ABSTRACT
The main impetus of immunological research has been to control infectious diseases. The specific immunological resistance of the host to infectious organisms can be conveniently divided into humoral and cell-mediated immunity (CMI). For most viral and bacterial infections, where both humoral and CMIs are deemed to be important, percutaneous or intravenously/intraperitoneally routes appear equally effective in experimental models. Synthetic peptides and recombinent fragments are more likely to be successful vaccines if CMI rather than antibody is the protective mechanism. It is generally believed that live vaccines are superior to inactivated vaccines in inducing long-lasting protective immunity. For mass vaccination, the ideal means of vaccine delivery would be the oral route. Most studies to determine critical antigenic sites for vaccine development have concentrated on defining sites recognized by neutralizing antibodies. Comparatively little is known about the determinants involved in T cells to infectious diseases.
