Carbohydrate determinant NeuAc-Gal beta (1-4) of N-linked glycans modulates the antigenic activity of human immunodeficiency virus type 1 glycoprotein gp120.
In the present study we investigated to what extent the peripheral carbohydrate structure of N-linked glycans influences the antigenic properties of human immunodeficiency virus type 1 glycoprotein 120 (gp120). Recombinant gp120 was purified from GMK cells infected with a recombinant vaccinia virus expressing gp120. Purified gp120 was then coated onto 96-well ELISA microplates and subjected to sequential removal of peripheral monosaccharide units. Modified or unmodified gp120 was then incubated with monoclonal antibodies recognizing specific epitopes of gp120 and with a reporter lectin to determine the extent of carbohydrate elimination. Antibody and lectin binding was quantified in an enzyme-linked system. We found that the carbohydrate structure NeuAc-Gal beta (1-4) of N-linked glycans, defined both by lectin reactivity and by specific glycosidases, is involved in modulating the binding of antibody to a number of epitopes of peptide nature. The binding of antibody to one class of epitopes, situated in a region between amino acids 200 and 230, was strongly increased by removal of NeuAc-Gal beta (1-4), whereas the binding to epitopes in the V3 region was decreased and the binding to epitopes in the far N-terminal region was not altered by the treatment. These results suggested that peripheral structures of N-glycans are involved in modulating the overall conformation of gp120.
D000911:Antibodies, Monoclonal / Q000276:immunology; D002240:Carbohydrate Sequence; D000939:Epitopes; D015488:HIV Antigens / Q000737:chemistry*; D015699:HIV Envelope Protein gp120 / Q000737:chemistry* / Q000276:immunology; D015497:HIV-1 / Q000276:immunology*; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000276:immunology; D012795:Sialoglycoproteins / Q000276:immunology*; D013329:Structure-Activity Relationship
D000911:Antibodies, Monoclonal; D000939:Epitopes; D015488:HIV Antigens; D015699:HIV Envelope Protein gp120; D011994:Recombinant Proteins; D012795:Sialoglycoproteins