猪红斑丹毒丝菌制苗用菌株的筛选

为筛选出致病力强、抗原性优良、遗传性状相对纯一稳定的猪红斑丹毒丝菌制苗用菌株,对42株临床分离的猪红斑丹毒丝菌进行筛选,通过小鼠致死性试验确定4株受试菌株,编号为AEr9、AEr21、AEr31和AEr32。采用改良寇氏法测定受试菌株的半数致死量(LD₅₀),通过微量平板凝集和琼脂扩散试验测定反应原性,基于小鼠免疫攻毒试验测定免疫原性,并通过连续传代培养,分别对第10、20、30代受试菌株进行LD₅₀、沉淀抗体滴度和免疫保护率检测,以确定稳定性。结果显示,AEr9、AEr21、AEr31、AEr32的LD₅₀分别为845、50.3、35.5和10.1 cfu·mL^-1,微量平板凝集试验和琼脂扩散试验进一步筛选出反应原性高的菌株AEr21和AEr31。灭活全菌体免疫小鼠,均产生免疫保护力,以AEr31免疫保护力最好。细菌传10代后,两株菌毒力均出现致病力减弱的情况,第10、20、30代菌株致病力趋向于稳定,AEr21引起的兔抗猪丹毒血清沉淀抗体滴度水平更稳定。说明菌株AEr21、AEr31具备毒力强、抗原性好、遗传稳定的特性,可作为猪红斑丹毒丝菌制灭活苗用的候选菌株。

Screening of strains for inactivated vaccine of Erysipelothrix rhusiopathiae

In order to screen out appropriate Erysipelothrix rhusiopathiae vaccine strains, which had strong pathogenicity, antigenicity and excellent genetic stability, four strains named AEr9, AEr21, AEr31 and AEr32 were screened from 42 clinically isolated strains of Erysipelothrix rhusiopathiae by lethality test in mice. The half lethal dose (LD₅₀) of these strains was determined by modified Karber’s method, the reactivity was determined by microplate agglutination test and agar diffusion test, the immunogenicity was determined by immunization test in mice, and the genetic stability of the 10th, 20th, 30th generation of the tested strains was evaluated by LD₅₀, precipitation antibody titer test and inactivated total bacterial immune protection rate test in mice. The results showed that the LD₅₀ of AEr9, AEr21, AEr31 and AEr32 were 845, 50.3, 35.5 and 10.1 cfu·mL^-1, respectively. The strains AEr21 and AEr31 with high reactivity were further screened by microplate agglutination test and agar diffusion test. The immune protection test showed that the immune protection of AEr31 was the best. Pathogenicity tended to be weakened in the virulence of the two strains after 10 generations, and the pathogenicity tended to be stable on the 10th, 20th and 30th generation strains, and the level of antibody precipitation of AEr21 was more stable. The results showed that the strains AEr21 and AEr31 could be used as candidate strains for inactivated vaccine of Erysipelothrix rhusiopathiae with the characteristics of strong virulence, good antigenicity and genetic stability.