immune response (and therefore activate an antigen-specific adaptive immune re-

sponse), but in a very measured fashion, making sure that the vaccine will not cause

severe disease. The idea is to create immunological memory, such that, faced with the

same infection, the body will be to reactivate the response that is specific to that

infectious agent. In an ideal situation, once vaccinated, the individual should stay

FIGURE 3.12 Cytotoxic T-cell. Cells expressing antigens on their cell surface that are

recognized by specific receptors on T-cells. This triggers the release of perforin that generates

pores in the membrane of the target cell, allowing the entry of granzyme, an apoptosis-

causing molecule.

FIGURE 3.13 Helper vs cytotoxic T-cells. This figure illustrates the differences in the

action of the two types of T-cells. Upon activation, helper T-cells promote B-cell ma-

turation, whereas cytotoxic T cells release perforin and granzyme that results in apoptosis

of the target cell.

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Bioprocessing of Viral Vaccines