N-linked glycans in the CD4-binding domain of human immunodeficiency virus type 1 envelope glycoprotein gp160 are essential for the in vivo priming of T cells recognizing an epitope located in their vicinity.
Deglycosylation of viral glycoproteins has been suggested to influence the number of available T cell determinants and to increase T cell recognition of antigens. In this study, we have investigated whether T cell responses to the HIV-1 envelope glycoprotein gp160 were influenced by deletion of three N-glycans of the protein. Wild type (wt) and a mutated form of gp160 (gp160A123) lacking the three N-glycans in the C-terminal CD4-binding region efficiently induced antigen-specific T cell responses in mice of the H-2b, H-2d, and H-2k haplotypes. Further, T cells primed by either wt gp160 or gp160A123 were stimulated in vitro to a similar extent by the homologous and heterologous protein, indicating that deletion of the glycans did not affect the overall immunogenicity and antigenicity of gp160A123. Wild-type gp160 and gp160A123 induced comparable T cell responses to those of epitopes which with respect to the secondary structure of gp160 were distant from the deleted glycans. However, in mice of the H-2b haplotype, wt gp160 primed T cells which responded in vitro to a peptide containing one of the deleted N-glycosylation sites (Asn448), whereas T cells induced by gp160A123 were unable to recognize this peptide. Thus, deletion of the glycans abrogated the in vivo priming of T cells recognizing an epitope in close proximity to the deletion sites. Furthermore, enzymatically deglycosylated gp160 failed to induce a T cell response to this epitope. These results indicate that the in vivo generation of certain T cell determinants from glycoproteins is dependent on the glycosylation of the protein.
Sjölander
S
S
Department of Veterinary Microbiology, College of Veterinary Medicine, Swedish University of Agricultural Sciences, Uppsala, Sweden.
Bolmstedt
A
A
Akerblom
L
L
Horal
P
P
Olofsson
S
S
Morein
B
B
Sjölander
A
A
D000595:Amino Acid Sequence; D000818:Animals; D001216:Asparagine / Q000276:immunology; D015704:CD4 Antigens / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D000939:Epitopes / Q000276:immunology; D005260:Female; D015686:Gene Products, env / Q000276:immunology*; D006031:Glycosylation; D019302:HIV Envelope Protein gp160; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008969:Molecular Sequence Data; D011134:Polysaccharides / Q000276:immunology* / Q000378:metabolism; D011498:Protein Precursors / Q000276:immunology*; D013045:Species Specificity; D013329:Structure-Activity Relationship
D015704:CD4 Antigens; D000939:Epitopes; D015686:Gene Products, env; D019302:HIV Envelope Protein gp160; D011134:Polysaccharides; D011498:Protein Precursors; D001216:Asparagine