Virology Chapter: Viral Latency and Reactivation

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Questions and Answers

Which of the following is NOT a potential outcome of infection with a DNA virus?

Chronic infection leading to cell transformation and oncogenesis

Persistent infection characterized by viral replication without cell death and eventual resolution (correct)

Acute infection leading to cell death and clearance

Latency leading to reactivation and productive infection

During latency, why are viral transcripts made to inhibit viral replication?

To facilitate the reactivation of the virus and subsequent productive infection

To trigger an immune response that will clear the virus from the infected cell

To ensure the virus remains dormant by preventing the production of viral proteins (correct)

To decrease the likelihood of cell death and ensure the survival of the infected cell

What is the primary reason why CD8+ T cells are unable to recognize and eliminate infected cells during latency?

The viral genome is integrated into the host cell's DNA, making it undetectable to CD8+ T cells

Latency triggers a suppression of the immune system, rendering CD8+ T cells ineffective

The infected cells are protected by a viral protein coat that prevents CD8+ T cell recognition

The virus is not actively replicating, so there are no viral proteins present on the cell surface for CD8+ T cells to recognize (correct)

Why is latency considered a successful strategy for some viruses?

It allows the virus to evade the host's immune system and establish a long-term infection Signup and view all the answers

Which of the following statements concerning reactivation of a latent viral infection is TRUE?

Reactivation can occur frequently in immunocompromised individuals Signup and view all the answers

What is the main difference between acute and chronic viral infection?

Acute infections are transient and resolve quickly, while chronic infections persist for a long period Signup and view all the answers

What is the primary mode of transmission for a virus that establishes latency?

Transmission through infected bodily fluids Signup and view all the answers

What is the main reason why antiviral drugs are less effective during latency?

Antiviral drugs can only target actively replicating viruses Signup and view all the answers

Which of the following viral characteristics is NOT directly associated with the establishment of latency?

Ability to spread to other cells and cause rapid replication Signup and view all the answers

A patient presents with a rash that follows a single dermatome, along with acute pain and redness in the area. What is the most likely diagnosis?

Herpetic Whitlow Signup and view all the answers

What is the most common cause of corneal blindness, excluding trauma?

HSV-1 Signup and view all the answers

A pregnant woman with active genital herpes should undergo what procedure to minimize the risk of transmission to her newborn?

Cesarean section Signup and view all the answers

Which of these conditions is NOT a secondary manifestation of HSV-1 and HSV-2 infections?

Lymphadenopathy Signup and view all the answers

Acyclovir and its derivatives are used to treat which of the following viral infections?

HSV-1, HSV-2, and VZV Signup and view all the answers

Which of the following statements correctly reflects the relationship between HSV-1 and HSV-2?

HSV-1 and HSV-2 are distinct viruses with separate modes of transmission and distinct primary manifestations. Signup and view all the answers

What is the role of LATs mRNA during HSV and VZV recurrences?

LATs mRNA inhibits the transcription of IE genes, thus suppressing a productive viral infection and preventing recurrence. Signup and view all the answers

What is the primary site of viral latency for both HSV-1 and HSV-2?

Neurons Signup and view all the answers

Which of the following is NOT a characteristic of the human herpesviruses (HHVs) discussed in the context provided?

Their infection results in only lytic infections, without latent phases. Signup and view all the answers

From the text, which statement best outlines the impact of a strong cellular immune response on herpes simplex virus (HSV) infections?

A strong cellular immune response can reduce the frequency and severity of HSV recurrences but cannot eliminate the virus completely. Signup and view all the answers

What does the term "tegument" refer to in the context of herpesviruses, as outlined in the text?

The space located between the envelope and the capsid of the virus. Signup and view all the answers

Which of the following statements is TRUE about the initial infection of HSV?

The initial infection typically resolves within two weeks, but the virus remains latent in the infected cells. Signup and view all the answers

What is the primary clinical presentation of HSV-1 infection in children?

Herpes labialis Signup and view all the answers

How does the transmission of VZV differ from other herpesviruses?

VZV is spread through airborne transmission and direct contact, unlike other herpesviruses. Signup and view all the answers

Which of the following DNA viruses is classified as double-stranded?

Adenovirus Signup and view all the answers

What type of transmission is commonly associated with herpesviruses?

Direct contact with infected lesions Signup and view all the answers

Which of the following viruses is known for having a latency phase in its infection process?

Hepatitis B virus Signup and view all the answers

Which DNA virus is associated with genital warts and can lead to cervical cancer?

Papillomavirus Signup and view all the answers

Which of these DNA viruses is typically vaccine-preventable?

Hepatitis B virus Signup and view all the answers

What is the characteristic feature of parvoviruses compared to other DNA viruses?

They have a single-stranded genome Signup and view all the answers

What is a common clinical manifestation of infection by poxviruses?

Skin lesions or rash Signup and view all the answers

Which of the following statements accurately describes the typical outcome of a primary polyomavirus infection in an immunocompetent individual?

The virus is usually asymptomatic and establishes a latent infection in the kidneys. Signup and view all the answers

What is the most common mode of transmission for polyomaviruses?

Exposure to contaminated water, stool, urine, or saliva. Signup and view all the answers

What is the primary cellular target of JC Virus (JCV) in the body?

Monocyte-lineage cells and B cells Signup and view all the answers

Under what circumstances is reactivation of a latent polyomavirus infection most likely to occur?

In individuals with a compromised immune system, such as those with AIDS. Signup and view all the answers

What is the primary clinical manifestation of a reactivated BK Virus (BKV) infection?

Hemorrhagic cystitis, characterized by bloody urine. Signup and view all the answers

What is the most definitive diagnostic method for confirming a PML diagnosis?

Histological examination of brain tissue for areas of demyelination and inclusions. Signup and view all the answers

What is the most effective approach to managing a case of PML?

Reducing or eliminating immunosuppressive therapy. Signup and view all the answers

What is the primary reason for the high fatality rate associated with PML?

The virus disrupts the myelin sheath, leading to demyelination and neurological dysfunction. Signup and view all the answers

Which of the following individuals is most likely to be at risk for developing PML?

An AIDS patient with a severely compromised immune system. Signup and view all the answers

Which of the following options represent current strategies for preventing and controlling polyomavirus infections? (Choose all that apply)

Maintaining good personal hygiene and sanitation practices. Signup and view all the answers

Study Notes

Medically Important DNA Viruses

Study content focuses on DNA viruses.
Learning objectives include classifying DNA viruses by structure and genome, discussing the importance of latency in clinical disease, and describing the following viruses: herpesviruses, adenoviruses, papillomaviruses, polyomavirus, parvoviruses, hepatitis B virus, and poxviruses. Each description should include the source/transmission, infection timeline, disease associations/manifestations, and if vaccine-preventable.

Classification of DNA Viruses

DNA viruses are categorized by their structure and genome, distinguishing between single-stranded and double-stranded forms.

Importance of Latency

The presentation highlights the critical role of latency in clinical disease processes.

General Characteristics of DNA Viruses (Human)

There are seven viral families of DNA viruses (–viridae) relevant to humans.
Viral genomes can be linear or circular, partially circular, partially double-stranded, double-stranded, or single-stranded.
Viral replication may occur in the nucleus or cytoplasm.
Viruses utilize cellular or viral DNA or RNA polymerases to replicate their genomes and synthesize mRNA.

DNA Viruses & Their Characteristics

The presentation provides detailed characteristics of various DNA viruses, including those with different envelopes and shapes: non-enveloped, linear, icosahedral; enveloped, linear, icosahedral; non-enveloped, circular, icosahedral; etc.
Specific examples of viral families and types, such as Parvoviridae (Parvovirus B19), Adenoviridae (Adenovirus), Papillomaviridae (Human Papilloma Virus [HPV]), Polyomaviridae (JC Virus, BK Virus), Poxviridae (Molluscum contagiosum, Cowpox, Variola virus (smallpox), vaccinia virus, monkeypox), Hepadnaviridae (Hepatitis B virus), and Herpesviridae (Herpes Simplex Virus [HSV] 1, Herpes Simplex Virus [HSV] 2, Varicella-zoster virus [VZV], Epstein Barr Virus [EBV] and others)

Parvovirus B19

Structure: non-enveloped, icosahedral, single-stranded DNA virus.
Transmission: respiratory, direct contact with oral secretions.
Tropism: erythroblasts.
Outcome: cell lysis, drop in mature red blood cells [anemia].
Geography: worldwide.
Clinical presentation: involves a rash ("slapped-cheek" appearance), arthritis, and anemia.

Adenovirus

Structure: non-enveloped, icosahedral, double-stranded DNA virus.
Transmission: aerosols, fecal-oral, direct contact, auto-inoculation (eye).
Tropism: mucosal epithelium of upper respiratory and GI tract.
Outcome: lytic, persistent, and latent infections.
Geography: worldwide.

Human Papillomavirus (HPV)

Structure: non-enveloped, circular, icosahedral, double-stranded DNA virus.
Transmission: direct contact, possibly contaminated fomites.
Tropism: epithelial cells of skin, mucous membranes.
Outcome: lytic, chronic, or transforming. - Causes warts, condylomas, papillomas. - Can lead to cervical, penile, or anal carcinomas.
Geography: worldwide.

Polyomavirus

Structure: non-enveloped, icosahedral, double-stranded DNA virus.
Transmission: inhalation; fecal-oral; contact with contaminated water, stool, urine, or saliva.
Tropism: tonsils, lymphocytes, kidneys [BK Virus], kidney, B cells, monocyte-lineage cells [JC Virus].
Outcome: persistent, latent infection.
Geography: worldwide.

Herpesviridae

Structure Enveloped, linear DNA virus, icosahedral.
Transmission: direct contact, bodily fluids, and potentially aerosolized.
Tropism: varies
Outcome: Lytic, latent, recurrent infections
Causes: cold sores, genital herpes, chicken pox, shingles, mononucleosis, roseola, other related viral diseases.
Geography: worldwide.

Poxviruses

Structure: Complex DNA virus, enveloped.
Transmission: direct contact, respiratory.
Tropism: varies.
Outcome: Lytic.
Causes: smallpox, vaccinia, cowpox, monkeypox, molluscum contagiosum.

Hepadnaviridae

Structure: Enveloped, DNA virus, partially circular, icosahedral.
Transmission: blood and body fluids
Tropism: hepatocytes.
Outcome: acute and chronic liver infections.

Diagnosis, Treatment, Prevention and Control of DNA Viral Infections

Specific to each viral types with considerations for supportive therapies, antiviral medications, and vaccinations, where available.

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Description

Test your knowledge on viral latency and reactivation in this quiz. Explore how DNA viruses establish latency, the immune response to such infections, and the implications for antiviral treatments. Ideal for students studying virology and infectious diseases.