Fish Immunology (1+1)

Unit 9- Immune response

9.3. Secondary immune response
During vaccine, the injection of the same antigen for the second time is called secondary dose or booster dose.
When the animal is invaded by the same pathogen that caused primary response, the immune system responds very quickly because of the presence of memory cells. Secondary immune response differ both qualitatively and quantitatively from primary response. In the case of secondary response the log phase is very short because of the presence of memory B cells specific for antigen induce the production of antibody with the level of antibody peaking up in a short time. The rise of antibody is around 100 to 1000 times higher than the primary response.
The antibodies formed in response to the secondary antibody is IgG type. IgG type of antibodies have a life span of around 3 weeks so the duration of plateau phase is much extended in the secondary response, and the antibodies decline very steadily even if the plasma cells does not produce antibody.