Diagnosis of varicella-zoster virus infections in the clinical laboratory by LightClycler PCR

Varicella-zoster virus (VZV) causes vesicular dermal lesions which are clin ically evident as varicella (primary infection) or tester (reactivated) dis eases, The LightCycler system (Roche Molecular Biochemicals) is a newly dev eloped commercially available system designed to rapidly perform PCR with r eal-time detection of PCR products using a fluorescence resonance energy tr ansfer. We compared the detection of VZV from dermal specimens by shell via l cell culture (MRC-5) and by LightCycler PCR. Of 253 specimens, VZV was de tected in 23 (9.1%) by shell vial cell cultures and 44 (17.4%) by LightCycl er PCR directed to a nucleic acid target sequence in gene 28, Twenty-one of 44 (47.7%) specimens were exclusively positive by LightCycler PCR; the she ll vial cell culture assay was never positive when DNA amplification was ne gative (specificity, 100%). VZV DNA was detected in 39 of 44 (88.6%) specim ens positive during cycles 10 through 30 of the LightCycler PCR, These VZV DNA-positive specimens (cycles 10 to 30) and 5 of 11 other PCR positive spe cimens (cycles 31 to 36) were confirmed by another LightCycler PCR directed to another (gene 29) target of the viral genome. For routine laboratory pr actice, all specimens yielding amplified DNA to the VZV gene 28 target can be considered positive results. The increased sensitivity (91%) of the Ligh tCycler PCR for detection of VZV, rapid turnaround time for reporting resul ts, virtual elimination of amplicon carryover contamination, and equivalent costs compared to shell vial cell culture for detection of VZV indicate th e need for implementation of this technology for routine laboratory diagnos is of this viral infection.