Vaccines

Vaccines can be composed of the infectious agent itself, a portion of the agent that induces a protective immune response, or a product of the agent. To be effective, vaccines should stimulate an immune response that ideally prevents infection but, at the very least, should interfere with the development of severe disease. Adjuvants are used to influence the types of immune response elicited by an antigen. The administration route of a vaccine may be defined as the path by which a vaccine is delivered to the host. Immunization of animals with viral vaccines is critical to prevent many viral diseases. Many inactivated vaccines have been developed for use in veterinary medicine. As with viral vaccines, the basis of an effective toxoid, bacterin, or bacterial vaccine is the ability to induce an immune response or responses capable of eliciting protection from field exposure to the pathogenic microorganism. Bacterial toxins are of two kinds: exotoxins and endotoxins.