Molecular characteristics of the full-length genome of dengue serotype 1 virus strains isolated from dengue fever cases in Sino-Myanmar border region in Yunnan Province, China / 中国人兽共患病学报

ABSTRACT

We investigated the molecular characteristics of the full-length genome of 14 dengue serotype 1 virus (DENV-1)strains isolated in Sino-Myanmar border region in Yunnan Province,China during 2013-2015.Isolation of dengue virus was using C6/36 cell culture method.Viral RNA was extracted from virus isolates,and then the full-length genome was amplified by RT-PCR.The homology and phylogenetic analysis was made on the nucleotide and deduced amino acid sequences by bioinformatics software including ClastalX1.83 and MEGA6 etc.Results showed that fourteen strains of DENV-1 isolated from dengue fever cases,of these,9 strains from Ruili City of Dehong Prefecture,3 from Lincang Prefecture,2 from Kunming City.RT-PCR and sequencing indicated that the full-length genes (10 735 nt) of 14 DENV-1 strains were obtained,and their open reading frame (95-10 271) were coded 3 392 amino acid residues.The genotypes of DENV-1 were revealed by homology and phylogenetic analysis based on structural and non-structural proteins.Thirteen were genotype Ⅰ (G-Ⅰ) (7 from indigenous cases in Ruili and Lincang and 6 from imported case from Myanmar to Ruili,Lincang and Kunming),and 1 G-Ⅲ from imported case from India to Kunming.The phylogenic analysis indicated that the 13 isolates from Yunnan divided into 2 phylogenic subgroups,and they had a closer genetic relationship with the strains isolated from Southeast Asia.The gene sequences of the 13 G-Ⅰ strains have been acquired,the rate of their nucleotide homology and amino acid homology were 97.02 ％-100 ％ and 98.78 ％100 ％ respectively.Compared with 6 strains from Southeast Asia,nucleotide homology and amino acid homology were 96.53％-99.53％ and 97.33％-100％ respectively.Compared with prototype strain (US_Hawaii) of DENV-1,nucleotide homology and amino acid homology were 93.76％-94.45 ％ and 95.86 ％-96.91％ respectively.Compared with US_Hawaii strain,there were 44 and 150 different sites in amino acid of structural and non-structural proteins,respectively.The G-1 of DENV-1 have been popular in Sino-Myanmar border region in Yunnan,2013-2015.They have genetic diversity but multiple transmission sources were from Myanmar,and should strengthen control cross-border spread of dengue fever in this region.It is necessary to further study that change of the amino acid sites of Yunnan strains of DENV-1 is related to its antigenicity and pathogenicity.