Analysis of composition and neutralization of Naja kaouthia venom: a study for the enhancement of antielapid serum

Abstract

Naja kaouthia is a medically important snake from the Elapidae family, widely distributed throughout Southeast Asia in various habitats. This species has a diverse venom composition, including 16 protein families, from which 13 are toxin families, and considerable intraspecific variation. The clinical manifestations of Naja kaouthia snakebite are characterized by predominantly neurotoxic symptoms, mainly caused by two protein families: three-finger toxins (3FTx) and phospholipases A2 (PLA2), which respectively have pre-synaptic and post-synaptic effects, being named ±-neurotoxins and ²-neurotoxins.Besides being the major components of Naja kaouthia venom, most of the impact on the venom's lethality is attributed to these families. Although 3FTx and PLA2 are abundant in snake venoms, they are poorly recognized by antivenoms because of their low antigenicity, which means they don't have much capability of generating an immune response like the production of antibodies, as a consequence of their low molecular weight.In Brazil and worldwide, there are snakebites caused by Naja kaouthia and other non-native snake species because of the illegal breading of exotic animals, something that is problematic because there is no specific antivenom for those species available in the health units and national antivenoms are not effective in neutralizing them. In Naja kaouthia's case, the venom would not be effectively neutralized by the antielapid antivenom produced with a pool of Micrurus corallinus and M. frontalis venoms, even though there are considerable similarities in the venom compositions of the three species. The Micrurus corallinus and M. frontalis have venoms constituted mainly by 3FTx and PLA2, besides other minor protein families.The antielapid antivenom has some production difficulties in Instituto Butantan, such as breeding of some snakes from the Micrurus genus and the small amount of venom extracted from the individuals, due to their reduced venom glands and general size. Due to evolutionary and venom composition proximities between Naja kaouthia, Micrurus corallinus and Micrurus frontalis, it is interesting to search for similar proteins in N. kaouthia's venom as a possible alternative to include them in the pool with Micrurus' venom in the production of antielapid antivenom. (AU)