ObjectiveTo investigate the pathogens carried by Culex pipiens pallens in Zichuan district.
MethodsCx.pipiens pallens were collected in Zichuan District during the peak period of mosquito vector activity from 2017 to 2018.The presence of ISFVs, Bunyavirus, Alphavirus and Liaoningvirus were tested using RT-PCR-based assay, followed by the sequencing of PCR products to detect the type and number of viruses carried by mosquitoes.The virus infection rates of mosquitoes were calculated by Bias-corrected maximum likelihood estimation (MLE) using the Excel add-in PooledInfRate v4 statistical software package.MEGA 7.0 software was used to construct phylogenetic tree between the nucleic acid sequences of the obtained virus NS5 gene and E gene and the known reference strains of CxFV in GenBank to determine the genotype of the virus.
ResultsCxFV was amplified from three groups (ZCB10_ A22_ 2、ZCB11_ A23_ 2、ZCC2_ A26_ 2).The overall MLE values (and 95% confidence interval) for CxFV of peak period of mospuito vector activity was 5.04 (1.35－13.78) per 1 000.No other viruses were detected.Phylogenetic analysis of NS5 gene showed that the genetic relationship between the three groups of virus and the virus strain (MG602497.1) isolated from Shanghai was the closest, with the similarity of 96.83%－97.23%.And phylogenetic analysis of E gene showed that the genetic relationship between the three groups of viruses and the virus strains (AB262759.2, AB377213.1) isolated from Tokyo, Japan was the closest, with the similarity of 97.55%－97.72%.The virus was identified as CxFV and genotype Ⅰ.
ConclusionCx.pipiens pallens carries CxFV in Zichuan district. It is imperative to carry out continuously surveillance of mosquito carryied pathogens.
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