A Multicenter Evaluation of Assays for Detection of SV40 DNA and Results in Masked Mesothelioma Specimens

This nine-laboratory multicenter investigation was designed to assess the sensitivity, specificity, and reproducibility of previously described assays for detection of SV40 DNA with three goals, i.e., (a) to compare methods for testing human tissues, (b) to examine the ability of these methods to detect SV40 in human mesotheliomas, and (c) to uncover assay differences that could explain conflicting findings in some past investigations. Each laboratory received, in a masked fashion, paired replicate DNA samples extracted from 25 fresh frozen mesotheliomas (50 samples) and one from each of 25 normal human lungs. Interspersed were masked positive (titrations of the SV40 genome) and negative control samples. Preliminary studies confirmed the adequacy of the samples for testing high molecular weight double-stranded linear DNA targets. All 15 PCR-based assays detected 5,000 copies or less of the SV40 genome spiked into 2 mg of WI38 DNA. A high level of specificity and reproducibility was found among the PCR assays performed in most laboratories. However, none of the selected normal human lung tissue or the 25 mesothelioma tumor specimens obtained from archival samples at a single center was reproducibly positive for the presence of SV40 DNA. Further studies are needed to reconcile these results with previous reports of detection of SV40 DNA in tumor specimens.