Clinical Application And Protective Effect Evaluation Of Clostridium Perfringens Type A Toxoid Vaccine

Clostridium perfringens, also called Clostridium welchii, is present in the intestines of various healthy animals. when the feeding and environmental conditions changed, it can cause Clostridium perfringens disease of livestock and poultry. It can lead to rapid death of livestock and poultry, often without effective treatment before death. In recent years,Clostridium perfringens disease has caused huge economic losses to livestock industry.Clostridium perfringens type A is the main pathogenic bacteria causing rabbit diarrheal enteritis. The bacteria in the intestine produces alpha toxin and leads to the diarrhoea of rabbit.The disease is characterized by acute onset, high mortality, and not obvious treatment effect of drug after the onset. So in order to effectively prevent and control of Clostridium perfringens disease, efficient and safe toxoid vaccine is urgently needed. Using a method of specific, sensitive, and rapid indirect ELISA for the detection of large quantities of antibodies,it is the important means and method of effective detection and diagnosis of Clostridium perfringens disease. The method of ELISA is also applied to the protective effect of the vaccine evaluation and epidemiological investigations.In this study, the standard strain of Clostridium perfringens type A(NCTC528) was recovered, enriched, and produced toxin, in order to obtain a large number of ? toxin. The toxin was inactivated by formaldehyde mixed with white oil, and successfully prepared for the toxoid vaccine of Clostridium perfringens type A. Additionally, the bacteria in the culture was filtered for obtaining Exotoxin supernatant, which is extracted by saturated ammonium sulfate precipitation method. The toxin protein was used as coating antigen of indirect ELISA.Finally, indirect ELISA method for detection of exotoxin antibody was established by exploring and optimizing the reaction conditions. By this method, antibody levels in rabbits immunized with the vaccine was continuously monitored, in order to determine the minimum immune dose of vaccine and reasonable immunization program.In evaluation test of vaccine protective effect for animal experiments, the vaccine was divided into four different doses, which was firstly immunized for 28 days and 45-day-old rabbits, with 400 rabbits in each group. Through challenge protection experiment and continuous monitoring of serum antibody titers, the results show that when the antibody titer of rabbit serum reached 6.83×100 log2, the vaccine protective effect for the rabbit is better. So the minimum vaccine immune dose was ultimately determined 0.5 ml, and the protective effect is better after the second immunization.