Diagnosis Of Mixed Infection Of Clostridium Perfringens And Escherichia Coli In A Cattle Farm, Preparation Of Inactivated Vaccine And Immunization

Clostridium perfringens and Escherichia coli were isolated from the liver tissue of the dying calf with typical symptoms.The Clostridium perfringens was identified by PCR and the E.coli contained irp2 and fyua pathogenic factors.Mouse pathogenicity experiments showed that the two isolates were highly pathogenic.The results of drug susceptibility test showed that Clostridium perfringens was sensitive to erythromycin,chloramphenicol and Pioneer V,and E.coli was sensitive to enrofloxacin,cefazolin and chloramphenicol.It is diagnosed that the yak death was caused by a mixed infection of Clostridium perfringens and Escherichia coli.After treatment with sensitive drugs,the effect was obviously.Conventional methods for preparing Clostridium perfringens toxoid and E.coli double adjuvant-free and aluminum gel adjuvant and oil adjuvant inactivated vaccine,respectively.The number of experimental data show that the two-inactivated vaccine is stable and safe to use.The optimum incubation time for Clostridium perfringens and Escherichia coli was 7 h and 20 h,and the optimal detoxification condition was 0.4%formaldehyde 120 r/min 37°C 6 d and 0.4%formaldehyde 120 r/min 37°C 88 h.The mice were immunized with 0.1 mL,0.2 mL,and 0.4 mL by subcutaneous and intramuscularroutesusingtheabovethreevaccines,respectively,indirect hemagglutination and tube agglutination tests were used to detect the antibody titer of Clostridium perfringens and Escherichia coli in serum.The level of mouse-specific serum antibody in the adjuvant group was higher than that in the non-adjuvant group,and the aluminum gel adjuvant group was higher than the white oil adjuvant group;the same immune route,the same adjuvant group,with the increase of the immune dose,the specific antibody level Significantly rising.The mice were challenged with 5LD₅₀Clostridium perfringens exotoxin solution and E.coli bacterial solution on the 7th,14th and 21st day after immunization with the aluminum gel adjuvant group.The data showed that different immunization doses of mice can obtain different degrees of protection;while intramuscular injection of 0.4 mL of aluminum gel adjuvant vaccine mice,100%protection can be obtained 14 days after 1 immunization.The results showed that intramuscular injection of 0.4 mL of aluminum gel adjuvant vaccine had the best effect.InactivatedvaccineusingClostridiumperfringensandEscherichiacoli double-aluminum gel adjuvant,pre-natal 3 and 2 muscle immunizations of pregnant cows,detection of serum antibody titers of pregnant cows and calves and observation of immunity Clinical effects.The results showed that pregnant cows were better than 3 times in immunity.The prepared inactivated vaccine immunization of the aluminum-aluminum gel adjuvant can well control the epidemic of Clostridium perfringens and Escherichia coli in the cattle farm.