Abstract:
Objective To understand lysis spectrum and genome characteristics of Yersinia pestis bacteriophage isolated from cats, an index animal, in the plague foci in Yuanmou county of Yunnan province by the observation of its morphology to further enrich the Y. pestis bacteriophage database in Yunnan.
Methods Plague vaccine strain EV76 was used as host strain, Y. pestis bacteriophage was isolated from anal swabs of cats in Yunnan plague foci and purified by double agar plate method, and the titer was measured. Then, the morphology of the bacteriophage was observed by transmission electron microscope, and the lytic ability of the bacteriophage YMM68 on 66 test strains was observed at room temperature (about 18−22 ℃), 28 ℃ and 37 ℃ by single layer plate method. The DNA of the bacteriophage was extracted for second-generation sequencing, and the characteristics and functions of the genome were analyzed by bioinformatics software.
Results A Y. pestis bacteriophage strain was isolated and named as YMM68. This bacteriophage plaque of the Y. pestis strain was clear and uniform in size, with a diameter of 0.7−1.4 mm. The transmission electron microscope results showed that it had the head of the icosahedral and the tail of the contraction. At room temperature (18−22 ℃), 28 ℃, 37 ℃, YMM68 could lyse the tested Y. pestis and Shigella flexneri 2a. But other tested strains could not be lysed by YMM68. The genome of YMM68 was 46 902 bp in length, and the G+C content was 50%. A total of 71 proteins in the genome of YMM68 were found, which did not encode the tRNA gene, and no antibiotic resistance genes were found in the genome.
Conclusion A strain of bacteriophage of Y. pestis was isolated for the first time from cats in Yunnan province, which belonged to Myoviridae with a certain lysisbroadth. According to its lysis spectrum and genomic characteristics, we believe that YMM68 has certain potential application value.
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