用斑马鱼检测猪链球菌2型的致病力

 【目的】猪链球菌2型（Streptococcus suis type 2，SS2）菌株致病力各异，以斑马鱼为实验动物，建立了较为简便可靠的SS2致病力检测方法。【方法】选用1 005尾AB系斑马鱼（Danio rerio）以检测SS2不同分离株的致病力。检测8株基因型均为mrp+ef+、对猪有致病力的SS2菌株。【结果】结果斑马鱼接种菌株12 h后呈败血症病变，96 h内对斑马鱼的半数致死量（LD50）在5.36×103至5.01×104 cfu之间。上述接种菌株的斑马鱼均从体内重新分离到接种菌。同时检测1株基因型为mrp-ef-、对猪无致病力的SS2菌株，斑马鱼接种后96 h内不表现任何病变，亦不出现死亡，对斑马鱼的LD50>106 cfu。SS2有毒力株和无毒力株对斑马鱼的LD50差异极显著（P＜0.01）。【结论】斑马鱼可作为研究猪链球菌2型菌株感染的动物模型。

Virulence Detection of Streptococcus suis Type 2 in Zebrafish

Zebrafish (Danio rerio) is a new infection model for studying mammal pathogens. 1 005 80-day-old AB line inbred zebrafish were grouped and infected intraperitoneally with 8 highly virulent strains for pigs（mrp+ef+）. The 50% lethal dose(LD50) were in the range of 5.36×103cfu to 5.01×104 cfu1 at 96 h. The SS2 strains which highly virulent for pigs also caused high morbidity and mortality in zebrafish. Acute septicemia were observed in inoculated fish. The bacteria inoculated could be reisolated from the organs of the fish. 1 strain avirulent for pigs（mrp - ef -）was also inoculated but not lethal for fish, and its LD50 was >106 cfu. There is significant difference between the LD50 of SS2 virulent strains and avirulent one(p<0.01). It concludes that zebrafish will be useful for further research of SS2 infection as an new animal model.