Study On The Production Technology Of Duck Infectious Serositis And Escherichia Coli Combined Inactivated Vaccine(Cz12 Strain+ Sh Strain)

Duck infectious serositis and duck colibacillosis are the two most important bacterial disease of ducks and often occur in the form of mixed infection.They aresimilar in clinical manifestation,onset age and autopsy lesions,with high morbidity and mortality.At present,drugs were used to control the disease but the effect is not satisfied due to bacterial resistance.Apparently,vaccine control is the best choice.This experiment optimize the production process of the vaccine based on the laboratory study of "the two combined inactivated vaccine of duck infectious serositis and duck colibacillosis(CZ12 strain+SH strain).The experiment is divided into four parts:culture medium screening,fermentation technology research,concentration technology research and inactivation technologyresearch.1.Culture medium screening:modified Martin broth,TB,yeast broth and P-L broth were used to culture CZ12 strain and SH strain,and the number of live bacteria in the culture medium was determined post inoculation 12h,14h,16h,16h,18h,20h,22 h and 24 h respectively.The aim of this study is to choose a easy-to-use and efficient medium for the production of the inactived vaccine.The results showed that modified Martin broth and TB were better than yeast broth and P-L broth medium,and there was no significant difference between them.On modified Martin broth,the bacteria proliferation of CZ12 strain reached the highest level at 20-24 hours post inoculation and the number of live bacteria reached 5.2×109?8.1×109 CFU/ml,SH strain reached the highest level PI 16-20 hours,and the number of live bacteria was 9.5×1010?1.4×1010 CFU/ml.Because of the low cost and simple preparation of modified Martin broth,it is the best choice.2.Fermentation technology study:the fermentation techniques of CZ12 strain and SH strain were studied in 5L fermenter and the culturing technology of two str-ains was determined.The inoculation amount was 1%,the culture medium pH value was 7.2,stir and ventilation incubation,the live bacteria number of CZ12 strain was 6.0?8.0×109CFU/ml,the number of live bacteria of Escherichia coli SH was 1.2?1.45×1010CFU/ml.3.Concentration technology study:the culture of CZ12 strain and SH strain were concentrated by ultrafiltration method and continuous centrifugation sedimentati-on method.To evaluate the feasibility of the concentration process,the physical properties,safety and immunological efficacy of the inactivated vaccine were compar-ed and the results show that both the two methods can be used as antigen concent-ration method.4.Inactivation technology study:the antigens of CZ12 strain and SH strain before and after concentration were inactivated at 37? with formaldehyde solution,0.1%,0.3%,and 0.5%respectively.The samples were taken at different times to carry outinactivation test.The results showed that the concentrated CZ12 antigen was inactivated completely with formaldehyde solution of 0.3%at 37? for 16 hours.Concentrated SH antigen was inactivated at 37? with 0.5%formaldehyde solution for 16 hours.In order to ensure the antigen can be inactivated thoroughly,the inacti-vation process of the inactivated vaccine was set as follows:formaldehyde solution was added to antigen solutions at a ratio of 0.3%(volume/volume)for CZ12 strain of Riemerella anatipestife,and 0.5%(volume/volume)for SH strain of Escheric-hia coli respectively.Inactivate at 37? for 24 hours,shake or stir every 2 hours.