S100A4+ macrophages facilitate zika virus invasion and persistence in the seminiferous tubules via interferon-gamma mediation.

Testicular invasion and persistence are features of Zika virus (ZIKV), but their mechanisms are still unknown. Here, we showed that S100A4+ macrophages, a myeloid macrophage subpopulation with susceptibility to ZIKV infection, facilitated ZIKV invasion and persistence in the seminiferous tubules. In ZIKV-infected mice, S100A4+ macrophages were specifically recruited into the interstitial space of testes and differentiated into interferon-γ-expressing M1 macrophages. With interferon-γ mediation, S100A4+ macrophages down-regulated Claudin-1 expression and induced its redistribution from the cytosol to nucleus, thus increasing the permeability of the blood-testis barrier which facilitated S100A4+ macrophages invasion into the seminiferous tubules. Intraluminal S100A4+ macrophages were segregated from CD8+ T cells and consequently helped ZIKV evade cellular immunity. As a result, ZIKV continued to replicate in intraluminal S100A4+ macrophages even when the spermatogenic cells disappeared. Deficiencies in S100A4 or interferon-γ signaling both reduced ZIKV infection in the seminiferous tubules. These results demonstrated crucial roles of S100A4+ macrophages in ZIKV infection in testes.