Serological evidence for protection by human papillomavirus (HPV) type 6 infection against HPV type 16 cervical carcinogenesis

Human papillomavirus (HPV) exists as more than 100 genotypes. It is not wel l-established whether the different HPV types interfere with infection or p athogenesis by each other. Possible interactions in cervical carcinogenesis between infection with the most common HPV types (6, 11, 16, 18 and 33) we re studied in a seroepidemiological case-control study of 218 women with pr imary untreated cervical cancer and 219 healthy age-matched control women. As previously shown, HPV-16 seropositivity was associated with cervical can cer risk [odds ratio (OR), 2.39], but HPV-16 was not associated with cervic al cancer risk among HPV-6 seropositive women (OR, 1.0). The relative exces s risk due to interaction between HPV-6 and -16 was -2.35 (95 % confidence interval, -0.04 to -4.65), indicating significant antagonism. The results s uggest that infection with HPV-6 may interfere with HPV-16-associated cervi cal carcinogenesis.