Molecular Characteristics of Dengue Viruses in Patients Hospitalized at the Bamrasnaradura Infectious Diseases Institute, Thailand.

Dengue virus (DENV), one of the rapidly spreading mosquito-borne pathogens, causes acute febrile illness with various clinical symptoms. Four DENV serotypes are known, designated DENV-1 to 4. We previously determined whole-genome sequences of 21 DENV isolates during 2016-2017 and reported the emergence of the Cosmopolitan genotype of DENV-2 and genotype III of DENV-3 in Thailand. The objective of this study, conducted in 2018 at the Bamrasnaradura Infectious Diseases Institute, was to study the prevalence of DENV genotype. A total of 100 patients, hospitalized with severe dengue infection, were enrolled with written informed consent. Serum specimens were tested by multiplex real-time reverse transcription-polymerase chain reaction. Among them, 94 were DENV-positive, with 46 DENV-1, 38 DENV-2, 10 DENV-4, and no DENV-3 cases. Nucleotide sequence of DENV gene for envelope-protein was determined in 73 cases. Genotyping of the sequences revealed 40 cases with DENV-1 genotype I, 26 with DENV-2, that included 18 of Cosmopolitan and 8 Asian I genotypes, and 7 with DENV-4 genotype I. DENV-1 was the most prevalent in this study, and the frequency of DENV-2 Cosmopolitan genotype appears to have increased since our previous study, indicating that genotypic diversity of DENV is increasing in Thailand.