Intra-Spike Crosslinking Overcomes Antibody Evasion by HIV-1

Galimidi, Rachel P.; Klein, Joshua S.; Politzer, Maria S.; Bai, Shiyu; Seaman, Michael S.; Nussenzweig, Michel C.; West, Anthony P.; Björkman, Pamela J.

doi:10.1016/j.cell.2015.01.016

Cited by 114 publications

(140 citation statements)

References 62 publications

Supporting

Mentioning

136

Contrasting

Order By: Relevance

“…The low density of HIV Env on virions may have a profound impact on HIV transmission and host immune responses, the quantitative aspects of which are just beginning to be understood (6,20). Transmission of HIV-1 from an infected person to a new host usually occurs through a mucosal port of entry.…”

Section: Discussionmentioning

confidence: 99%

Quantitative Correlation between Infectivity and Gp120 Density on HIV-1 Virions Revealed by Optical Trapping Virometry

DeSantis

Kim

Song

et al. 2016

Journal of Biological Chemistry

View full text Add to dashboard Cite

The envelope glycoprotein (Env) gp120/gp41 is required for HIV-1 infection of host cells. Although in general it has been perceived that more Env gives rise to higher infectivity, the precise quantitative dependence of HIV-1 virion infectivity on Env density has remained unknown. Here we have developed a method to examine this dependence. This method involves 1) production of a set of single-cycle HIV-1 virions with varied density of Env on their surface, 2) site-specific labeling of Envspecific antibody Fab with a fluorophore at high efficiency, and 3) optical trapping virometry to measure the number of gp120 molecules on individual HIV-1 virions. The resulting gp120 density per virion is then correlated with the infectivity of the virions measured in cell culture. In the presence of DEAE-dextran, the polycation known to enhance HIV-1 infectivity in cell culture, virion infectivity follows gp120 density as a sigmoidal dependence and reaches an apparent plateau. This quantitative dependence can be described by a Hill equation, with a Hill coefficient of 2.4 ؎ 0.6. In contrast, in the absence of DEAE-dextran, virion infectivity increases monotonically with gp120 density and no saturation is observed under the experimental conditions. These results provide the first quantitative evidence that Env trimers cooperate on the virion surface to mediate productive infection by HIV-1. Moreover, as a result of the low number of Env trimers on individual virions, the number of additional Env trimers per virion that is required for the optimal infectivity will depend on the inclusion of facilitating agents during infection.Like other enveloped viruses, HIV-1 uses the trimer-of-hairpins mechanism to catalyze the fusion between viral and cell membranes, an essential step during the life cycle of all envel- (7), suggesting that more Env may indeed confer selective advantages in HIV-1 transmission. At the mechanistic level, however, how the Env copy number may enhance virion transmission is not well understood. Although greater amounts of Env have been observed to increase infectivity (8), the dependence of HIV-1 virion infectivity on Env density has not been precisely described or explained.In this paper, we introduce a quantitative approach to this problem. In our approach, we use a provirus clone that is env Ϫ together with a separate wild-type env plasmid (pEnv) to generate HIV-1 virions (9). It is essential that the provirus is env Ϫ so that we can titrate pEnv from low to high quantities (8) to generate a set of virions that are expected to carry varied densities of Env on their surface, limited by the pEnv inputs (10). Meanwhile, the resulting virions are only infectious for a single cycle. The infectivity of the virions can thus be correlated with the Env content of these virions that can be directly measured by singlemolecule techniques without the complications from multiple rounds of infection.To determine Env density on individual virions, we have recently developed a technique named optical trapping virometry (OTV)...

show abstract

Section: Discussionmentioning

confidence: 99%

Quantitative Correlation between Infectivity and Gp120 Density on HIV-1 Virions Revealed by Optical Trapping Virometry

DeSantis

Kim

Song

et al. 2016

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…When binding is truly bivalent, that is, both arms are simultaneously engaged in binding the same antigen molecule, there could be significant improvement in the off-rate and thereby neutralization potency as well. This has been demonstrated in a recent study that obtained bivalent binding by linked Fab molecules which exhibited superior potency over the physical combination of Fabs (24). Other studies have used different formats of bispecific antibodies.…”

Section: Discussionmentioning

confidence: 89%

“…This has led to the consideration of bispecific antibody formats that can incorporate two different antigen specificities into one molecule. For targeting HIV-1 infection, bispecific antibodies have been developed in multiple formats that combine either receptor-targeting antibodies or domains with anti-HIV-1 antibodies or linking the variable domains of two anti-HIV-1 antibodies (24)(25)(26)(27)). These antibodies demonstrate increased potency and breadth against HIV-1, although the ability to develop them for clinical use may be limited due to their use of nontraditional IgG formats.…”

Section: Importancementioning

confidence: 99%

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

Asokan

Rudicell

Louder

et al. 2015

J Virol

View full text Add to dashboard Cite

The 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. T he neutralizing antibody response to human immunodeficiency virus type 1 (HIV-1) is directed initially to the infecting viral strain but generally broadens over time to recognize diverse isolates. The recognition that some HIV-1-infected individuals generate highly potent and broadly reactive neutralizing antibodies (bNAbs) led to the eventual isolation and characterization of numerous HIV-1 neutralizing monoclonal antibodies (MAbs) (1, 2). Characterization and structural analysis of these bNAbs have revealed the specific neutralization binding regions on the HIV-1 envelope glycoprotein (Env). We now appreciate at least five regions of vulnerability on the HIV-1 Env trimer: the CD4 binding site (CD4bs), a glycan-dependent site near the variable loop 3 (V3) region (V3-glycan), a variable-region (V1V2) glycan-dependent site on the trimer apex, a membrane-proximal external region (MPER) of gp41, and a region at the interface of gp120 and gp41 (3). Our understanding of the structural mode of recognition by many bNAbs, together with the structure of the native trimer (4-6), is providing new insights relevant to vaccine design. In addition, studies of the immune pathways leading to the development of these bNAbs are providing new approaches for immunization (7)(8)(9).Despite these advances, current vaccine immunogens elicit antibodies with limited neutralization breadth (7,10,11), and it will likely take years of improved vaccine designs and iterative clinical trials to developed more effective vaccines. This challenge has led to an interest in the use of bNAbs as part of an overall strategy to prevent new HIV-1 infections (12). Passive immunization in humans has proven highly effective for infections with many viruses, including hepatitis A, hepatitis B, rabies, and respiratory syncytial

show abstract

“…Comparisons of the neutralization potencies of IgG and Fab fragments of anti-HIV-1 antibodies revealed similar potencies, suggesting that bivalent recognition is uncommon (214). However, an elegant study by Galimidi et al using engineered antibody-based molecules capable of intraspike bivalent binding demonstrates greatly increased neutralization potencies for antibodies with certain epitope specificities (215). While the densely packed, pseudoicosahedral arrangement of E proteins on flavivirus virions may allow bivalent engagement by antibodies, only one DENV E protein DIII-reactive antiflavivirus MAb that requires bivalent binding for its neutralizing activity has been characterized to date (216).…”

Section: Low Density Of Surface Glycoproteinsmentioning

confidence: 99%

Deconstructing the Antiviral Neutralizing-Antibody Response: Implications for Vaccine Development and Immunity

VanBlargan

Goo

Pierson

2016

Microbiol Mol Biol Rev

View full text Add to dashboard Cite

SUMMARY The antibody response plays a key role in protection against viral infections. While antiviral antibodies may reduce the viral burden via several mechanisms, the ability to directly inhibit (neutralize) infection of cells has been extensively studied. Eliciting a neutralizing-antibody response is a goal of many vaccine development programs and commonly correlates with protection from disease. Considerable insights into the mechanisms of neutralization have been gained from studies of monoclonal antibodies, yet the individual contributions and dynamics of the repertoire of circulating antibody specificities elicited by infection and vaccination are poorly understood on the functional and molecular levels. Neutralizing antibodies with the most protective functionalities may be a rare component of a polyclonal, pathogen-specific antibody response, further complicating efforts to identify the elements of a protective immune response. This review discusses advances in deconstructing polyclonal antibody responses to flavivirus infection or vaccination. Our discussions draw comparisons to HIV-1, a virus with a distinct structure and replication cycle for which the antibody response has been extensively investigated. Progress toward deconstructing and understanding the components of polyclonal antibody responses identifies new targets and challenges for vaccination strategies.

show abstract

Intra-Spike Crosslinking Overcomes Antibody Evasion by HIV-1

Cited by 114 publications

References 62 publications

Quantitative Correlation between Infectivity and Gp120 Density on HIV-1 Virions Revealed by Optical Trapping Virometry

Quantitative Correlation between Infectivity and Gp120 Density on HIV-1 Virions Revealed by Optical Trapping Virometry

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

Deconstructing the Antiviral Neutralizing-Antibody Response: Implications for Vaccine Development and Immunity

Contact Info

Product

Resources

About