CSF1 and infection: To further examine if binding of influenza virus to CLEC5A expressed on the cell surface is sufficient to trigger the proinflammatory cytokine or chemokine induction, CLEC5A− and CLEC5A+ M-CSF macrophages were infected with live or UV-inactivated VNHA,NA viruses (UV-VNHA,NA) at a multiplicity of infection (MOI) of 2.