Analysis Of The Genetic Evolution Of China's Newly Equine Flavivirus From 2015 To 2017

Equine hepacivirus(EqHV),Equine Pegivirus(EPgV)and Theiler's Disease-associated virus(TDAV)are three newly discovered Equine Flavivirus.Since the first report,EqHV,EPgV and TDAV have been found in both horse and horse serum products worldwide.So far,there have been few reports on the detection of new-found equine viruses in horse serum and horse serum products.The viral nucleic acid of flaviviruses is prone to mutations in the process of genetic evolution.At present,there are few reports on the genetic information of the newly equine flaviviruses in the world.Therefore,this study examined the prevalence of the three new-found flaviviruses in the country and tested them.Genetic information is analyzed.At present,there has been no detection of flavivirus in commercial horse serum and horse serum products in China.In order to detect the prevalence of new-found horse virus in commercial horse serum and horse serum products,9 horse serums were purchased for the commercialization of cell culture and 6 PMSGs were specifically amplified by nested PCR and ordinary PCR for the more conserved NS3 gene,of which 2 commercial horse serum samples were identified as positive for EqHV and TDAV,and 2 were identified as EqHV,EPgV and TDAV.Positive,all PMSG samples were negative for these three viruses.According to the sequencing and genetic analysis of the three viral parts of the NS3 gene,a variety of EqHV,EPgV and TDAV strains were found in commercial horse serum samples.In order to detect the prevalence of new-found equine flaviviruses in horses,94 serum samples of horses were collected from Guangzhou and Inner Mongolia in 2015-2017.The NS3 gene was specifically amplified by nested PCR and ordinary PCR.Among them,5 horse serum samples were identified as EPgV positive,of which the positive rate in Inner Mongolia was 4/47(8.5%),and the positive rate in Guangzhou was 1/47(2.1%).According to the genetic analysis of some NS3 genes,No.45 sample and No.46 sample were shown in the same branch,the remaining three are in the same branch.6 horse serum samples were identified as positive for EqHV,of which Inner Mongolia had a positive ratio of 1/47(2.1%)and Guangzhou had a positive ratio of 5/47(10.6%).All were in one group based on genetic analysis.In this study,a strain of EPgV(LW/2016)was screened from 52 horse serum collected in China,and its near complete genome sequence was obtained by PCR.Further analysis of its nucleotide sequence showed that the nucleotide sequence similarity between LW/2016 and C0035 is 89.02%.Phylogenetic tree analysis based on the NS3 and NS5 B genes showed that the two viruses evolved into two separate branches.So far,this is the first domestic report of the genetic evolution of the EPgV genome.In this study,EqHV,EPgV,and TDAV detection and genetic evolution analysis of commercial horse serum,racehorse serum,and cautious horse serum collected from 2015 to 2017 in China were performed.It laid the foundation for the detection and research of China's new-found equine flavivirus and provided technical support for the prevention of animal diseases in China.