Antibody-mediated neutralization and binding-reversal studies on α-neurotoxins from micrurus nigrocinctus nigrocinctus (coral snake) venom

Abstract

An ELISA based, non-radioactive acetylcholine receptor (AchR) binding assay was used to detect the α-neurotoxins present in Micrurus nigrocinctus nigrocinctus venom. Sera from horses hyperimmunized against M. nigrocinctus venom contain antibodies which inhibit the binding of M. n. nigrocinctus α-neurotoxins to AchR and reverse the binding of toxins already complexed with the receptor. This result supports the importance of using antivenom therapeutically in M. n. nigrocinctus envenomations even after the onset of neurological symptoms. M. nigrocinctus antivenoms cross-reacted in an ELISA with several elapid α-neurotoxins and inhibited the binding of Bungarus multicinctus α-bungarotoxin and Naja naja oxiana neurotoxin II to AchR in vitro, suggesting the presence of short-chain and long-chain α-neurotoxins in M. nigrocinctus venom. In vivo neutralization experiments with M. nigrocinctus antivenom demonstrate that M. nigrocinctus venom contains short-chain α-neurotoxin(s) which share common neutralizing epitope(s) with Naja naja oxiana neurotoxin II.