| Background Arboviruses refer to a group of viruses that can cause natural infectious diseases and zoonotic diseases caused by the biting of sensitive vertebrates by blood-sucking arthropods.As an arbovirus,it must be able to multiply in arthropods and,after a certain external incubation period,transmit the virus to a new host by biting and sucking blood.Common arthropod vectors that can transmit diseases are mosquitoes,ticks,sand flies,midges,gadflies,gnats and mites,of which mosquitoes,ticks,midges and sand flies are the most important.Among the known arboviruses,there are more than 300 species of mosquito-borne viruses transmitted exclusively by mosquitoes.They cause a serious burden of disease,including dengue fever caused by dengue virus,Japanese Encephalitis caused by Japanese Encephalitis virus,Guillain-Barre syndrome caused by Zika virus and other diseases.Therefore,diseases caused by mosquito-borne arboviruses are a great threat to human health and a public health issue of international concern.Inner Mongolia autonomous region is located in the northern border of China,the east and west long but south and north narrow,there are a more than a thousand rivers,the Yellow River within the flow and alluvial formed a hetaoplain,climate is dominated by the temperate continental monsoon climate.In summer,sunshine is abundant and rainfall is concentrated.There are mountains,plains,deserts and other landforms.A diverse environment harbors a wide variety of mosquitoes,and there may be a wide variety of arboviruses.The Inner Mongolia autonomous region was once a historical and old epidemic area of hemorrhagic fever,je and other insect-borne diseases.From 1950 to 2007,a total of 4,850 cases of je were reported,and there was an outbreak of je in the 1980 s,causing huge economic losses.Inner Mongolia autonomous region has a vast area and vast natural grassland,which is an important animal husbandry base in China.However,the transmission of arboviruses depends on vectors such as humans and livestock,and the close relationship between humans and livestock will increase the transmission rate of arboviruses.Border length and Inner Mongolia autonomous region,east longitude 126 ° 04 ',the west and the east longitude 97 ° 12 ',across 28 ° 52 ',longitude things straight line distance of more than 2400 km,and Mongolia,the Russian federation and China ningxia,shanxi,hebei and other eight provinces border,which means that the arboviruses in the Inner Mongolia autonomous region to the border region around the widespread,could become a local arboviruses foci,and insect-borne virus spread in our country and abroad arboviruses to enter "port",along with the development of local tourism trade,regional countries as well as the personnel flow,But so far only Tahyna virus,Banna virus and culex pipiens pallens virus have been found in the 2007-2008 arbovirus survey.No mosquito specimens collected from investigation and systemic arboviruses investigation and study,for the sake of arbovirus species and distribution of Inner Mongolia autonomous region have a more comprehensive understanding,to master the local mosquitoes and gnats virus types and prevalence,this study in 2014,2017,2018,3 years in Inner Mongolia autonomous region 5 counties(banners)system of specimen and arboviruses mosquitoes and gnats research.Objective To understand the species and density of mosquitoes and midges in summer in parts of Inner Mongolia Autonomous Region,and to find out the arboviruses carried by the main blood sucking insects(mosquitoes and midges).The results of this study provide basic data for the prevention and control of human and animal diseases transmitted by local mosquitoes and midges.Methods Mosquitoes and midges were collected from houses and feeding pens,such as pigsties,and cowsheds,in July and August 2014,2017 and 2018 in the Inner Mongolia Autonomous Region,five counties.Morphological classification of the collected specimens under ice bath conditions,according to the collection environment and mosquitoes information to number registration(50-100 mosquitoes per pool,500-1000 midges per pool).Store in liquid nitrogen and transfer to the laboratory for identification immediately.Specimens were ground and centrifuged in the laboratory,and the supernatant was inoculated in parallel with BHK-21 cells(Golden hamster kidney cells)and C6/36 cells(Aedes albopictus eggs cells)for virus isolation.When the cell has a pathological effect(CPE),the virus solution is collected.The molecular biology method is used to identify the positive isolate,and the homologous analysis and molecular genetic phylogenetic analysis of the viral genome nucleotide sequence are performed using various softwares.Results A total of 24,240 mosquitoes(Culex pipiens pallens,Aedes aegypti,Aedes aegypti aedes dorsi,and aedes punctatus)belonging to 2 genera and 3 species were collected in Inner Mongolia autonomous region from July to August 2014,2017 and 2018,and 17,110 midges were collected.Culex pipiens pallens and Aedes dorsalis are local dominant mosquito species,accounting for 64.4%(15600/24240)and 33.5%(8120/24240)of the total mosquito collection,respectively.A total of 223 pools of mosquito and midges specimens were ground.After routine treatment in the laboratory,BHK-21 cells and C6/36 cells were inoculated in parallel,and 4 strains of virus isolates which could be stably passaged were obtained.Molecular biological detection and identification showed that 1 strain of virus was Getah virus,3 strains were Densonucleosis Virus,and no virus isolate was obtained from midges specimen.Five positive results were obtained by using 11 generation-specific and species specific primers for virus gene amplification in 223 pools of specimens.After molecular biological identification,one of them was Getah virus,and three of them were Densonucleosis virus,one is JE virus.The JEV sequence is a genotype I type JEV.It is closely related to the SXYC1523 virus strain in the NS4 b and NS5 gene segments.The Getah virus is closely related to GS10-2 on the E2 gene,and the homology of nucleotide(amino acid)sequence of E2 gene segment with Mongolian isolates(LEIV17741MPR)was 98.6%(99.8%).Conclusion In the summer of 2014,2017 and 2018,this study collected a large number of mosquitoes and midges in the natural environment of 5 counties in Inner Mongolia Autonomous Region of China.Three species of mosquitoes were collected in 5 counties of Inner Mongolia Autonomous Region and Culex pipiens pallens is the dominant species.4 strains of virus isolates that can be stably passaged were isolated from the mosquito samples in the above areas.The Getah virus was isolated from the mosquito specimens collected in Dengkou County.This is the first time that China has isolated the Getah virus in Inner Mongolia and it has important epidemiological significance.3 strains Densonucleosis virus were also isolated,which is consistent with the results of the Densonucleosis virus isolated by Cao Yuqi and others in Inner Mongolia in 2008,suggesting that there may be a circulation of Densonucleosis virus in nature.One JEV was detected in mosquito specimens in Wuyuan County.This is the first time that JEV has been detected in mosquito specimens in Inner Mongolia,suggesting that there may be a circulation of Japanese encephalitis virus in nature.The discovery of these viruses,especially Getah virus and JEV,poses new challenges to the prevention and control of human and animal diseases caused by mosquito-borne viruses not only in Inner Mongolia,but also in the Mongolian plateau region and inland China. |
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