Specific identification of human papillomavirus type in cervical smears and paraffin sections by in situ hybridization with radioactive probes: a preliminary communication

An improved in situ DNA hybridization protocol for detection of human papillomavirus (HPV) DNA sequences in paraffin-embedded biopsies

In situ DNA hybridization is becoming rapidly an important technique for detection and typing of human papillomaviruses (HPV) in epithelial lesions, some of which (those due to HPV 16, 18 and 31) seem to possess an increased risk for progression into an invasive squamous cell carcinoma. An improved in situ DNA hybridization technique (Technique II) was described, and the results obtained in a series of cervical and penile HPV lesions were compared with those given by the in situ hybridization technique (Technique I) previously used in our laboratory. Special emphasis was made to increase the sensitivity with three basic alterations of the hybridization protocol; omission of the 0.2 N HCl wash, use of increased proteinase K concentration (from 50 micrograms/ml to 1 mg/ml), and elevated denaturation temperature (obtained by a heating block instead of an incubator). Poly-D-lysine as a slide-coating medium was replaced by Kodak Photo-Flo 200 to improve the attachment of the tissue sections on the slides. Identical HPV DNA types were discovered by the two hybridization techniques. The attachment of the tissue sections was equal on the slides coated with either poly-D-lysine or Kodak Photo-Flo 200, and the latter did not interfere with the sensitivity of in situ hybridization. The hybridization signals for HPV DNA were weak or moderate in 15/16 lesions with Technique I, but intense in 10/16 lesions with Technique II (P less than 0.001). Furthermore, the resolution of Technique II seemed to be superior to that of Technique I, while being capable of disclosing HPV DNA in the intermediate cell layers (P less than 0.001) and in basal/parabasal cell layers (P less than 0.025) of both the cervical and penile lesions. The discovery of HPV DNA in the parabasal cells provides important clues to the understanding of the biology of HPV infection in the squamous epithelium, and makes this improved in situ DNA hybridization technique invaluable in assessing the lesions, where low copy numbers of HPV are to be expected.

Human papillomavirus (HPV) DNA sequences demonstrated by in situ DNA hybridization in serial paraffin-embedded cervical biopsies

An in situ DNA hybridization technique was used to identify various types of Human papillomavirus (HPV) in paraffin sections of serial punch biopsies taken from 64 patients having colposcopy because of abnormal smears. There women were in fact 64 consecutive patients out of 505 attending our clinic (at 6-month intervals) since 1981 for HPV infections. HPV 6 DNA sequences were found in 20%, HPV 11 in 17%, HPV 16 in 8% and HPV 18 in 5% of the 64 biopsies analysed with this method so far. More than 60% of HPV 6-positive lesions belong to HPV-NCIN (HPV lesion without concomitant CIN) or HPV-CIN I categories, as contrasted with HPV 16-positive lesions, 80% of which belong to HPV-CIN II and III categories. None of the HPV 16- or HPV 18-infected lesions regressed, as contrasted with 23% and 45% in those infected with HPV 6 and HPV 11, respectively (P less than 0.01). The rate of progression (38.4% and 45.5%, respectively) was markedly lower in HPV 6- and HPV 11 lesions as compared with that (80%) of HPV 16 lesions. The present results while supporting the concept on HPV 16 and HPV 18 as the high risk HPV types in cervical carcinogenesis also emphasize the applicability of the in situ DNA hybridization as a powerful tool in analysis of the specific HPV DNA sequences in routinely progressed biopsies of these lesions.

Identification of genital tract papillomaviruses HPV-6 and HPV-16 in warts of the oral cavity

Warty lesions of the oral cavity were examined for etiologic association with genital tract papillomaviruses HPV-6, HPV-11, and HPV-16. DNAs extracted from ten oral biopsies were screened for HPV genomic sequences by Southern transfer hybridization with 32P-labeled viral DNA probes. Nonstringent hybridization with an HPV-6 probe revealed papillomavirus DNA sequences in four of seven tissues with histologic evidence of papillomatosis, in none of two tissues without histologic evidence of papillomatosis, and in one tissue that was not examined by histology. Stringent hybridization tests with HPV-6 and HPV-16 probes identified the genome in one tissue as being HPV-16, in a second tissue as being HPV-6 subtype a, and in a third tissue as HPV-6 (subtype unidentified); papillomavirus DNA sequences in two tissues are as yet not identified. An additional case of HPV-6 or HPV-11 related oral cavity lesion was diagnosed by in situ hybridization of paraffin sections with a 35S-labeled, mixed HPV-6 + HPV-11 probe. The hybridization in the positive section was extensive and confined to epithelial nuclei. The oral lesions associated with genital tract papillomaviruses were asymptomatic, multiple or single, and were located in different parts of the oral cavity, for example, on the gingivae, on the tongue, on the lip, on the tonsillar pillar, and on the floor of the mouth.