Studies On The Characreristics Of Riemerella Anatipestifer

The infection of Riemerella anatipestifer (RA) is one of the most important diseases in duck. The disease occurs as an acute or chronic septicemia, characterized by fibrinous pericarditis, parahepatitis, air sacculitis, meningitis, caseous salpingitis, arthritis, and conjunctivitis.A strain of suspected Riemerella anatipestifer, RAf 104, was isolated from healthy duck. The culture character, colonies observed, serotype and 16s rDNA identification showed that RAf 104 strain was identified to be serotype 1 Riemerella anatipestifer. Inoculation test to duck embryo and challenge test to non-immune duck showed the RAf 104 strain was low pathogenic Riemerella anatipestifer.In order to find Pathogenic factor of Riemerella anatipestifer. We analyse the outer membrane protein, OmpA gene, CAM gene of RAf 104 and passage in duck embryo strains RAf 104m6, RAf 104m15, compared with the virulent strain.Result of the tests as follows:1.Challenge test to non-immune duck showed that Cherry Valley duck was more sentive than Muscovy duck at RAf104 passage.2 . By SDS-PAGE analysis, RA 1 outer membrane proteins composed of 13 peptide, molecular weight size was 20 - 100 Ku. The outer membrane proteins of RAf 104, RAf 104m6, RAf 104m15 strains compare with the other strains, had one less band. It's molecular weight was 23.89 KD.3 .OmpA (Outer membrane Protein A)gene sequence homology of Riemerella anatipestifer strain RAf 104 with the other strains between 89.3%-90.6%;With lowest homology to RAf 39, 89.3%.It showed that the OmpA gene of pathogenic and non-pathogenic Riemerella anatipestifer had difference.And the difference possible contributed to virulence factors. The OmpA gene of RAf 104m6, RAf 104m15 had not changed. The OmpA antigenicity of RAf104 had not different from RAf 39. RAf 104m6, RAf 104m15 had the same OmpA antigenicity with RAf 104.4 .CAM gene homology of non-pathogenic Riemerella anatipestifer strain RAf104 with the other strains 95.3% - 96.7%, amino acid homology were 97.7% - 98%. It showed that CAM gene of strain RAf 104 had little difference with the other strains. The pathogenic of strain RAf 104 had nothing to do with CAM. The CAM gene sequence of strains RAf 104m6, RAf 104m15 did not change.