Analysis of memory B cell responses and isolation of novel monoclonal antibodies with neutralizing breadth from HIV-1-infected individuals.
BACKGROUND
The isolation of human monoclonal antibodies (mAbs) that neutralize a broad spectrum of primary HIV-1 isolates and the characterization of the human neutralizing antibody B cell response to HIV-1 infection are important goals that are central to the design of an effective antibody-based vaccine.


RESULTS
We immortalized IgG(+) memory B cells from individuals infected with diverse clades of HIV-1 and selected on the basis of plasma neutralization profiles that were cross-clade and relatively potent. Culture supernatants were screened using various recombinant forms of the envelope glycoproteins (Env) in multiple parallel assays. We isolated 58 mAbs that were mapped to different Env surfaces, most of which showed neutralizing activity. One mAb in particular (HJ16) specific for a novel epitope proximal to the CD4 binding site on gp120 selectively neutralized a multi-clade panel of Tier-2 HIV-1 pseudoviruses, and demonstrated reactivity that was comparable in breadth, but distinct in neutralization specificity, to that of the other CD4 binding site-specific neutralizing mAb b12. A second mAb (HGN194) bound a conserved epitope in the V3 crown and neutralized all Tier-1 and a proportion of Tier-2 pseudoviruses tested, irrespective of clade. A third mAb (HK20) with broad neutralizing activity, particularly as a Fab fragment, recognized a highly conserved epitope in the HR-1 region of gp41, but showed striking assay-dependent selectivity in its activity.


CONCLUSIONS
This study reveals that by using appropriate screening methods, a large proportion of memory B cells can be isolated that produce mAbs with HIV-1 neutralizing activity. Three of these mAbs show unusual breadth of neutralization and therefore add to the current panel of HIV-1 neutralizing antibodies with potential for passive protection and template-based vaccine design.
Corti
Davide
D
Institute for Research in Biomedicine, Bellinzona, Switzerland.
Langedijk
Johannes P M
JP
Hinz
Andreas
A
Seaman
Michael S
MS
Vanzetta
Fabrizia
F
Fernandez-Rodriguez
Blanca M
BM
Silacci
Chiara
C
Pinna
Debora
D
Jarrossay
David
D
Balla-Jhagjhoorsingh
Sunita
S
Willems
Betty
B
Zekveld
Maria J
MJ
Dreja
Hanna
H
O'Sullivan
Eithne
E
Pade
Corinna
C
Orkin
Chloe
C
Jeffs
Simon A
SA
Montefiori
David C
DC
Davis
David
D
Weissenhorn
Winfried
W
McKnight
Aine
A
Heeney
Jonathan L
JL
Sallusto
Federica
F
Sattentau
Quentin J
QJ
Weiss
Robin A
RA
Lanzavecchia
Antonio
A
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000276:immunology*; D057134:Antibodies, Neutralizing / Q000737:chemistry / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D001666:Binding Sites, Antibody; D015704:CD4 Antigens / Q000276:immunology; D000939:Epitopes / Q000737:chemistry; D015658:HIV Infections / Q000276:immunology*; D015497:HIV-1; D006801:Humans; D007156:Immunologic Memory; D008969:Molecular Sequence Data
D000911:Antibodies, Monoclonal; D057134:Antibodies, Neutralizing; D015704:CD4 Antigens; D000939:Epitopes