Epidemiological and Genetic Evolutionary Characteristics of Dengue Virus in Hainan Province, China, Based on Whole-Genome Sequencing and Serological Data

BACKGROUND: Dengue fever is one of the most widely distributed vector-borne infectious diseases globally, prevalent in tropical and subtropical regions. An estimated 3.9 billion people in 128 countries are at risk of infection globally, and the 2024 outbreak was the most severe. As a tropical region, Hainan Province in China serves as a significant endemic area for dengue fever, where epidemic prevention and control remain critical. OBJECTIVE: To analyze the transmission dynamics and pathogen variation characteristics of the 2024 dengue fever outbreak in Hainan Province. METHODS: Acute-phase serum samples from 18 confirmed dengue cases during the 2024 outbreak in Hainan Province were collected and serotyped using TaqMan real-time PCR. The viral envelope (E) gene and representative whole genomes were sequenced and compared with domestic reference strains to assess epidemic trends. Phylogenetic and molecular clock analyses were performed based on E gene and full-genome sequences to infer spatiotemporal transmission dynamics. Sequence alignment and homology modeling were used to identify E gene mutations and evaluate their potential effects on E protein functional domains and viral pathogenicity. RESULTS: Among the 18 samples, 17 were dengue virus (DENV)-1, and 1 was DENV-3. Phylogenetic analysis revealed that the primary strains in this outbreak were highly homologous to those circulating in Guangdong Province; however, two strains exhibited significant genetic differences, suggesting possible independent introduction. Additionally, two unique DENV-1 E gene mutations (D147N and S338L) were identified, which we hypothesize may be associated with viral characteristics, subject to further functional verification. CONCLUSION: This study systematically reveals the epidemiological characteristics of the 2024 dengue fever outbreak and provides a scientific basis for formulating local control strategies and a research foundation for further exploring the molecular-level pathogenicity and transmissibility of DENV.