Comparative analysis of full-length genomic sequences of 10 dengue serotype 1 viruses associated with different genotypes, epidemics, and disease severity isolated in Thailand over 22 years.

Comparative sequence analysis was performed on the full-length genomic sequences of 10 representative dengue virus serotype 1 (DENV-1) strains sampled from patients at Children's Hospital, Bangkok, Thailand over a 22-year period, which represented different epidemics, disease severity, and sampling time. The results showed remarkable inter-genotypic variation between predominant and non-predominant genotypes and genotype-specific amino acids and nucleotides throughout the entire viral genome except for the 5'-non-translated region. The frequency of intra-genotypic variation was correlated with dengue transmission rate and sampling time. The 5'-non-translated region of all 10 viruses was highly conserved for predominant and non-predominant genotypes and NS2B was the most conserved protein. Some intra-genotypic substitutions of amino acids and nucleotides in predominant genotype strains were fixed in the viral genome since 1994, which indicated that the evolution of predominant genotype strains in situ over time might contribute to increased virus fitness important for sustaining dengue epidemics in Thailand.