Molecular characterization and phylogeny of Dengue virus serotypes 2 and 4 from Southern Thailand (2015-2016)

Alexandre Adele Dauve, Dr. dr. Hera Nirwati, M.Kes, Sp.MK; dr. Widya Wasityastuti, M.Sc, M.Med.Ed, Ph.D

2018 | Tesis | MAGISTER ILMU BIOMEDIK

Dengue fever is a vector-borne disease for which the pathogen agent is the dengue virus (DENV) transmitted to human through a bite of Aedes mosquitos. Dengue can be either asymptomatic, moderate or severe and life-threatening. DENV is endemic in Thailand and many severe cases have been reported in the South of the country. We conducted a molecular characterization study of circulating DENV serotype 2 and 4 in three southern regions, to identify their genotypes and study their phylogeny. Sera were collected from laboratory-confirmed DENV infected patients: six sera DENV-2 infected and four sera DENV-4 infected. Viral genomes were directly extracted from serum, reverse-transcribed and amplified in order to perform sequencing to obtain the full-length sequences of the envelope gene. Phylogenetic analysis revealed two DENV-2 identical E gene sequences and grouped them in the Cosmopolitan Genotype. The four others DENV-2 strains are related and grouped in Asian Genotype I. The four strains of DENV-4 are all grouped in the Genotype I and are also closely related to each other. Both Cosmopolitan and Asian I genotype are circulating in a same city (Hat Yai). Seven out of nine genotyped strains might be related to outbreaks: one in Singapore and Southern Malaysia from 2013 to 2014, and another one in Myanmar and Yunnan province (China) in 2015. For further work, genotyping should be done on more DENV-2 and DENV-4 in order to investigate a possible genotype prevalence transition and to provide DENV molecular data that will be useful to understand the dynamic of dengue disease and contribute to its management in Southern Thailand.

Dengue fever is a vector-borne disease for which the pathogen agent is the dengue virus (DENV) transmitted to human through a bite of Aedes mosquitos. Dengue can be either asymptomatic, moderate or severe and life-threatening. DENV is endemic in Thailand and many severe cases have been reported in the South of the country. We conducted a molecular characterization study of circulating DENV serotype 2 and 4 in three southern regions, to identify their genotypes and study their phylogeny. Sera were collected from laboratory-confirmed DENV infected patients: six sera DENV-2 infected and four sera DENV-4 infected. Viral genomes were directly extracted from serum, reverse-transcribed and amplified in order to perform sequencing to obtain the full-length sequences of the envelope gene. Phylogenetic analysis revealed two DENV-2 identical E gene sequences and grouped them in the Cosmopolitan Genotype. The four others DENV-2 strains are related and grouped in Asian Genotype I. The four strains of DENV-4 are all grouped in the Genotype I and are also closely related to each other. Both Cosmopolitan and Asian I genotype are circulating in a same city (Hat Yai). Seven out of nine genotyped strains might be related to outbreaks: one in Singapore and Southern Malaysia from 2013 to 2014, and another one in Myanmar and Yunnan province (China) in 2015. For further work, genotyping should be done on more DENV-2 and DENV-4 in order to investigate a possible genotype prevalence transition and to provide DENV molecular data that will be useful to understand the dynamic of dengue disease and contribute to its management in Southern Thailand.

Kata Kunci : Dengue, DENV-2, DENV-4, genotyping, phylogeny, Thailand