Question

Which of the following would not help a virus avoid triggering an adaptive immune response?

(A) Having frequent mutations in genes for surface proteins

(B) Infecting cells that produce very few MHC molecules

(C) Producing proteins very similar to those of other viruses

(D) Infecting and killing helper T cells

Short answer

(A) The statement “having frequent mutations in genes for surface proteins” is false.

(B) The statement “infecting cells that produce very few MHC molecules” is false.

(C) The statement “producing proteins very similar to those of other viruses” is true.

(D) The statement “infecting and killing helper T cells” is false.

Step-by-step solution

Adaptive immune system

The immune system that assists in eliminating pathogens by producing specific antibodies is called the adaptive immune system. It is acquired later or acts as a secondary defense line by preparing the body’s immune system for repeated entries of a pathogen, hence the name “adaptive.”

T and B lymphocytes are the primary immune cells of adaptive immunity.

Explanation of option (A)

When the virus undergoes frequent mutation, the body fails to recognize the virus. The variants or mutant viruses do not trigger the adaptive immune system.

Therefore, variants produced by a virus due to mutation infect the host body quickly.

Thus, the given statement is false.

Explanation of option (B)

A virus can infect cells that do not possess a large number of MHC molecules. Hence, those cells fail to present a virus that is endogenous or intracellular. The adaptive immune system does not work during such times and is quickly infected by the virus.

Therefore, the virus has adapted to infect the cells with less MHC to slower the activation of adaptive immunity.

Thus, the given statement is false.

Explanation of option (C)

Synthesizing protein similar to other viruses would not help the virus avoid activating the adaptive immune response. The MHC molecules of the cells recognize the other protein molecules. It triggers the adaptive immune system.

Thus, copying the protein synthesis of other viruses would not help the virus avoid the immune response.

Thus, the given statement is true.

Explanation of option (D)

Helper T cells serve in the destruction of infected target cells that are killed by cytotoxic T cells. They also help in the secretion of antibodies from the B cells. When a virus infects the helper T cells, the body fails to trigger the adaptive immune response.

Therefore, helper T cells are necessary to activate the adaptive immune system.

Thus, the given statement is false.