Human papillomavirus sperm infection: a possible risk factor for male infertility

and normal morphology. Curiously, some previous studies have also focused on elucidating the relationship between HPV-infection with sperm function and male infertility. Whereas, the inconsistent results they obtained made the issue controversial. For instance, in 1997, Lai et al. 5 found the incidence of asthenozoospermia among patients infected with either HPV-16 or HPV-18 was significantly higher than in those without HPV-infection (75% vs 8%) (P < 0.01), and the sperm motility parameters represented by straight-line velocity, curvilinear velocity and mean amplitude of lateral head displacement were significantly affected by the presence of HPV (P < 0.05). Paradoxically, Rintala et al. 6 claimed that although seminal high-risk HPV DNA was detected in 15.4% of 65 men, and the indirect factor semen pH was subtly lower in HPV DNA positive samples than negative samples (7.4 vs 7.5), HPV DNA did not affect semen volume, sperm concentration, motility and viability. Therefore, neither oligo-nor asthenozoospermia was associated with seminal HPV DNA. Another study by Bezold et al. 1 presented multiple lines of evidence that semen HPV-infections are frequently seen even in asymptomatic males, and they are often associated with sperm dysfunction, even if the reduction of motile sperm concentration or total motile sperm count was not statistically significant for the HPV-positive group compared with the HPV-negative group (P > 0.05). This conclusion was supported by Garolla et al., 7 they addressed that semen volume, pH, total count, normal morphology and viability were not different in the HPV-infected and noninfected samples. However, a significant reduction of mean PR was found in semen samples of infected patients (29.6% ± 14.2%) versus noninfected references (42.4% ± 22.7%) (P < 0.05). Later on, two independent studies conducted by the same research group have brought some important clues for us to better understanding the correlation between HPV-infection and male infertility. In 2010, Foresta et al. 8 found that semen volume, pH, normal morphology, viability, and even sperm concentration were not different in HPV-infected (HI) and noninfected (HNI) sperm samples. In contrast, a significant reduction of mean sperm motility was found in the 10 semen samples that tested positive for HPV (motility a + b = 53.7% ± 18.2% in HPV-negative group vs 37.7% ± 16.8% in HPV-positive group) (P < 0.05). In their follow-up study, 9 they divided another cohort of people to distinct groups by strict criterion as Yang et al., 4 namely they distinguished the infertile males …