Ligation of Fc gamma receptor IIB enhances levels of antiviral cytokine in response to PRRSV infection in vitro

PRRSV infection ADE facilitates the attachment and internalization of the virus onto its host cells, such as monocytes and macrophages, through Fc receptor-mediated endocytosis. Fc gamma RIIB is the only inhibitory receptor with a tyrosine-based inhibitory motif (ITIM) in its cytoplasmic tail, where counters the ITAM triggered activation signals and down-regulates phagocytosis. However, porcine Fc gamma RIIB'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 Fc gamma RIIB in PAM cells up-regulated significantly mRNA levels of IFN-alpha and TNF-alpha at any time point post-pretreatment, suggesting that porcine Fc gamma RIIB signal can enhance the innate antiviral response of host cells. PRRSV infection assay mediated by Fc gamma RIIB indicated that selective activation of porcine Fc gamma RIIB in PAM cells enhanced mRNA levels of antiviral cytokine (IFN-alpha and TNF-alpha) and repressed mRNA levels of IL-10 in response to PRRSV infection, suggesting that Fc gamma RIIB ligation can enhance the antiviral immune response to PRRSV infection. In addition, Fc gamma RIIB ligation to infection indicated that PRRSV replication in PAM was not positive correlation with increasing of IFN-alpha mRNA levels and decreasing of IL-10 mRNA levels, suggesting that there is complex viral replication mechanism in immune cells such as PAM for PRRSV. (C) 2012 Elsevier B.V. All rights reserved.