Diversity,evolution And Transmission Of Jingmen Tick Virus In Ticks And Mammals

Objectives:Jingmen tick virus(JMTV)is the first discovered Jingmen virus.Its genome contains four gene segments.Two nonstructural protein genes share homology with unsegmented flavivirus,whereas the other two structural protein genes have no known homologs.In addition to Asia,JMTV is also discovered in Africa,Europe,South America and so on.Moreover,host range of the virus is expanding from ticks to rodents,cattle,dogs and even primates,especially when the nucleic acid of JMTV was detected in clinical samples from Kosovo and China,it means that the virus may be pathogenic to human beings,people should pay more attention to it.However,although JMTV has been detected in many hosts,the evolution history,transmission and the phylogenetic relationship between JMTV and its hosts need to be further explored.In addition,as a special small mammal,bat is the natural host of many pathogens of emerging or re-emerging infectious diseases and plays a key role in the evolution of many RNA viruses However,its role in the transmission and evolution of JMTV is still unclearMethods:(1)During 2012-2016,Wenzhou city in Zhejiang Province,Neixiang county in Henan Province and Anlong county in Guizhou Province were selected as monitoring sites for samples collection.Ticks,rodents,bats and cattle blood were collected in Wenzhou city of Zhejiang Province,and some bats were also sampled in Neixiang county of Henan Province and Anlong county of Guizhou Province.(2)Based on all known Jingmenviruses,two sets of primers were designed for screening JMTV and JMTV-like by nested PCR,respectively.(3)JMTVs with host and geographical representation were selected to obtain the whole genome sequences by PCR and Rapid Amplification of cDNA Ends.The diversity,transmission and evolution of this virus were identified by homology analysis,comparison of JMTV genome characteristics from different hosts and phylogenetic analysis.Furthermore,to analysis the evolutionary relationship between the viruses and their hosts,a tanglegram was generated by matching each JMTV to their associated hosts.(4)Mantel test was used to analyze which ecological factors(host and geography)were related to the formation of genetic diversity of JMTV;The online website Datamonkey was used to analyze the selection pressure of JMTV in different hostsResults:(1)A total of 104 cattle blood samples,215 ticks,216 bats and 119 rodents were collected in Wenzhou City,Zhejiang Province.JMTV was identified in 10 cattle blood samples,107 ticks,19 bats and 8 rodents.Additionally,35 JMTV positive samples were detected from 240 bats collected in Henan and Guizhou provinces According to statistics,the positive rates of JMTV in ticks,bats,rodents and cattle were 49.8%,11.8%,6.7%and 9.6%,respectively.Further identification of the species of animals showed that these positive samples contained 2 species of ticks,3 species of rodents and 11 species of bats.However,JMTV-like was not detected in these samples(2)All JMTV identified in the three provinces shared over 93%nucleotide identity and over 95%amino acid identity.The nucleotide and amino acid similarity between JMTV in ticks and mammals from Wenzhou City,Zhejiang Province were up to 93.7%-100%All viruses newly identified in this study shared high sequence similarity with known Chinese JMTVs:92.1%-99.7%at the nucleotide level and 95.1%-99.9%at the amino acid level.In addition,the similarity between JMTVs identified inside and outside of China was 76.3%-95.0%at the nucleotide level and 81.2%-99.1%at the amino acid level.(3)JMTV from different hosts shared a consistent genomic structure by comparing the characteristics of coding region and noncoding region.(4)In the phylogenetic trees,all JMTV could be further divided into two branches,and showed obvious geographic clustering in the world.At the same time,a JMTV from Trinidad and Tobago was unstable in the four phylogenetic trees,which confirmed the occurrence of gene rearrangement.In addition,the topologies of the virus and host phylogenies was obviously inconsistent,which further indicated the frequent cross-species transmission of JMTV.(5)Although JMTV showed high homology in China,it showed high genetic diversity in the world.Mantel tests suggest that the genetic diversity of JMTV is largely related to host geographic location rather than host genetic distance.(6)By selection pressure analysis,JMTV have experienced long-term purifying selection in ticks and mammals,which may be one of the reasons for its frequent cross species transmissionConclusion:(1)Bats are important host of JMTV,and may play an important role in the transmission of it.(2)The high similarity of JMTV between ticks and mammals in the same area means that the vector-borne transmission is one important way of JMTV in nature.(3)JMTV can widely spread in ticks and mammals without significant genomic changes,suggesting that JMTV may become a pathogen of emerging or re-emerging infectious diseases in the future,so it needs to be paid more attention.(4)The complex evolutionary history of JMTV is characterized by extensive genetic diversity,in situ evolution,reassortment and frequently cross-species transmission.In addition,the formation of JMTV genetic diversity is mainly related to the geographical distribution of host.