23.02.3 Recombinant Protein Vaccines

Whereas addition of exogenous antibody can be seen to provide passive immunity against a pathological condition, a vaccine is an antigenic preparation that produces an active immunity to a disease such as to prevent or ameliorate the effects of infection by any natural or wild strain of the causative organism. Vaccines have been used in one form or another for over 200 years when Edward Jenner, using inoculation with cowpox virus demonstrated protection against the deadlier smallpox virus.

Vaccines may be obtained from living, weakened strains of the pathogens (bacteria or virus) which intentionally give rise to trivial infections or they may be obtained from killed or inactivated (attenuated) pathogens or purified products derived from them.

Increasingly, however, a new generation of vaccines derived from appropriate immunogenic (but non-pathogenic) protein components of a micro-organism produced through recombinant DNA technology, has shown that vaccines can be created that provide immunity in an individual without exposure of that individual to the risks of infection. Such recombinant protein vaccines are proving invaluable in the treatment of infection, autoimmune diseases and cancer. For example, a new hepatitis B vaccine was created by from the production of a recombinant HBsAg protein, a non-infectious protein of the Hepatitis B virus. Similarly, two vaccines, the quadrivalent Gardasil and the bivalent Cervarix have been developed to combat human papillomavirus (HPV) infection, the causative agent that is responsible for 70% of precancerous lesions that can develop into cervical cancer. These vaccines were developed from recombinant viral coat proteins and are designed as preventative (rather than therapeutic) vaccines, recommended for women who are 9 to 25 years old and have not contracted HPV.