CCL2 and Zika virus infectious disease: In this study, we used RNA-seq to analyze gene profile of ZIKV-infected testes and found that the expression of S100a4, a calmodulin predominantly expressed in a myeloid macrophage subpopulation [43], was dramatically increased, accompanied by similarly enhanced expression of monocyte chemokines Saa3, Ccl2 and Ccl5. This inspired us to characterize the S100A4+ macrophages in ZIKV-infected testes, and subsequently investigate their roles in ZIKV infection.