Equine herpesvirus type 1 (EHV1) induces alterations in the immunophenotypic profile of equine monocyte-derived dendritic cells

•EHV1 alters the immunophenotypic profile of equine MDDC.•CD83 and CD86 downregulation is partially mediated by the viral protein pUL56.•Cell surface markers are not downregulated by the viral proteins VHS and pUL49.5.

Equine herpesvirus 1 (EHV1) is an α-herpesvirus that can infect a variety of different cells in vitro and in vivo, including dendritic cells (DC) which are essential in the immune response against EHV1. Infection of equine monocyte-derived DC (MDDC) with EHV1 induced down-regulation of major histocompatibility complex I (MHCI), CD83, CD86, CD206, CD29 and CD172a, but not of CD11a/CD18 and MHCII. This down-regulation was not mediated by the virion host-shutoff (VHS) protein or pUL49.5. Interestingly, down-regulation of CD83 and CD86 was in part mediated by pUL56. Taken together, these data indicate that EHV1 employs different and still unresolved mechanisms to induce down-regulation of several functionally important cell surface proteins on equine DC.