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

Next, we analyzed the immunogenicity of recombinant L. casei pPG-eGFP-VP60/LC393 and effectiveness of the inactivated virus vaccine in rabbits after oral and intramuscular immunization. Systemic and mucosal immune responses were assessed by detecting the presence of anti-RHDV IgG and IgA antibodies; the levels of these antibodies were quantified using ELISA. Starting at day 7 after primary vaccination, a significantly increased level of anti-VP60(VP1)-specific IgG was detected in rabbits orally administered with pPG-eGFP-VP60/LC393, and in those injected with the inactivated vaccine, compared with the responses of the PBS-treated control group (p < 0.01). Additionally, there was less IgG present for the L. casei vaccine in comparison to the inactivated vaccine ( Figure 5) . Similarly, localized levels of anti-VP60(VP1)-specific SigA in the feces, tears, vagina, and nasal cavity lavage of the immunized rabbits were measured via ELISA. In brief, mucosal SigA levels increased significantly in the feces (Figure 6a), vagina (Figure 6b ), nasal cavity (Figure 6c) , and tears (Figure 6d ) of the group orally immunized with pPG-eGFP-VP60/LC393 compared with those of the PBS-treated control group (p < 0.01). The level of SigA induced by oral immunization with pPG-eGFP-VP60/LC393 was higher than that induced by the inactivated vaccine.