Detection of Human Papillomavirus DNA by the Nucleic Acid Sandwich Hybridization Method From Cervical Scraping

Abstract

Cervical scrapes collected from 100 consecutive patients participating in a prospective follow-up study for cervical human papillomavirus (HPV) infections were tested for the presence of HPV 11 DNA by the nucleic acid sandwich hybridization method, which allows testing the specimens in a crude form. Part of each specimen was processed through phenol extraction and DNA purification to a dot blot hybridization assay. The dot blots were serially hybridized with HPV 6, 11, 16, and 18 probes as well as with an Alu-repeat probe to estimate the number of cells in the specimen. In PAP smears, HPV-infection was suspected in 63 patients whereas in 37 patients the smear was negative. In the first group, the dot blot assay revealed three cases of HPV 11, two of HPV 16, and one of HPV 18 infection. In the second group with normal PAP smear, one additional HPV 18 infection was found. The sandwich hybridization assay detected 5 HPV 11 infections, including the three mentioned above. All HPV DNA-positive samples contained at least 1.6 × 10⁶ cells. Since we considered this a prerequisite for successful diagnosis, only 25 specimens in the first group and 15 in the second were adequate specimens. Thus the HPV-DNA detection rate was 32% (8/25) in the first group and 1115 in the second. This study demonstrates that sandwich hybridization, detecting 1–3 × 10⁵ HPV 11 molecules is a reliable diagnostic method. Cervical scrape is a valuable altenative to punch biopsy, but the number of cells collected is critical for the outcome of the assay.