Isolation, Identification Of Riemerella Anatipestifer And Pathogenicity Observation On Duckling

The Rimerella anatipestifer disease is an acute or chronic septic disease occuring in ducklings.It is one of the most seriously infectious diseases in the duck industry throughout the world, and aslo in our country. After invading in the host, the Rimerella anatipestifer can result in polyserositis, mainly manifested as Pericarditis, Periheptosis and air sacculitis, accompanied with different degrees of pathological damage in other tissues and organs.Different stains of the same serotypes have different virulence.In this study, a Rimerella Anatipestifer serotypel was isolated and identificated from duck samples with serositis in Wuhan city, at the same time its drug resistance and virulence were studied. The research contents are as follows:1 By the serum agglutination test and PCR identification, a Rimerella anatipestifer serotypel was isolated and identificated from a duck samples with serositis in Wuhan city. The16S rRNA sequencing result showed that there were some point-mutations in conserved domain.2 The duplication of animal model:The 20 days old Cherry Valley ducks were infected with 3×108 CFU bactarial solution through flipper injection. The typical serositis in ducks which was caused by the bacteria could be found and the couse of disease would last 2-4 days.The ducks began to show lassitude, impaired appetite, and yellowish green sparse feces at 12h post infection(h.p.i);a few of infected ducks died at 24 h.p.i;the number of dead ducks reached at the peack at 2-3 days post infection(d.p.i);4 d.p.i, the mortality rate decreased, but the clinical symptoms were still obvious;5 d.p.i, there was not death duck any more, and the clinical symptoms relieved, however, the growth of ducks was inhibited.3 20 days old Cherry Valley ducks were respectively infected with two different Rimerella anatipestifer strains of the same serotypes in half lethal dose through flipper injection,which were isolated from different areas.The animals of each group including experimental group and control group were dissected in different time points respectively to observe the damage of tissues and organs caused by these two strains.The results showed that aithough these two strains both could cause obviously typical pathological changes, such as serositis, but there are differences between them. One difference was the different time points of the symptoms occurrence, the other was the different tissues damages in same timepoints. There was no obviously phathological damage in control group. 4 The distribution of 5-hydroxytryptamine in infected ducks were observed by the method of immunohistochemistry.The results showed that the 5-hydroxytryptamine positive cells in infected ducks mainly distributed in organs full of blood vessels, such as perivascular and lymphoidregion.The number of 5-HT positive cells was significantly higher than control group.The result indicated that the 5-hydroxytryptamine involved in the course of Rimerella Anatipestifer infection.