Protective monoclonal antibodies to diphtheria toxin

G, Danelli M das; Lm, Teixeira; Lc, Formiga; Jm, Peralta

doi:10.1590/s0074-02761991000200017

Cited by 4 publications

(3 citation statements)

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“…However, using the phage display approach the T-domain of the B-fragment was identified showing that the conformation of the recognized MER may depend on the formation of T-and R-domains. It was demonstrated that all three DT domains are targets of highly neutralizing recombinant antibodies which is in accordance with previous publications showing that neutralizing human recombinant antibodies 70,71 or murine monoclonal antibodies 72 can target all three domains.…”

Section: Discussionsupporting

confidence: 91%

Human antibodies neutralizing diphtheria toxin in vitro and in vivo

Wenzel

Bosnak

Tierney

et al. 2020

Sci Rep

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Diphtheria is an infectious disease caused by Corynebacterium diphtheriae. the bacterium primarily infects the throat and upper airways and the produced diphtheria toxin (Dt), which binds to the elongation factor 2 and blocks protein synthesis, can spread through the bloodstream and affect organs, such as the heart and kidneys. For more than 125 years, the therapy against diphtheria has been based on polyclonal horse sera directed against Dt (diphtheria antitoxin; DAt). Animal sera have many disadvantages including serum sickness, batch-to-batch variation in quality and the use of animals for production. In this work, 400 human recombinant antibodies were generated against DT from two different phage display panning strategies using a human immune library. A panning in microtiter plates resulted in 22 unique in vitro neutralizing antibodies and a panning in solution combined with a functional neutralization screening resulted in 268 in vitro neutralizing antibodies. 61 unique antibodies were further characterized as scFv-Fc with 35 produced as fully human IgG1. The best in vitro neutralizing antibody showed an estimated relative potency of 454 IU/mg and minimal effective dose 50% (MED50%) of 3.0 pM at a constant amount of DT (4x minimal cytopathic dose) in the IgG format. The targeted domains of the 35 antibodies were analyzed by immunoblot and by epitope mapping using phage display. All three Dt domains (enzymatic domain, translocation domain and receptor binding domain) are targets for neutralizing antibodies. When toxin neutralization assays were performed at higher toxin dose levels, the neutralizing capacity of individual antibodies was markedly reduced but this was largely compensated for by using two or more antibodies in combination, resulting in a potency of 79.4 IU/mg in the in vivo intradermal challenge assay. these recombinant antibody combinations are candidates for further clinical and regulatory development to replace equine DAt.Diphtheria is an infectious disease and caused by Corynebacterium diphtheriae. The bacterium primarily infects the throat and upper airways but can also affect other body sites. The produced toxin can spread through the bloodstream and affect organs, such as the heart and kidneys. In severe cases, diphtheria toxin (DT) may cause myocarditis or peripheral neuropathy. Due to a membrane of dead tissue over the throat and tonsils, swallowing and breathing can be difficult. The disease is spread through direct physical contact or by coughing or sneezing of infected individuals 1-3 . Diphtheria is fatal in 5-10% of cases, but children under the age of five have a mortality rate of up to 20%. Treatment involves antibiotics to kill the bacteria (erythromycin or penicillin for 14 days) and administering of diphtheria antitoxin (DAT) to neutralize the effects of the toxin 4-6 . C. diphtheriae was identified as the causative agent of diphtheria in 1883 and in 1888 the diphtheria toxin was first described in the culture medium of C. diphtheriae 7 . The gene for DT is encoded on a coryn...

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Section: Discussionsupporting

confidence: 91%

Human antibodies neutralizing diphtheria toxin in vitro and in vivo

Wenzel

Bosnak

Tierney

et al. 2020

Sci Rep

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“…More recently, an in vitro neutralization assay that uses Vero cells has shown promise as an alternative to these in vivo assays (23,26). In the present study, we utilized both in vitro and in vivo approaches to assign the potency of 315C4.…”

Section: Fig 3 315c4 Inhibits Diphtheria Toxin Cytotoxicity On Vero Cmentioning

confidence: 99%

Identification of a Human Monoclonal Antibody To Replace Equine Diphtheria Antitoxin for Treatment of Diphtheria Intoxication

et al. 2013

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Diphtheria antitoxin (DAT) has been the cornerstone of the treatment of Corynebacterium diphtheriae infection for more than 100 years. Although the global incidence of diphtheria has declined steadily over the last quarter of the 20th century, the disease remains endemic in many parts of the world, and significant outbreaks still occur. DAT is an equine polyclonal antibody that is not commercially available in the United States and is in short supply globally. A safer, more readily available alternative to DAT would be desirable. In the current study, we obtained human monoclonal antibodies (hMAbs) directly from antibody-secreting cells in the circulation of immunized human volunteers. We isolated a panel of diverse hMAbs that recognized diphtheria toxoid, as well as a variety of recombinant protein fragments of diphtheria toxin. Forty-five unique hMAbs were tested for neutralization of diphtheria toxin in in vitro cytotoxicity assays with a 50% effective concentration of 0.65 ng/ml for the lead candidate hMAb, 315C4. In addition, 25 g of 315C4 completely protected guinea pigs from intoxication in an in vivo lethality model, yielding an estimated relative potency of 64 IU/mg. In comparison, 1.6 IU of DAT was necessary for full protection from morbidity and mortality in this model. We further established that our lead candidate hMAb binds to the receptor-binding domain of diphtheria toxin and physically blocks the toxin from binding to the putative receptor, heparin-binding epidermal growth factor-like growth factor. The discovery of a specific and potent human neutralizing antibody against diphtheria toxin holds promise as a potential therapeutic.

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“…The discovery of potent neutralising antibodies against the diphtheria toxin holds great promise as potential therapeutic. Several diphtheria antitoxin mAbs have been developed and investigated in preclinical studies (Table 2) [34][35][36]. In particular, a neutralising human mAb developed by Massachusetts Biologic Laboratories (MBL) has proven highly efficacious and completely protected guinea pigs from diphtheria intoxication in an in vivo lethality model [36].…”

Section: Alternatives For Diphtheria Antitoxin Therapymentioning

confidence: 99%

Access to diphtheria antitoxin for therapy and diagnostics

et al. 2014

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The most effective treatment for diphtheria is swift administration of diphtheria antitoxin (DAT) with conjunct antibiotic therapy. DAT is an equine immunoglobulin preparation and listed among the World Health Organization Essential Medicines. Essential Medicines should be available in functioning health systems at all times in adequate amounts, in appropriate dosage forms, with assured quality, and at prices individuals and the community can afford. However, DAT is in scarce supply and frequently unavailable to patients because of discontinued production in several countries, low economic viability, and high regulatory requirements for the safe manufacture of blood-derived products. DAT is also a cornerstone of diphtheria diagnostics but several diagnostic reference laboratories across the European Union (EU) and elsewhere routinely face problems in sourcing DAT for toxigenicity testing. Overall, global access to DAT for both therapeutic and diagnostic applications seems inadequate. Therefore − besides efforts to improve the current supply of DAT − accelerated research and development of alternatives including monoclonal antibodies for therapy and molecular-based methods for diagnostics are required. Given the rarity of the disease, it would be useful to organise a small stockpile centrally for all EU countries and to maintain an inventory of DAT availability within and between countries.

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Protective monoclonal antibodies to diphtheria toxin

Cited by 4 publications

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Human antibodies neutralizing diphtheria toxin in vitro and in vivo

Human antibodies neutralizing diphtheria toxin in vitro and in vivo

Identification of a Human Monoclonal Antibody To Replace Equine Diphtheria Antitoxin for Treatment of Diphtheria Intoxication

Access to diphtheria antitoxin for therapy and diagnostics

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