Background

The role of circumcision in male HPV acquisition is not clear.

Methods

Male university students (18–20 years of age) were recruited from 2003–2009 and followed tri-annually. Shaft/scrotum, glans, and urine samples were tested for 37 alpha HPV genotypes. Cox proportional hazards methods were used to evaluate the association between circumcision and HPV acquisition. Logistic regression was used to assess whether number of genital sites infected at incident HPV detection or site of incident detection varied by circumcision status.

Results

In 477 men, rates of acquiring clinically-relevant HPV types (high-risk types plus types 6 and 11) did not differ significantly by circumcision status (hazard ratio [HR] for uncircumcised relative to circumcised subjects: 0.9[95%CI:0.7–1.2]). However, compared to circumcised men, uncircumcised men were 10.1 (95%CI:2.9–35.6) times more likely to have the same HPV type detected in all 3 genital specimens than in a single genital specimen and were 2.7 (95%CI:1.6–4.5) times more likely to have an HPV-positive urine or glans specimen at first detection.

Conclusions

While the likelihood of HPV acquisition did not differ by circumcision status, uncircumcised men were more likely than circumcised men to have infections detected at multiple genital sites, which may have implications for HPV transmission.

Plasmodium vivax Duffy binding protein (DBP) is a merozoite microneme ligand vital for blood-stage infection, which makes it an important candidate vaccine for antibody-mediated immunity against vivax malaria. A differential screen with a linear peptide array compared the reactivities of noninhibitory and inhibitory high-titer human immune sera to identify target epitopes associated with protective immunity. Naturally acquired anti-DBP-specific serologic responses observed in the residents of a region of Papua New Guinea where P. vivax is highly endemic exhibited significant changes in DBP-specific titers over time. The anti-DBP functional inhibition for each serum ranged from complete inhibition to no inhibition even for high-titer responders to the DBP, indicating that epitope specificity is important. Inhibitory immune human antibodies identified specific B-cell linear epitopes on the DBP (SalI) ligand domain that showed significant correlations with inhibitory responses. Affinity-purified naturally acquired antibodies on these epitopes inhibited the DBP erythrocyte binding function greatly, confirming the protective value of specific epitopes. These results represent an important advance in our understanding of part of blood-stage immunity to P. vivax and some of the specific targets for vaccine-elicited antibody protection.