Analysis of Defined Combinations of Monoclonal Antibodies in Anthrax Toxin Neutralization Assays and Their Synergistic Action

Ngundi, Miriam M.; Meade, Bruce D.; Little, Stephen F.; Quinn, Conrad P.; Corbett, Cindi R.; Brady, Rebecca A.; Burns, Drusilla L

doi:10.1128/cvi.05714-11

Cited by 17 publications

(15 citation statements)

References 42 publications

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“…Avidity effects of multivalent and bispecific formats have been modeled (51) and have been proposed as a way to drive higher-affinity and higher-specificity binding of targets with multiple epitopes. Alternatively, bridging of two toxin molecules by one monoclonal antibody can allow bivalent binding of a second antibody to a different epitope, which has been proposed as a mechanism for synergy in the neutralization of anthrax toxin (52). Regardless of the exact mechanism, bivalency enhanced the effective binding affinity (Fig.…”

Section: Discussionmentioning

confidence: 99%

Synergistic Neutralization of Pertussis Toxin by a Bispecific Antibody In Vitro and In Vivo

Wagner

Wang

Bui

et al. 2016

Clin Vaccine Immunol

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Bispecific antibodies are a rapidly growing class of therapeutic molecules, originally developed for the treatment of cancer but recently explored for the treatment of autoimmune and infectious diseases. Bordetella pertussis is a reemerging pathogen, and several of the key symptoms of infection are caused by the pertussis toxin (PTx). Two humanized antibodies, hu1B7 and hu11E6, bind distinct epitopes on PTx and, when coadministered, mitigate disease severity in murine and baboon models of infection. Here we describe the generation of a bispecific human IgG1 molecule combining the hu1B7 and hu11E6 binding sites via a knobs-in-holes design. The bispecific antibody showed binding activity equivalent to that of the antibody mixture in a competition enzyme-linked immunosorbent assay (ELISA). A CHO cell neutralization assay provided preliminary evidence for synergy between the two antibodies, while a murine model of PTx-induced leukocytosis definitively showed synergistic neutralization. Notably, the bispecific antibody retained the synergy observed for the antibody mixture, supporting the conclusion that synergy is due to simultaneous blockade of both the catalytic and receptor binding activities of pertussis toxin. These data suggest that a hu1B7/hu11E6 bispecific antibody is a viable alternative to an antibody mixture for pertussis treatment. Despite vaccination, pertussis infection continues to cause ϳ195,000 deaths worldwide, primarily of infants (1). Of the estimated 16 million cases of pertussis each year, ϳ95% occur in the developing world. Even in developed countries, the disease incidence has increased dramatically over the last decade, reaching prevaccination levels in some countries (2, 3). This rise has been attributed to shortcomings of the current acellular vaccine (4) as well as pathogen adaptation (5). In both cases, high levels of circulating disease place young infants at risk, as this population is the most susceptible to severe disease. An antibody therapeutic could be used to treat seriously ill infants in the developing world and to prevent disease in high-risk areas.Pertussis toxin (PTx) is one of several virulence factors secreted by the Gram-negative bacterium Bordetella pertussis. PTx is directly responsible for suppression of the innate immune system (6) and for systemic leukocytosis, which is the key clinical indicator of severe disease and appears to be directly responsible for pulmonary hypertension and organ failure (7). In addition, low titers of PTx-neutralizing antibodies correlate with susceptibility to clinical infection (8). We previously developed a binary mixture of two humanized anti-pertussis toxin antibodies which was able to mitigate whooping cough in mouse and baboon models of infection (9). The antibody hu11E6 blocks binding of the toxin to host cells, while the antibody hu1B7 interferes with the catalytic pathway. At a dose selected to demonstrate efficacy but not synergy, the individual antibodies and the mixture were able to completely suppress leukocytosis in a murine ...

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Section: Discussionmentioning

confidence: 99%

Synergistic Neutralization of Pertussis Toxin by a Bispecific Antibody In Vitro and In Vivo

Wagner

Wang

Bui

et al. 2016

Clin Vaccine Immunol

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“…The mixing of protective mAbs targeting different epitopes of a toxin molecule can synergize protective efficacy (Cheng et al, 2009; Demarest et al, 2010; Varshney et al, 2011; Ngundi et al, 2012). Combining neutralizing mAbs to individual toxin components boosts protection against toxicity (Brossier et al, 2004; Chen et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Disease-Enhancing Antibodies Improve the Efficacy of Bacterial Toxin-Neutralizing Antibodies

Chow

Smith

MacCarthy

et al. 2013

Cell Host & Microbe

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SUMMARY During infection, humoral immunity produces a polyclonal response with various immunoglobulins recognizing different epitopes within the microbe or toxin. Despite this diverse response, the biological activity of an antibody (Ab) is usually assessed by the action of a monoclonal population. We demonstrate that a combination of monoclonal antibodies (mAbs) that are individually disease-enhancing or neutralizing to Bacillus anthracis protective antigen (PA), a component of anthrax toxin, results in significantly augmented protection against the toxin. This boosted protection is Fc gamma receptor (FcγR)-dependent and involves the formation of stoichiometrically defined mAb-PA complexes that requires immunoglobulin bivalence and simultaneous interaction between PA and the two mAbs. The formation of these mAb-PA complexes inhibits PA oligomerization, resulting in protection. These data suggest that functional assessments of single Abs may inaccurately predict how the same Abs will operate in polyclonal preparations and imply that potentially therapeutic mAbs may be overlooked in single Ab screens.

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“…While cooperativity and synergism of monoclonal antibody mixtures have been reported in the past (16)(17)(18)(19), emerging data have illustrated striking examples of situations wherein the activity of a monoclonal antibody can be drastically altered when assessed in the context of other antibodies (20,21). Indeed, the benefits of using polyclonal antibody preparations to treat disease in therapeutic settings are just beginning to be realized (22).…”

mentioning

confidence: 99%

Broadly Neutralizing Anti-Influenza Virus Antibodies: Enhancement of Neutralizing Potency in Polyclonal Mixtures and IgA Backbones

Mullarkey

Duty

et al. 2015

J Virol

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Current influenza virus vaccines rely upon the accurate prediction of circulating virus strains months in advance of the actual influenza season in order to allow time for vaccine manufacture. Unfortunately, mismatches occur frequently, and even when perfect matches are achieved, suboptimal vaccine efficacy leaves several high-risk populations vulnerable to infection. However, the recent discovery of broadly neutralizing antibodies that target the hemagglutinin (HA) stalk domain has renewed hope that the development of "universal" influenza virus vaccines may be within reach. Here, we examine the functions of influenza A virus hemagglutinin stalk-binding antibodies in an endogenous setting, i.e., as polyclonal preparations isolated from human sera. Relative to monoclonal antibodies that bind to the HA head domain, the neutralization potency of monoclonal stalk-binding antibodies was vastly inferior in vitro but was enhanced by several orders of magnitude in the polyclonal context. Furthermore, we demonstrated a surprising enhancement in IgA-mediated HA stalk neutralization relative to that achieved by antibodies of IgG isotypes. Mechanistically, this could be explained in two ways. Identical variable regions consistently neutralized virus more potently when in an IgA backbone compared to an IgG backbone. In addition, HA-specific memory B cells isolated from human peripheral blood were more likely to be stalk specific when secreting antibodies of IgA isotypes compared to those secreting IgG. Taken together, our data provide strong evidence that HA stalk-binding antibodies perform optimally when in a polyclonal context and that the targeted elicitation of HA stalk-specific IgA should be an important consideration during "universal" influenza virus vaccine design. IMPORTANCEInfluenza viruses remain one of the most worrisome global public health threats due to their capacity to cause pandemics. While seasonal vaccines fail to protect against the emergence of pandemic strains, a new class of broadly neutralizing antibodies has been recently discovered and may be the key to developing a "universal" influenza virus vaccine. While much has been learned about the biology of these antibodies, most studies have focused only on monoclonal antibodies of IgG subtypes. However, the study of monoclonal antibodies often fails to capture the complexity of antibody functions that occur during natural polyclonal responses. Here, we provide the first detailed analyses of the biological activity of these antibodies in polyclonal contexts, comparing both IgG and IgA isotypes isolated from human donors. The striking differences observed in the functional properties of broadly neutralizing antibodies in polyclonal contexts will be essential for guiding design of "universal" influenza virus vaccines and therapeutics. I nfluenza A viruses (IAVs) remain one of the most pressing global public health concerns due to their widespread distribution, rapid evolution, and potential for reassortment (1). These traits contribute to the abil...

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Analysis of Defined Combinations of Monoclonal Antibodies in Anthrax Toxin Neutralization Assays and Their Synergistic Action

Cited by 17 publications

References 42 publications

Synergistic Neutralization of Pertussis Toxin by a Bispecific Antibody In Vitro and In Vivo

Synergistic Neutralization of Pertussis Toxin by a Bispecific Antibody In Vitro and In Vivo

Disease-Enhancing Antibodies Improve the Efficacy of Bacterial Toxin-Neutralizing Antibodies

Broadly Neutralizing Anti-Influenza Virus Antibodies: Enhancement of Neutralizing Potency in Polyclonal Mixtures and IgA Backbones

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