Acquisition, Persistence, and Clearance of Human Papillomavirus Infection Among Male Virgins Residing in Brazil, Mexico, and the United States.

Background: Little is known about the natural history of human papillomavirus (HPV) infection in male virgins. This study estimated the incidence and clearance of genital HPV infection and the factors associated with these measures among men who denied at baseline ever having penetrative sex. Methods: A cohort of 4123 men residing in Brazil, Mexico, and the United States were followed every 6 months for up to 10 visits. Genital exfoliated cells were collected and genotyped for 36 HPV types. Eighty-seven men were classified as virgins and included for analysis. Cox proportional hazards models identified factors associated with the incidence and clearance of genital HPV infection. Results: The incidence rates for any HPV infection among virgins who did and those who did not initiate sex during follow-up were 26.2 and 14.6 cases/1000 person-months, respectively. After penetrative sex initiation, 45.5% of men acquired HPV within 24 months. Younger age, current smoking, no recent female sex partners, and prevalent HPV infection were associated with high-risk HPV clearance. Conclusion: Virgins who did not initiate sex during follow-up still acquired HPV infection, possibly through nonpenetrative sexual contact. Further prospective cohort studies are needed to better understand factors associated with HPV acquisition and clearance in male virgins and recent nonvirgins.

Family-based exome-wide association study of childhood acute lymphoblastic leukemia among Hispanics confirms role of ARID5B in susceptibility.

We conducted an exome-wide association study of childhood acute lymphoblastic leukemia (ALL) among Hispanics to confirm and identify novel variants associated with disease risk in this population. We used a case-parent trio study design; unlike more commonly used case-control studies, this study design is ideal for avoiding issues with population stratification bias among this at-risk ethnic group. Using 710 individuals from 323 Guatemalan and US Hispanic families, two inherited SNPs in ARID5B reached genome-wide level significance: rs10821936, RR = 2.31, 95% CI = 1.70-3.14, p = 1.7×10-8 and rs7089424, RR = 2.22, 95% CI = 1.64-3.01, p = 5.2×10-8. Similar results were observed when restricting our analyses to those with the B-ALL subtype: ARID5B rs10821936 RR = 2.22, 95% CI = 1.63-3.02, p = 9.63×10-8 and ARID5B rs7089424 RR = 2.13, 95% CI = 1.57-2.88, p = 2.81×10-7. Notably, effect sizes observed for rs7089424 and rs10821936 in our study were >20% higher than those reported among non-Hispanic white populations in previous genetic association studies. Our results confirmed the role of ARID5B in childhood ALL susceptibility among Hispanics; however, our assessment did not reveal any strong novel inherited genetic risks for acute lymphoblastic leukemia among this ethnic group.

Heterologous expression of Streptococcus mutans Cnm in Lactococcus lactis promotes intracellular invasion, adhesion to human cardiac tissues and virulence.

In S. mutans, the expression of the surface glycoprotein Cnm mediates binding to extracellular matrix proteins, endothelial cell invasion and virulence in the Galleria mellonella invertebrate model. To further characterize Cnm as a virulence factor, the cnm gene from S. mutans strain OMZ175 was expressed in the non-pathogenic Lactococcus lactis NZ9800 using a nisin-inducible system. Despite the absence of the machinery necessary for Cnm glycosylation, Western blot and immunofluorescence microscopy analyses demonstrated that Cnm was effectively expressed and translocated to the cell wall of L. lactis. Similar to S. mutans, expression of Cnm in L. lactis enabled robust binding to collagen and laminin, invasion of human coronary artery endothelial cells and increased virulence in G. mellonella. Using an ex vivo human heart tissue colonization model, we showed that Cnm-positive strains of either S. mutans or L. lactis outcompete their Cnm-negative counterparts for tissue colonization. Finally, Cnm expression facilitated L. lactis adhesion and colonization in a rabbit model of infective endocarditis. Collectively, our results provide unequivocal evidence that binding to extracellular matrices mediated by Cnm is an important virulence attribute of S. mutans and confirm the usefulness of the L. lactis heterologous system for further characterization of bacterial virulence factors.

Human Papillomavirus Prevalence Among 88 Male Virgins Residing in Brazil, Mexico, and the United States.

This study determined the prevalence and risk factors for genital human papillomavirus (HPV) detection among men who deny ever engaging in penetrative sex. A questionnaire was administered to 4123 men from a cohort study of HPV natural history. Genital exfoliated cells were collected and genotyped for 36 HPV types. Eighty-eight men were classified as virgins. Log-binomial regression models identified factors associated with genital HPV detection. The prevalence of any and high-risk HPV types among 88 male virgins was 25.0% and 18.2%, respectively. Age and smoking status were associated with HPV detection. Further studies are needed to better understand the risk for HPV infection among male virgins.