Adjuvants for veterinary vaccines--types and modes of action.

Adjuvants are used to improve the immune response to vaccines. Formulation with adjuvants can result in an earlier onset of immunity, an overall stronger immune response, a specific type of immunity, or a longer duration of immunity to the vaccine. Adjuvants were discovered empirically, and for decades, have been used in both humans and animals without understanding the mechanisms of action. With an improved understanding of the immune system, and in particular the interplay between innate and adaptive immunity, we are now getting better insight into the function of adjuvants. As a result, new adjuvants are being developed that are safe and highly effective for common use in humans and animals, as well as for use in high risk populations such as immunocompromised animals, neonates or very old animals. Furthermore, adjuvants can help to reduce the amount of antigen needed in the vaccine, increase the stability of the vaccine and enable alternatiye administration routes such as needle-free delivery of the vaccine. Here, I will provide an over view of the existing adjuvant technologies for veterinary vaccines and provide an outlook into some of the new technologies in preclinical and clinical development.