Recombinant Lactobacillus casei Expressing Capsid Protein VP60 can Serve as Vaccine Against Rabbit Hemorrhagic Disease Virus in Rabbits

Wang, Li; Xia, Tian; Guo, Tiantian; Ru, Yi; Jiang, Yanping; Cui, Wen; Zhou, Han; Qiao, Xinyuan; Tang, Lijie; Xu, Yigang; Li, Yijing

RHDV spreads mainly through the upper respiratory and digestive tracts. The initial steps leading to RHDV infection take place on mucosal surfaces [15, 16] . It is generally believed that mucosal immunization is an effective approach for preventing systemic infection by pathogens present on mucosal surfaces [17] . The gastrointestinal (GI) tract is the largest mucosal surface accessible via oral administration [18] . Oral vaccination can trigger a response involving neutralizing mucosal antibodies (IgA) and cell-mediated immunity, and does not interfere with IgG-based responses [19] [20] [21] [22] . Additionally, oral vaccines show better safety and compliance profiles, and are simpler to manufacture and administer, than traditional injectable preparations [23, 24] . However, the delivery of antigens for oral vaccination of the GI tract is hindered by multiple physicochemical and biological barriers; antigens can be subjected to early disintegration and advanced degradation by low pH and proteases present in the GI tract [25, 26] . L. casei is a probiotic that is well known for its health-promoting properties, such as maintaining homeostasis and suppressing pathogens in humans and animals [27] . L. casei has shown a good safety profile, can colonize the intestine, and exerts a nonspecific immunoadjuvant effect. For those reasons, oral vaccines using L. casei as a delivery system for pathogenic antigens have garnered much interest in vaccine development [27] [28] [29] . Currently, there is increasing interest in the development of L. casei oral vaccines, and this approach is significant for the effective induction of a mucosal immune response [30] . The results to date have been confirmed that the safety and the effectiveness of L. casei were used as the oral vaccine vehicle, which were extensively used in protecting individuals against a variety of pathogens [31] [32] [33] [34] [35] [36] [37] .