title: Transcytosis-blocking abs elicited by an oligomeric immunogen based on the membrane proximal region of HIV-1 gp41 target non-neutralizing epitopes.
abstract: CTB-MPR(649-684), a translational fusion protein consisting of cholera toxin B subunit (CTB) and residues 649 684 of gp41 membrane proximal region (MPR), is a candidate vaccine aimed at blocking early steps of HIV-1 mucosal transmission. Bacterially produced CTB MPR(649-684) was purified to homogeneity by two affinity chromatography steps. Similar to gp41 and derivatives thereof, the MPR domain can specifically and reversibly self-associate. The affinities of the broadly-neutralizing monoclonal Abs 4E10 and 2F5 to CTB MPR(649-684) were equivalent to their nanomolar affinities toward an MPR peptide. The fusion protein's affinity to GM1 ganglioside was comparable to that of native CTB. Rabbits immunized with CTB-MPR(649-684) raised only a modest level of anti-MPR(649-684) Abs. However, a prime-boost immunization with CTB-MPR(649-684) and a second MPR(649-684)-based immunogen elicited a more productive anti-MPR(649-684) antibody response. These Abs strongly blocked the epithelial transcytosis of a primary subtype B HIV-1 isolate in a human tight epithelial model, expanding our previously reported results using a clade D virus. The Abs recognized epitopes at the N-terminal portion of the MPR peptide, away from the 2F5 and 4E10 epitopes and were not effective in neutralizing infection of CD4+ cells. These results indicate distinct vulnerabilities of two separate interactions of HIV-1 with human cells - Abs against the C-terminal portion of the MPR can neutralize CD4+-dependent infection, while Abs targeting the MPR's N-terminal portion can effectively block galactosyl ceramide dependent transcytosis. We propose that Abs induced by MPR(649-684)-based immunogens may provide broad protective value independent of infection neutralization.
authors.affiliation: Center for Infectious Diseases and Vaccinology, The Biodesign Institute and School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Matoba
authors.forename: Tagan A
authors.initials: TA
authors.lastname: Griffin
authors.forename: Michele
authors.initials: M
authors.lastname: Mittman
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Doran
authors.forename: Annette
authors.initials: A
authors.lastname: Alfsen
authors.forename: David C
authors.initials: DC
authors.lastname: Montefiori
authors.forename: Carl V
authors.initials: CV
authors.lastname: Hanson
authors.forename: Morgane
authors.initials: M
authors.lastname: Bomsel
authors.forename: Tsafrir S
authors.initials: TS
authors.lastname: Mor
mesh_terms: D016915:AIDS Vaccines / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification / Q000494:pharmacology*; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology; D001667:Binding, Competitive; D002772:Cholera Toxin / Q000235:genetics / Q000276:immunology; D000939:Epitopes; D005260:Female; D015483:HIV Antibodies / Q000096:biosynthesis / Q000276:immunology*; D015700:HIV Envelope Protein gp41 / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D015497:HIV-1 / Q000276:immunology*; D019073:HT29 Cells; D006801:Humans; D007114:Immunization; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000276:immunology; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification / Q000494:pharmacology*
chemical_list: D016915:AIDS Vaccines; D000911:Antibodies, Monoclonal; D000939:Epitopes; D015483:HIV Antibodies; D015700:HIV Envelope Protein gp41; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D002772:Cholera Toxin