Gene Polymorphism Of Dominant Mosquitos In Inner Mongolia And Establishment Of West Nile Virus Detection Method

The incidence of mosquito-borne diseases is rising worldwide as a result of global climate change,worsening ecological environment,accelerated urbanization,more frequent trade between countries and faster and convenient transportation.The regions where mosquito-borne diseases are prevalent are expanding and the prevalence of the diseases is increasing.Inner Mongolia has vast grasslands,abundant water and grass,more cattle and sheep and borders Mongolia and Russia.It has long border line and its unique climate and geographical environment bring conditions boosting mosquito breeding.mosquitoes were collected from 10 sampling sites in the border regions of Hulunbuir and Xilingol League,identified to species and their genetic polymorphism were analyzed according to conservative gene.In addition,the presence of West Nile virus in mosquitoes was preliminarily tested.Method:Mosquito samples were collected from grasslands in the Hulunbuir and Xilingol League regions of Inner Mongolia between 2018 and 2019.The traditional morphological identification method was used to observe the mosquito samples under the microscope and the species were preliminarily identified.The sequence of the mitochondrial cytochrome C oxidase I gene(COI)was amplified by polymerase chain reaction(PCR).Homology analysis and genetic evolution analysis of mosquito gene sequences were performed after sequencing,the phylogenetic tree was constructed by Mega6.06 software and the phylogenetic tree was clustered with the COI genes of mosquitoes in GenBank database to determine the evolution of mosquitoes.Base composition,base substitution types at different sites,genetic distance and haplotype diversity were analyzed by relative biological software.In successive studies,TaqMan real-time quantitative PCR was used to preliminarily detect west Nile virus in mosquito samples from 10 sampling sites according to the E2 protein gene of West Nile virus.Results:Morphological and molecular analysis showed that the mosquitoes in 7 sampling regions belonged to Ochlerotatus and the mosquitoes in 3 regions belonged to Chironomus in two project regions.A total of more than 6000 mosquitoes were collected,all of which were Ochlerotatus dorsalis in Hulunbuir area,3 sampling points in Xilingol area were Ochlerotatus dorsalis,and the remaining 3 sampling points were Chironomus.Base component analysis of COI gene showed that the content of A+T was significantly higher than that of G+C.Haplotype diversity analysis showed that haplotype diversity was higher in two species and Hapl-hap4 was the common haplotype gene,which was the original haplotype gene.There was significant genetic diversity among mosquitoes in different regions.This result fully indicates that the genetic resources of mosquitoes in the project region are relatively rich.According to 33 percent of the samples,no West Nile virus has been found in mosquitoes in these two areas of Inner Mongolia.Conclusion:The Ochlerotatus dorsalis and Chironomus are the dominant species hulunbuir and xilingol of in Inner Mongolia,there are abundant genetic diversity among mosquitoes in different sampling regions.TaqMan real-time fluorescent quantitative PCR assay showed no presence of West Nile virus in mosquitoes in this region.