| Goose parvovirus(GPV),also known as Gosling plague,is an acute or subacute,highly infectious disease that seriously threatens goslings and Muscovy ducks.It is characterized by intestinal embolism.Goose reovirus(GRV),also known as "goose hemorrhagic necrotic hepatitis",mainly affects 2~3 week old goslings.The main pathological changes of infected gooses are liver and spleen necrosis,pancreatic bleeding,kidney Necrosis and so on.These two viruses are usually mixed infections,with rapid onset and high mortality.In this study,GPV and GRV strains were isolated and identified,and a goose small-reovirus inactivated vaccine was preliminarily developed.The immunological efficacy of the vaccine was evaluated through biological techniques such as antibody level detection.1.Separation and identification of GPV and GRVIn this study,the pathogens suspected of having GPV and GRV pathogens collected in the laboratory were isolated and identified,and were named GPV strain(AHDY strain)and GRV strain(JSXZ strain),respectively.The above two strains were sequenced and analyzed,and animal regression tests were performed.Sequence homology alignment and evolutionary tree construction of VP3 gene of AHDY isolate,?C gene of JSXZ isolate and corresponding reference strain were performed by DNAStar software.The results showed that the AHDY isolate had more than 92.1% homology with the GPV reference strain isolated in recent years,and was on a different branch from the MDPV reference strain,with homology between 74.6% and 80.4%.The nucleotide sequence of JSXZ isolate has high homology with waterfowlderived reovirus,which can reach 95.9%~98.0%,while its homology with chicken-derived reovirus is only 42.9% ~46.6%.The JSXZ isolate has a closer genetic relationship with waterfowl-derived reovirus and a relatively far genetic relationship with chicken reovirus.Animal regression tests have shown that healthy goslings at 2 weeks of age infected with the above two strains can show clinical symptoms and post-mortem changes consistent with naturally occurring cases,respectively.2.Preliminary development of GPV and GRV combined inactivated vaccines and immune efficacy testsGPV and GRV seed poisons were extensively propagated and tested for virulence.The above two dialysis-concentrated antigen solutions were mixed in equal volumes,mixed with Tween-80 at a ratio of 96: 4,and emulsified at an oil-water ratio of 2: 1 to prepare a goose micro-reovirus inactivated vaccine The results of managerial traits,safety,and shelf life tests showed that it complies with the oil emulsion emulsion inactivated vaccine preparation standards.In order to evaluate the immune efficacy of the trial-manufactured dual inactivated vaccine,the vaccine was inoculated to non-immunized breeding geese,and its minimum immunization dose and duration of immunization were monitored.The results of the minimum immunization dose showed that within a certain range,the serum antibody levels of GPV and GRV were positively correlated with the immunization dose,and their antibody levels also gradually increased with the extension of the immunization time.When the geese were immunized with 0.8mL / head,the serum antibodies of GPV and GRV could rise above the threshold of negtive and postive by 2 weeks after immunization,and the antibody level in the 1mL immunization dose group was higher.The results of the duration of immunization test showed that the serum antibody level of GPV rose to a high level 3 weeks after immunization,and rose to the highest level 4 weeks after immunization,and remained positive until 8 weeks after the immunization was monitored;GRV serum antibody levels were 3 weeks after immunization it rose to a higher level,reached a peak at 5 weeks after immunization,serum antibody was positive at 7 weeks after immunization,and was below the threshold of negtive and postive at 8 weeks after immunization.In conclusion,the serum antibody levels of GPV and GRV lasted at least 7 weeks at 0.8 mL / head of immunized breeding geese.The results showed that the double vaccine immunized breeding geese developed in this study had good immunogenicity,which provided a certain theoretical basis for further research on the bivalent inactivated vaccine. |
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