Study On The Biological And Genomic Characteristics Of Plague Phage Isolated From Inner Mongolia

Plague is a natural epidemic disease caused by Yersinia pestis.Plague mainly occurs among rodents,which is characterized by strong infectivity,rapid spread and high mortality.The Law of the People's Republic of China on the Prevention and Treatment of Infectious Diseases stipulates that plague is a Class A infectious disease.Y.pestis is also a kind of biological weapon,which has the possibility of bioterrorism.As a kind of bacterial virus,plague phage is parasitic on Y.pestis.The identification of Y.pestis depends on phages pecific lytic test,but it has been found that Y.pestisis resistant to the phage lysis in our work,so it is very important to isolate and identify more specific plague phages.In this study,7 strains of plague phages were isolated from 11 rat nests and 345 rat samples collected from natural foci of plague in Inner Mongolia by the method of drop and double-deck plate,and the biological characteristics of one plague phage EL0801 were studied.The results showed that the morphology of the phage EL0801 was in accordance with that of the Podoviridae.The head of the phage was a regular polyhedron with a diameter of about 51 nm and a tail length of about 10 nm.The optimal multiplicity of infection was 0.01,the incubation period of EL0801 one step growth curve was 20 min,the outbreak period was 100 min,and the lytic amount was 200 PFU/cell.The lytic host spectrum of EL0801 was narrow.Only the plague vaccine strain EV76,wild strains and individual Y.pseudotuberculosis strains were lysed,and other Yersinia strains are not lysed,which indicated that the phage had strong specificity.The genomic structure and population analysis of five phage isolates showed that four bacteriophages of Podoviridae,EL0801,HD0901,HD1001 and HD1101,were clustered in the diagnostic phage Yep-phi subgroup,while the HD0902 of Myoviridaewas closely related to Lysogenic Phage L-413C.The purpose of this study is to establish a plague phage library in our district,analyze the influence of plague phage on the biological evolution,natural preservation and plague outbreak,explore the relationship between plague and plague phage,find out the reasons for the mutual transformation between plague epidemic and rest in the micro environment,and provide research materials for predicting the occurrence of plague and trying to develop the physical therapy of plague phage.