Ligation of porcine Fc gamma receptor I inhibits levels of antiviral cytokine in response to PRRSV infection in vitro

PRRSV infection ADE facilitates the attachment and internalization of the virus onto macrophages through Fc receptor-mediated endocytosis. FcγRI is the activating receptor with a tyrosine-based activating motif (ITAM) in its cytoplasmic tail, where up-regulates phagocytosis. However, porcine FcγRI's role in the antiviral immune response to PRRSV infection has not been studied. In this study, our results indicated that selective activation of porcine FcγRI in PAM cells down-regulated significantly mRNA levels of IFN-α and TNF-α post-pretreatment, suggesting that porcine FcγRI signal can inhibit the innate antiviral response of host cells. PRRSV infection assay mediated by FcγRI indicated that selective activation of porcine FcγRI in PAM cells inhibited significantly mRNA levels of antiviral cytokine (IFN-α and TNF-α) in response to PRRSV infection, suggesting that FcγRI ligation can inhibit the antiviral immune response to PRRSV infection.