Study On Inactivated Vaccine Against Duck Infectious Seriositis And Colibacillosis

Duck infectious serositis is one the most common bacterial disease of ducks.It is caused by Riemerella anatipestifer(RA)infection.Ducklings of all ages can be infected by R.anatipestifer all ages,and the morbidity is very high,with acute death and neurological symptoms.Necropsy symptoms are characterized by fibrinous pericarditis,glissonitis,airbag inflammation,and meningitis.The clinical symptoms of diseases caused by Escherichia coli are similar to those of infectious serositis.It is difficult to distinguish by on-site diagnosis.Laboratory diagnosis is needed to differentiate these two diseases.Riemerella anatipestifer and colibacillosis are the major influent bacterial disease which have a great damage to the duck industry.Drug control and vaccine immunization are important measures to control these diseases.With the restriction of antibiotics use and even prohibition,the incidence of these two diseases is more frequency,vaccination is the most economical and labor-saving way.So the development of effective vaccine is the trend.These diseases occur in commercial meat ducks earlier,at the earliest age of 2 weeks,and the slaughter time for meat ducks is about 40 days.The development of vaccines with early antibody formation,good absorption and high protection efficiency can meet the needs of the market.53 strains of Riemerella anatipestifer were isolated from Shandong and other places,and identified serotypes.28 strains were identified as dominant serotypes type1(52.8%);55 strains of Escherichia coli were isolated and serotypes were identified to identify 29 strains as dominant serotypes O78 type,accounting for 52.7%.Duck virulence tests were carried out on all strains of Riemerella anatipestifer type 1 and E.coli O78,respectively,and finally the strongest virulence strains were selected as the vaccine strains.The duck Riemerella anatipestifer type 1 QL-DZ11 strain and the Escherichia coli O78 type QL-WF04 strain were fermented and cultured to prepare inactivated vaccine with aluminum gel adjuvant.The vaccine was routinely tested,and the duck safety test and efficacy test were carried out.The vaccine was finally determined to besafe and effective for ducks.The 1 day old meat duck was injected subcutaneously into the neck of 0.2 mL.After 14 days,antibodies were produced,which could effectively protect the ducks from the challenge of QL-DZ11 and QL-WF04.The protection rate was reach up to 90%.The vaccine is characterized by early immunization,rapid antibody formation,one-day-age immunization,and antibody formation two weeks later,effectively overcoming the defect of other vaccines,which vaccination at 10-day-age,and producing antibodies after three weeks.Another feature is that the use of aluminum gel adjuvant has a good absorption effect and overcomes the disadvantage that the absorption difference of white oil adjuvant affects the quality of the duck carcass.