Zika virus infection in semen: Effect on human reproduction

Unique among vector-borne flaviviruses, Zika virus can infect testis and male genital tract, can persist in semen for months after symptoms onset, and be sexually transmitted. In The Lancet Infectious Diseases, Guillaume Joguet and colleagues report alterations of sperm and testicular function in men with Zika virus infection, with potential effect on human reproduction. In this prospective longitudinal study, the authors detected viral RNA in the semen of 11 of 15 tested men, including five with persistent seminal shedding after viral clearance in blood. Notably, they were able to isolate infectious virus from motile spermatozoa obtained using semen separation methods that are generally used in assisted reproductive procedures. Semen alterations were observed, including a decreased sperm count and a concurrent increment of multiple sperm anomalies, especially in patients with Zika virus RNA-positive seminal specimens, while recovery was observed at day 120 post infection. In addition, inhibin β concentrations decreased after infection, suggesting an impairment of Sertoli cells, which are key components of the blood–testis barrier, produce immunoregulatory factors, and provide support to sperm cells during spermatogenesis. These findings suggest a direct effect of viral infection on the testis or epididymis with impairment of sperm development, in agreement with findings in animal models