Investigation Of Human Parechoviruses From Rats And Shrews In Several Areas In Southern China

Background and objectiveAlthough diarrheal diseases are very common,but to human health,especially the health of infants and children,also poses a great threat.Among all causes of diarrhea,viral infection is themost important component.Human parechoviruses(HPeVs)is one of the most common diarrheal viruses and was isolated for the first time in an outbreak of diarrhea in children in the United States in 1956.Subsequent studies have found that HPeVs not only causes humans to have relatively mild symptoms of gastrointestinal tract and respiratory tract,but also causes more serious and fatal diseases of the central nervous system.HPeVs are endemic in the general population,and are mainly transmitted through the fecal-oral route and droplet inhalation.Infants and the elderly are susceptible to HPeVs.Previous studies have shown that Ljungan Virus,which also belongs to parechoviridae,is widely prevalent among rats in European and American continents,and leads to serious intrauterine stillbirths in rats.In addition,Ljungan virus can also be isolated from samples of human with adverse pregnancy outcomes.Based on this,we speculated that rats and shrews may also carry HPeVs.Methods1.Sample collectionCages were used to capture rats and shrews between September 2015 and June 2017 in Guangzhou,Maoming,Yiyang,Malipo.Total RNAs extracted from feces collected from captured animals were used for viral nucleic acid detection.2.Species identificationThe PCR method was used to amplify the CytB gene fragment,and the species of animals was determined based on the BLAST results and morphological characteristics.3.Screening test for viral nucleotideA nested PCR method was used to detect viral nucleic acid.Nested-PCR methods targeting on viral VP3/VP1 gene fragment were designed to confirmed genomic type of each positive sample.Positive rates were calculated separately for different animals and regions.4.Phylogenetic tree analysisThe sequences of the-samples were aligned with the known HPeVs reference sequences,MEGA 7.0 was used to construct phylogenetic trees.Results1.Sample collectionA total of 1199 fecal samples from 5 species of rats and Asian musk shrew were included in this study,which 793 from Rattus norvegicus,64 from Rattus losea,37 from Rattus tanezumi,1 from Bandicota indica,1 from Niviventer,and 303 from Suncus murinus.2.Screening test for viral nucleotideA total of 23 samples were detected with a total positive rate of 1.9%(23/1199).The positive rate of rats and Asian musk shrews were 1.67%(15/896)and 2.64%(8/303)respectively.Rattus losea had the highest positive rate4.68%(3/64),followed by Rattus tanezumi(2.70%),Asian musk shrews(2.64%)and Rattus norvegicus(1.39%).The positive rates of HPeVs in Xiamen,Malipo,Yuexiu district in Guangzhou were 6.09%,5.77%,and 3.97%respectively.None of HPeVs was detected in Huadu District,Yiyang and Maoming.3.Species identificationGenotyping of all HPeVs positive samples were failed.ConclusionHPeVs can be detected in Rats and Asian musk shrews,but the genotype of HPeVs is yet to be further verified.