Horse Innate Immunity in the Control of Equine Infectious Anemia Virus Infection: A Preliminary Study

The mechanisms of the innate immunity control of equine infectious anemia virus in horses are not yet widely described. Equine monocytes isolated from the peripheral blood of three Equine infectious anemia (EIA) seronegative horses were differentiated in vitro into macrophages that gave rise to mixed cell populations morphologically referable to M1 and M2 phenotypes. The addition of two equine recombinant cytokines and two EIA virus reference strains, Miami and Wyoming, induced a more specific cell differentiation, and as for other species, IFNγ and IL4 stimulation polarized horse macrophages respectively towards the M1 and the M2 phenotypes. Infection with EIAV reference strains resulted in a morphological transformation of macrophages compatible with the M1 differentiation pattern. All samples were also analyzed by molecular analyses for equine herpesviruses that could have acted as an interference and were found to be negative. The mRNA expression level of the pro-inflammatory genes MMP13 and IL6 in treated equine monocyte-derived macrophages (eMDMs) was evaluated by a SYBR^® Green real-time PCR. In this study, MMP13 represented a reliable target gene to evaluate pro-inflammatory status of macrophages in horses because IFNγ and EIAV infection considerably increased its expression. A more in-depth study of the expression genes of both cytokine-induced and virus-induced markers of eMDM polarization may help us to understand whether these markers in horses are the same as those found in other animal species with similar pathways of innate immunity activation. The identified markers of each macrophage population would allow analysis of the differentiation profiles that could provide information on virus infectivity control in equid populations, envisioning their use in therapeutic strategies.