Isolation And Identification Of Haemophilus Parasuis And Preparation Of Inactivated Vaccine

To identify the pathogens and biological characteristics of suspected H.parasuis caused by some large-scale pig farms in northern Xinjiang.Methods: Collecting materials from large-scale pig farms in different regions,including lungs,lymph nodes and joint effusions;selecting TSA medium culture,using 10% CO2 facultative anaerobic conditions to separate bacteria,according to the bacteria The primers were designed by16 S rRNA,and the isolates were identified by PCR.The culture,physiological and biochemical,serological and drug susceptibility characteristics were observed.Finally,the pathogenicity of the isolates to mice was observed.In order to improve the culture efficiency of the candidate strains,the growth characteristics of the candidate strains were mastered,which provided a theoretical basis for the preparation of vaccine strains.In this experiment,a live bacterial count method based on continuous measurement of OD value was selected,and the candidate strain was inoculated on TSB medium and cultured in 10% CO2,and the OD600 value of the strain was measured.In view of the large number of serotypes of Haemophilus parasuis,commercial vaccines have not yet been fully covered.In this experiment,strains with different serotypes were used as candidate strains,and expanded culture was carried out to prepare bacterial inactivated vaccines,and the physical properties,safety and immune protection of the vaccine were evaluated.Results: A total of 31 isolates were isolated from 174 samples.Their physiological,biochemical,culture and molecular characteristics were consistent with the characteristics of Haemophilus parasuis;and the serotypes of the isolates included 1,4,5,and 12 The resistance rates of isolates of Haemophilus parasuis to gentamicin,sulfisoxazole,oxytetracycline,cefotaxime,lincomycin and florfenicol were: 35% 44%,26%,11%,48%,and 21% provide a theoretical basis for further control of Haemophilus parasuis in the region;results from mouse infection experiments show: 67% of HPS isolates Strong disease,can lead to the death of experimental mice;the growth curve of the isolate HZG-6 showed that the OD600 value of the isolate HZG-6 increased rapidly within 16 ~ 21 hours,and at 21 h The maximum is reached and then decreases.The results revealed that the optimal time for the bacteria to be expanded as a candidate for vaccine was 21 h after culture.Three isolates of different serotypes,HZG-6(type 5),HZG-11(type 1)and HZG-26(type 12),were screened to prepare a trivalent inactivated vaccine of Haemophilus parasuis.The physical properties and safety of the vaccine were tested.The results showed that the traits were good.The antibody values before and after immunization of the vaccine showed significant changes,and the vaccine had a certain protection rate.Conclusion: A total of 31 Haemophilus parasuis isolates were isolated in this study.Among them,81% of the strains were sensitive to ciprofloxacin,lomefloxacin and cephalosporins,and the prepared trivalent bacterial inactivated vaccine had a certain protection rate.