While most human papillomavirus (HPV) infection clears on its own, persistent HPV infection can cause genital warts and anal, penile and oropharyngeal cancers in men. Dr. Sadeep Shrestha, associate professor of epidemiology, and recent MPH alum, Mr. Bigyan Mainali, at the University of Alabama at Birmingham School of Public Health, worked with a research team to conduct genetic analysis in a sub-cohort of the HPV infection in men (HIM) study to test the hypothesis that differences in host genes influence HPV persistence in men.
Baseline and longitudinal genital HPV status at the genitals was measured every 6-months using the Linear Array assay amplified HPV L1 gene fragment using the PGMY09/11 L1 consensus primer system. DNA was extracted from peripheral blood and single nucleotide polymorphisms (SNPs) in the customized genome-wide genotyping array, the “TxArray,” were examined using logistic regression in a case-control study design to assess the association with HPV16 persistence/clearance.
Of the total of 737,742 autosomal SNPs in the array, 605,885 passed basic quality control and were examined between 40 men (cases) with >18 months persistent genital HPV 16 infection vs. 151 controls who were HPV 16-positive, but whose infections cleared in <18 months. The logistic regression analysis from this case-control study showed variants in several gene regions associated with genital HPV 16 persistence, with the strongest association detected with SNPs on chromosomes 20 (p < 5.72 ×10-6) and 15 (p < 5.89 ×10-6), after adjusting for age, smoking status, number of sex partners and four principal components (ancestral background).
The authors concluded that the results provide a preliminary basis for understanding the biological mechanism of oncogenic HPV 16 pathogenesis at the genitals in men. Some of the genes flanking the top hit SNPs are consistent with previous findings in both HPV related and non-related cancers but further genetic studies in larger cohorts are warranted to confirm these and identify novel major susceptibility genes involved in the pathogenesis of genital HPV persistence in men.