In the present study, a trial was carried out to maximize the immune response of horses against inactivated equine herpes virus vaccine (EHV-1) immunomodulated by pre-vaccination with inactivated Parapox Ovis virus (iPPOV) and inactivated sheep pox virus. The role of these formulae of vaccines is enhancing non-specific innate immunity to reduce the immune
suppression of horses due to exposure to different stressors especially transportation and respiratory infections. Serum samples for application of serological tests and whole heparinized blood for lymphocyte cell proliferation assay were taken before and after the administration of both immunomodulator (2ml/horse, I/M injection on days 0, 2 and 9) and also through different intervals after vaccination with inactivated equine herpes virus vaccine(EHV-1). The results of serological investigations (ELISA and VNT) and cellular assay (XTT) clarify the changes in immune responses of two groups of horses (B, C) that prevaccinated by inactivated Parapox Ovis virus (iPPOV) and inactivated sheep pox virus followed by vaccination
with inactivated equine herpes virus vaccine (EHV-1) in comparing with the third group (A) which vaccinated with inactivated equine herpes virus vaccine (EHV-1) alone. As theduration of immune responses increased to eight months' post vaccination and also the levels for group (B and C) detected with ELISA antibody titers (72, 1105 and742) and neutralizing index (1.2, 2.0 and 1.8) in groups A, B, C, respectively. The results of this study throw the light on effect and importance to use immunomodulators for improving the immune response against inactivated equine herpes virus vaccine (EHV-1) either by elongation of intervals for revaccination or by raising the level of cellular and humoral immune responses. Also this study presented inactivated sheep pox virus that prepared locally without adjuvant as another effective, safe immunomodulator for equines