Antiviral Immune Characters And Function Of Goose TLR7 And TLR21

TLRs are important pattern recognition receptors, which can recognize various component of pathogenic microorganism. Previous studies have shown that TLR7 can be induced by single strand RNA virus like avian influenza virus and active host immune response. Here in vivo study, after the geese were infected with H9N2, GoTLR7 was significantly upregulated at 3d to 7d post infection (PI) in the lung, while no change was observed in GoTLR21 expression during infection. The OASL was highly induced in Bursa of Fabricius, Harderian Gland and Lung, the increase of GoRIG-I in Lung and Small Intestine was detected, while PKR showed an increase in Lung, but a decrease in thymus. In vitro study, GoTLR7 and GoRIG-I were induced, while GoTLR21 was not. OAS and PKR were significantly induced. In contrast, MX was surprisely suppressed. As many research reports in the innate immune regulation of chicken and duck, Goose also showed a complex immune response after challenged with H9N2, which probably because of the different cellular localization of virus nucleic acid recognition receptors GoTLR7 and GoTLR21 during H9N2 infection.To investigate the antiviral function of GoTLR7 and GoTLR21, we constructed the recombinant plasmid PEGFP-C1-GoTLR7 and pDs-Red1-N1-GoTLR21. When DF-1 cells were transfected with GoTLR7 before challenging with Newcastle disease virus, the replication of virus was inhibited at 12h and 24h, while not GoTLR21. Detecting the TCID50 of experimental group and control group, virus titers declined in the group of transfected with GoTLR7 at 24h, the group transfected with GoTLR21 did not have significant change.The subcellular localization of TLRs can affect their signaling transduction and immune function. In this research, we explored the distinct cellular localization of GoTLR7 and GoTLR21 both in heteroloGous (DF-1, BHK21) and homoloGous cells (GEF). GoTLR7 was concentrated distribute in one side around the cell nucleus both in DF-1 and BHK cells and exclusively cytoplasm straining was observed in GEF at 24h transfection, surprisingly its localization characters changed into scattered dot shape in cytoplasm at 72h transfection in BHK21. GoTLR21 showed a similar cellular localization feature on different cell types (GEF, DF-1, BHK and MDCK) within 24h, as exclusively scattered around the cell nucleus. But from 24h afterward, the localization and the shape of GoTLR21 fusion protein changed a lot in the BHK21 cells.