Detection of herpes simplex virus DNA in genital and dermal specimens by LightCycler PCR after extraction using the IsoQuick, MagNA pure, and BioRobot 9604 methods

We evaluated two automated systems, MagNA Pure (Roche Molecular Biochemical s, Indianapolis, Ind.) and BioRobot 9604 (Qiagen, Inc., Chatsworth, Calif.) as effective replacements for the manual IsoQuick method (Orca Research, I nc., Bothell, Wash.) for extraction of herpes simplex virus (HSV) DNA from dermal and genital tract specimens prior to analysis by LightCycler PCR, Of 198 specimens (152 genital, 46 dermal), 92 (46.2%) were positive for HSV D NA by LightCycler PCR after automated extraction of specimens with either t he MagNA Pure or BioRobot 9604 instrument. The manual IsoQuick method yield ed HSV DNA (total n = 95) from three additional specimens that were negativ e by the automated method (P = 0.25, sign test), Although the mean numbers of LightCycler PCR cycles required to reach positivity differed statistical ly significantly among all three of the methods of extraction, the estimate d means differed by no more than 1.5 cycles (P < 0.05), Seventy (76%) of th e 92 specimens that were LightCycler PCR positive by all three extraction m ethods were also positive by shell vial cell culture assay, HSV DNA was det ected by a lower LightCycler PCR cycle number (26.1 cycles) in specimens cu lture positive for the virus than in culture-negative samples (33.3 cycles) (P < 0.0001), The manual IsoQuick and automated MagNA Pure and BioRobot 96 04 methods provide standardized, reproducible extraction of HSV DNA for Lig htCycler PCR, The decision to implement a manual versus an automated proced ure depends on factors such as costs related to the number of specimens pro cessed rather than on the minimal differences in the technical efficiency o f extraction of nucleic acids among these methods.