Two-dimensional gel-based approaches for the assessment of N-Linked and O-GlcNAc glycosylation in human and simian immunodeficiency viruses.

The glycosylation state of envelope glycoproteins in human and simian immunodeficiency viruses (HIV/SIV) is critical to viral infectivity and tropism, viral protein processing, and in virus evasion of the immune system. Using a rapid fluorescent 2-D gel-based method coupled with enzymatic pre-treatment of virus with PNGase F (Peptide: N-Glycosidase F) and fluorescent 2-D gels or 2-D gel Western blotting, we show significant differences in the glycosylation patterns of two SIV strains widely used in animal models of HIV disease and vaccine studies. We also demonstrate the modification of a host protein important in HIV biology (HLA-DR) by O-GlcNAc. Further, this experimental pipeline allows for the identification of the modified protein and the site of N-linked glycosylation by fluorescent 2-DE coupled with MS and the qualitative and semi-quantitative assessment of viral glycosylation. The method is fully compatible with downstream glycomics analysis. This approach will permit correlation of virus glycosylation status with pathological severity and may serve as a rapid screen of viruses from physiological samples for further study by more advanced MS methodology.