>> Association Between HPV-16 L1 VLP Serum Antibodies and Future Risk of Genital HPV Infections in Men
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1Risk Assessment, Detection and Intervention Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA; 2School of Medicine, Johns Hopkins University, Baltimore, MD, USA; 3Instituto Nacional de Salud Pública, Cuernavaca, México; 4Ludwig Institute for Cancer Research, São Paulo, Brazil; 5College of Public Health, University of South Florida, Tampa, FL, USA.
Background: No study has examined whether anti-HPV-16 serum antibodies elicited by natural infections protect against future genital HPV infections in men.
Objectives: We examined risk of genital infection with HPV-16 and phylogenetically-related types in the alpha-9 genus in an international cohort of men.
Methods: HPV-16 antibodies were detected using an L1-VLP-based ELISA and classified using low and high seroreactivity cut-points. Incidence rates of new infection and 6-month persistent infections with HPV-16 and other alpha-9 genotypes were estimated. Tests based on binomial distribution were applied to compare incidence rates between seropositive and seronegative men.
Results: 2482 men aged 18-70 years residing in USA, Brazil and Mexico were followed every 6 months for a median duration of 17.9 months. HPV 16 seroprevalence at enrollment was 10.8% and 8.2%, using low and high cut-points respectively. Seroprevalence was significantly higher among men with male sexual partners (MSM and MSMW). Overall the HPV 16 incidence rate was 6.0 and 5.5 per 100-person-years for HPV-16 seropositive and seronegative men (p=0.796) using the lower cut-point. Incidence of other alpha-9 genotypes was 10.9 and 8.1 per 100-person-years, respectively (p=0.138). Incidence rates of 6- and 12-month persistent infection with HPV-16 or other alpha-9 genotypes did not differ significantly by enrollment HPV-16 sero-status. No significant differences in incidence rates by sero-status were detected for any age group or subgroups of men with different number of lifetime sexual partners or sexual practice using the lower cut point. When a higher seroreactivity cut-point was applied, a significantly lower incidence rate of genital HPV-16 was observed in seropositive men compared to seronegative men (p=0.015) among MSM.
Conclusion: The presence of HPV-16 serum antibodies at enrollment does not appear to confer protection against future genital infection with HPV-16 or its phylogenetically-related types. However, a protective effect was observed among MSM with higher seroreactivity at enrollment.