Equine herpesvirus type-1 modulates CCL2, CCL3, CCL5, CXCL9, and CXCL10 chemokine expression

Equine herpesvirus type 1 (EHV-1) is highly prevalent in horses and causes rhinopneumonitis, abortion, and encephalopathy. Studies on the related human herpes simplex virus and of murine models of EHV-1 suggest that chemokines play important roles in coordinating of innate and adaptive immune responses, and thus effective control of herpesvirus infection and prevention of severe clinical disease. Here, equine peripheral blood mononuclear cells (PBMC) were infected with one of three EHV-1 strains, which differ in pathogenicity (RacL11, NY03 = abortogenic, Ab4 = neurogenic). Changes in CCL2, CCL3, CCL5, CXCL9 and CXCL10 chemokine gene expression relative to non-infected PBMC were measured by real-time PCR. CXCL9 and CXCL10 gene expression was up-regulated 10 h post infection and decreased to the level of non-infected cells after 24 h. CCL2 and CCL3 were significantly down-regulated 24 h post infection with NY03 and Ab4. CCL5 was up-regulated 24 h after infection with RacL11. Ab4 infected PBMC had significantly lower expression of all chemokines except CCL2 24 h post infection then RacL11 infected cells. While there was not a significant difference between NY03 and the other strains, there was a trend with each chemokine toward NY03 inducing less expression then RacL11 but more then Ab4. The data suggested that EHV-1 infection of PBMC induced up-regulation of inflammatory chemokines CCL5, CXCL9 and CXCL10, and down-regulation of chemotactic CCL2 and CCL3. The data also implies that different EHV-1 strains have varying effects on all five chemokines, with the nuropathogenic strain, Ab4, having the greatest suppressive potential.