Repeated antigen exposure and vaccine antibody responses
THE CONTEXT
Repeated antigen stimulation influences antibody levels and explains the priming and booster roles of vaccine doses.
Priming and booster doses
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Effective antibody levels are usually induced only by subsequent antigen injections; killed vaccines are therefore given in multiple doses for active immunisation.
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The first injection is the priming dose, and subsequent injections are booster doses.
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With live vaccines, a single dose is sufficient because multiplication of the organism provides continuing antigenic stimulation that serves both priming and booster functions.
Negative phase
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Injection of an antigen into an animal already carrying its specific antibody causes a temporary fall in circulating antibody through antigen–antibody combination. This is called the negative phase.
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The negative phase is followed by an antibody titre that exceeds the initial level.
Antibody development
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The appearance of different antibody classes from conception to adulthood varies with antigenic stimulation.