Analysis of Memory B Cell Responses and Isolation of Novel Monoclonal Antibodies with Neutralizing Breadth from HIV-1-Infected Individuals

Abstract

BackgroundThe 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.Methods and FindingsWe 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.ConclusionsThis 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.

Trimeric HIV-1 glycoprotein gp140 immunogens and native HIV-1 envelope glycoproteins display the same closed and open quaternary molecular architectures

“…Nevertheless, the differential ability of KNH1144 and JR-FL trimers to bind antibodies such as 17b could be useful for immunogen design, and variant gp140 trimers preferentially stabilized in distinct intermediate states could potentially be engineered and then mixed to create a composite vaccine, with the goal of increasing the breadth of the neutralizing antibody response. Any variations in the extent to which different regions on gp120 and gp41 are accessible in the open state may also increase the likelihood of inducing broadly neutralizing antibodies, such as b12 (23), PG9/16 (24), VRC01 (25), or HJ16 (26).…”

Identification and specificity of broadly neutralizing antibodies against HIV

“…This bnAb, in contrast to VRC01, does not induce conformational changes in gp120 upon binding 25. Many additional CD4‐binding site bnAbs were isolated using RSC356 or other Env baits40 and one by EBV immortalization of B cells followed by an ELISA‐based binding screen 75. Structural studies have enabled comparison of the CD4‐binding site bnAbs and the definition of two subclasses: those that bind predominantly using their CDRH3 and those that are genetically restricted and use either the VH1‐2 or VH1‐46 V gene 76.…”

Antibody‐virus co‐evolution in HIV infection: paths for HIV vaccine development

“…VRC01 and CH31) and 8ANC131-class of bnAbs that use V H 1-46 (e.g.8ANC131 and CH235) (16, 18,26,27,33,42, 43). In contrast, the variable heavy third complementarity determining region (CDR H3)-binder -class of CD4bs bnAbs, such as CH103, HJ16 and CH98 bnAbs, use multiple V H genes (17, 21, 42, 44). …”