Explain the following observation: A very nasty virus started spreading through

Question

Explain the following observation: A very nasty virus started spreading through the New England area causing infected people to start supporting the New York Jets. A vaccine was very quickly manufactured by heatkilling purified virus. A test group of uninfected Bostonians were immunized with the vaccine and a good adaptive immune response developed. However, when exposed to the live virus all the patients started supporting the Jets (i.e. became infected). What was it about the vaccine that made it fail? Could a better vaccine be made, if so what characteristics would it require to protect people from infection?

Explanation / Answer

The adaptive immune response to a killed/inactivated vaccine is very similar to a toxoid vaccine with the exception that the antibody response generated is directed against a much broader range of antigens. Thus, following injection, the whole organism is phagocytosed by immature dendritic cells; digestion within the phagolysosome produces a number of different antigenic fragments which are presented on the cell surface as separate MHC II:antigenic fragment complexes. Within the draining lymph node, a number of TH2, each with a TCR for a separate antigenic fragment, will be activated through presentation by the activated mature dendritic cell. B cells, each with a BCR for a separate antigenic fragment, will bind antigens that drain along lymph channels: the separate antigens will be internalized and presented as an MHC II:antigenic fragment; this will lead to linked recognition with the appropriate TH2. Release by the TH2 of IL2, IL4, IL5 and IL6 induces B-cell activation, differentiation and proliferation with subsequent isotype switch (IgM to IgG) and memory cell formation.

In this case it had failed because the heat killed virus have started replication as normal form inspite of creating immune response. This occured due to proteins present in the viral form have interacted with viral gene by causing development of mutant strain or the given viral dose is not suffiencent to boost immunity.

To eradtcate this the people should be given regular doses of attenuated vaccine.

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