猪链球菌9型GZ0565株体外传代的生物学稳定性

Biological stability of Streptococcus suis serotype 9 strain GZ0565 cultured in vitro

选取猪链球菌9型(SS9)GZ0565株连续传代培养至20代(S1～S20代),用API20Strep生化鉴定试剂条和全自动生化分析仪对各代次之间进行了比较鉴定。生化试验结果表明,GZ0565株传代稳定性好。以特殊品系的黑色小鼠C57BL/6作为SS9感染的动物模型,经腹腔注射接种S1、S5、S10、S15和S20代不同稀释度菌液,统计1周内小鼠的死亡数量。结果显示,攻毒后死亡的小鼠具有典型的细菌性败血症病理变化,肝及脑内可分离到革兰氏阳性球菌,短链状,绵羊血平板上呈β溶血,经PCR检测,从死亡小鼠体内分离的细菌与攻毒菌株为同一种细菌。S1、S5、S10、S15和S20代菌株对小鼠的LD50分别为3.63×108、6.03×108、2.63×109、1.45×109和8.7×1010。证明SS9GZ0565株经过20代传代培养后毒力相对稳定,可作为疫苗候选株。

Streptococcus suis serotype 9 strain GZ0565 was subcultured to 20 generations（S1-S20） .The properties of each generation were compared by combination of API 20 Strep and full automatic biochemical analyzer.The results of biochemical experiments showed that the properties of each generation remained stable.C57BL/6 mice were challenged with strain GZ0565 intraperitoneally,and septicaemia was observed in diseased mice.Gram positive bacteria with short chain could be isolated from the liver and brain of di-seased animals and β-haemolysis on sheep blood agar could be detected.The isolate bacterium from the infected mice was further confirmed as GZ0565 by PCR.One week post-infection,the 50% lethal dose（LD 50） value of strain GZ0565 of S1,S5,S10,S15,and S20 was 3.63×10 8,6.03×10 8,2.63×10 9,1.45×10 9 and 87×10 10,respectively.This suggested that the virulence strain GZ0565 remained stable after being subcultured to 20 generations,indicating that the strain GZ0565 had the potentiality to be a vaccine.