Molecular characteristics of dengue viruses in patients hospitalized at the Bamrasnaradura Infectious Diseases Institute, Thailand.

Dengue virus (DENV), one of the most 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 obtained 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 the present study, conducted in 2018 at the Bamrasnaradura Infectious Diseases Institute, was to characterize the DENV genotype distribution among severe dengue patients. A total of 100 hospitalized severe dengue patients were enrolled with written informed consent. Serum specimens were tested by multiplex real-time reverse transcription-polymerase chain reaction. A total of 94 cases were DENV detected, with 46 DENV-1, 38 DENV-2, 10 DENV-4, and no DENV-3 cases. Sequence determination of the DENV envelope-protein gene was successful in 73 cases. Genotyping of the resultant sequences revealed 40 DENV-1 genotype I, 26 DENV-2 including 18 genotype Cosmopolitan and 8 genotype Asian I, and 7 DENV-4 genotype I cases. DENV-1 was the most prevalent in the current study, and the ratio of DENV-2 genotype Cosmopolitan apparently increased since our previous study. These results suggest that genotypic diversity might be increasing in Thailand. (200 words).