HPV infection in cervical-cancer cases in Russia

The presence of human papillomavirus (HPV) sequences in 21 biopsies from cervical carcinomas, 11 specimens of tissues adjacent to tumours, 2 specimens of cervical tissues with radiation fibrosis from patients after radiation therapy of cervical cancer and 7 normal epithelial tissues from the patients with other genital tumours were examined by polymerase chain reaction (PCR) and Southern-blot analysis. All tumours were HPV-positive by type-specific PCR and 86% by Southern-blot analysis. In normal epithelial and adjacent tissues, HPV sequences were detected in 20% of samples by Southern-blot analysis and in 70% of samples by PCR, including 2 cases of tissues after radiation therapy. HPV16 was the most prevalent type in tumours (18/21) as well as in normal epithelial tissues (5/7). One HPV-positive tumour contained HPV18 DNA and 2 were doubly infected with HPVs 16 and 18 (2/21). The persistence of exclusively episomal HPV16 DNA was observed in 5 out of 11 tumours examined: 3 cases of squamous-cell carcinomas on the early stage of tumour progression and 2 advanced tumours (squamous-cell carcinoma and adenocarcinoma). The integration of HPV16 genome was detected in 6 out of 11 tumours, but most of them contained episomal forms of viral DNA simultaneously (5 out of 6). The integrative HPV18 genome was found in 2 tumours examined, and the persistence of episomal forms was also observed in one of them. Our data demonstrate that cervical tumours are associated invariably with high-risk types of HPV in Russia.