PAEP and infection: After the initial interaction with cell surface heparan sulfate, the next stage of HSV entry involves the binding of gD to one of its specific receptors: HVEM, nectin-1, and 3-O-sulfated heparan sulfate (3-O-HS).48, 49, 50, 51, 52 This receptor diversity underpins the broad tropism of HSV-1, enabling infection across various cell types.