Viral Infection and Hepatitis C Quiz

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Questions and Answers

What happens to the infectivity of the Hepatitis C virus during the uncoating stage?

It remains unchanged

It is lost (correct)

It only decreases slightly

It increases significantly

What is the hallmark of viral infection of a host cell?

Formation of resistant viral particles

Cytopathic effect (CPE) (correct)

Replication of viral RNA

Blocking host cell division

Which statement best describes the cytopathic effect (CPE) observed in infected cells?

Cell rounding and darkening are initial signs (correct)

It causes immediate cell division

It leads to an increase in cell size and activity

All infected cells exhibit the same changes

What is the basis for the plaque assay in quantifying viruses?

The appearance of CPE in cell culture Signup and view all the answers

How do RNA viruses generally affect host cells compared to DNA viruses?

RNA viruses induce apoptosis, while DNA viruses block apoptosis Signup and view all the answers

Which type of virus produces Negri bodies?

Rabies virus Signup and view all the answers

Which inclusion body is characteristic of Cytomegalovirus?

Owl's eye inclusion bodies Signup and view all the answers

What is the first step in viral replication?

Binding Signup and view all the answers

What method can viruses use to enter host cells?

Endocytosis followed by fusion with the endosome Signup and view all the answers

Which step in viral replication involves the physical separation of the viral nucleic acid from its structural components?

Uncoating Signup and view all the answers

Which type of inclusion bodies are associated with the Vaccinia virus?

Guarineri bodies Signup and view all the answers

During which step do viral proteins start being synthesized?

Transcription of mRNA Signup and view all the answers

Which of the following viruses is NOT associated with intranuclear inclusion bodies?

Rabies virus Signup and view all the answers

What defines a virus?

An obligate intracellular parasite with a nucleic acid genome and a protein coat Signup and view all the answers

Which type of virus does not replicate in the nucleus?

POXVIRIDAE Signup and view all the answers

What is a key characteristic of viroids?

They consist of small, circular, single-stranded RNA Signup and view all the answers

Which statement is true regarding prions?

They cause other proteins to misfold Signup and view all the answers

Which classification represents the negative-sense single-stranded RNA viruses?

(-) Signup and view all the answers

What distinguishes virusoids from standard viruses?

Virusoids lack the ability to replicate on their own Signup and view all the answers

Which of the following statements is false regarding generalizations of DNA viruses?

POXVIRIDAE replicates in the nucleus Signup and view all the answers

Characteristics of a naked virus include?

It does not have an envelope covering its protein coat Signup and view all the answers

Which type of cells show activity of the promoter-enhancer region of JC polyomavirus?

Human glial cells Signup and view all the answers

How do encephalitis viruses typically spread to the CNS after transmission by insect bites?

Hematogenous and neural routes Signup and view all the answers

What is the response of the innate antiviral defense aimed at?

Site of virus incursion Signup and view all the answers

What impact does vitamin A deficiency have on viral infections?

Enhanced susceptibility to measles virus Signup and view all the answers

Which of the following is NOT a step in viral pathogenesis?

Cellular proliferation Signup and view all the answers

What is NOT a characteristic of apoptotic cell death?

Rapid cell division Signup and view all the answers

What is true about VEE virus after oral inoculation?

Is incapable of primary replication Signup and view all the answers

What occurs after viral entry and primary replication?

Viral shedding Signup and view all the answers

What defines the term 'tropism' in the context of viral infections?

The capability of a virus to infect specific host cells Signup and view all the answers

Which of the following factors can influence susceptibility to viral infection?

Age and nutritional status Signup and view all the answers

What is an important determinant of virulence in viruses?

Availability of virus receptors on host cells Signup and view all the answers

What role do enhancers play in the viral replication process?

They stimulate transcription of viral genes Signup and view all the answers

In the context of virus-host interactions, what does pathogenesis refer to?

The process by which a virus causes disease in a host Signup and view all the answers

What cellular process is activated during apoptosis that contributes to DNA fragmentation?

Endogenous endonuclease activation Signup and view all the answers

How can cells not susceptible to poliovirus replication be made susceptible?

Through recombinant expression of the poliovirus receptor Signup and view all the answers

What occurs during the post-attachment steps in viral replication?

Regulation of viral gene expression Signup and view all the answers

What do viral PAMPs primarily evoke in the immune system?

An innate immune response Signup and view all the answers

What is the primary role of IFN-α and IFN-β in the immune response?

To mediate expression of antiviral gene products Signup and view all the answers

What is the function of dsRNA-dependent protein kinase (PKR) in the immune response?

To inhibit viral protein synthesis Signup and view all the answers

Which of the following cytokines is released as part of the innate immune response following viral infection?

IL-1β Signup and view all the answers

What type of immune response is characterized by the expansion of viral antigen–specific T and B lymphocytes?

Adaptive immunity Signup and view all the answers

How do PRRs contribute to the production of interferons?

By activating signaling pathways Signup and view all the answers

What is the effect of 2′,5′-oligoadenylate synthetase (OAS) when activated?

Degrades viral RNA Signup and view all the answers

Which factor is phosphorylated by PKR to inhibit protein synthesis?

eIF2α Signup and view all the answers

Study Notes

Introduction: Viral Effects on Host Cells

Viruses are obligate intracellular parasites, requiring host cells for replication.
Viroids are small, circular, single-stranded RNA pathogens infecting plants.
Virusoids are small, circular RNA pathogens requiring a helper virus for replication.
Prions are misfolded proteins causing other proteins to misfold, leading to cellular damage.

Viral Structure

Viruses have a nucleic acid genome (DNA or RNA) enclosed in a protein coat (capsid).
Some viruses have an envelope, a lipid membrane surrounding the capsid.
The capsid structure may be icosahedral for some viruses.
Viral particles are called virions.

Viral Classification

Viruses are classified based on genetic material (DNA or RNA), strand type (single or double), and morphology (naked or enveloped).
Naked viruses lack an envelope; enveloped viruses possess one.
Icosahedral viruses have an icosahedral (20-sided) capsid.
Helical viruses have a helical capsid.
Complex viruses have an irregular capsid structure.

Viral Replication

Viruses bind to specific host cell receptors (tropism).
Penetration of host cell occurs by endocytosis or direct fusion.
Viral nucleic acid is released into the host cell (uncoating).
Host cell machinery is hijacked to produce viral components.

Viral Effects on Host Cells

Cytopathic effects (CPE) are morphological alterations in infected cells.
Viruses can induce apoptosis (programmed cell death).
Viral replication can lead to cell lysis (destruction).

Innate Immunity

Innate immunity is a rapid, nonspecific response to viral infection.
Recognition of viral components (PAMPs) by pattern recognition receptors (PRRs) triggers an immune response.
Interferons (IFNs) are induced by viral infection and inhibit viral replication.

Adaptive Immunity

Adaptive immunity is a specific response to viral infection.
Specific antiviral T (cytotoxic T Lymphocytes - CTLs) and B cells are generated.
Memory cells are produced for long-term immunity.

Viral Replication and Expression

Viral infection leads to expression of viral genes.
Expression produces viral proteins crucial for replication.

Viral Pathogenesis

Pathogenesis describes the steps of viral infection causing disease.
Viruses enter hosts through various routes (e.g., respiratory tract, gastrointestinal tract).
Spreading can be via blood to reach target tissues for secondary replication.
Viral replication occurs in specific cell types.

Portals of Entry to Human Host

Viruses enter through various portals such as respiratory tract (Influenza).
Infectious mononucleosis via Epstein-Barr virus.

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Description

Test your knowledge on the infectivity of the Hepatitis C virus during the uncoating stage, the hallmark of viral infection, and the cytopathic effects observed in infected cells. This quiz also explores the plaque assay methodology and compares the effects of RNA and DNA viruses on host cells.