Study: Zika Shrinks Testicular Tissue in Mice

The virus may persist in testes even after the infection is no longer detectable in blood, leading to sexual transmission of the disease and fertility impairments.

Feb 23, 2017
Bob Grant

Mouse epididymisWIKIMEDIA, ZHOU, Q. AND GRISWOLD, M.D.Zika virus (ZIKV) can persist in mouse testes long after the infection is cleared from the blood, and cause atrophy of testicular tissues with potential effects on fertility, according to a study published yesterday (February 22) in Science Advances.

“This study shows how the Zika virus replicates in and damages testes,” Yale University biologist and coauthor Ryuta Uraki said in a statement.

Uraki and his team infected mice with a pathogenic but nonlethal strain of Zika and tracked the animals for several weeks. After 21 days, the virus was undetectable in the bloodstreams of the infected mice, but the researchers found that the infected mice had significantly smaller testes than the control animals. The scientists also noted a reduction in testosterone levels in the blood of the infected mice, suggesting that the testes were also functionally impaired, which could affect fertility.

“Our findings have important implications for nonvector-borne vertical transmission, as well as long-term potential reproductive deficiencies, in ZIKV-infected males,” Uraki and colleagues wrote in the paper.

The findings echo previous results that also found testicular damage in mice infected with ZIKV, and offers a possible mechanistic explanation for why ZIKV seems to be sexually transmissible.

Although the findings have yet to be replicated in humans, a US Centers for Disease Control and Prevention (CDC) team is conducting a similar study in Zika-infected men in Puerto Rico. “It’s going to be important for us to follow them up for several months to rule in or rule out any effects of Zika infection,” Tyler Sharp, chief epidemiologist at the CDC’s Dengue Branch in San Juan, Puerto Rico, told WebMD.