Prevalence and molecular characterization of dengue viruses serotypes in 2010 epidemic

During August to November 2010, a dengue (DEN) outbreak occurred, and several cities of Pakistan were affected. In this study, serum samples from 317 patients, based on clinical symptoms and blood test, were included from Lahore, Sheikhpura and Gujranwala cities for further diagnosis of different genotypes of DEN virus. The samples were categorized into 2 groups: group 1 containing patients with dengue fever (DF) without hemorrhagic manifestations (DF) (n=228) and group 2 involving patients having DF with hemorrhagic manifestations (dengue hemorrhagic fever) (n=89). The samples found positive for DEN in reverse transcriptase polymerase chain reaction (PCR) by targeting capsid and premembrane genes containing fragment of size ∼2.5 kb for groups 1 and 2 were found to be 83.33% and 91.01%, respectively; however, the detection limit was quite low by immunoglobulin M antibody capture enzyme linked immunosorbent assay in case of both groups and was found to be 34.70% and 68.53%, respectively. The 16.67% and 8.99% samples of groups 1 and 2, respectively, were found negative in reverse transcriptase PCR analysis. In case of group 1 and group 2, by adopting seminested multiplex PCR strategy, predominant genotype was DEN virus type 2 with prevalence rates of 45.17% and 65.16%, respectively. DEN virus type 1 was the second most prevailing genotype in the population with prevalence rates of 18.85% and 19.10% for groups 1 and 2, respectively.