Evaluation of the immunoprotection efficacy of Riemerella anatipestifer fur-deficient mutant as an attenuated vaccine
Mi Huang, Mafeng Liu, Jiajun Liu, Mingshu Wang, Renyong Jia, Dekang Zhu, Shun Chen, Xinxin Zhao, Qiao Yang, Ying Wu, Shaqiu Zhang, Qun Gao, Juan Huang, Xumin Ou, Sai Mao, Bin Tian, Di Sun, Anchun Cheng
Abstract
Riemerella anatipestifer (R. anatipestifer, RA) is an infectious pathogen that causes septicemia and polyserositis in ducks. Our previous studies showed that RA CH-1 ∆fur was significantly attenuated in ducklings, which highlights the potential of this strain as a live attenuated vaccine. In this study, it was shown that infection with 109 CFU of the fur mutant did not cause any clinical symptoms or significant histological lesions in 3-day-old ducklings and that the bacteria were readily cleared by the host within 3 d. Compared with the nonvaccinated group, the group inoculated with the mutant strain RA CH-1 ∆fur exhibited protection of ducklings against a high-dose (2.28 × 1010 CFU) challenge with the wild-type strain RA CH-1. Moreover, the average body weights and body weight gains of the Δfur-inoculated group were not significantly affected by the challenge. Further analysis revealed that RA CH-1 ∆fur elicited higher IgY titers and that the serum antibody levels persisted for at least 49 d after immunization. Overall, our study showed that RA CH-1 ∆fur is a safe and effective vaccine candidate that is expected to play an important role in RA CH-1 infection prevention in the duck industry.