Isolation and identification of Yersinia pestis bacteriophage from plague foci of domestic rats in Pu'er City, Yunnan

Abstract

Objective An investigation was carried out to identify the status of Yersinia pestis bacteriophage carried in the host animals in the plague foci of house mouse in Pu'er City.

Methods From November 2015 to June 2016, 9 epidemic areas were selected in Lancang County, Mojiang County and Simao District of Pu'er City, the method of mouse trap was used to capture mice with their intestinal tracts taken as specimens. Isolation of Yersinia pestis Phage with vaccine strain EV76 as host bacterium by double - layer agar plate method, Yersinia pestis bacteriophage was identified by electron microscope scanning. Meanwhile the intestinal specimens were tested for the specific gene caf1 of Yersinia pestis.

Results A total of 286 samples were collected, from which 4 strains of Yersinia pestis bacteriophage were separated, with a total separation rate of 1.40%. 4 strains of Yersinia pestis bacteriophage were separated from 3 epidemic sites, 2 strains were isolated from 226 specimens from Mengbin Village, Menglang Town, Lancang County, 1 strain was isolated from 4 specimens in Dashaba Village, Longtan Township, Mojiang County, and 1 strain was isolated from 7 specimens in Dashitou Village, Yunxian Township, Simao District. Among 4 strains of Yersinia pestis bacteriophage, 3 strains were separated from Rattus flavipectus and 1 strain was separated from Rattus steini. 4 strains of Yersinia pestis bacteriophage showed polymorphism in their bacteriophage plaque when they were separated for the first time, 2 of which were selected for electron microscopy scanning, and electron microscopy showed bacteriophages of the Myoviridae family. The caf1 test of all the intestinal specimens was negative.

Conclusion For the first time, Yersinia pestis bacteriophage was separated from the plague foci in Pu'er City. The isolated plague bacteriophages belong to the Myoviridae family and are polymorphic, thus deserving further study.

Abstract

摘要：目的 调查云南省普洱市家鼠鼠疫疫源地宿主动物中携带鼠疫噬菌体的情况，并进行鉴定 。方法2015年 11月一2016年6月在普洱市的澜沧县、墨江县及思茅区选取9个疫点，采用鼠铗法捕获老鼠，取其肠道标本；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，并对噬菌体进行电镜扫描等鉴定。同时对肠道标本进行鼠疫 菌特异基因 cf检测。 结果 共采集286份样本，从中分离到4株鼠疫噬菌体，总分离率1.40%；4株鼠疫噬菌体分离自 3个疫点，其中澜沧县勐朗镇勐宾村自226份标本中分离到2株，墨江县龙潭乡大沙坝村自4份标本中分离到1株，思茅 区云仙乡大石头村自7份标本中分离到1株;4株鼠疫噬菌体中，有3株分离自黄胸鼠，1株分离自斯氏家鼠;4株鼠疫噬 菌体初次分离时其噬斑表现出多态性，选择其中2株噬菌体进行电镜扫描，皆为肌尾病毒科噬菌体;所有肠道标本 cf 检测阴性。 结论 首次在普洱市家鼠鼠疫疫源地中分离到鼠疫噬菌体，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。