| Object: Cricetidae triton which came from central part plain of china was chosen to be research subjects. To analyze the S segment nucleotide acid sequence and clarify its type and gene characteristic of Hantavirus which carried by C.triton. Methods: The method of IFA was used to screen mice lungs primarily. The positive samples were adopted in Vero-E6 cell line, blindly tree generation's passage was needed, then the infectious material was cultured in suck mice in order to increase titer. Total RNA was extracted , the isolated virus was classified with the special typing primers. The nested RT-PCR and the designed primers were applied to amplify the whole S segment , PCR products were purified and linked into PMD18-T vector in accordance with proper ratio, then was transferred into JM109 bacteria. The positive plasmid was sequenced after the procedure of screen and extraction. The method of molecular evolution and softwares were applied to calculate the nucleotide and amino acid homology, and to draw the phylogenetic evolution figures. Results: The positive antigen particle could be seen through IFA primary screen, and high titer Hantavirus were obtained after three generation's cell culture and three mice adoption.YU61 and YU62 belonged to HTN type. The cloning plasmids of YU61 and YU62 were sequenced, the results showed that: YU61 and YU62 include 1701nt in length, the percent of A,T,C,G was 31.22%, 25.81%, 19.93%, 23.05% respectively. A+T and C+G accounted for 57.03%and 42.97% respectively. S segment consisted of 3 sections: 5'non-coding region (NCR), one open-reading frame (ORF) and 3'NCR. The nucleotide length of 5'NCR and 3'NCR was 36nt and 375nt respectively. The S segment contained only one complete ORF, encoding the N protein (429 amino acid), which started at the 36th nt and ended at the 1326th nt. Some obvious or obscure repeats such as (GGGT) repeats and (CTACCTCA) repeats appeared in 3'NCR. The S segment nucleotide homology of the two strains were very high, but small discrepancy still existed: two distinct base pairs in 5'NCR (which were neglected because of its primers region), a transition in ORF (747nt, YU61 G, YU62 A), a substitution in 3'NCR (1552nt, YU61 A, YU62 G). The nucleotide homology between two strains and HTN typical strains (A16,SN7,84FLi,A9,Z10,76-118,LIU,AH09) was higher than the two strains with the SEO typical strains(L99, R22,SR11).The results which obtained by comparing the YU61/62 nucleotide and amino acid with other type hantavirus'showed that : HTN type was the closest relative, secondly SEO, DOB followed. The homology with PUU and HPS related virus (SN, NY, BAY, BCC, ORN, AND) in America was very low. The phylogenetic tree based on the complete S segmentindicated that: 3 branches were formed in Hantavirus in accordance with the host animals of nurinae, microtinae, and cricetinae rodents respectively. YU61 and YU62 formed one lineage within the clade containing HTN type. A16 was the closest relative in all the Hantavirus strains. The phylogenetic tree based on the ORF and 3'NCR confirmed this point further. Conclusion: 1.YU61 and YU62 include 1701nt in length, consisting of 3 sections: 5'NCR, one ORF and 3'NCR. The complete ORF contained 1290nt, encoding the N protein (429 amino acid), which had the highest identity with other HTN type. 2. The nucleotide homology of two strains was up to 99.3%, the existing small discrepancy did not lead to the different amino acid. 3.Three branches were formed in Hantavirus in accordance with the host animals of nurinae, microtinae, and cricetinae rodents respectively. YU61 and YU62 formed one lineage within the clade containing HTN type. The closest relative to YU61 and YU62 was A16, the identities were 99.1% in complete nucleotide sequence of S segment and 99.8% in ORF. The nucleotide and amino acid homology between YU61/62 and other Hantavirus carried by cricetinae host animals in America was very low. 4. In china, Hantavirus carried by C. Criton was not HPS related virus but HTN type virus. C. Criton was an alternative...
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