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). Here, CXCL1 is linked to infection.