title: Differential glycosylation of envelope gp120 is associated with differential recognition of HIV-1 by virus-specific antibodies and cell infection.
abstract: BACKGROUND
  HIV-1 entry into host cells is mediated by interactions between the virus envelope glycoprotein (gp120/gp41) and host-cell receptors. N-glycans represent approximately 50% of the molecular mass of gp120 and serve as potential antigenic determinants and/or as a shield against immune recognition. We previously reported that N-glycosylation of recombinant gp120 varied, depending on the producer cells, and the glycosylation variability affected gp120 recognition by serum antibodies from persons infected with HIV-1 subtype B. However, the impact of gp120 differential glycosylation on recognition by broadly neutralizing monoclonal antibodies or by polyclonal antibodies of individuals infected with other HIV-1 subtypes is unknown.
  
  
  METHODS
  Recombinant multimerizing gp120 antigens were expressed in different cells, HEK 293T, T-cell, rhabdomyosarcoma, hepatocellular carcinoma, and Chinese hamster ovary cell lines. Binding of broadly neutralizing monoclonal antibodies and polyclonal antibodies from sera of subtype A/C HIV-1-infected subjects with individual gp120 glycoforms was assessed by ELISA. In addition, immunodetection was performed using Western and dot blot assays. Recombinant gp120 glycoforms were tested for inhibition of infection of reporter cells by SF162 and YU.2 Env-pseudotyped R5 viruses.
  
  
  RESULTS
  We demonstrated, using ELISA, that gp120 glycans sterically adjacent to the V3 loop only moderately contribute to differential recognition of a short apex motif GPGRA and GPGR by monoclonal antibodies F425 B4e8 and 447-52D, respectively. The binding of antibodies recognizing longer peptide motifs overlapping with GPGR epitope (268 D4, 257 D4, 19b) was significantly altered. Recognition of gp120 glycoforms by monoclonal antibodies specific for other than V3-loop epitopes was significantly affected by cell types used for gp120 expression. These epitopes included CD4-binding site (VRC03, VRC01, b12), discontinuous epitope involving V1/V2 loop with the associated glycans (PG9, PG16), and an epitope including V3-base-, N332 oligomannose-, and surrounding glycans-containing epitope (PGT 121). Moreover, the different gp120 glycoforms variably inhibited HIV-1 infection of reporter cells.
  
  
  CONCLUSIONS
  Our data support the hypothesis that the glycosylation machinery of different cells shapes gp120 glycosylation and, consequently, impacts envelope recognition by specific antibodies as well as the interaction of HIV-1 gp120 with cellular receptors. These findings underscore the importance of selection of appropriately glycosylated HIV-1 envelope as a vaccine antigen.
authors.affiliation: Department of Immunology, Palacky University in Olomouc, 77100 Olomouc, Czech Republic ; Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: Milan
authors.initials: M
authors.lastname: Raska
authors.affiliation: Department of Immunology, Palacky University in Olomouc, 77100 Olomouc, Czech Republic.
authors.forename: Lydie
authors.initials: L
authors.lastname: Czernekova
authors.affiliation: Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: Zina
authors.initials: Z
authors.lastname: Moldoveanu
authors.affiliation: Department of Immunology, Palacky University in Olomouc, 77100 Olomouc, Czech Republic.
authors.forename: Katerina
authors.initials: K
authors.lastname: Zachova
authors.affiliation: Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: Matt C
authors.initials: MC
authors.lastname: Elliott
authors.affiliation: Department of Surgery, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: Zdenek
authors.initials: Z
authors.lastname: Novak
authors.affiliation: Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: Stacy
authors.initials: S
authors.lastname: Hall
authors.affiliation: Department of Infectious Diseases & Tropical Medicine, Clinic of the University of Munich, Munich, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Hoelscher
authors.affiliation: NIMR-Mbeya Medical Research Programme, Mbeya, Tanzania.
authors.forename: Leonard
authors.initials: L
authors.lastname: Maboko
authors.affiliation: Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: Rhubell
authors.initials: R
authors.lastname: Brown
authors.affiliation: Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA ; VA Medical Center, Birmingham, AL 35205, USA.
authors.forename: Phillip D
authors.initials: PD
authors.lastname: Smith
authors.affiliation: Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA ; Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA ; Institute of Microbiology and Immunology, First Faculty of Medicine, Charles University, 12108 Prague, Czech Republic.
authors.forename: Jiri
authors.initials: J
authors.lastname: Mestecky
authors.affiliation: Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: Jan
authors.initials: J
authors.lastname: Novak
keywords: Deglycosylation resistance; Glycan-specific antibody; Neutralization inhibition; gp120 glycosylation