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.