Genetic variations and relationship among dengue virus type 3 strains isolated from patients with mild or severe form of dengue disease in Indonesia and Thailand.

Sequence analysis was conducted on structural and non-structural genes of 7 strains of dengue virus type-3 (DENV-3 virus) isolated in Indonesia and Thailand in the year 1973, 1994, and 1998 from patients with different clinical manifestations. In general, sequence similarity among isolates was greater than 93%, indicating that the mutation rate of DENV-3 circulating in this region was not more than 7% in the last 3 decades and suggesting that sequences that may responsible for viral architectures and/or biological function were strictly conserved. Mutations unique to viral strains associated with specific clinical manifestations were not found. Alignment of PrM/M and E nucleic acid sequences followed by parsimony analysis of sequences obtained in this study and published elsewhere allowed generation of phylogenetic trees, demonstrating that DENV-3 strains isolated in Indonesia in 1998 belonged to a separate cluster (subtype 2) from those isolated between 1973-1985 (subtype 1).

Genetic variation among Dengue Virus that possibly correlate with pathogenesis.

Dengue disease are reemerging disease and major health concern in tropical and subtropical regions because of the increasing number of patients, expanding endemic areas and increased occurrence of severe clinical manifestation (DHF/DSS) in the last two decades. Despite extensive studies, it is not fully elucidated mechanism by which dengue infection progress to DHF/DSS. Information obtained so far indicates that both host-related factor and virus virulence are involved. Recent studies have shown several structural differences of dengue virus genome between those associated with DF only and those with the potential to cause DHF. That genome differences might be correlated with pathogenesis.