HSV-1 exploits the innate immune scavenger receptor MARCO to enhance epithelial adsorption and infection

Herpes simplex virus type 1 is an important epithelial pathogen and has the potential for significant morbidity in humans. Here we demonstrate that a cell surface scavenger receptor, macrophage receptor with collagenous structure (MARCO), previously thought to enhance antiviral defense by enabling nucleic acid recognition, is usurped by herpes simplex virus type 1 and functions together with heparan sulphate proteoglycans to mediate adsorption to epithelial cells. Ligands of MARCO dramatically inhibit herpes simplex virus type 1 adsorption and infection of human keratinocytes and protect mice against infection. Herpes simplex virus type 1 glycoprotein C closely co-localizes with MARCO at the cell surface, and glycoprotein C binds directly to purified MARCO with high affinity. Increasing MARCO expression enhances herpes simplex virus type 1 infection while MARCO^-/- mice have reduced susceptibility to infection by herpes simplex virus type 1. These findings demonstrate that herpes simplex virus type 1 binds to MARCO to enhance its capacity for disease, and suggests a new therapeutic target to alter pathogenicity of herpes simplex virus type 1 in skin infection.