Host Virus interaction

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Questions and Answers

What are the three host responses to viral infections?

Innate, adaptive, and passive immunity

Adaptive immunity includes __ and components

Humoral and cellular

What is the first requirement for a virus to establish an infection in a host?

Evasion of the immune system
Breaching the barriers at its portal of entry (correct)
Rapid replication inside host cells
Direct entry into the bloodstream

Viruses transmitted by which route generally have LOW environmental stability?

Respiratory route (B) Signup and view all the answers

Viruses transmitted by which route generally have HIGH environmental stability?

Fecal-oral route (D) Signup and view all the answers

What is the primary function of Natural Killer (NK) cells in viral infections?

Mediating the apoptosis of virus-infected cells (B) Signup and view all the answers

What type of molecules do Pattern Recognition Receptors (PRRs) recognize?

PAMPS Signup and view all the answers

Why are DNA viruses generally better at blocking immune responses than RNA viruses?

They have evolved sophisticated mechanisms to evade immune detection (C) Signup and view all the answers

Which group of cytokines plays a major role in antiviral defense, immunomodulation, and cancer inhibition?

Interferons (IFNs) (C) Signup and view all the answers

Why are RNA viruses stronger inducers of interferons (IFNs) than DNA viruses?

They produce more PAMPs, leading to stronger immune recognition (B) Signup and view all the answers

Why must interferons be administered parenterally (e.g., injection)?

Because they are orally inactive Signup and view all the answers

Interferons are virus specific, for each virus there will be a specific interferon

False (B) Signup and view all the answers

What are the three major classes of interferons based on antigenic and chemical differences ?

Type 1, Type 2 and type 3 Signup and view all the answers

What are examples of a Type I interferon?

IFN alpha and beta Signup and view all the answers

Which immune cells produce IFN-α in large quantities?

Plasmacytoid dendritic cells (C) Signup and view all the answers

Which type of interferon is known as "fibroblast interferon" and is secreted by virus-infected fibroblasts?

IFN-β (B) Signup and view all the answers

How do Type I interferons contribute to antiviral immunity?

They inhibit viral replication and activate NK cells (B) Signup and view all the answers

Type I interferons enhance the immune response by increasing the expression of which molecules?

MHC I (A) Signup and view all the answers

Which of the following is an example of a Type II interferon?

IFN-γ (C) Signup and view all the answers

What cells produce type II interferons?

T cells and NK cells Signup and view all the answers

Which of the following is an example of a Type III interferon?

IFN-λ1 (D) Signup and view all the answers

Type III interferons (IFN-λ1, IFN-λ2, IFN-λ3) play a primarily __________ role in the immune system.

Immunoregulatory (D) Signup and view all the answers

What triggers the expression of Type III interferons?

Pattern recognition receptors (PRRs) such as Toll-like receptors (TLRs) (B) Signup and view all the answers

What is the primary function of virus neutralization by antibodies?

Preventing viral entry into host cells (A) Signup and view all the answers

What is the result of immune complex formation between viruses and antibodies?

Clumping of viruses, facilitating clearance (C) Signup and view all the answers

Antibody-dependent cell-mediated cytotoxicity (ADCC) involves which immune cells?

Natural killer cells Signup and view all the answers

How does complement contribute to antiviral defense?

By promoting opsonization and lysis of virus-infected cells (B) Signup and view all the answers

What are the four outcomes of cell mediated immunity?

Activation of macrophages, inflammation ,stimulation of B lymphocytes and killing the infected cell Signup and view all the answers

What is the primary mechanism behind antigenic plasticity in viruses?

Changing antigens through mutations, reassortment, or recombination (B) Signup and view all the answers

Which viral immune evasion strategy involves producing new antigens with little or no cross-reactivity?

Antigenic multiplicity (C) Signup and view all the answers

How do viruses negatively regulate cytokine signaling?

By blocking interferon signaling (D) Signup and view all the answers

What are virokines?

Viral homologs of cytokines or interferons (A) Signup and view all the answers

How does viral latency help evade the immune system?

By hiding within host cells without active replication (B) Signup and view all the answers

What is the primary function of neutralizing antibodies in antiviral defense?

Preventing virus attachment and entry into host cells (B) Signup and view all the answers

What is the effect of clumping (immunocomplex formation) of viruses?

It reduces the number of viral particles available for infection (C) Signup and view all the answers

Flashcards

Host responses to viral infections

Three types: innate, adaptive, passive immunity.

Adaptive immunity components

Includes humoral and cellular components.