5.4 Summary of Section 5

• When designing a vaccine, the antigens it contains must be immunogenic and selected to induce a protective immune response in genetically different recipients.

• The molecular structure of the antigen, the route of administration and the presence of adjuvants in the vaccine can all influence the efficacy of the immune response, and the type and location of antibody-mediated and cell-mediated defences.

• Adjuvants in vaccines function either by concentrating antigen in ‘depots’ where they are more effectively taken up by antigen-presenting cells, or by stimulating components of the immune response directly.