Whole-genome characterization of prevalent dengue virus serotype-1 in 2023 dengue outbreak of Xishuangbanna, a border area of Laos, Myanmar, and China.

OBJECTIVES

From June to November 2023, a severe dengue fever outbreak occurred in Xishuangbanna, China, a border area with Myanmar and Laos. This study aimed to identify the pathogen responsible for this outbreak and analyze the genomic characteristics of epidemic strains, providing reference data for dengue prevention and control.

METHODS

Serum samples from dengue virus (DENV) NS1-positive patients (July-October 2023) were collected. RNA extraction, serotyping via probe quantitative polymerase chain reaction, and whole-genome amplification using 18 primer pairs followed by sequencing were performed. Base and amino acid mutations were analyzed using DNAMAN. Phylogenetic trees (maximum likelihood for the whole genome and neighbor-joining for the E protein) were constructed using MEGA11. Protein secondary structures were compared via online tools provided by PRABI Lyon-Gerland.

RESULTS

Among 1465 samples, 833 were DENV-1 positive, with no other dengue serotype or flavivirus co-infection. Genomic analysis of 10 isolates showed high similarity to the 2023 Guangdong strain (PP540291). Non-structural proteins had higher base mutation rates than structural ones, with NS2 showing the highest (10.92%). Many unique 2013 Yunnan strain mutations were preserved. Phylogenetic trees clustered the epidemic strains with Guangdong and Southeast Asian isolates. NS1 RNA-binding sites remained stable.

CONCLUSIONS

This study provides valuable insights for dengue control in the China-Myanmar-Laos border areas, as well as for viral pathogenesis research and vaccine development.