CCL4 and infection: Compared to virulent MERS-CoV-MA-WT and MERS-CoV-MA-mNLS infection, attenuated MERS-CoV-MA-Δ4b induced, either at 4 or 6 dpi, lower levels of CCL2, CCL4 and CXCL10, which are monocyte and macrophage chemoattractants, and CXCL1 and CXCL2, which are neutrophil chemoattractants (Fig 3A and 3B).