Genotypic and phenotypic characteristics of DENV-3 isolated from patients with different disease severities in Indonesia

We have investigated the genetic diversity of DENV-3 isolated during an outbreak of dengue haemorrhagic fever (DHF) in the city of Palembang, south Sumatra, Indonesia. Four viruses were isolated from patients with different disease severities. Amino acid differences were detected at 40 positions throughout the structural and non-structural proteins, except for the preM protein. Of the 40 positions, amino acids were conserved at 24 positions among three DSS/DHF strains, and the DF strain possessed different amino acids at these positions. Five nucleotide substitutions were identified on 3′ UTR. In monocyte cell line, U937, the three DSS/DHF strains were able to propagate to higher levels compared to the DF strain. These preliminary results showed that the DSS/DHF strains have unique amino acid residues that are different from the DF strain and have better ability to propagate to a higher level in human monocytes. These characteristics of the DSS/DHF strains may contribute to enhanced infection and induction of severity of the disease.