Infection And Genetic Variation Of Hantavirus In Small Mammals In Some Regions Of China

Hantaviruses, the members of genus Hantavirus family Banyaviridae, are enveloped, negative-sense RNA viruses. Its gemome consists of small(S), medium(M) and large(L) segements. Up to now, there are at least 23 species of Hantavirus exist around the world. And the pathogenicity, spectrum of disease and natural reservoir between them are distinct, causing Hemorrhagic Fever of Renal Syndrome (HFRS) in Eurasia and Hantavirus Pulmonary Syndrome (HPS) in North and South America. There are about 20,000-50,000 people infected by HV annually in China counting almost 90% of the global epidemics. Hantaan virus and Seoul virus with Apodemus agrarius and Rattus norvegicus as their hosts respectively, are the two major serotypes existing in mainland, China. Recently, in accordance with the progress and development of modern biotechnology, the study of hantaviruses in China have steadily intensified, and thus some non-reported new Hantavirus or its subtype were recovered continually. However, it is necessary to make a further investigation and study on whether or not there are still some new hantavirus or its new subtype that are not discovered in such a country with vast terri, varying geographic surroundings, complex living environment and enormous species.In this study, we combined on-scene investigation and in-lab detection together and constructed a systemic and in-depth molecular epidemiological investigation and study on DaXiaoZhongDian Mountain in northwest, Yunnan, MoLiDaWa County of Inner Mongolia Autonomous Region and Xi'an, Shanxi province to make out probably existed new hantavirus or its new subtype, the distribution of host and the infectious status of hantavirus in these regions. Furthermore, we were eager to find out the genomic characterizations of these Hantavirus and the relationship between them and others.More than 600 small animals (the amount of specie is in the forties) were captured in the 11 sampling sites in northwestern region, Yunnan province. Reverse-transcription PCR based on partial L segment was performed to detect the positives. The results indicated that great mutation happened in the hantavirus strains carried by these animals and the positive rate was 6.4%. Beside rodents, animals which belonged to Insectivora such as Sorex cylindericauda, Soriculus leucops, Nasillus gracilis and Chodsigoa parcafurva et al were discovered to be the reservoirs of Hantavirus for the time, and the viruses they carried had great mutations. All the findings above indicated that the epidemical situation of Hantavirus in this region was quite complex. From the detection result of 80 samples from MoLiDaWa county, we could conclude that there were at least two kinds of animals, Apodemus peninsulae and Apodemus agrarius, were the major host of hantavirus. The infectious rate of Ap was relatively high, and the mutation of Hantavirus genome carried by Ap was great. So we should pay more attention to this kind of reservoir. Meanwhile, according to the diction result of 26 samples from Aa, which were previously tested as antigen-positives, conclusions could be drew that the Hantaan virus which was predominated in this region had more divergence with the precedingly reported virus strains, but had the highest homology with the Hantaan virus isolated in Guizhou province, also ,the difference between these strains were quite small, showing the characterization of geographic aggregation.The virus strains that were amplified from Sorex cylindericauda, specie of Insectivora, and Niviventer confucianus, specie of rodent, which were captured in different sampling sites, were chose as representatives. Sequence alignments and Phylogenetic analysis were performed based on entire S, partial M and L segments of Hantavirus. The results showed that although the Hantavirus carried by Sorex cylindericauda shared the same ancient ancestor with other Sorex-associated Hantaviruses, the homology between them was low, indicating our target virus strain was probably a newfound Hantavirus. The hantavirus carried by Niviventer confucianus was clustered together with the previously reported Da Bie Shan virus (DBSV) in China, but forming a separated small branch, and the identities of each segment between the strain in our study and other DBSV virus were 84.7%, 82.5% and 84.0%, respectively, indicating that the virus strain in our study was likely to be new subtype of DBSV. The sequence alignment and Phylogenetic analysis results based on entire S, partial M and L segments of the hantavirus strain from MoLiDaWa county, Inner Mongolia Autonomous Region showed us that there were at least two type of hantaviruses in this region and the strain amplified from Apodemus peninsulae was probably a new subtype of Amur-like hantavirus with great mutations.In a word, it was the first time that some new types or subtypes of Hantaviruses with many species as their host were discovered Yunnan and Inner Mongolia, and the Hantaviruses in the older pandemic region were proved to have some new genetic features. The investigation and characterizations of new Hantavirus in these regions helped us to better understand the epidemical situation and distribution features and to discuss about the genetic characterizations and the law of evolution and offered basic theory and rationales to make up scientific and effective control and prevention meatures.