ABSTRACT
A vaccine can be defined as an immunogenic preparation of a pathogen which engenders immunity without causing disease. A vaccine exploits the immunological phenomenon of memory (section 1.3), such that the primary exposure to the antigen in the vaccine elicits a pool of memory T and B lymphocytes that, upon subsequent exposure to the same antigen, are activated and effect clearance of the pathogen before disease occurs. In this chapter we will learn about conventional vaccine design, and how recombinant DNA technology has opened up opportunities for the production of engineered vaccines that promise to resolve several shortcomings of the conventional approaches.
