Question 1

Which of the following best describes the primary function of the skin as a barrier in host resistance to viral infections?

Accepted Answer

It acts as a physical and chemical barrier, preventing the entry of viruses, bacteria, and toxins into the body.

Question 2

Interferons play a crucial role in the innate immune response to viral infections. Which of the following is NOT a direct effect of interferon signaling?

Accepted Answer

Destruction of viral particles by phagocytosis.

Question 3

Which of the following best explains the function of interferon-stimulated genes (ISGs) in establishing an antiviral state?

Accepted Answer

ISGs encode proteins that interfere with various stages of the viral life cycle, such as degrading viral RNA and inhibiting viral protein synthesis.

Question 4

Natural Killer (NK) cells are part of the innate immune system. Which mechanism do they use to destroy virus-infected cells?

Accepted Answer

Release of perforin and granzymes to induce apoptosis in infected cells.

Question 5

Which of the following best describes Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC)?

Accepted Answer

NK cells recognize and kill infected cells that are coated with antibodies via Fc receptors.

Question 6

Which of the following is a key difference between the roles of B cells and cytotoxic T cells in the adaptive immune response to viral infections?

Accepted Answer

B cells target extracellular viruses with antibodies, while cytotoxic T cells destroy host cells infected with viruses.

Question 7

A patient with a genetic defect in MHC class I molecules would most likely have impaired function in which immune cell type?

Accepted Answer

Cytotoxic T cells (CD8+)

Question 8

Which of the following best describes the process of opsonization in antiviral immunity?

Accepted Answer

Antibodies coat viral particles, marking them for phagocytosis by immune cells.

Question 9

Which of the following statements about immunological memory is correct?

Accepted Answer

Immunological memory allows for a faster and more robust immune response upon re-exposure to the same virus.

Question 10

Which of the following best explains the difference between host resistance and host tolerance to viral infections?

Accepted Answer

Resistance reduces the viral burden, while tolerance minimizes tissue damage without necessarily reducing viral load.

Question 11

A patient with chronic hepatitis C infection develops significant liver damage. Which immune mechanism is most likely contributing to this tissue damage?

Accepted Answer

Excessive activity of Natural Killer (NK) cells leading to immunopathology.

Question 12

Which of the following best describes the role of dendritic cells in the immune response to viral infection?

Accepted Answer

They act as antigen-presenting cells, displaying viral peptides on MHC molecules to activate T cells.

Question 13

Which of the following equations best represents the relationship between the rate of viral clearance ($$C$$), the number of cytotoxic T cells ($$T$$), and the efficiency of apoptosis induction ($$E$$)?

Accepted Answer

$$C = T 	imes E$$

Question 14

During a viral infection, which of the following events occurs first in the time course of the immune response?

Accepted Answer

Activation of interferon and other nonspecific defenses.

Question 15

Which of the following is a real-world example of antibody-mediated neutralization of a virus?

Accepted Answer

Antibodies binding to the spike protein of SARS-CoV-2, blocking its attachment to host cell receptors.

Question 16

Which of the following factors would most likely decrease an individual's resistance to viral infections?

Accepted Answer

Malnutrition leading to impaired immune cell function.

Question 17

A virus evolves a mechanism to downregulate MHC class I expression on infected cells. Which immune response is most likely to be evaded by this viral strategy?

Accepted Answer

Cytotoxic T cell (CD8+) mediated killing of infected cells.

Question 18

Which of the following best describes the role of helper T cells (CD4+) in the adaptive immune response to viral infections?

Accepted Answer

They coordinate the immune response by activating B cells, cytotoxic T cells, and innate immune cells through cytokine secretion.

Question 19

Which of the following is a correct statement about the co-evolution of viruses and host defenses?

Accepted Answer

Viruses and hosts are engaged in an evolutionary arms race, with each evolving new strategies to overcome the other's defenses.

lec 13:Host Resistance to Viral Infections: Mechanisms and Immune Responses

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