A Molecular Mechanism View Of Dendritic Cell-mediated Cross-presentation Of Neuraminidase Of H5N1AIVs

The induction of neutralizing antibodies against its surface antigens including theneuraminidase and hemagglutinin is the major strategy of vaccination against the avianinfluenza. In turn, the variable of the surface antigens enables the influenza virus toavoid relevant antibody-mediated immune surveillance. As such the surface antigenicmolecules are frequently changing, the immune response cytotoxic T-lymphocytes(CTLs) require broad cross-reactions with serologically distinct subtypes of theinfluenza A virus. To sustain the strong immunity driven by T cells, DCs are crucial forcross-priming of the na ve CD8+T lymphocytes against exogenous antigen and thusplay a key role in antiviral immunity. In fact, a series of strategies established arounddendritic cells and targeted to strengthen specificity anti-tumor immunity have exhibitedgreat clinical application prospects, however, the research of cross-presentationmechanism limited to soluble model antigen OVA, coupled OVA antigen, cells orliposome-associated antigen, bacterial particulate antigen and other forms of antigen,the mechanisms underlying the cross-presentation of specific-exogenous influenza virusantigen NA to CD8+T cells are not clearly elucidated.Therefore, here, we first explored whether and how the viral surface antigenneuraminidase is cross-presented by DCs using the technology of the FCM,fluorescence localization and inhibitors.(1) Internalization: The results indicate that the antigen is taken up bymacropinocytosis and phagocytosis upon stimulation of the DCs maturation.(2) Processing: Thereafter, the antigen is internalized through conserved ‘hybrid’compartments that have functions similar to those exerted by both the endoplasmicreticulum (ER) and early endosome. Whereby, the antigen is preserved for protectionfrom early degradation such that it is endowed with the long-lasting, cross-primingpotency. The antigen is also retrotransfered to the cytoplasm, whereupon it is degradatedby26S proteasomes;(3) Loading: Then, the resulting peptides are retransported to the hybridcompartments, where they are further processed through the MHC class I-peptidecomplex-loading pathway;(4) Transport: Finally, the MHC class I-peptide complex is transported to the cellmembrance through the non-classical MHC class I antigen transport pathway to active the CD8+T lymphocytes.Overall, our data demonstrate a new-type strategy to design vaccines against theinfluenza H5N1infection, allowing activation of its neuraminidase antigentcross-presentation pathway.