马链球菌兽疫亚种10株国内猪源分离株对小鼠免疫效力的评价

目的近年来马链球菌兽疫亚种引起的猪链球菌病在我国造成重大损失。为评价猪源兽疫亚种分离株的抗原变异,取国内10省市分离的10株猪源兽疫亚种分离株,分别制备灭活抗原,加入弗氏完全佐剂免疫12 w龄ICR小鼠,4 w后加入弗氏不完全佐剂进行再次免疫,再次免疫2 w后分别用5 LD50同源菌株和1.6×105CFU ATCC35246株攻击。结果表明,同源菌株攻击,免疫保护率均在90%以上;而以ATCC35246攻击的异源菌免疫小鼠,免疫保护率为80%-100%。可见我国不同地区的猪源马链球菌兽疫亚种分离株的抗原性差异不大,单一菌株制备的疫苗具有应用前景。

Evaluation on the immunization potency of 10 strains of Streptococcus equi subsp. zooepidemicus of pig-orgin isolated in China

Streptococcus equi subsp.zooepidemicus can cause swine diseases,thus making substantial economic losses in recent years.To evaluate the antigenic variability among 10 strains of Streptococcus equi subsp,zooepidemicus of pig-origin isolated in China,the formalin-inactivated whole bacterial cells of these 10 local strain were immunized to inbred ICR mice of 12 weeks old with addition of the complete Freund's ajuvant(CFA),and re-immunized 4 weeks later with a similar dose of bacteria emulsified in imcomplete Freund's adjuvant.Two weeks after immunizations,the vaccinated and the control mice were all challenged intraperitoneally with 5 LD_(50) of homologeous strain and 1.6×10~(5) CFU of ATCC35246 strain.The result demonstrated that the immunization protection rate of mice challenged with the homologeous strain was above 90%,while those of mice challenged with ATCC35246 was around 80%-100%,with no significant difference.From these observations,it is evident that no great antigenic variability can be detected among these 10 local strains of S.equi subsp.zooepidemicus isolated in China,and this result would favor the use of single strain of bacteria for the preparation of vaccine.