Comparison of methods for extraction of viral DNA from cellular specimens.

The accuracy and precision of quantitative polymerase chain reaction (PCR) results depend not only on the PCR reaction but also on the extraction of viral nucleic acid. Although the extraction of viral nucleic acid from fluids has been extensively studied, less data are available regarding extractions from cellular specimens. We therefore evaluated several commercially available kits for the extraction of nucleic acid from cellular specimens. Although the kits generally performed well, there were some differences in extraction efficiency, especially at low numbers of input cells. Inclusion of a multivirus positive control allowed careful monitoring of extraction efficiency during routine clinical use. Laboratories are encouraged to validate extraction methods carefully in the context of the proposed viral testing.