune systems Signup and view all the answers

What is the typical clinical presentation of CMV infections in children and adults?

Mild or asymptomatic disease Signup and view all the answers

Which location listed has the lowest reported CMV infection rate?

Buenos Aires Signup and view all the answers

Which of the following is NOT a primary mode of CMV transmission according to the provided information?

Via consumption of contaminated food Signup and view all the answers

What is the main function of the viral homologue of IL-10 in the context of CMV infection?

To inhibit T cell proliferation Signup and view all the answers

A pregnant woman is CMV-seronegative. What percentage range represents the likelihood of transmission to the foetus?

30 - 50 % Signup and view all the answers

What is the most common outcome of a primary CMV infection in an immunocompetent individual?

Asymptomatic infection Signup and view all the answers

What impact does maternal immunity have on the transmission of CMV infection to the foetus?

It reduces the risk of transmission by 70% Signup and view all the answers

Which of these is a consequence of CMV's inhibition of MHC-I expression?

Decreased immune detection by CD8+ T cells Signup and view all the answers

According to the information, what is a defining characteristic of congenital CMV infection in high-income countries?

It is the most common congenital infection Signup and view all the answers

Which of the following best describes an abortive HPV infection?

An infection where early viral products are produced but the viral life cycle is incomplete. Signup and view all the answers

In the context of HPV infection, which of the following cell types is considered permissive, aiding viral replication?

Ectocervical cells Signup and view all the answers

What is the primary role of the E2 protein in HPV infection?

To promote viral replication in permissive cells. Signup and view all the answers

What is the consequence of blocking E2 expression in non-permissive cells?

It leads to the inhibition of viral replication and may contribute to cancer progression Signup and view all the answers

What are the primary functions of the E6 and E7 proteins?

Increase cell survival by interfering with tumor suppressor activity. Signup and view all the answers

Which tumor suppressor protein is directly affected by the E7 protein in HPV oncogenesis?

retinoblastoma protein (pRb) Signup and view all the answers

How does HPV typically gain access to basal cells?

Through a break in the epithelial layer. Signup and view all the answers

What is the typical time frame for most HPV infections to clear on their own?

Within 3 years Signup and view all the answers

Which of the following mucosal syndromes is associated with low-risk HPV types?

Anogenital warts. Signup and view all the answers

What is the primary method for diagnosing HPV infections in the laboratory?

Genome detection using real-time PCR Signup and view all the answers

Why are HPV antibody tests not useful for diagnosing infection?

Because antibody levels do not correlate well with active infection. Signup and view all the answers

What does the L1 protein in HPV vaccines do?

It self-assembles to form virus-like particles. Signup and view all the answers

Which of the following is NOT a component of the 9-valent HPV vaccine (Gardasil 9)?

HPV type 2 Signup and view all the answers

What are the basic components of HPV subunit vaccines?

Recombinant virus-like particles (VLPs) Signup and view all the answers

Why is continued cervical cancer screening needed even after HPV vaccination?

Because it is not fully effective against all HPV types. Signup and view all the answers

What is the primary route of transmission for Epstein-Barr Virus (EBV)?

Oral route through saliva. Signup and view all the answers

Which of the following describes the typical course of a primary Cytomegalovirus (CMV) infection?

A largely asymptomatic primary infection, that may have long-term risks in later life Signup and view all the answers

Which serological marker suggests the resolution of an active EBV infection?

Generation of antibody to EBNA (Epstein-Barr nuclear antigen). Signup and view all the answers

What is the primary mechanism by which EBV promotes B cell proliferation?

Through the expression of specific latent gene products like LMP-1 and EBNA. Signup and view all the answers

In which type of cells does EBV establish latent infection?

Memory B cells. Signup and view all the answers

What is the significance of atypical T-cells in the context of EBV infection?

They are characteristic of infectious mononucleosis. Signup and view all the answers

Which statement best describes the relationship between oncogenic viruses and cancer development?

Oncogenic viruses establish persistent infections; cancer development requires additional co-factors. Signup and view all the answers

What is the primary method for diagnosing congenital CMV infection?

Detection of the viral genome using PCR in urine or saliva samples of neonates. Signup and view all the answers

Which of the following is considered an oncogenic RNA virus?

Hepatitis C virus (HCV). Signup and view all the answers

What is the primary mode of transmission for Human Papillomavirus (HPV)?

Sexual transmission and direct contact with skin lesions. Signup and view all the answers

What is a significant consequence of HPV infection on human health?

Increased risk of developing certain cancers. Signup and view all the answers

What determines the productive stage of Papillomavirus infection?

The production of viral particles within sensitive and permissive cells. Signup and view all the answers

Why are maternal CMV serological tests recommended during the first trimester of pregnancy?

The risk of congenital CMV sequelae is limited to maternal infection acquired during the first trimester. Signup and view all the answers

What is the role of angiogenic factors in tumor growth within the context of viral infections?

They promote nutrient delivery to support tumor development. Signup and view all the answers

Which of these factors has been linked to the development of Burkitt lymphoma in sub-Saharan Africa, alongside EBV infection?

Malaria infections Signup and view all the answers

Study Notes

DNA Viruses

DNA viruses are a diverse group of viruses
They have genomes of double-stranded DNA, either linear or circular.
Different families of DNA viruses have different structures (icosahedral, helical, complex)
Some DNA viruses are enveloped, while others are naked.
Viral genome sizes vary among different viruses.

Herpesviridae

Double-stranded linear DNA, genome
Icosahedral capsid, 150 nm
Enveloped viruses (fragile viruses)
Characterized by latent infection, whereby the viral genome persists in the host cell without causing immediate disease symptoms.

Herpesviruses

The primary cell target of Herpes simplex virus type 1 (HSV-1) and Herpes simplex virus type 2 (HSV-2) is mucoepithelial cells
Latency sites (HSV-1): mainly the trigeminal ganglia
Latency sites (HSV-2): mainly the sacral ganglia
HSV transmission routes include close contact, contact with oral fluids, or sexual contact.
Clinical signs are characterized by painful, often benign and recurrent lesions such as oral herpes and genital herpes.
In severe cases, the virus can cause encephalitis or disseminate infections in immunosuppressed patients
Neonatal Herpes: Herpes genitalis in pregnant women is the main risk factor for neonatal herpes. Transmission can occur during delivery (30-50% of primary maternal infection cases).Reactivation of maternal infection (1-5%).
Diagnosis can be made through virus isolation (liquid from vesicles, CSF), genome detection by PCR (liquid from vesicles, crusted lesions, CSF, blood), and serology.
Treatment is with nucleoside analogs (acyclovir, valacyclovir, famciclovir).

Varicella-zoster Virus (VZV)

VZV establishes latent infection in sensory ganglia.
Primary infection is varicella (chickenpox) characterized by fever and a diffuse rash of vesicles that develop into pustules and then crusts.
Reactivation leads to herpes zoster (shingles) - this is characterized by severe pain in the area innervated by the affected nerve, which is followed by a rash.
It typically affects persons over age 50, and the incidence increases with age.
Transmission occurs primarily through the respiratory route; and direct contact with skin vesicles is also possible
Diagnosis of VZV infections is generally clinical.
Treatment is with acyclovir, valacyclovir, or famciclovir.

Cytomegalovirus (CMV)

Infects only humans.
Infects fibroblasts, epithelial cells, endothelial cells, and macrophages.
Usually causes mild or asymptomatic disease.
However, CMV can cause severe disease in immunocompromised patients, (immunocompromised patients, those with immature immune systems, or fetuses).
Seroprevalence studies suggest that a high percentage of people globally have been exposed to CMV.
CMV can be transmitted vertically from a pregnant woman to a fetus, through transplanted organs, or through saliva (children) or sexual transmission (adults).
Immunological mechanisms help prevent widespread infection, but persistent infections can cause disease or complications in some individuals.
Symptoms and signs of congenital CMV infections include intrauterine growth retardation, premature birth, hepatosplenomegaly, jaundice, thrombocytopenia, and anemia. Complications may include neurological issues like hypotonia or lethargy, as well as possible intracranial calcifications or hearing loss.
In immunocompromised individuals, almost every organ can be affected by CMV, with clinical signs varying among individuals.

Epstein-Barr Virus (EBV)

EBV is ubiquitous, with 80–90% of adults seropositive.
Transmission is primarily through oral contact (saliva).
EBV establishes a latent infection in B lymphocytes.
The majority of infections in childhood are asymptomatic, and those in adulthood may result in infectious mononucleosis (also called kissing disease), a self-limiting lymphoproliferative disorder.
Viral infection may result in swollen lymph nodes (lymphadenopathy), pharyngitis/sore throat, splenomegaly (enlarged spleen), or hepatitis.
EBV is recognized as an oncogenic virus, linked to endemic Burkitt lymphoma, B-cell lymphomas in immunocompromised individuals, Hodgkin's disease, and nasopharyngeal carcinoma.

Human Papillomavirus (HPV)

HPV belongs to the Papillomaviridae family; it is a non-enveloped virus.
HPV can replicate in epithelial cells causing cutaneous or mucosal lesions and warts.
Causes latent infection in memory B cells
HPV is an oncogenic virus that can lead to cervical cancer, oropharyngeal cancer, penile cancer, and anal cancers.
HPV infection is typically transient (90% clear within three years)
Diagnosis is primarily through genome detection with real-time PCR tests of cervical swabs and other tissue samples.
HPV vaccines provide protection against a variety of HPV types, and routine vaccination for both males and females is recommended.

Oncogenic Viruses

Oncogenic viruses can cause various cancers.
They can either be DNA or RNA Oncogenic viruses.
DNA oncogenic viruses include EBV, HBV (hepatitis B virus), HPV (human papillomavirus), and HHV-8.
RNA oncogenic viruses include HCV (hepatitis C virus) and HTLV-1 (human T-cell lymphotropic virus-1).
Viruses themselves are not the sole cause of cancer, and other factors (co-factors), such as chronic inflammation or immunosuppression, are necessary for cancer development.

Viral Infections (general)

Viruses can cause both productive and abortive viral infections.
Productive infection occurs in cells in which the virus can replicate successfully, resulting in the production of new viral particles.
Abortive infection occurs when the virus cannot replicate in the cell but may cause some early viral gene expression.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz covers the basics of DNA viruses, focusing on the Herpesviridae family. Learn about the structure, transmission, and latency of herpes viruses, along with their clinical signs. Test your knowledge on the intricate details and characteristics of these important pathogens.