Commonly used protein-based subunit vaccines are the following:
Acellular pertusis (aP) vaccines contain inactivated pertussis toxin (protein) and may contain one or more other bacterial components. The pertusis toxin is detoxified either by treatment with a chemical or by using molecular genetic techniques
Hepatitis B vaccines are composed of the hepatitis B virus virus surface antigen (HBsAg), a protein produced by hepatitis B virus. Earlier vaccine products were produced using purified plasma of infected individuals. This production method has been replaced by recombinant technology that can produce HBsAg without requiring human plasma increasing the safety of the vaccine by excluding the risk from potential contamination of human plasma.
Protein based subunit vaccines present an antigen to the immune system without viral particles, using a specific, isolated protein of the pathogen. A weakness of this technique is that isolated proteins, if denatured, may bind to different antibodies than the protein of the pathogen.
Subunit vaccines, like inactivated whole-cell vaccines do not contain live components of the pathogen. They differ from inactivated whole-cell vaccines, by containing only the antigenic parts of the pathogen. These parts are necessary to elicit a protective immune response
This precision comes at a cost, as antigenic properties of the various potential subunits of a pathogen must be examined in detail to determine which particular combinations will produce an effective immune response witthin the correct pathway
Often a response can be elicited, but there is no guarantee that immunological memory will be formed in the correct manner