A comparative retrospective study of RT-PCR-based liquid hybridization assay for early, definitive diagnosis of dengue.

Dengue is an important flaviviral infection in tropical and subtropical regions. Early diagnosis of dengue infection helps in monitoring the disease, determining when hospital admission is necessary and reducing case fatalities. The objective of this study was to carry out a retrospective comparison of an RT-PCR-based liquid hybridization (RT-PCR-LH) assay with PCR amplification, virus isolation and serological techniques for laboratory diagnosis of dengue infection. Amplified products of non-structural 3 gene were hybridized with a mixture of four dengue type-specific DNA probes in liquid phase. The assay was validated in a comparative retrospective study using acute serum samples collected from 119 fever patients with or without dengue, confirmed by haemagglutination inhibition (HAI) assay, the gold standard assay for diagnosis of dengue infection. The RT-PCR-LH assay was highly specific for dengue and, as an early laboratory diagnostic method, had 100% sensitivity in detecting dengue patients confirmed by HAI assay. A high analytical sensitivity of two fluorescent focus units of dengue virus/reaction was achieved. This RT-PCR-LH assay using a single serum specimen offers distinct advantages of specificity and sensitivity over other diagnostic techniques for early definitive laboratory diagnosis of dengue infection when serological methods are of little value.