Zika virus tropism during early infection of the testicular interstitium and its role in viral pathogenesis in the testes.

Sexual transmission and persistence of Zika virus (ZIKV) in the testes pose new challenges for controlling virus outbreaks and developing live-attenuated vaccines. It has been shown that testicular infection of ZIKV is initiated in the testicular interstitium, followed by spread of the virus in the seminiferous tubules. This leads to testicular damage and/or viral dissemination into the epididymis and eventually into semen. However, it remains unknown which cell types are targeted by ZIKV in the testicular interstitium, and what is the specific order of infectious events leading to ZIKV invasion of the seminiferous tubules. Here, we demonstrate that interstitial leukocytes expressing mir-511-3p microRNA are the initial targets of ZIKV in the testes, and infection of mir-511-3p-expressing cells in the testicular interstitium is necessary for downstream infection of the seminiferous tubules. Mir-511-3p is expressed concurrently with CD206, a marker of lineage 2 (M2) macrophages and monocyte derived dendritic cells (moDCs). Selective restriction of ZIKV infection of CD206-expressing M2 macrophages/moDCs results in the attenuation of macrophage-associated inflammatory responsesin vivoand prevents the disruption of the Sertoli cell barrierin vitro. Finally, we show that targeting of viral genome for mir-511-3p significantly attenuates early ZIKV replication not only in the testes, but also in many peripheral organs, including spleen, epididymis, and pancreas. This incriminates M2 macrophages/moDCs as important targets for visceral ZIKV replication following hematogenous dissemination of the virus from the site of infection. Author summary Zika virus (ZIKV) has recently gained global media attention as a major emerging pathogen. Unique among the flaviviruses, ZIKV can be transmitted sexually as well as through the canonical arthropod route. Transmission through sexual contact raises new challenges for controlling ZIKV outbreaks, and infection of the testes poses a unique challenge for the development of live attenuated vaccines against ZIKV. In this manuscript, we utilized the microRNA targeting technique to demonstrate that testicular macrophages/DCs are a critical first target for ZIKV, and infection of these cells is required for passage of the virus through the Sertoli cell barrier and subsequent infection of the seminiferous tubules. Our investigations are the first to clearly show the sequence of infection events required for testicular infection that would subsequently lead to sexual transmission of ZIKV.