The Function of Antibody

Every normal human body will create Antibody, and antibody (Ab) has 3 important functions:

1. The first function of antibody to prevent an infection by neutralization of viral infectivity. The generation of protective antibody has usually been the only response measured by vaccine developers. Generally antibody reacts with just a few epitopes on one or two surface antigens of the infecting agent. It is inefective if the protective epitopes are subject to pronounced antigenic drift.
2. Infected cells which express viral antigen on their cell surface may be lysed by 2 antibody dependent cell cytotoxicity.
3. Antibody may facilitate on remove of debris (a scavening mechanism)

T cell response in an important mechanism for overcoming antigenic variation of an agent and the genetic variability of the host population. Although such an agent may bypass the protection afforded by a preformed antobody after vaccination, the cell mediated immune response allows most people to recover from an acute infection. Infections agents causing chronic persistent infections have found a way of escaping a cell mediated immune response.

Requirements of a Vaccine
To be effective a vaccine should be capable of eliciting the following:

• Activation of Antigen-Presenting Cells to initiate antigen processing and producing interleukins.
• Activation of both T and B cells to give a high a high yield of memory cells.
• Generation of Th and Tc cells to several epitopes, to overcome the variation in the immune response in the population due to MHC polymorphism.
• Persistence of antigen, probably on dendritic follicular cells in lymphoid tissue, where B memory cells are recruited to form antibody-secreting cells that will continue to produce antibody.