Molecular characterization of the viral structural protein genes of 2018 dengue virus serotype 1 epidemic in Yunnan, Southwest China

Background There was a dengue virus serotype 1 (DENV-1) epidemic from October to December in 2018 in Xishuangbanna, Yunnan, southwest China, neighboring Myanmar, Laos and Vietnam. And the molecular characterization, evolution and potential source of DENV from Xishuangbanna were investigate. Methods C (capsid)/prM(premembrane)/E (envelope) genes of DNEV isolated from 87 serum samples obtained from local patients were amplified and sequenced, then evaluated using mutation, phylogenetic and homologous recombination analyses and secondary structure prediction. Results Phylogenetic analysis show that all the DENV strains from Xishuangbanna can grouped in two branch of DENV-1. Out of 52, 50 of isolates were grouped in branch one, and were most similar to Fujian (DQ193572) and Singapore 2016(MF314188) strains. The other two isolates have the closest relationship to Myanmar 2017 (MG679801) . When compared with DENV-1SS (standard strain), we found the amino acid residue of E155 was mutation from T to S,which may related to the virulence of virus and no obvious homologous recombination signals. Secondary structure prediction showed that some changes were found in the helical of MN123849 and MN123854 strains and few changes observed in disordered region. Conclusions This study revealed the molecular characterization of structural genes of xishuangbanna, 2018 epidemic strain, providing a reference for molecular epidemiology, infection, pathogenicity and vaccine development .