[Detection of flaviviruses by reverse-transcription polymerase chain reaction with universal primer set]

For the purpose of early and rapid diagnosis of flavivirus infection, the universal primer set was selected on the NS1 gene. Another five different internal primers were selected on the NS1 genes of DEN1, 2, 3, 4 and JEV. With the universal primer set designed, the NS1 fragment about the size of 413 bp and with the five internal primers, the NS1 fragments about the sizes of 262 bp (DEN1), 189 bp (DEN2), 392 bp (DEN3), 97 bp (DEN4) and 323 bp (JEV) were amplified respectively. The reverse transcription-polymerase chain reaction (RT-PCR) was used to amplify gene fragments of flaviviruses. cDNA of DEN1, 2, 3, 4 and JEV were successfully amplified with universal primer set and internal primers. Sera from 78 patients with dengue fever were assayed by nested PCR, DEN1 was detected from 18 of the 40 patients' sera and DEN2 was detected from 48 patients' sera. Sera from 42 patients with Japanese encephalitis were also assayed by nested PCR, JEV was detected from 35 of the 42 patients' sera. By nested PCR, we completed identification of flaviviruses within 2 days. The results showed that this method has the potential value in rapid clinical diagnosis of flavivirus infection.