我国鼠疫耶尔森菌毒力特征研究

Virulence characteristics of Yersinia pestis in China

目的 研究我国各疫源地分离的鼠疫耶尔森菌（以下简称鼠疫菌）毒力特征.方法 以1943-2012年我国11块鼠疫自然疫源地不同时间、地区、宿主、媒介体内分离的894株鼠疫菌作为研究对象.将每株菌的37℃24h培养物用灭菌生理盐水制成菌悬液,比浊后稀释为2×10^1、2×10^2、2×10^3、2× 10^4、2×10^5、2× 10^6、2×10^7、2×10^8、2×10^9个/ml,分别取0.5 ml皮下注射于小白鼠鼠鼷部,每组5只动物,分笼饲养观察14 d,动物死亡后取淋巴、肝、脾、肺、心组织进行细菌培养,以分离出鼠疫菌为特异性死亡,并计算半数致死量（LD50）.结果 894株代表性菌株中,87.36％（781/894）属于强毒菌,4.36％（39/894）为中等毒力株,8.28％（74/894）为弱毒菌;对不同生态型鼠疫菌株进行毒力比较,青藏高原喜马拉雅旱獭鼠疫自然疫源地的青藏高原型、祁连山型鼠疫菌绝大多数属于鼠疫强毒株,分别占94.42％（457/484）、93.10％（27/29）.结论 我国各鼠疫自然疫源地鼠疫菌的毒力特征以鼠疫强毒株为主.

Objective To study the toxicity of Yersinia （Y.） pestis separated from each plague foci in China.Methods Total 894 Y.pestis isolates were separated from 11 plague natural foci from 1943 to 2012 in China at different times,areas,hosts and media.Each strain＇s 37 ℃,24 h culture was made into bacteria suspension,then diluted for 2 × 10,2 × 102,2 × 103,2 × 104,2 × 105,2 × 106,2 × 107,2 × 108 and 2 ×109/ml after nephelometry; 0.5 ml bacteria suspension were injected into rat＆#39;s inguinal region by hypodermic injection; each group consist of five rats,which were observed for 14 d; after death lymphatic tissue,liver,spleen,lung and heart were dissected for bacterial culture; if Y.pestis was separated in the animals the death was treated as specific death,and the median lethal dose（LD50） was calculated.Results Among these representative 894 strains,87.36%（781/894） were velogenic strains,4.36%（39/894） were moderate ones,and 8.28%（74/894） were attenuated ones.After comparison of different ecotype strains＆#39; virulence,most of the Qinghai-Tibet Plateau strains and the Qilian Mountain strains in Qinghai-Tibet Plateau Himalayan Marmot plague foci belonged to velogenic strains,which were 94.42% （457/484）,93.10% （27/29）,respectively.Conclusion Most Y.pestis strains of each plague foci in China are velogenic.