Investigation On The Infection Of Hepatitis E In Rodents From Three Counties Of Plague Natural Foci In Yunnan Province

ObjectivesTo confirm the infection of HEV-C in rodents in this target natural village,to determine the type of HEV-C in positive samples,and to evaluate the risk of transmission of HEV-C to human by rodents for providing scientific basis to effective prevention and control of hepatitis E.MethodsTaking 491 samples of rat-shaped animal liver collected by the research group in August 2019 from 16 natural villages in 3 cities in southwest Yunnan,RNA extraction and detection of liver samples,Quantitative PCR,of real-time fluorescence using one-step method.According to the primers and probes,to detect the target gene of hepatitis E virus,and then using two rounds of PCR to amplify positive samples,sequencing the amplified products,construction of a database of rat hepatitis E virus nucleic acid sequences and highly similar standard reference sequences selected in the Gen Bank,using DNA star software to carry out sequence homology alignment and Mega7.0 software package to construct phylogenetic tree to determine the genotype of rat animal hepatitis E virus.R software was used to analyze the infection of hepatitis E virus in rats with different factors.ResultsThe collected rodents belong to 15 species of 8 genera and 3 orders 5 families.RNA liver samples were extracted and 491 samples were obtained（Mi Le 67,Mang Shi192,Liang He 232）.The dominant species were Rattus tanezumi 49.90%（245/491）,Suncus murinus 30.75%（151/491）.A one-step fluorescence quantitative PCR test showed 24 positive samples,the positive rate was 4.89%（24/491）.HEV-C of rats infected with Rattus tanezumi and Niviventer fulvescens.There was a significant difference in HEV-C infection rate(c^（17）=5.043,P=0.025)between 5.81%（23/396）and1.05%（1/95）of the dominant rat species（constituent proportion>10%）and other rat species（constituent proportion<10%）.The infection rate among the dominant rat species was higher than that of other rat species,Rattus tanezumiis is an important HEV-C host.The infection rates of Mi Le,Mang Shi and Liang He were 0（0/67）,4.69%（9/192）,6.47%（15/232）respectively.There was no significant difference between the three regions(c^（17）=4.702,P=0.095).By sex,The ratio of females（53.77%）to males（46.23%）was 1.16:1.Statistical analysis of infection rates in females（4.17%,11/264）males（5.73%,13/227）showed no statistically significant difference(c^（17）=0.639,P=0.424).It can be classified as grass（2.34%）,cultivated land（2.68%）,shrub（8.42%）,woodland（2.41%）,residential area（11.59%）and mountainous area（0）.The difference of infection rate between different habitats was statistically significant.Further analysis:There was a statistical difference in infection rate between grass and shrub(c^（17）（28）4.305,P=0.038),and the infection rate of rodents which infected with HEV-C in shrub was higher than that in grass.The infection significant difference in infection rate between residential area and grass,cultivated land and woodland（P=0.009,P=0.016,P=0.020）,and the infection rate of rodent which infected with HEV-C in residential area was higher than that of grass,cultivated land and woodland.In addition,HEV-C genotypes mainly include Orthohepevirus C.ConclusionsThere were two types rodents infected with HEV-C in the plague natural foci of the southwestern Yunnan Province,and the HEV-C infection rate was 4.89%.There is potential of rat animals transmitting HEV-C to people.Statistical analysis learned that the infection rate is related to whether the dominant rat species and habitats.The infection rate of dominant rat species was higher than that of other rat species,Rattus tanezumiis is an important HEV-C host;In different habitats,the rate of rodent infection in shrub was higher than that in grass,and the rate of rodent infection in residential area was higher than that in grass,cultivated land and woodland,Human contact with rat animals requires high attention.Furthermore,the genotype of HEV-C in the plague foci was Orthohepevirus C.