Fish oral vaccine and mucosal immunity

Abstract

Fish can be vaccinated by injection, intramuscularly (IM) or intraperitoneally (IP), and orally. Using oral immunization provides the most attractive approach of immunization of fish due to the ease of antigen delivery and less stress to the fish. However, not many commercial fish oral vaccines are available now. Enzymatic degradation of oral vaccine antigen in the acidic gastrointestinal (GI) environment has hampered the development of fish oral vaccine. Thus, strategies to protect vaccine antigen have become critical determinants of the efficacies of many oral vaccines. In this study, strategies to enhance fish oral vaccine including antigen encapsulation techniques, addition of adjuvants, and the mechanism of mucosal immunity induced in the fish gut by oral vaccine will be discussed. In addition, the avoidance of oral tolerance phenomenon during the use of fish oral vaccines will also be studied.