Comparative evaluation of different DNA extraction methods for HPV genotyping by linear array and INNO-LiPA.

In order to investigate the influence of DNA extraction on two PCR-based HPV genotyping tests (Linear Array, Roche and INNO-LiPA Extra, Innogenetics), three different procedures were used to purify DNA from 28 cervico-vaginal samples tested previously by the Hybrid Capture 2: the AmpliLute Liquid Media Extraction kit (Roche), the QIAamp DNA Blood mini kit (QIAGEN), and the NucliSENS EasyMAG automated platform (bioMérieux). All HC2-positive samples were found positive by both assays, independently of the extract used. Type-specific concordance (i.e., identical HPV type-specific profile in all the extracts of the same sample) was observed in 55% and 75% of the cases testing samples by the Linear Array and the INNO-LiPA, respectively. Using the DNA extracted with the two manual methods the results were concordant in 75% of the cases both for the Linear Array and the INNO-LiPA. When comparing the Linear Array results obtained on either of the two manual extracts with those obtained following automated extraction, 65% of the samples showed type-specific concordance in both cases. The INNO-LiPA results were concordant in 80% of the cases comparing the AmpliLute versus the automated extract, while concordant results were observed in 90% of the cases when comparing the QIAGEN versus the automated extract. In conclusion, the Linear Array and INNO-LiPA results are affected by the method of DNA extraction. Consequently, different HPV type-specific profiles may be observed using different extracts of the same sample. The use of consistent protocols for DNA purification is a priority to guarantee intra-assay reproducibility over time.