ABSTRACT
Conventional vaccines have evolved from those of wild type of attenuated or killed organisms. However, in many instances, unacceptable side effects may still be present. Moreover, subunit vaccines produced from biological fluids, may be contaminated with known or unknown infectious agents. Recent advances in recombinant DNA and monoclonal antibody technology and the understanding of the immunological structure of proteins and of factors regulating immune responses have laid the foundations of a new generation of recombinant subunit and synthetic peptide vaccines representing small regions of microbial proteins. These vaccines are capable of inducing specific immune responses that control infectious micro-organisms and, being defined at the molecular level, are potentially safe. Unfortunately, subunit and peptide vaccines are only weakly or non-immunogenic.
