Viral Taxonomy and Pathogenesis Quiz

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Questions and Answers

Which virus is primarily responsible for the common cold?

Rhinovirus (correct)

Adenovirus

Influenza A

SARS-CoV-2

What characteristic is true about the human papillomavirus (HPV)?

It is primarily transmitted airborne.

It has a long incubation period, up to 12 months. (correct)

It is an enveloped virus.

It is a lysogenic virus.

Which of the following viral infections is NOT associated with an enveloped virus?

Mumps

Rubella

Common cold (correct)

Chicken pox

What is the primary causative agent of foot (verruca) and finger warts in children?

Human papillomavirus Signup and view all the answers

Which of the following viruses has a lysogenic replication cycle?

SARS-CoV-2 Signup and view all the answers

What role do cytotoxic T cells play in the immune response to a viral infection?

They kill infected cells. Signup and view all the answers

Which statement best describes viral latency?

The viral genome remains dormant without symptoms. Signup and view all the answers

What is a major consequence of chronic infections like hepatitis B and C?

They may result in long-term health complications. Signup and view all the answers

Which feature distinguishes adaptive immunity from innate immunity?

It generates memory cells for quicker future responses. Signup and view all the answers

What is the primary function of pattern recognition receptors (PRRs) in the immune system?

To recognize and respond to viral components. Signup and view all the answers

Why do some viruses, like influenza, require repeated vaccinations or exposures?

They have multiple strains that mutate frequently. Signup and view all the answers

What happens to the immune response once a viral infection is resolved?

Memory T and B cells remain in the body. Signup and view all the answers

Under what conditions can latent viruses reactivate?

During periods of immune suppression or stress. Signup and view all the answers

What is the primary function of type I interferons (IFN-α and IFN-β)?

Signal neighboring cells to produce antiviral proteins Signup and view all the answers

Which cell type is responsible for identifying and destroying infected cells?

Natural Killer (NK) Cells Signup and view all the answers

What role do cytokines play in the inflammatory response?

They attract additional immune cells to the site of infection Signup and view all the answers

How do cytotoxic T cells (CD8+ T Cells) contribute to resolving an infection?

By recognizing and killing virus-infected cells Signup and view all the answers

What is the main function of memory cells in the immune response?

To provide long-term immunity by responding more quickly to subsequent infections Signup and view all the answers

What enables some viruses to establish chronic or recurrent infections?

The rapid mutation and evolution of viral strains Signup and view all the answers

What is the role of B Cells in the immune response?

To produce antibodies with help from helper T cells Signup and view all the answers

Which of these is a mechanism by which viruses can evade the immune response?

Hiding within host cells Signup and view all the answers

What is the role of viral attachment proteins in the viral life cycle?

They facilitate the entry of the virus into the host cell. Signup and view all the answers

Which viral structure is primarily responsible for the virus's transmission?

Virion Signup and view all the answers

During the lytic cycle, what is the immediate consequence of the assembly phase?

New virus particles begin to lyse the host cell. Signup and view all the answers

What happens during the dormancy phase of the lysogenic cycle?

The viral DNA remains inactive and is copied with the host DNA. Signup and view all the answers

Which feature distinguishes the lytic cycle from the lysogenic cycle?

The immediate destruction of the host cell. Signup and view all the answers

What is pleomorphism in the context of viruses?

The variation in virus shapes such as helical or spherical. Signup and view all the answers

Which statement accurately describes viruses?

They are classified as obligatory intracellular parasites. Signup and view all the answers

What triggers the activation of viral DNA in the lysogenic cycle?

Stressful conditions such as UV light exposure. Signup and view all the answers

What role do Pattern Recognition Receptors (PRRs) play in viral infections?

They detect viral molecules and initiate immune responses. Signup and view all the answers

Which statement about type I interferons is accurate?

They create an antiviral state in neighboring cells. Signup and view all the answers

What is the significance of apoptosis in viral infections?

It prevents further viral replication by sacrificing infected cells. Signup and view all the answers

Which protein is NOT associated with the apoptotic response to viral infections?

Protein kinase R (PKR) Signup and view all the answers

How do antiviral proteins respond to viral infections?

They inhibit viral replication and modify cellular processes. Signup and view all the answers

What is the primary role of MHC molecules in the immune response?

To display viral peptides and activate immune cells Signup and view all the answers

What is the primary function of autophagy during viral infections?

To engulf and degrade viral components. Signup and view all the answers

During which phase do early nonspecific symptoms regarding viral infections typically appear?

Prodromal phase Signup and view all the answers

What initiates the cytotoxic T cell-induced apoptosis in infected cells?

Recognition of viral peptides on infected cell surfaces. Signup and view all the answers

What type of cells are primarily responsible for targeting and destroying infected cells when MHC presentation is disrupted?

Natural Killer (NK) cells Signup and view all the answers

Which of the following best describes chronic viral infections?

They are characterized by frequent viral reactivation and relapses. Signup and view all the answers

What initiates the release of inflammatory cytokines during a viral infection?

The immune response to the infection Signup and view all the answers

What is generally the defining characteristic of the acute phase of a viral infection?

The virus replicates at a high rate with pronounced symptoms Signup and view all the answers

Which cytokine is typically NOT released in response to viral infections?

Insulin Signup and view all the answers

The incubation period of a viral infection is primarily characterized by which of the following?

Viral replication without causing noticeable symptoms Signup and view all the answers

Which option best defines the role of helper T cells in the immune response?

Regulating and coordinating the immune response Signup and view all the answers

Study Notes

Viral Taxonomy

Viral taxonomy is a classification system for viruses.
Viruses require binomial nomenclature.
Virus: Broad term encompassing all infectious stages and taxonomic classifications.
Virion: Full, complex form of a virus, including viral genome, capsid, and envelope.
Pleomorphism: Describes different shapes of viruses (e.g., helical, spherical, polyhedral, complex).
Viral characteristics include being obligatory intracellular parasites.
Viral structure includes viral attachment proteins, envelope, and matrix protein.

Pathogenesis of Viral Disease

Lytic Cycle

Attachment: Virus binds to host cell surface receptors.
Entry: Virus injects genetic material (DNA or RNA).
Replication: Viral genetic material controls host cell machinery, making viral components and copies.
Assembly: New viral particles are made from replicated components.
Lysis and Release: Host cell bursts, releasing new viruses to infect others.

Lysogenic Cycle

Attachment and Entry: Virus attaches and injects genetic material into the host cell.
Integration: Viral DNA becomes prophage (bacteriophages) or provirus (in other organisms), integrating into host DNA.
Dormancy: Viral DNA replicates along with host DNA.
Activation: Virus exits the host DNA, initiating lytic cycle.

Acute Infection

Recovery
Progression to chronic
Death

Chronic Infection

Silent infection for life
Long period before disease
Reactivation
Relapses + exacerbations
Neoplastic changes

Viral Infection Detection

Pattern recognition receptors (PRRs) detect viral molecules (RNA or DNA) on the cell surface or within cells.
PRRs include Toll-like receptors (TLRs) and RIG-I-like receptors.

Antiviral Interferon Response

Interferon production (IFN-α and IFN-β) alerts neighboring cells to the infection, initiating antiviral defenses.
Antiviral state in neighboring cells inhibits viral replication as interferon binds to receptors.

Inhibition of Viral Replication

Antiviral proteins (e.g., PKR, RNase L) in infected and neighboring cells, interfere with replication.

Activation of Apoptosis (Programmed Cell Death)

Infected cells activate programmed cell death (apoptosis).
Cytotoxic T cells, part of the adaptive immune system, recognize viral peptides on infected cells, triggering apoptosis.
Autophagy pathway helps cells degrade viral components.

Antigen Presentation

Infected cells display viral peptides on major histocompatibility complex (MHC) molecules to activate immune cells.
Coordination between T-helper Cells and cytotoxic T cells is essential for immune response.
Natural killer (NK) cells target cells with low MHC expression.

Production of Inflammatory Cytokines

Immune cells (infected cells and immune cells) release cytokines (e.g., IL-1, TNF-α, and interferons).
Cytokines amplify immune response to contain infection, contributing to symptoms (e.g., fever).

Course of Infections

Entry: Viruses enter the body via mucosal surfaces, breaks in skin, or direct inoculation.
Incubation Period: Time between entry and appearance of symptoms.
Prodromal Phase: Early, non-specific symptoms (e.g., fever, malaise).
Acute Phase: Peak viral replication, specific symptoms.

Resolution or Persistence

Resolution: Successful immune system elimination of virus.
Persistence: Virus evades immune system, resulting in chronic infection (e.g., hepatitis B and C, HIV).

Latency and Reactivation (some viruses)

Latency: Viral genome remains dormant in host cells.
Reactivation: Viral reactivation under stress or immunosuppression, leading to recurrent infection.

Adaptive Immunity and Memory

Following resolution, memory T and B cells remain, reacting quickly to a reinfection.
Different viral infections have variable durations of immunity

Innate Immunity

Pattern recognition receptors (PRRs) recognize viral components on cells.
Interferons (IFNs) trigger early immune responses by infected cells in neighboring cells, inhibiting replication.
NK (natural killer) cells destroy infected cells.

Adaptive Immune Response

Helper T cells (CD4+ T cells) coordinate response.
Cytotoxic T Cells (CD8+ T cells) kill virus-infected cells.
B cells produce antibodies against viruses.
Memory cells provide long-term immunity.

Viral Evasion Mechanisms

Viruses can evade or suppress the immune system, preventing effective immune response.

Common Viral Infections

Common viral infections (e.g., cold, flu, COVID-19, measles, mumps, rubella, chicken pox, herpes simplex) have different characteristics of transmission, symptoms and severity.
Examples (such as HPV) show detailed information about specific infections.

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Description

Test your understanding of viral taxonomy, the structure and characteristics of viruses, and the mechanisms of viral disease pathogenesis. This quiz covers the lytic and lysogenic cycles of viral replication, exploring the stages from attachment to release. Ideal for students studying virology or related fields.