Comparison of the genetic variation in type 1 dengue virus isolates in Taiwan, 1987-1992

In this study, the genetic variation of eight dengue-1 strains isolated in Taiwan from 1987 to 1992 (including two imported strains) were studied. A fragment of 490 nucleotides from the E/NS1 junction was amplified and studied by reverse transcription-polymerase chain reaction (RT-PCR) and vector cloning. By comparing the nucleotide sequences of these strains, it was found that local strains in Taiwan shared geographic similarity. The nucleotide differences among local strains were less (0.61% to 2.24%) than the differences between imported strains and other strains (2.04% to 4.29%). The differences of nucleotide sequences between local strains and the prototype remain constant (5.10%-5.29%). However, the differences in nucleotide sequences between imported strains and the prototype ranged from 3.89% to 7.14%. Since the point mutations occurred in the wobble position of the codon, only conserved changes resulted in the amino acid among the isolates.