title: Evolutionary relationship of 5'-untranslated regions among Thai dengue-3 viruses, Bangkok isolates, during 24 year-evolution.
abstract: OBJECTIVE
  To study evolutionary relationship of the 5'untranslated regions (5'UTRs) in low passage dengue3 viruses (DEN3) isolated from hospitalized children with different clinical manifestations in Bangkok during 24 year-evolution (1977-2000) comparing to the DEN3 prototype (H87).
  
  
  METHODS
  The 5'UTRs of these Thai DEN3 and the H87 prototype were amplified by RT-PCR and sequenced. Their multiple sequence alignments were done by Codon Code Aligner v 4.0.4 software and their RNA secondary structures were predicted by MFOLD software. Replication of five Thai DEN3 candidates comparing to the H87 prototype were done in human (HepG2) and the mosquito (C6/36) cell lines.
  
  
  RESULTS
  Among these Thai DEN3, the completely identical sequences of their first 89 nucleotides, their high-order secondary structure of 5'UTRs and three SNPs including the predominant C90T, and two minor SNPs including A109G and A112G were found. The C90T of Thai DEN3, Bangkok isolates was shown predominantly before 1977. Five Thai DEN3 candidates with the predominant C90T were shown to replicate in human (HepG2) and the mosquito (C6/36) cell lines better than the H87 prototype. However, their highly conserved sequences as well as SNPs of the 5'UTR did not appear to correlate with their disease severity in human.
  
  
  CONCLUSIONS
  Our findings highlighted evolutionary relationship of the completely identical 89 nucleotide sequence, the high-order secondary structure and the predominant C90T of the 5'UTR of these Thai DEN3 during 24 year-evolution further suggesting to be their genetic markers and magic targets for future research on antiviral therapy as well as vaccine approaches of Thai DEN3.
authors.affiliation: Department of Clinical Chemistry, Faculty of Medical Technology, Mahidol University, Bangkok 10700, Thailand. Electronic address: mtwap@mahidol.ac.th.
authors.forename: Watcharee
authors.initials: W
authors.lastname: Attatippaholkun
authors.affiliation: Department of Clinical Chemistry, Faculty of Medical Technology, Mahidol University, Bangkok 10700, Thailand.
authors.forename: Panyupa
authors.initials: P
authors.lastname: Pankhong
authors.affiliation: Department of Virology, US Army Medical Component, Armed Forces Research Institute of Medical Sciences, Bangkok 10400, Thailand.
authors.forename: Ananda
authors.initials: A
authors.lastname: Nisalak
authors.affiliation: Queen Sirikit National Institute of Child Health, Bangkok 10400, Thailand.
authors.forename: Siripen
authors.initials: S
authors.lastname: Kalayanarooj
keywords: 24 Year–evolution; 5'untranslated regions; Evolutionary relationship; Thai dengue-3 viruses