scholarly journals Bispecific Antibodies Targeting Different Epitopes on the HIV-1 Envelope Exhibit Broad and Potent Neutralization

2015 ◽  
Vol 89 (24) ◽  
pp. 12501-12512 ◽  
Author(s):  
M. Asokan ◽  
R. S. Rudicell ◽  
M. Louder ◽  
K. McKee ◽  
S. O'Dell ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Bispecific Antibody ◽  
Rhesus Macaques ◽  
Bispecific Antibodies ◽  
Pharmacokinetic Parameters ◽  
Highly Active ◽  
Antibody Specificities ◽  
The Individual ◽  
Hiv 1

ABSTRACTThe potency and breadth of the recently isolated neutralizing human monoclonal antibodies to HIV-1 have stimulated interest in their use to prevent or to treat HIV-1 infection. Due to the antigenically diverse nature of the HIV-1 envelope (Env), no single antibody is highly active against all viral strains. While the physical combination of two broadly neutralizing antibodies (bNAbs) can improve coverage against the majority of viruses, the clinical-grade manufacturing and testing of two independent antibody products are time and resource intensive. In this study, we constructed bispecific immunoglobulins (IgGs) composed of independent antigen-binding fragments with a common Fc region. We developed four different bispecific IgG variants that included antibodies targeting four major sites of HIV-1 neutralization. We show that these bispecific IgGs display features of both antibody specificities and, in some cases, display improved coverage over the individual parental antibodies. All four bispecific IgGs neutralized 94% to 97% of antigenically diverse viruses in a panel of 206 HIV-1 strains. Among the bispecific IgGs tested, VRC07 × PG9-16 displayed the most favorable neutralization profile. It was superior in breadth to either of the individual antibodies, neutralizing 97% of viruses with a median 50% inhibitory concentration (IC50) of 0.055 μg/ml. This bispecific IgG also demonstratedin vivopharmacokinetic parameters comparable to those of the parental bNAbs when administered to rhesus macaques. These results suggest that IgG-based bispecific antibodies are promising candidates for the prevention and treatment of HIV-1 infection in humans.IMPORTANCETo prevent or treat HIV-1 infection, antibodies must potently neutralize nearly all strains of HIV-1. Thus, the physical combination of two or more antibodies may be needed to broaden neutralization coverage and diminish the possibility of viral resistance. A bispecific antibody that has two different antibody binding arms could potentially display neutralization characteristics better than those of any single parental antibody. Here we show that bispecific antibodies contain the binding specificities of the two parental antibodies and that a single bispecific antibody can neutralize 97% of viral strains with a high overall potency. These findings support the use of bispecific antibodies for the prevention or treatment of HIV-1 infection.

scholarly journals Envelope residue 375 substitutions in simian–human immunodeficiency viruses enhance CD4 binding and replication in rhesus macaques

2016 ◽  
Vol 113 (24) ◽  
pp. E3413-E3422 ◽  
Author(s):  
Hui Li ◽  
Shuyi Wang ◽  
Rui Kong ◽  
Wenge Ding ◽  
Fang-Hua Lee ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Germ Line ◽  
Virus Entry ◽  
Rhesus Macaques ◽  
Critical Determinant ◽  
Human Immunodeficiency Viruses ◽  
Subtype A ◽  
Hiv 1

Most simian–human immunodeficiency viruses (SHIVs) bearing envelope (Env) glycoproteins from primary HIV-1 strains fail to infect rhesus macaques (RMs). We hypothesized that inefficient Env binding to rhesus CD4 (rhCD4) limits virus entry and replication and could be enhanced by substituting naturally occurring simian immunodeficiency virus Env residues at position 375, which resides at a critical location in the CD4-binding pocket and is under strong positive evolutionary pressure across the broad spectrum of primate lentiviruses. SHIVs containing primary or transmitted/founder HIV-1 subtype A, B, C, or D Envs with genotypic variants at residue 375 were constructed and analyzed in vitro and in vivo. Bulky hydrophobic or basic amino acids substituted for serine-375 enhanced Env affinity for rhCD4, virus entry into cells bearing rhCD4, and virus replication in primary rhCD4 T cells without appreciably affecting antigenicity or antibody-mediated neutralization sensitivity. Twenty-four RMs inoculated with subtype A, B, C, or D SHIVs all became productively infected with different Env375 variants—S, M, Y, H, W, or F—that were differentially selected in different Env backbones. Notably, SHIVs replicated persistently at titers comparable to HIV-1 in humans and elicited autologous neutralizing antibody responses typical of HIV-1. Seven animals succumbed to AIDS. These findings identify Env–rhCD4 binding as a critical determinant for productive SHIV infection in RMs and validate a novel and generalizable strategy for constructing SHIVs with Env glycoproteins of interest, including those that in humans elicit broadly neutralizing antibodies or bind particular Ig germ-line B-cell receptors.

scholarly journals New SHIVs and Improved Design Strategy for Modeling HIV-1 Transmission, Immunopathogenesis, Prevention and Cure

2021 ◽  
Author(s):  
Hui Li ◽  
Shuyi Wang ◽  
Fang-Hua Lee ◽  
Ryan S. Roark ◽  
Alex I. Murphy ◽  
...  
Keyword(s):  
T Cells ◽  
Neutralizing Antibodies ◽  
Large Scale ◽  
Rhesus Macaques ◽  
Passive Immunization ◽  
Design Strategy ◽  
Efficient Replication ◽  
Hiv 1

Previously, we showed that substitution of HIV-1 Env residue 375-Ser by bulky aromatic residues enhances binding to rhesus CD4 and enables primary HIV-1 Envs to support efficient replication as simian-human immunodeficiency virus (SHIV) chimeras in rhesus macaques (RMs). Here, we test this design strategy more broadly by constructing SHIVs containing ten primary Envs corresponding to HIV-1 subtypes A, B, C, AE and AG. All ten SHIVs bearing wildtype Env375 residues replicated efficiently in human CD4+ T cells, but only one replicated efficiently in primary rhesus cells. This was a subtype AE SHIV that naturally contained His at Env375. Replacement of wildtype Env375 residues by Trp, Tyr, Phe or His in the other nine SHIVs led to efficient replication in rhesus CD4+ T cells in vitro and in vivo. Nine SHIVs containing optimized Env375 alleles were grown large-scale in primary rhesus CD4+ T cells to serve as challenge stocks in preclinical prevention trials. These virus stocks were genetically homogeneous, native-like in Env antigenicity and tier-2 neutralization sensitivity, and transmissible by rectal, vaginal, penile, oral or intravenous routes. To facilitate future SHIV constructions, we engineered a simplified second-generation design scheme and validated it in RMs. Overall, our findings demonstrate that SHIVs bearing primary Envs with bulky aromatic substitutions at Env375 consistently replicate in RMs, recapitulating many features of HIV-1 infection in humans. Such SHIVs are efficiently transmitted by mucosal routes common to HIV-1 infection and can be used to test vaccine efficacy in preclinical monkey trials. Importance SHIV infection of Indian rhesus macaques is an important animal model for studying HIV-1 transmission, prevention, immunopathogenesis and cure. Such research is timely, given recent progress with active and passive immunization and novel approaches to HIV-1 cure. Given the multifaceted roles of HIV-1 Env in cell tropism and virus entry, and as a target for neutralizing and non-neutralizing antibodies, Envs selected for SHIV construction are of paramount importance. Until recently, it has been impossible to strategically design SHIVs bearing clinically relevant Envs that replicate consistently in monkeys. This changed with the discovery that bulky aromatic substitutions at residue Env375 confer enhanced affinity to rhesus CD4. Here, we show that 10 new SHIVs bearing primary HIV-1 Envs with residue 375 substitutions replicated efficiently in RMs and could be transmitted efficiently across rectal, vaginal, penile and oral mucosa. These findings suggest an expanded role for SHIVs as a model of HIV-1 infection.

scholarly journals A Bispecific Antibody That Simultaneously Recognizes the V2- and V3-Glycan Epitopes of the HIV-1 Envelope Glycoprotein Is Broader and More Potent than Its Parental Antibodies

mBio ◽  
2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Meredith E. Davis-Gardner ◽  
Barnett Alfant ◽  
Jesse A. Weber ◽  
Matthew R. Gardner ◽  
Michael Farzan
Keyword(s):  
Envelope Glycoprotein ◽  
Neutralizing Antibodies ◽  
Bispecific Antibody ◽  
Bispecific Antibodies ◽  
Single Chain ◽  
Broadly Neutralizing Antibodies ◽  
New Class ◽  
And Control ◽  
Hiv 1 ◽  
Established Infection

ABSTRACT Broadly neutralizing antibodies (bNAbs) can prevent and control an HIV-1 infection, but their breadth is invariably too limited for use as monotherapy. To address this problem, bi- and trispecific antibody-like constructs have been developed. These engineered antibodies typically have greater breadth than the native bNAbs from which they were derived, but they are not more potent because they do not, in most cases, simultaneously engage more than a single epitope of the HIV-1 envelope glycoprotein (Env). Here, we describe a new class of bispecific antibodies targeting the V2-glycan (apex) and V3-glycan regions of the HIV-1 envelope glycoprotein (Env). Specifically, bispecific antibodies with a single-chain (scFv) form of the CAP256.VRC26.25 V2-glycan (apex) antibody on one antibody arm and a full V3-glycan Fab on the other arm neutralizes more HIV-1 isolates than the bNAbs from which they were derived. Moreover, these bispecific antibodies are markedly more potent than their parental bNAbs, likely because they simultaneously engage both the apex and V3-glycan epitopes of Env. Our data show that simultaneous engagement of two critical epitopes of a single Env trimer can markedly increase the potency of a bispecific antibody. IMPORTANCE Broadly neutralizing antibodies (bNAbs) can prevent a new HIV-1 infection and can at least temporarily suppress an established infection. However, antibody-resistant viruses rapidly emerge in infected persons treated with any single bNAb. Several bispecific antibodies have been developed to increase the breadth of these antibodies, but typically only one arm of these bispecific constructs binds the HIV-1 envelope glycoprotein trimer (Env). Here, we develop and characterize bispecific constructs based on well-characterized V2-glycan and V3-glycan bNAbs and show that at least one member of this class is more potent than its parental antibodies, indicating that they can simultaneously bind both of these epitopes of a single Env trimer. These data show that bispecific antibody-like proteins can achieve greater neutralization potency than the bNAbs from which they were derived.

scholarly journals Characterization and Implementation of a Diverse Simian Immunodeficiency Virus SIVsm Envelope Panel in the Assessment of Neutralizing Antibody Breadth Elicited in Rhesus Macaques by Multimodal Vaccines Expressing the SIVmac239 Envelope

2015 ◽  
Vol 89 (16) ◽  
pp. 8130-8151 ◽  
Author(s):  
Katie M. Kilgore ◽  
Megan K. Murphy ◽  
Samantha L. Burton ◽  
Katherine S. Wetzel ◽  
S. Abigail Smith ◽  
...  
Keyword(s):  
Simian Immunodeficiency Virus ◽  
Nonhuman Primate ◽  
Neutralizing Antibodies ◽  
Rhesus Macaques ◽  
Neutralizing Antibody ◽  
Cd40 Ligand ◽  
Antibody Activity ◽  
Immunodeficiency Virus ◽  
Antibody Profile ◽  
Hiv 1

ABSTRACTAntibodies that can neutralize diverse viral strains are likely to be an important component of a protective human immunodeficiency virus type 1 (HIV-1) vaccine. To this end, preclinical simian immunodeficiency virus (SIV)-based nonhuman primate immunization regimens have been designed to evaluate and enhance antibody-mediated protection. However, these trials often rely on a limited selection of SIV strains with extreme neutralization phenotypes to assess vaccine-elicited antibody activity. To mirror the viral panels used to assess HIV-1 antibody breadth, we created and characterized a novel panel of 14 genetically and phenotypically diverse SIVsm envelope (Env) glycoproteins. To assess the utility of this panel, we characterized the neutralizing activity elicited by four SIVmac239 envelope-expressing DNA/modified vaccinia virus Ankara vector- and protein-based vaccination regimens that included the immunomodulatory adjuvants granulocyte-macrophage colony-stimulating factor, Toll-like receptor (TLR) ligands, and CD40 ligand. The SIVsm Env panel exhibited a spectrum of neutralization sensitivity to SIV-infected plasma pools and monoclonal antibodies, allowing categorization into three tiers. Pooled sera from 91 rhesus macaques immunized in the four trials consistently neutralized only the highly sensitive tier 1a SIVsm Envs, regardless of the immunization regimen. The inability of vaccine-mediated antibodies to neutralize the moderately resistant tier 1b and tier 2 SIVsm Envs defined here suggests that those antibodies were directed toward epitopes that are not accessible on most SIVsm Envs. To achieve a broader and more effective neutralization profile in preclinical vaccine studies that is relevant to known features of HIV-1 neutralization, more emphasis should be placed on optimizing the Env immunogen, as the neutralization profile achieved by the addition of adjuvants does not appear to supersede the neutralizing antibody profile determined by the immunogen.IMPORTANCEMany in the HIV/AIDS vaccine field believe that the ability to elicit broadly neutralizing antibodies capable of blocking genetically diverse HIV-1 variants is a critical component of a protective vaccine. Various SIV-based nonhuman primate vaccine studies have investigated ways to improve antibody-mediated protection against a heterologous SIV challenge, including administering adjuvants that might stimulate a greater neutralization breadth. Using a novel SIV neutralization panel and samples from four rhesus macaque vaccine trials designed for cross comparison, we show that different regimens expressing the same SIV envelope immunogen consistently elicit antibodies that neutralize only the very sensitive tier 1a SIV variants. The results argue that the neutralizing antibody profile elicited by a vaccine is primarily determined by the envelope immunogen and is not substantially broadened by including adjuvants, resulting in the conclusion that the envelope immunogen itself should be the primary consideration in efforts to elicit antibodies with greater neutralization breadth.

scholarly journals Enhanced clearance of HIV-1-infected cells by broadly neutralizing antibodies against HIV-1 in vivo

Science ◽  
2016 ◽  
Vol 352 (6288) ◽  
pp. 1001-1004 ◽  
Author(s):  
C.-L. Lu ◽  
D. K. Murakowski ◽  
S. Bournazos ◽  
T. Schoofs ◽  
D. Sarkar ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Broadly Neutralizing Antibodies ◽  
Infected Cells ◽  
Hiv 1

scholarly journals Therapeutic Efficacy and Resistance Selection of a Lipopeptide Fusion Inhibitor in Simian Immunodeficiency Virus-Infected Rhesus Macaques

2020 ◽  
Vol 94 (15) ◽  
Author(s):  
Danwei Yu ◽  
Jing Xue ◽  
Huamian Wei ◽  
Zhe Cong ◽  
Ting Chen ◽  
...  
Keyword(s):  
Membrane Fusion ◽  
Therapeutic Efficacy ◽  
Rhesus Macaques ◽  
Heptad Repeat ◽  
Fusion Inhibitor ◽  
Resistance Mutations ◽  
Fusion Inhibitors ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT We recently reported a group of lipopeptide-based membrane fusion inhibitors with potent antiviral activities against human immunodeficiency virus type 1 (HIV-1), HIV-2, and simian immunodeficiency virus (SIV). In this study, the in vivo therapeutic efficacy of such a lipopeptide, LP-52, was evaluated in rhesus macaques chronically infected with pathogenic SIVmac239. In a pilot study with one monkey, monotherapy with low-dose LP-52 rapidly reduced the plasma viral loads to below the limit of detection and maintained viral suppression during three rounds of structurally interrupted treatment. The therapeutic efficacy of LP-52 was further verified in four infected monkeys; however, three out of the monkeys had viral rebounds under the LP-52 therapy. We next focused on characterizing SIV mutants responsible for the in vivo resistance. Sequence analyses revealed that a V562A or V562M mutation in the N-terminal heptad repeat (NHR) and a E657G mutation in the C-terminal heptad repeat (CHR) of SIV gp41 conferred high resistance to LP-52 and cross-resistance to the peptide drug T20 and two newly designed lipopeptides (LP-80 and LP-83). Moreover, we showed that the resistance mutations greatly reduced the stability of diverse fusion inhibitors with the NHR site, and V562A or V562M in combination with E657G could significantly impair the functionality of viral envelopes (Envs) to mediate SIVmac239 infection and decrease the thermostability of viral six-helical bundle (6-HB) core structure. In conclusion, the present data have not only facilitated the development of novel anti-HIV drugs that target the membrane fusion step, but also help our understanding of the mechanism of viral evolution to develop drug resistance. IMPORTANCE The anti-HIV peptide drug T20 (enfuvirtide) is the only membrane fusion inhibitor available for treatment of viral infection; however, it exhibits relatively weak antiviral activity, short half-life, and a low genetic barrier to inducing drug resistance. Design of lipopeptide-based fusion inhibitors with extremely potent and broad antiviral activities against divergent HIV-1, HIV-2, and SIV isolates have provided drug candidates for clinical development. Here, we have verified a high therapeutic efficacy for the lipopeptide LP-52 in SIVmac239-infected rhesus monkeys. The resistance mutations selected in vivo have also been characterized, providing insights into the mechanism of action of newly designed fusion inhibitors with a membrane-anchoring property. For the first time, the data show that HIV-1 and SIV can share a similar genetic pathway to develop resistance, and that a lipopeptide fusion inhibitor could have a same resistance profile as its template peptide.

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