New data show that Zika virus (ZIKV) causes acute and chronic prostatitis in mice and macaques. These observations have implications for the potential long-term health effects of ZIKV infection in men.

First, the researchers investigated the effects of ZIKV infection on the prostates of mice. They created a model in which interferon signalling was blocked in male mice, sensitizing them to ZIKV infection. Mice were then inoculated with either Asian-American or African lineage ZIKV. The anterior, ventral, dorsal and lateral prostate lobes all contained high levels of ZIKV RNA 7 days post infection, which diminished at 21 days.

In mice infected with African-lineage ZIKV, histological analysis showed immune cell infiltration in the anterior, ventral, dorsal and lateral prostate lobes 14 days post infection. At 21 days after infection, the dorsal and lateral lobe tubules showed evidence of damage to the inner epithelial lining, hyperplasia of luminal epithelial cells and disruption of lumen architecture, with an increased density of nuclei, some of which were pyknotic. Cell death was apparent at 14 and 21 days post infection. At 90 days post infection, low levels of ZIKV RNA were present in the ventral lobe. Tubules with necrotic luminal cells were evident and mononuclear cell infiltration was persistent in the stroma. Disruption of luminal cell adhesions was also observed, as was the presence of proapoptotic cells.

In rhesus macaques (a more relevant, immunocompetent model of ZIKV infection than mice) infected with a Puerto Rican strain of ZIKV, prostates harvested 7 days after infection showed periglandular lymphocyte infiltration, formation of microabscesses and intraglandular neutrophils. At 35 days after infection, no ZIKV RNA was detected but periglandular inflammation was still evident.

These results show that ZIKV can cause acute and chronic prostatic inflammation, even after the virus is no longer present in the prostate.