Vaccinia virus binds to the scavenger receptor MARCO on the surface of keratinocytes

Patients with altered skin immunity, such as individuals with atopic dermatitis (AD), can have a life-threatening disruption of the epidermis known as eczema vaccinatum (EV) after vaccinia virus (VV) infection of the skin. Here, we sought to better understand the mechanism(s) by which VV associates with keratinocytes. The class A scavenger receptor known as MARCO (macrophage receptor with collagenous structure) is expressed on human and mouse keratinocytes and found to be abundantly expressed in the skin of patients with AD. VV bound directly to MARCO, and overexpression of MARCO increased susceptibility to VV infection. Furthermore, ligands with affinity for MARCO, or excess soluble MARCO, competitively inhibited VV infection. These findings indicate that MARCO promotes VV infection and highlights potential new therapeutic strategies for prevention of VV infection in the skin.