Seroepidemiology of human papillomavirus type 73: A sexually transmitted low-risk virus

Human papillomavirus type 73 (HPV 73) has been detected in some invasive ce rvical cancers and has been cloned from a squamous-cell carcinoma of the es ophagus, but the epidemiology of this infection and its associated risk of cancer is unknown. We investigated the seroepidemiology of this virus using virus-like particles. The IgG response to HPV 73 appeared to be HPV type-s pecific, since a comparison of HPV 73 antibody levels before and after infe ction with HPV 6, 11, 16, 18 or 33 found no evidence of cross-induction of HPV 73 antibodies and since there was little correlation between the antibo dy levels to HPV 73 and the other 5 investigated HPV types. In both a cross -sectional serosurvey that included 274 women and a 7-year follow-up study that enrolled 98 women, HPV 73 seropositivity was found to be strongly depe ndent on the number of lifetime sexual partners [OR for > 4 vs. 0 to I part ners: 6.0 (95%CI: 1.4-53.6) and 7.9 (95% CI: 2.8-28.3), respectively]. Fina lly, the risk for HPV 73 seropositive women to develop CIN was investigated in a prospective study nested in a cohort of 15,234 Swedish women. The pop ulation-based HPV 73 seroprevalence in Sweden was 14%. No excess risk for C IN was found (OR: 0.77). We conclude that HPV 73 is a mainly sexually trans mitted, probably mostly transient, infection that does not confer any measu rably increased risk for CIN development. (C) 2000 Wiley-Liss, Inc.