HIV-1 subtype B clone JRFL was provided by Dennis Burton (Scripps Institute, La Jolla, US)

HIV-1 subtype B clone JRFL was provided by Dennis Burton (Scripps Institute, La Jolla, US). Dimethocaine IC50 titers against HIV-1 M7-Luc cells.(0.05 MB PDF) pone.0008805.s006.pdf (45K) GUID:?054ECC8A-1E85-443C-B575-59191EF3AC51 Abstract 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. Methods and Findings 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 Dimethocaine the CD4 binding site on gp120 selectively neutralized a multi-clade panel of Tier-2 HIV-1 pseudoviruses, and exhibited 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, acknowledged 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. Introduction Neutralizing antibodies provide one arm of the adaptive immune response against the human immunodeficiency computer virus type 1 (HIV-1). Several reports demonstrated that this neutralizing antibody response exerts selective pressure during HIV-1 replication gene observed soon after primary contamination [1], [2]. Furthermore, selective pressure imposed by neutralizing antibodies has been demonstrated in a human trial where three neutralizing monoclonal antibodies (mAbs) administered during HAART treatment-interruption led to a reduction in viremia followed by selection of escape mutants [3], [4]. Passive Dimethocaine transfer studies in macaques showed that this administration of HIV-1 neutralizing mAbs protects against vaginal or intravenous challenge with SIV-HIV-1 chimeric viruses (SHIV) [5], [6], [7], [8], [9]. In some models protection depended not only on viral neutralization but also on Fc-mediated antibody effector functions [10], [11]. Given the predicted low-titer inoculum driving HIV-1 sexual transmission, a vaccine capable of eliciting antibodies that neutralize a broad spectrum of viral strains could potentially reduce or prevent contamination. It has been anticipated that this identification of broadly neutralizing mAbs from HIV-1 infected individuals, and the characterization of their cognate epitopes will be instrumental in the design of immunogens capable of eliciting such a broad neutralizing response [12]. This idea has led to a major international cooperative effort within consortia of laboratories with complementary expertise in human Rabbit Polyclonal to PPP4R2 immunology, structural biology and vaccine design [13], [14]. HIV-1 is usually characterized by an extraordinary genetic diversity, reflected by the presence of several clades (subtypes), a fact that represents a significant impediment to vaccine development. is the most variable HIV-1 gene, with up to 35% sequence diversity among clades, 20% diversity within clades, and 10% diversity in a single infected individual [15], [16], [17]. Several conserved epitopes have been defined by a small panel of neutralizing mAbs isolated using different experimental approaches. One epitope that appears to be relatively conserved and overlaps with the CD4 binding site (CD4bs) on the surface Env glycoprotein gp120 is usually recognized by mAb b12, which is the most potent and broadly-reactive mAb of such specificity [18], [19], [20]. This site was recently shown to be a significant target of.