Human papillomavirus seroprevalence and association with anal HPV infection and squamous intraepithelial lesions in Australian gay and bisexual men

Background: Gay and bisexual men (GBM) are at disproportionately high risk of anal cancer. The precursor lesions, high-grade squamous intraepithelial lesions (HSIL), are very common and it is evident that not all HSIL progresses to cancer. The serologic response to anal human papillomavirus (HPV) in GBM has not been well characterized. Methods: The Study of the Prevention of Anal Cancer is an ongoing cohort study of GBM ages 35 years and older. At six visits over three years, anal samples are collected for cytology, HPV DNA testing, and histology. Baseline serum was tested for HPV L1, E6, and E7 antibodies for 10 HPV types. Seroprevalence and associated predictors were analyzed. Results: A total of 588 of 617 participants were included in this analysis. A total of 436 (74.2%) were seropositive for at least one of the 10 HPV types. Almost half had L1 antibodies to HPV6 (48.5%), over a third to HPV11 (36.4%) and HPV16 (34.5%). HIV-positive men were more likely to be HPV L1 seropositive. HSIL detection was highest among participants who were HPV serology and DNA positive. There was a borderline significant association between presence of HPV16 E6 antibodies and prevalent HSIL (OR = 2.97; 95% confidence interval, 0.92-9.60; P = 0.068). Conclusions: HPV L1 seropositivity was common in this cohort of older GBM. These results suggest that HPV L1 seropositivity, in conjunction with anal HPV DNA detection, predicts concurrent HSIL. The apparent association between HPV16 E6 antibodies and prevalent HSIL is a finding with potential clinical significance that needs further exploration. Impact: HPV seropositivity with concurrent DNA detection predicted anal HSIL detection.