Detection of Human Papillomavirus on Papanicolaou-Stained Cervical Smears Using Indirect In Situ Polymerase Chain Reaction Hybridization

Objective.—Polymerase chain reaction (PCR) and indirect in situ hybridization were combined to detect human papillomavirus (HPV) DNA on Papanicolaou (PAP)-stained cervical smears. To our knowledge, this is the first report of an experiment using indirect in situ PCR (IS-PCR) on PAP-stained cervical smears. Design.—We collected native cell specimens from cervicovaginal lavage of 162 patients with squamous intraepithelial lesions. Solution-phase PCR (SP-PCR) was performed as the reference method in the detection of HPV DNA. Indirect IS-PCR was carried out for the same patients to detect the HPV DNA types 6/11 and 16/18 after the PAP-stained smears had been decolorized. Low-risk and high-risk HPV DNA types were also detected by both SP-PCR and indirect IS-PCR. Results.—In the evaluation by indirect IS-PCR, 48 of 81 PAP-stained cell smears of low-grade squamous intraepithelial lesions were positive for HPV DNA, as compared to 40 positive cell smears determined by indirect SP-PCR (sensitivity of indirect IS-PCR compared to SP-PCR, 98.1%). Forty-two of 42 high-grade squamous intraepithelial lesion samples were positive for HPV DNA, as determined by both methods (sensitivity of IS-PCR, 100%). Cell lines investigated in this study as positive or negative controls for HPV DNA were confirmed by indirect IS-PCR and SP-PCR. Conclusions.—Our data show that in comparison to SP-PCR, indirect IS-PCR is a highly sensitive method to detect HPV DNA in cell smears from the uterine cervix. The advantages of indirect IS-PCR are (a) low numbers of cells needed, (b) the possibility of using PAP-stained specimens, and (c) cytologic details of smears can be preserved.