剑川野鼠鼠疫疫源地鼠疫噬菌体的分离及其流行病学意义

Isolation of Yersinia pestis phage from the Jianchuan plague foci and its epidemiological significance

目的 调查剑川野鼠鼠疫疫源地宿主动物中是否携带鼠疫噬菌体,并探讨其流行病学意义。方法 2017年1-6月采集剑川野鼠鼠疫疫源地4个曾流行过鼠疫乡镇6个自然村的鼠类标本,以鼠疫疫苗株EV76为饲养菌,采用双层平板法分离鼠疫噬菌体,并对分离结果进行流行病学分析,同时挑取部分噬菌体进行电镜扫描。结果 共获得641份标本(齐氏姬鼠334只,大绒鼠236只,其余71只),分离到9株鼠疫噬菌体,总分离率1.40%;有4个疫点(白山母村、石龙村、新松村、大庆村)分离到了鼠疫噬菌体,另外2个点(长乐村、西门社区)未分到鼠疫噬菌体;9株鼠疫噬菌体中,8株分离自齐氏姬鼠,1株自大绒鼠;初次分离这些鼠疫噬菌体时,其噬斑在双层平板上表现为大(直径～2.0 mm)、中(～1.0 mm)及小(<0.5 mm)3种噬斑;4株有代表性噬菌体皆为肌尾病毒科噬菌体。结论 剑川野鼠鼠疫疫源地中普遍存在鼠疫噬菌体,齐氏姬鼠是主要的携带宿主,所分鼠疫噬菌体为肌尾病毒科噬菌体且具有多态性,值得进一步研究。

Objective To investigate whether the rodents of Jianchuan plague foci carry Yersinia pestis phage,and to explore its epidemiologieal significance.Methods Rodent specimens were collected in 6 villages of 4 towns of Jianchuan plague loci during January to June in 2017.Vaccine strain EV76was used as breeding bacteria to phage.We isolated phage from above specimens by double-layer plate method,and the separation results were applied for epidemiological analysis.At the same time,some phages were selected for scanning electron microscope.Results A total of 9 strains of Yersinia pestis phage were isolated from 641 samples (334 of Apodemus chevrieri,236of Eothenomys miletus and 71of the others),with the total isolation rate of 1.40%.The Yersinia pestis phage was isolated in 4villages (Baishanmu Village,Shilong Village,Xinshong Village,Daqing Village),non-phage in other 2villages (Changle Village and Ximen Community).In the 9 strains of phage,8 strains were isolated from Apodemus chevrieri,1strains from Eothenomys miletus.The plaque of the phage was divided by three appearance of big (diameter about 2.0mm),middle (about 1.0mm)and small (<0.5mm).There were 4 representative bacteriophages which were all bacteriophages of the Myoviridae family.Conclusions The plague phage is common in the plague loci of the wild rat of Jianchuan.The main host of the phage is Apodemus chevrieri,and these plague phages are belong to the Myoviridae family and are polymorphic.It is worth further study.