mechanism of antigen presentation of avian dendritic cells regulated by H9N2 AIV

The most important ability for dendritic cells (DCs) is to present antigen, which plays an irreplaceable role in recognizing and presenting viruses. Avian influenza virus (AIV), an enveloped virus with a segmented, single-stranded, negative-sense RNA genome, can cause clinical diseases in a wide range of mammalian and avian species. Previous study demonstrated H9N2 AIV inhibited the antigen present ability of avian DCs. To better understood the underline mechanism, we evaluated the entirety microRNAs and lncRNAs changing on avian DCs stimulated by H9N2 AIV and found that 19significant altered microRNAs and 332 hugely changed lncRNAs. Considered the activating function of structure protein, we turned to check which non-structural protein of AIV might inhibit the antigen presentation of DCs. Phenotype alteration and lymphocyte proliferation test demonstrated that NS2 and M42 had the ability to inhibited the maturation of LPS stimulated DCs, while NS2 might has more power to block the antigen presenting progress of DCs. Moreover, global analysis was use to illustrate how non-structural protein NS2 hijack and inhibited the antigen presentation of avian BMDCs. Result show zero altered microRNAs in NS2 transfect avian BMDCs, compared with 2186 significant changed lncRNAs. This result hint us microRNAs biogenesis might be hijacked by NS2 protein on avian BMDCs. Further experiment demonstrated that NS2 transfect significant induced 37 significant expressed microRNAs in HEK293T cells, compared with 48 significant expressed lncRNAs. To clarify this phenomenon, further study convinced that NS2 protein could interact with expotin5, which response for pre-miRNA nuclear exporting transfer, to inhibit the microRNA biogenesis and might result in suppressed antigen present ability of DCs. Since HEK293T and BMDCs both did not produce IFN-beta to defending virus infection, we then predicted and demonstrated that NS2 could interact with IRF-3 to regulate the production of IFN, which might corrupt the main host defending system to suit for virus replication. Our result also demonstrated that virus induced miRNA hugely increased in NS2 or AIV treatment groups. Lastly, our result suggested that NS2 also might interacted with the M6A methylation protein Mettl13 to influence the antigen presentation ability of DCs. Altogether, our innovative study will shed new light on the role of Virus nonstructural protein in hijack avian DCs and inhibiting their antigen present ability.