Putative Outer Membrane Protein H Affects Virulence.

causes serious contagious disease in ducks, geese, and other fowl. However, as a harmful pathogen causing significant economic losses in the poultry industry, is still poorly understood for its pathogenesis mechanisms. In a previous study, we developed an indirect ELISA method for detecting infection using B739_0832 protein, a putative outer membrane protein H (OmpH) that is conserved among different serotypes of . Although OmpH in some pathogenic bacteria, such as , has been reported as a virulence factor, it is still not clear whether B739_0832 protein contributes to the virulence of . In this study, we confirmed that B739_0832 protein in localizes to the outer membrane. We constructed a deletion mutant strain (Δ) and assayed various effects from the deletion of B739_0832. Δ0832 strain had a similar growth rate to wild-type CH-1. However, the survival rate of ducklings in 10 days after infection from Δ0832 strain was 50%, whereas no ducklings survived from wild-type infection. Furthermore, the median lethal dose (LD) of the Δ0832 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 Δ0832-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 CH-1.