COMPARATIVE-ANALYSIS OF HUMAN PAPILLOMAVIRUS DETECTION BY PCR AND NONISOTOPIC IN-SITU HYBRIDIZATION

Aims-To assess the relative diagnostic performance of the polymerase c hain reaction (PCR) and non-isotopic in situ hybridisation (NISH) and to correlate these data with cytopathological assessment. Methods-Pair ed analysis of human papillomavirus (HPV) detection was performed by P CR and NISH on exfoliated cervical cells from 122 women attending a ro utine gynaecological examination. PCR amplification followed by generi c and HPV type specific hybridisation was compared with MSH on a paral lel cervical smear. Results-Overall, 32 cases were positive by NISH an d 61 positive by PCR. Of the 105 cases in which both PCR and NISH were interpretable, 76 (26%) were normal smears, 20 of which were HPV posi tive by NISH and 37 (49%) by PCR. Of 17 borderline smears, two were NI SH positive and 12 PCR positive. Eight of nine smears containing koilo cytes were positive by NISH and seven by PCR. Of three dyskaryotic sme ars, none were NISH and two were PCR positive. The concordance of MSH and PCR in these samples was 57%. To assess sampling error, NISH and P CR were performed on an additional 50 cases using aliquots from the sa me sample. This increased the concordance between assays to 74%. Filte r hybridisation of PCR products with the cocktail of probes used in MS H (under low and high stringency conditions) demonstrated that several cases of NISH positivity could be accounted for by cross-hybridisatio n to HPV types identified by PCR but not present in the NISH probe coc ktail. Conclusions-Sampling error and potential cross-hybridisation of probe and target should be considered in interpretation of these tech niques. PCR is more sensitive because it provides for the amplificatio n of target DNA sequences. In addition, the PCR assay utilised in this study detects a wider range of HPV types than are contained in the co cktails used for NISH. However, PCR assays detect viral DNA present bo th within cells and in cervical fluid whereas NISH permits morphologic al localisation.