AUTHOR=Gao Qun , Lu Shuwei , Wang Mingshu , Jia Renyong , Chen Shun , Zhu Dekang , Liu Mafeng , Zhao Xinxin , Yang Qiao , Wu Ying , Zhang Shaqiu , Huang Juan , Mao Sai , Ou Xumin , Sun Di , Tian Bin , Cheng Anchun 

TITLE=Putative Riemerella anatipestifer Outer Membrane Protein H Affects Virulence

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.708225

DOI=10.3389/fmicb.2021.708225

ISSN=1664-302X

ABSTRACT=<p><italic>Riemerella anatipestifer</italic> causes serious contagious disease in ducks, geese, and other fowl. However, as a harmful pathogen causing significant economic losses in the poultry industry, <italic>R. anatipestifer</italic> is still poorly understood for its pathogenesis mechanisms. In a previous study, we developed an indirect ELISA method for detecting <italic>R. anatipestifer</italic> infection using B739_0832 protein, a putative outer membrane protein H (OmpH) that is conserved among different serotypes of <italic>R. anatipestifer</italic>. Although OmpH in some pathogenic bacteria, such as <italic>Pasteurella</italic>, has been reported as a virulence factor, it is still not clear whether B739_0832 protein contributes to the virulence of <italic>R. anatipestifer</italic>. In this study, we confirmed that B739_0832 protein in <italic>R. anatipestifer</italic> localizes to the outer membrane. We constructed a <italic>B739_0832</italic> deletion mutant strain (Δ<italic>B739_0832</italic>) and assayed various effects from the deletion of B739_0832. Δ<italic>B739_</italic>0832 strain had a similar growth rate to wild-type <italic>R. anatipestifer</italic> CH-1. However, the survival rate of ducklings in 10 days after infection from Δ<italic>B739_</italic>0832 strain was 50%, whereas no ducklings survived from wild-type <italic>R. anatipestifer</italic> infection. Furthermore, the median lethal dose (LD<sub>50</sub>) of the Δ<italic>B739_</italic>0832 strain was approximately 150 times higher than that of the wild-type strain. Pathology examinations on infected ducklings found that, at 36 h after infection, bacterial loads in blood, liver, and brain tissues from Δ<italic>B739_</italic>0832-infected ducklings were considerably lower than those from wild-type infected ducklings. These results demonstrate that the B739_0832 protein contributes to the virulence of <italic>R. anatipestifer</italic> CH-1.</p>