Question

You are a microbe trying to establish an infection in a host. You are trying to evade the immune system as best you can. Explain how you would avoid the immune response in the following scenarios.A. You are a virus trying to avoid being killed by NK cells.B. You are a bacteria trying to avoid macrophage killing.C. You are a parasite trying to block cells from reaching you.D. You are a bacteria trying to avoid dendritic cell functions.E. You are trying to block B cell activation and antibody production.

Answer 1

Answer:

A. Natural killer (NK) cells are activated in response to interferons or macrophage and Major histocompatibility complex (MHC) and allows direct apoptosis of virus.

Viruses can invade NK cells by inhibiting MHC from reaching the cell surface. Using stimulating the inhibitory receptors and disrupting the activating receptors, viruses can avoid NK cells. MHC act as a ligand of inhibitory receptor, and when bind with inhibitory receptor allows damage to NK cells.

So, if i would be a virus i will use inhibitory receptors stimulation to avoid NK cells.

B. Bacteria are killed by phagocytic immune cell macrophages by engulfing them.

Bacteria avoid macrophages by escaping from phagosome before the lysosome fuses as lysosomal chemical kill the bacteria and some bacteria  prevent acidification of the phagosome.

C. Parasites can avoid macrophages by modulating the host's cell cytoskeleton to block proper phagocytosis.

D. Bacteria can avoid dendritic cells by avoiding  lysosomal degradation and prevent antigen presentation on MHC molecules that will modulate the entrance to DCs.

E. B cells are responsible for producing antibodies. Activation of B-cell  depends on positive and negative signals transmitted through the B-cell receptor (BCR), so genetic polymorphisms and mutations affects the positive and negative signals. If mutation is done showing negative signal, B cell will not the activate and no antibodies will produce.