Envision that a particular virus, chicken pox, has just entered the body. We might need millions of B and T cells to combat this virus. But, we only have a few B cells and a few T cells currently in the body that can recognize chicken pox virus.
In a brief description, what has to happen?

The whole situation will stimulate the Adaptive Immunity system along with Humoral responses.  As the individual is lacking both B and T cells, therefore the virus will be able to make infection by causing the disease.

Explanation:

Chickenpox has a particular antigen. It will act as an epitope that interacts with the particular sites of the lymphocyte. The epitope will stimulate the Adaptive Immunity system. The antigen will activate both B and T cells.  

Here 2 cases can happen.  

If the individual has experienced the disease before then Secondary Immune Response is gonna happen. B cells will be able to recognize those antigens and will secrete more antibodies in respect to that antigen particularly. T cells will also gonna bind with antigens and will secrete cytotoxic T cells which will fight against those antigens. If the individual is experiencing the disease for the first time then Primary Immune Response is gonna happen. B cells will take much more time to recognize the kind of antigens. Then it will give T cell the information about the antigen and will produce the antibody accordingly. As the individual is lacking both B and T cells, therefore the virus will be able to make infection by causing the disease.

Competition. interaction among organisms that compete for the same natural resource (food, shelter, water, space) in an ecosystem. predation. an interaction in which one organism kills another for food. predator. prey. symbiosis. mutualisum. commensalisum. parasitisum.

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