Investigation And Genetic Evolution Of Pathogens Carried By Rodents And Ticks In Some Areas Of Inner Mongolia

Objective: Emerging infectious diseases have become an important public health problem in the world today,posing a serious threat to the whole society and causing huge economic losses.Rodents have a wide variety of species,wide distribution,strong reproduction ability,and are closely related to human life,capable of carrying a variety of pathogens.Inner Mongolia has a vast area and developed animal husbandry.Therefore,it is of great epidemiological significance to further explore the situation of pathogens carried by rodents in this area.At the same time,ticks are the host and vector of many zoonotic diseases,including a variety of viruses,bacteria,parasites,such as Rickettsia,Anaplasma,Ehrlichia,Bartonella,etc.In this study,bacterial pathogens carried by rodents and ticks in some areas of Inner Mongolia were investigated and their genetic evolution was analyzed.Methods: The DNA of rodent and tick tissue samples was extracted,and the obligate intracellular parasitic bacteria carried by rodent and tick were detected by polymerase chain reaction(PCR).The species of pathogens were determined by sequence analysis and evolutionary tree analysis.Specific primers glt A,fts Z,16S～23S r RNA and gro EL were used to detect Rickettsia,Ehrilichia and Bartonella in rodents.Specific primers 16 S r RNA,gro EL and glt A were used for the detection of Rickettsia,Anplasma and Ehrilichia.Results: A total of 359 rodent tissue samples were collected,including 314 rodents from Siziwang Banner and 45 rodents from Arukerqin Banner.The 359 rodents were divided into 5 families,9 genera and 10 species of rodents.(1)In 359 rodents,the positive rate was 1.1%.The positive rate was 0.96%(3/314)in rodents from Siziwang Banner and 2.2%(1/45)in rodents from Alukorqin Banner.The amplified Ehrilichia sequences are very different from those reported so far.Forming a sequences branch of the evolutionary tree,which is a new Ehrilichia species.(2)The positive rate of Bartonella was 47.27%(52/110)in 110 rodent in Siziwang Banner.Bartonella species carried by rodents in Inner Mongolia are very rich,and some species are closely related to known pathogens such as B.grahamii,which may infect humans.The positions of key genes in glt A,fts Z and ITS in the evolutionary tree of all strains are basically the same,which their gro EL genes are not.It is possible that gro EL gene has relatively frequent recombination and mutation.The amplified Bartonella sequences are very different from those reported so far,which may be a new species of Bartonella.(3)A total of 76 ticks were collected in Siziwang Banner and Tumote Left Banner,Inner Mongolia.The positive rates of Rickettsia raoultii,anplasmosis and Ehrilichia were 10.5%(8/76),0%(0/76)and 0%(0/76),respectively,There is some prevalence and genetic diversity.Based on 16 S sequence and glt A sequence,Rickettsia LIoyd detected in Siziwang Qi had certain differences in nucleic acid,which could be divided into two different clades,indicating that Rickettsia LIoyd may have long-term evolution in this region.Meanwhile,no differences were found in all the gro EL genes detected.indicating that Rickettsia pathogens in Inner Mongolia were transmitted in ticks.Conclusion: In this study,Ehrilichia were detected from rodents in Siziwang Banner and Alukolqin Banner in Inner Mongolia,and the sequence was very different from the reported sequence,forming a separate branch of the evolutionary tree.Ehrlichia were rarely reported in rodents in Inner Mongolia.The geographic distribution and genetic diversity of Ehrilichia have been expanded.The Bartonella species detected in this study are very rich,not only similar to the sequences that have been reported Bartonella,but also individual strains with great differences from known sequences,which may be new species of Bartonella.In addition,it was found that gro EL gene had more frequent recombination and mutation than other genes.This discovery adds to the understanding of the diversity of Bartonella pathogens.Rickettsia raoultii has been detected in ticks in Siziwang Banner and Tumet Left Banner,Inner Mongolia.Rickettsia raoultii can cause serious disease in humans,and we need to pay attention to the potential threat posed by these pathogens to public health.