Question 1

Which of the following best describes why viruses are considered obligate intracellular pathogens?

Accepted Answer

They require host cell machinery to replicate their genetic material and produce new virions.

Question 2

Which immune component is primarily responsible for the early detection and elimination of virus-infected cells before the adaptive immune response is fully activated?

Accepted Answer

Natural Killer (NK) cells

Question 3

Type I interferons (IFN-α/β) are critical in antiviral defense. Which of the following is NOT a direct effect of Type I IFN signaling?

Accepted Answer

Direct neutralization of viral particles in extracellular fluids

Question 4

A virus infects a cell and downregulates MHC class I molecules on its surface. Which immune cell is most likely to recognize and kill this infected cell?

Accepted Answer

Natural Killer (NK) cell

Question 5

Which of the following best explains the role of Toll-like receptors (TLRs) in the immune response to viral infection?

Accepted Answer

TLRs detect pathogen-associated molecular patterns (PAMPs) such as viral nucleic acids and induce pro-inflammatory cytokine and interferon production.

Question 6

Which of the following equations correctly represents the phosphorylation of eIF-2α by PKR, leading to inhibition of translation during viral infection?

Accepted Answer

$$\mathrm{PKR} + \mathrm{eIF{-}2\alpha} + \mathrm{ATP} \rightarrow \mathrm{PKR} + \mathrm{eIF{-}2\alpha{-}P} + \mathrm{ADP}$$

Question 7

Which of the following is a mechanism by which antibodies neutralize viruses?

Accepted Answer

Antibodies bind to viral surface proteins, preventing attachment and entry into host cells.

Question 8

A patient is reinfected with a different serotype of Dengue virus and develops severe hemorrhagic fever. Which immune mechanism is most likely responsible for the increased severity?

Accepted Answer

Antibody-dependent enhancement (ADE), where IgG-virus complexes facilitate infection of phagocytes.

Question 9

Which of the following best describes the function of Viperin in the antiviral response?

Accepted Answer

It catalyzes the conversion of CTP to ddhCTP, which acts as a chain terminator during viral RNA synthesis.

Question 10

Which of the following is a key difference between the immune evasion strategies of small RNA viruses and large DNA viruses?

Accepted Answer

Large DNA viruses have a greater genetic coding capacity, allowing them to encode multiple proteins that inhibit host immune pathways.

Question 11

Which of the following best explains why the adaptive immune response takes several days to become effective after a viral infection?

Accepted Answer

It requires clonal expansion and differentiation of antigen-specific T and B lymphocytes.

Question 12

Which of the following statements about Pattern Recognition Receptors (PRRs) is correct?

Accepted Answer

PRRs detect conserved molecular patterns essential for pathogen survival, such as dsRNA or unmethylated CpG DNA.

Question 13

Which of the following best describes the role of the JAK-STAT pathway in the antiviral response?

Accepted Answer

It mediates the signaling of Type I interferons, leading to the expression of interferon-stimulated genes (ISGs).

Question 14

Which of the following is a consequence of errors in V(D)J recombination or class switch recombination in B cells?

Accepted Answer

Activation of oncogenes such as MYC, leading to lymphoid cancers like Burkitt’s lymphoma.

Question 15

Which of the following equations best represents the diversity generated by V(D)J recombination in human immunoglobulins?

Accepted Answer

$$200 	imes 120 	imes 80 = 1.92 	imes 10^6$

Question 16

Which of the following is a function of the protein Tetherin in the host antiviral response?

Accepted Answer

It blocks the release of enveloped viruses from infected cells.

Question 17

Which of the following best describes the role of CD4+ T cells in the antibody response to viral infection?

Accepted Answer

They provide help to B cells via cytokine secretion, promoting their differentiation into antibody-secreting plasma cells.

Question 18

Which of the following is a key feature of the innate immune response to arbovirus infection at the site of a mosquito bite?

Accepted Answer

Rapid influx of leukocytes, some of which may become infected and contribute to viral spread.

Immunity to Viral Infections: Innate and Adaptive Responses

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