Analysis of the source tracing and evolutionary mutation characteristics of imported dengue viruses in Guangzhou and Xishuangbanna in 2023

XU Yujuan; XU Yujie; JIANG Mengling; ZHANG Chuyu; LI Lihua; ZENG Fen; YANG Shujuan; MA Dehong; PAN Meifang; LI Linhua; WANG Jian; TAN Xinghua; LI Feng

doi:10.3969/j.issn.1007-8134.2024.05.016

Abstract：Objective This study aims to investigate the origin of the imported dengue virus(DENV)in Guangzhou and Xishuangbanna in 2023 and analyze their mutation characteristics in sequence.Methods Amplicon-based viral RNA sequencing strategy was used to sequence serum samples from 14 cases of dengue fever in Guangzhou and 66 cases of dengue fever in Xishuangbanna.A phylogenetic tree analysis was constructed to trace the viral origins,and an amino acid mutations were analyzed.Results The phylogenetic analysis confirmed that the origin of DENV-Ⅰ in Guangzhou could be traced back to Myanmar,while DENV-Ⅱ back to Indonesia and Kenya.Meanwhile,DENV-Ⅰ in Xishuangbanna could be from Myanmar and Thailand,and DENV-Ⅱ could be from Thailand and Singapore.Alignment with the selected reference sequences found approximately 700 nucleotide variations in each sample,10％of which caused missense mutations.Notably,the mutation frequency in C protein and non-structural protein 2A(NS2A)was significantly higher than in the other regions.In structural proteins,the missense mutation rate of the C and E proteins in the Guangzhou DENV strain was significantly lower than that observed in Xishuangbanna,whereas the missense mutation rate of the prM protein was markedly higher compared to Xishuangbanna.Among non-structural proteins,the missense mutation rates of NS1,NS2A,and NS5 in the Guangzhou strain were significantly elevated relative to those in Xishuangbanna;conversely,the missense mutation rate of NS3 protein was notably lower than that found in Xishuangbanna.Among the structural proteins,the missense mutation rates of C protein and E protein of Guangzhou DENV strain were significantly lower than those of Xishuangbanna,and the missense mutation rate of prM protein was significantly higher than that of Xishuangbanna.Among the non-structural proteins,the missense mutation rates of NS1,NS2A and NS5 of the Guangzhou strain were significantly higher than those of Xishuangbanna,and the mutation rates of NS3 were significantly lower than those of Xishuangbanna.Conclusions In 2023,imported DENV in Guangzhou was derived from Myanmar,Indonesia and Kenya,and imported DENV in Xishuangbanna was derived from Myanmar and Thailand.The missense mutations of the Guangzhou DENV strain mainly occurred in non-structural proteins,while the missense mutations of the Xishuangbanna DENV strain mainly occurred in structural proteins.