Efficient functional neutralization of lethal peptide toxins in vivo by oligonucleotides

Abstract

Medical means to save the life of human patients affected by drug abuse, envenomation or critical poisoning are currently limited. While the compounds at risks are most often well identified, particularly for bioterrorism, chemical intervention to counteract the toxic effects of the ingested/injected compound(s) is restricted to the use of antibodies. Herein, we illustrate that DNA aptamers, targeted to block the pharmacophore of a poisonous compound, represent a fast-acting and reliable method of neutralization in vivo that possesses efficient and long-lasting life-saving properties. For this proof of concept, we used one putative bioweapon, αC-conotoxin PrXA, a marine snail ultrafast-killing paralytic toxin, to identify peptide-binding DNA aptamers. We illustrate that they can efficiently neutralize the toxin-induced (i) displacement of [125I]-α-bungarotoxin binding onto nicotinic receptors, (ii) inhibition of diaphragm muscle contraction, and (iii) lethality in mice. Our results demonstrate the preclinical value of DNA aptamers as fast-acting, safe and cheap antidotes to lethal toxins at risk of misuse in bioterrorism and offer hope for an alternative method than donor sera to treat cases of envenomation.

Recent Advances in Next Generation Snakebite Antivenoms

“…Although the main work was performed on a cone snail toxin, and not a snake toxin, another approach to developing novel compounds for snakebite envenoming therapy focuses on the use of oligonucleotides. In 2017, El-Aziz and colleagues published an article arguing for favourable characteristics of oligonucleotides including low immunogenicity, small size, thermal stability, biocompatibility, and standardised production methods [38]. Oligonucleotides are devoid of many of the drawbacks associated with antibody production by immunisation (e.g.…”

“…The ED50 against lethality for the oligonucleotide was determined to be 0.18 µg/g mouse bodyweight when administered intraperitoneally, and 0.22 µg/g mouse bodyweight when administered subcutaneously. As the oligonucleotide was unable to inhibit a different blocker (waglerin) of the muscle nicotinic acetylcholine receptor targeted by the conotoxin, the oligonucleotide was assumed to be specific for αC-conotoxin PrXa [38]. Another benefit of working with oligonucleotides in the lab setting includes the low cost of small scale synthesis for R&D purposes, which makes it easy for researchers to quickly evaluate a large range of molecules at limited cost.…”

Recent Advances in Next Generation Snakebite Antivenoms

“…Although the main work was performed on a cone snail toxin, and not a snake toxin, another approach to developing novel compounds for snakebite envenoming therapy focuses on the use of oligonucleotide-based aptamers, which have found various applications, including in therapeutics [ 47 ]. In 2017, El-Aziz and colleagues published an article arguing for favourable characteristics of oligonucleotides, including low immunogenicity, small size, thermal stability, biocompatibility, and standardised production methods [ 48 ]. Oligonucleotides are devoid of many of the drawbacks associated with antibody production by immunisation (e.g., use of production animals, long production time, poor immunogenicity of many smaller toxins, and cost of production) and with the treatment itself (e.g., immunogenicity of animal-derived antibodies, limited shelf-life, need for refrigeration, and potential lack of specificity).…”

“…The ED 50 against lethality for the oligonucleotide was determined to be 0.18 µg/g mouse bodyweight when administered intraperitoneally, and 0.22 µg/g mouse bodyweight when administered subcutaneously. As the oligonucleotide was unable to inhibit a different blocker (waglerin) of the muscle nicotinic acetylcholine receptor targeted by the conotoxin, the oligonucleotide was assumed to be specific for αC-conotoxin PrXa [ 48 ]. Another benefit of working with oligonucleotides in the lab setting includes the low cost of small-scale synthesis for research and development (R&D) purposes, which makes it easy for researchers to quickly evaluate a large range of molecules at limited cost.…”

Innovative Immunization Strategies for Antivenom Development

“…In addition, a summary of the clinically most important toxin families in snake, scorpion, and spider venoms is presented, as well as how complementary biochemical, bioinformatic, and omics tools can be exploited to design cutting-edge immunization protocols. Novel approaches in the therapy of envenomings, such as the development of toxin inhibitors based on aptamers, small molecules, or recombinant antibodies (or fragments thereof) of human or camelid origin are beyond the scope of this review, and can be found elsewhere [ 32 , 33 , 34 , 35 , 36 , 37 ].…”