Effect of naturally acquired type-specific serum antibodies against human papillomavirus type 16 infection.

ABSTRACT

BACKGROUND: While vaccine-induced antibodies are known to confer protection against incident human papillomavirus (HPV) infection, there is inconsistent data regarding the protective effect of naturally acquired anti-HPV antibodies. OBJECTIVES: To estimate the protective effect of naturally acquired anti-HPV16 serum antibodies against incident anogenital infection with HPV16 in females aged 20-64 years and to assess whether antibodies influence the persistence/clearance of anogenital HPV16 infection. STUDY DESIGN: 4432 women attending the organized national cervical cancer screening program in Slovenia were initially enrolled. 2199 and 1848 women had valid HPV DNA results obtained using PCR-based assays and HPV antibody serotyping results obtained using pseudovirion-based serological assay, at baseline and at three-year follow-up, respectively. RESULTS: Baseline HPV16 seroprevalence was 2.4-fold higher among HPV16 DNA-positive women (55.7% vs. 23.2%; p<0.01). Baseline HPV16 DNA-positive/seronegative women frequently acquired anti-HPV16 antibodies during follow-up (OR=8.2; 95% CI 3.8-17.8). Baseline anti-HPV16 antibodies persisted at follow-up, irrespective of baseline HPV16 DNA status (OR=40.6; 95% CI 30.3-54.5). Baseline HPV16 DNA-negative/seropositive women were less likely to acquire HPV16 infection at follow-up (unadjusted OR=0.2; 0.1-0.9). However, the age-adjusted association was non-significant (adjusted OR=0.3; 0.1-1.2). The tendency for protective effect was stronger among women older than 25 years (OR=0.2; 0.03-1.8). Baseline anti-HPV16 antibodies were not associated with persistence/clearance of HPV16 infection at follow-up (OR=0.8; 0.3-1.9). CONCLUSIONS: Naturally acquired anti-HPV16 serum antibodies appeared to protect against anogenital HPV16 infection, but this association was at least partially confounded by age. Baseline anti-HPV16 serum antibodies did not influence persistence/clearance of HPV16 infection at follow-up.