DETECTION OF HUMAN PAPILLOMA VIRUS A study of normal cells, cervical intraepithelial neoplasia and cancer of the uterine cervix

Human papillomavirus (HPV) infections of the genital tract are now recognized to be among the most prevalent sexually transmitted diseases and also a contributing factor to some cancers of the lower genital tract of women and men. Presence of HPV in a clinical specimen is confined to detection of the HPV genome by DNA hybridization techniques. In this thesis, the commonly used DNA hybridization techniques Southern blot and filter in situ hybridization (FISH), were first used for detection of genital HPV infection. In order to increase and simplify the detection of HPV in clinical specimens a more sensitive technique, the polymerase chain reaction (PCR) was subsequently utilized. For type-specific amplificaiton of HPV 6, 16, 18 and 33 by PCR, oligonucleotide primers located in the E6 and E7 regions of the HPV genome were selected. They were found to specifically amplify the four types. To be able to amplify a broad spectrum of genital HPV types, general primers located in the E7 and El region of the HPV genome, were designed and evaluated. They were found to amplify a wide range of genital HPV types. To further increase the sensitivity and specificity, a two-step PCR using general primers, was assembled and evaluated against a one-step PCR on cervical scrapes from young women in a population-based study. The two-step PCR increased the sensitivity about three-fold compared to the one-step PCR. By Southern blot and FISH, 46% of women with abnormal Papanicolaou (Pap) smears were shown to carry HPV DNA. Of the women analysed by Southern blot, 39 % harboured HPV DNA and 25 % proved HPV 16 positive. Of the samples analysed with FISH, 27 % contained HPV DNA, compared to 11 % of samples from a group of reference women with normal cytology. With the Southern blot technique, HPV DNA was detected in 66% of women with cervical intraepithelial neoplasia grade III (CIN III) lesions. Fifty-four percent of the women with CIN III lesions were positive for HPV 16 DNA. By type-specific PCR, 12 out of 13 women with cervical squamous carcinoma were shown to carry HPV 16 and/or 18. Among women with adenosquamous carcinoma of the cervix, HPV 18 was the most prevalent type (26%) but HPV 16 was also found in a proportion of the women (15 %). Nine of 13 premenopausal cases with cervical adenocarcinoma were HPV positive compared to only 2 of 13 postmenopausal cases (p< 0.015). HPV 16 DNA was detected in 48% of women with cervical intraepithelial neoplasia (CIN), by the use of type-specific PCR. Three different groups of women with normal cytology were studied. Among women attending a family planning clinic in Kenya, 19% were shown to carry HPV virus, by the use of general primers. HPV 16 was found in 5.2% of these women and HPV 18 in 3.9%. In another group of women, attending the gynecological department in Umeå, HPV 16 DNA was detected in 21 % by type-specific PCR. However, if consideration was taken to the medical status of the women, only 10% of women without any medical history were HPV 16 DNA positive, versus 54% of women with diseases and women with a relative progesterone dominance. Finally, by use of a two-step PCR using general primers, 20% of young women from Umeå taking part in a population-based study were demonstrated to carry HPV DNA. The most prevalent types were HPV 6 (2.0%) and HPV 16(2.7%). Among the women in this study with normal cytology, 19% were HPV positive.