Preliminary Investigation On The Carriage Status Of Tick-arbovirus Virus Among The Rodents And Ticks In Parts Of Xinjiang Area

Xinjiang is in northwest of China and occupies 1/6 proportion of the country area, Which border on eight countries and five provinces in China.Many species of arthropods are distributed in Xinjiang.Mosquito and tick species are major part of arthropods, which might transmit arboviruses and cause zoonotic diseases.It is well known that Japanese Encephalitis(JEV), Dengue Fever(DEN), Tick-borne Encephalitis(TBEV), Xinjiang Hemorrhagic Fever(XHF) have been occurred epidemic in China.There are natural focuses of TBE and XHF in Xinjiang.Sindbis virus(SlNV),East Enquine Encephalitis vims(EEEV),West Enquine Encephalitis virus(WEEV) and some other arboviruses had been isolated in Xinjiang in recent years,which indicated the diversity of arboviruses in Xinjiang.However, previous research on ticks borne viruses mainly performed on Hyalomma asiaticum kozlovi in Xinjiang, and no such work on other kinds of ticks.Whether there are other tick-arbovirus and have not found a new virus and foci in the Xinjiang are subject to further investigation. In this paper, ticks and mice were collected from some regions of Xinjiang, and viruses were isolated and identified by molecular methods.The design of our study was to improve our knowledge on the distribution of arboviruses in Xinjiang, which is important to viral disease control and prevention in Xinjiang.The main results of this study were as follows: 1.Preliminary detection on the carriage virus status among the rodents in XinjiangA total of 210 rodents were collected from in Xinjiang Jimsar County, Turpan, Buerjin and Ruoqiang in 2013. Their liver, spleen, lung organs were used for detecting arboviruses nucleic acid by RT-PCR. Primer of 10 kinds of virus including Hantan virus, Japanese encephalitis virus, West Nile virus, cytomegalo virus, tick borne encephalitis virus, avian influenza virus and Xinjiang Hemorrhagic Fever virus(XHFV) S fragments and thrombocytopenia syndrome bunyavirus(SFTSV) S fragments, were designed and used to amplificating the specific nucleic acid. 210 rodents were divided into 78 groups. The results showed that 50 groups were CCHFV S fragment positive, and 10 groups were SFTSV S fragment positive. Therefore, from now on we focus our research on molecular epidemiology survey and virus isolation of CCHFV and SFTSV among ticks and rodents in Xinjiang. 2. Molecular epidemiology investigation of SFTSV among ticks and mice in Xinjiang and isolation of a new virusA total of 14726 Dermacentor nuttalli at Wusu gurt area, and A total of 1277 Hyalomma asiaticum at Qiemo, Tumushuker, Minfeng, Yutian, Yuli and Cele were collected the southern border of Xinjiang in 2014. In order to analysis weather they carry with SFTSV and to obtain the whole genome nucleic acid sequences, After ticks were divided into 68 groups, the specific nucleic acid of SFTSV S fragment were detected by RT-PCR. The 5 of 67 groups Dermacentor nuttalli were SFTSV S gene segment positive, then positive samples were used for virus isolation. Vero cell inoculated with 5 PCR-position pools, respectively, showed cytopathic effect(CPE). Then the presense of the virus was confirmed by RT-PCR at each passage. The cells(passages) were prapared for electron microscope(EM) and indirect immune fluorescence(IFA) detection. The results indicated that we succeed in isolating one virus strain. The virus strain can react with polyantibody of SFTSV recombinant nucleoprotein. EM phoograph showed spherical particles about 80 nm indiameter. The whole genome sequence of this virus were obtained, and the homology and phylogenetic trees were analysis with DNAstar and MEGA 5.05 software. Its genome have S, M and L three gene fragments, size with 1744, 3371 and 6366 nucleotides, respectively. Compared with nucleic acid sequence of S, M and L fragments of other prevalent SFTSV strains in China, the similarity of that was 74%, 72% and 75-76%, respectively. However, they have little difference with other related sequence of sandfly fever virus. The phylogenetic tree analysis showed that this virus and sandfly fever virus are belong to the same evolutionary branch, prompted that this virus belongs to the bunyavirus Phlebovirus. So, it is a novel virus and tentatively designated as ―Guerto virvs‖.To sum up, this is the first time that we found the new virus which belongs to the Bunyaviridae phlebovirus in Wusu Guerto mountains of Xinjiang. This virus is different from other known strains(JQ341190), it is indicated that Dermacentor nuttalli may be is another natural host of bunyavirus, and Xinjiang gurt mountain may be is the pathogen foci to SFTSV.Molecular epidemiology investigation and isolation of SFTSV from mice in Xinjiang were detected. The specific nucleic acid of SFTSV S, M, L fragments among 7 kinds of rodents of 5 counties in Xinjiang were tested by RT-PCR and analysis by using DNAstar and MEGA 5.05 software for homology and phylogenetic analysis. The results showed the 28 groups from 78 groups of rats have SFTSV nucleic acid positive. Compared with the other regions’ s SFTSV strains, S, M and L nucleic acid fragments sequence have very high homology and the similarity. They have a very high correlation with the other representative SFTSV which root in ticks and human, however, have very different from sandfly fever virus which belongs to Bunyaviridae virus. It is may indicate that Meriones meridianus is another natural host of SFTSV. 3. Molecular epidemiology investigation and isolation of XHFV among ticks and rodents in XinjiangThe nucleic acid of XHFV-S and XHFV-L among ticks and rodents in Xinjiang were detected by using the RT-PCR, The results showed one group of XHFV-S gene positive samples from D. nuttalli at Wusu gurt area, 50 groups of CCHFV S gene positive samples, and two groups XHFV-L gene positive samples from 78 group rats in nostudyrthern and souththern Xinjiang were found. The XHFV-L gene positive samples were used for vital isolating in rats intracerebral inoculation. The neonatal rats by this ways of virus inoculation showed increacing degeneration, The presense of nucleic acid of virus in the brain tissue from Meriones meridianus were conformed by RT-PCR. We speculate that XHFV infection exist in Wusu region of northern Xinjiang. It is for the first time that D. nuttalli and M. meridianus infected with XHFV were confirmed. The results showed the cycle spread of the XHFV may be expanded, and provide information for the prevention and control of XHFV in Xinjiang.In conclution, the natural infection pathogens of arboviruses were detected in rats and ticks in part regions of Xinjiang in 2013 and 2014, Guertu virus, a novel tick-borns virus was isolated and characteried, indicating its potential criculatal nature in Wusu area of Xinjiang. It is the first time that D. nuttalli and M. meridianus infected with SFTSV and XHFV were confirmed. It is likeiy to be a popular area of Guertu virus in Wusu region. This results showed that it is benefit for riching the arbovirus species in Xinjiang and good for understanding the local infectious diseases and provide the data for prevention and control of such disease.