Polysaccharide mimicry of the epitope of the broadly neutralizing anti-HIV antibody, 2G12, induces enhanced antibody responses to self oligomannose glycans

Glycobiology. 2010 Jul;20(7):812-23. doi: 10.1093/glycob/cwq020. Epub 2010 Feb 24.


Immunologically, "self" carbohydrates protect the HIV-1 surface glycoprotein, gp120, from antibody recognition. However, one broadly neutralizing antibody, 2G12, neutralizes primary viral isolates by direct recognition of Manalpha1-->2Man motifs formed by the host-derived oligomannose glycans of the viral envelope. Immunogens, capable of eliciting antibodies of similar specificity to 2G12, are therefore candidates for HIV/AIDS vaccine development. In this context, it is known that the yeast mannan polysaccharides exhibit significant antigenic mimicry with the glycans of HIV-1. Here, we report that modulation of yeast polysaccharide biosynthesis directly controls the molecular specificity of cross-reactive antibodies to self oligomannose glycans. Saccharomyces cerevisiae mannans are typically terminated by alpha1-->3-linked mannoses that cap a Manalpha1-->2Man motif that otherwise closely resembles the part of the oligomannose epitope recognized by 2G12. Immunization with S. cerevisiae deficient for the alpha1-->3 mannosyltransferase gene (DeltaMnn1), but not with wild-type S. cerevisiae, reproducibly elicited antibodies to the self oligomannose glycans. Carbohydrate microarray analysis of DeltaMnn1 immune sera revealed fine carbohydrate specificity to Manalpha1-->2Man units, closely matching that of 2G12. These specificities were further corroborated by enzyme-linked immunosorbent assay with chemically defined glycoforms of gp120. These antibodies exhibited remarkable similarity in the carbohydrate specificity to 2G12 and displayed statistically significant, albeit extremely weak, neutralization of HIV-1 compared to control immune sera. These data confirm the Manalpha1-->2Man motif as the primary carbohydrate neutralization determinant of HIV-1 and show that the genetic modulation of microbial polysaccharides is a route towards immunogens capable of eliciting antibody responses to the glycans of HIV-1.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Neutralizing
  • Epitopes / immunology*
  • HIV Antibodies / immunology*
  • HIV Envelope Protein gp120 / metabolism
  • Mannose / immunology*
  • Mannose / metabolism
  • Molecular Mimicry / immunology


  • Antibodies, Neutralizing
  • Epitopes
  • HIV Antibodies
  • HIV Envelope Protein gp120
  • Mannose