title: OmpA is a virulence factor of Riemerella anatipestifer.
abstract: Riemerella anatipestifer infection is probably the most economically important disease of farm ducks worldwide. The pathogen R. anatipestifer causes septicemia anserum exsudativa in ducks, but little is known about the molecular basis of its pathogenesis and the virulence factors involved. In this study, by deleting ompA gene from R. anatipestifer serotype 2 strain Th4, we constructed a mutant strain Th4ΔompA to investigate whether R. anatipestifer OmpA is an important virulence factor. Results showed that although the growth curve, bacterial and colony morphology of Th4ΔompA in tryptic soybean broth (TSB) or on TSB agar were similar to its parent strain Th4, the adhesion and invasion capacities of mutant strain to Vero cells were decreased significantly. Furthermore, the median lethal dose (LD(50)) of both strains was determined to measure the virulence with 10-day-old Cherry Valley ducklings. The results showed that LD(50) of Th4ΔompA mutant was >10(10) colony forming units (CFU), it was attenuated significantly in comparison with that of Th4 which LD(50) was 4.41 × 10(8) CFU. Additional analysis indicated that blood bacterial loading of ducklings infected with the Th4ΔompA mutant were much lower than those of Th4-infected ducklings. The results demonstrate that OmpA is a virulence factor of R. anatipestifer, and that it may act as an adhesin.
authors.affiliation: Shanghai Veterinary Research Institute, The Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai 200241, PR China.
authors.forename: Qinghai
authors.initials: Q
authors.lastname: Hu
authors.forename: Xiangan
authors.initials: X
authors.lastname: Han
authors.forename: Xiaojin
authors.initials: X
authors.lastname: Zhou
authors.forename: Chan
authors.initials: C
authors.lastname: Ding
authors.forename: Yinyu
authors.initials: Y
authors.lastname: Zhu
authors.forename: Shengqing
authors.initials: S
authors.lastname: Yu
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D002522:Chlorocebus aethiops; D004372:Ducks; D005260:Female; D017353:Gene Deletion; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology / Q000662:veterinary; D051379:Mice; D008807:Mice, Inbred BALB C; D011201:Poultry Diseases / Q000382:microbiology*; D060494:Riemerella / Q000235:genetics / Q000472:pathogenicity*; D014709:Vero Cells; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D001425:Bacterial Outer Membrane Proteins; D037521:Virulence Factors; C078167:OMPA outer membrane proteins