biostudies-literatureHuang MSichuan Veterinary Medicine and Drug Innovation Group of China Agricultural Research SystemSichuan Province Science and Technology Support ProgramNational Natural Science Foundation of ChinaMinistry of Oceans and Fisheries102450https://www.ebi.ac.uk/biostudies/studies/S-EPMC9841290biostudies-literatureUnknown102(3)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 Poultry scienceEvaluation of the immunoprotection efficacy of Riemerella anatipestifer fur-deficient mutant as an attenuated vaccine.PMC9841290SCCXTD-2020-18320728252020YJ0344Liu JMao SLiu MHuang JCheng AHuang MTian BZhang SZhu DZhao XWang MGao QJia RSun DYang QOu XChen SWu YfalseEvaluation of the immunoprotection efficacy of Riemerella anatipestifer fur-deficient mutant as an attenuated vaccine.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 2022-01-01T00:00:00Z2022 Dec2025-04-26T10:00:25.052Z2025-04-06T13:11:08.286ZS-EPMC98412903662109910.1016/j.psj.2022.102450