云南省鼠疫偶然宿主树鼩中鼠疫噬菌体的分离及流行病学意义

目的 调查云南省部分鼠疫疫源地鼠疫偶然宿主树鼩肠道中携带能裂解鼠疫菌的噬菌体的状况,并探讨其流行病学意义。方法 在云南省8个市/县（弥勒市、弥渡县、宜良县、梁河县、元江县、玉龙县、文山市及临沧市）捕获树鼩,采集其盲肠标本,以鼠疫菌疫苗株EV76为饲养菌,采用双层平板法分离噬菌体,电镜观察形态,并通过宿主谱检测其宿主特异性。结果 本次调查在8个疫点捕获到29只树鼩,其中在2个捕获点分别捕获的2只树鼩中分离到2株鼠疫噬菌体,分离率为6.90%;初次分离到这些鼠疫噬菌体时,其噬斑在双层平板上表现为大噬斑（直径2.5~3.5 mm）及中等噬斑（直径约1.0 mm）两种,噬菌斑透亮,边缘清晰;从形态上看,此次分离出的2株噬菌体均为肌尾病毒科噬菌体。通过宿主谱测定结果可知,2株噬菌体均具有一定的宿主谱宽度。噬菌体WSS44对1株鼠疫菌疫苗株EV76、5株云南鼠疫耶尔森菌、1株福氏志贺菌2a型及1株福氏志贺菌X变种裂解结果均较好,而噬菌体MLS302对鼠疫菌疫苗株EV76及5株云南鼠疫耶尔森菌有较好的裂解结果。结论 云南省鼠疫疫源地的偶然宿主树鼩中存在鼠疫噬菌体,树鼩作为鼠疫的偶然宿主,在鼠疫微生态中的作用值得进一步探讨。

Isolating and its epidemiological significance of Yersinia pestis bacteriophage from tree shrew,the occasional host of plague in Yunnan

Objective To investigate the status of phages carrying plague phage cleavage in the intestinal tract of tree shrews,the accidental host of plague,in some plague foci in Yunnan Province,and explore its epidemiological significance.Methods Tree shrews were captured in 8 cities/counties(Mile City,Midu County,Yiliang County,Lianghe County,Yuanjiang County,Yulong County,Wenshan City and Lincang City)of Yunnan Province,and their cecum specimens were collected.Yersinia pestis vaccine strain EV76 was used as feeding bacteria.Bacteriophages were isolated by double-layer plate method,and their morphology was observed by electron microscope scanning,and their host specificity was detected by host spectrum.Results In this investigation,29 tree shrews were captured in 8 epidemic spots,and 2 plague phages were isolated from 2 tree shrews in 2 captured spots,with an isolation rate of 6.90%.When these plague phages were isolated for the first time,their plaques showed two kinds of plaques on the double-layer plate:large plaques(diameter about 2.5-3.5 mm)and medium plaques(diameter about 1.0 mm),with clear plaques and clear edges.From the morphological point of view,the two phages isolated this time were both Myoviridae phages.According to the host spectrum measurement results,the two phages isolated this time all had certain host spectrum width.The lysis results of 1 strain of Yersinia pestis vaccine EV76,5 strains of Yersinia pestis from Yunnan,1 strain of Shigella f.2a and 1 strain of Shigella f.X were all good.And the results of lysis of Yersinia pestis by MLS302 vaccine strain EV76 and 5 strains of Yersinia pestis in Yunnan were good.Conclusion Yersinia pestis phages exist in tree shrews,the accidental host of plague in Yunnan Province.As the accidental host of plague,the role of tree shrews in plague microecology deserves further discussion.