Equine Herpesvirus type-1 (EHV-1) causes outbreaks throughout the United States. T-cell immunity is crucial to prevent severe neurologic disease caused by EHV-1 (EHM). However, the activation of the T cell response against EHV-1 is widely unexplored, hindering the development of effective vaccines against EHM. Our preliminary data suggest that monocyte (MO) subpopulation exhibit pronounced differences in their abilities to activate and regulate T cells. Our hypothesis is that MO majorly influence T cell effector functions during EHV-1 infection. Aim 1 is to characterize the repertoire of peripheral MO, their ability to present antigens to T cells, and the cytokine secretion profiles of MO subpopulations in response to EHV-1. Aim 2 will analyze the roles of MO subpopulations in activating EHV-1 specific T cells after EHV-1 infection. The project's objective is to advance our knowledge about activation and regulation of EHV-1 specific T cells by MO towards the design of EHM vaccines.