Men having high-risk HPV infection could have impaired fertility, study suggests

New Delhi: Men having the high-risk form of the cervical cancer-causing virus, or HPV, were found to possess higher amounts of dead sperm, thereby negatively affecting their fertility, according to a new study.

Human Papillomavirus (HPV), a sexually transmitted infection, comprises high-risk and low-risk viruses. While the former is known to pose a high risk for developing malignancies and the latter is known for causing largely benign warts or marks, researchers explained in the study, published in the journal Frontiers in Cellular and Infection Microbiology.

The researchers from Argentina, including those from the National University of Cordoba, looked at the quality of 205 adult men's semen.

About a fifth of them, or 39, tested positive for HPV -- 20 having the high-risk form of the virus, seven with the low-risk form and 12 in whom the team could not identify high-risk or low-risk. The 39 HPV-positive men were compared with 43 HPV-negative men.

While semen quality of men across these groups did not differ, upon looking more closely, the researchers found that the samples taken from the men infected with the high-risk virus contained a significantly lower count of immune cells known to help fight infection -- CD45+ white blood cells.

Senior author Virginia Rivero explained that the lower count of immune cells seen in these samples were a result of the HPV's known ability to dodge an immune response.

This would lead to fewer white blood cells moving to the site of HPV infection, thereby impairing their ability to clear this infection, Rivero, a professor at the National University of Cordoba, said.

The researchers also found evidence that sperm of the men infected with the high-risk version of the HPV could suffer repeated damage due to oxidative stress, judging by these men's elevated production of reactive oxygen species (ROS).

While low levels of ROS are a product of normal sperm function, elevated levels can lead to rupturing of cells' outer covering, breaks in genetic material and cell death.

Consistent with this, the researchers found more numbers of dead sperm cells in HPV-positive men having the high-risk virus.

"... higher frequencies of ROS+ dead spermatozoa were shown by HR-HPV infected individuals with respect to those infected with LR-HPV genotypes," the authors wrote.

"We concluded that men infected with high risk-HPV, but not men infected with low risk-HPV, show increased sperm death due to oxidative stress and a weakened local immune response in the urogenital tract," Rivero said.

The results suggested that men infected with the high-risk form of the virus could have impaired fertility, Rivero said.

The high-risk form of the HPV can be detected in almost all of cervical cancers in women and a in high number of anal, genital, and mouth and throat cancers in women and men, the authors explained.

The low-risk form of the HPV is typically detectable in abnormal but benign cervical cells in women and warts on the surface of the larynx (voice box) and genitals in both men and women, but without causing cancer, they said.