Comparative Studies of Antisera Against Different Toxins

Abstract

Snake venom main components are proteins and peptides, many of them presenting enzymatic and/or toxic activities. Neutralization of these activities is one of the goals of envenomation treatment and this is usually achieved by mean of serotherapy. Snake venom antisera are produced in horses and, due to high toxicity of the immunogens, about 10% of the animals die after prime injection. Previous works of our group have shown gamma rays to attenuate snake venom toxicity without affecting its immunological properties, inducing an enhanced humoral and cellular immune response without the deleterious effects of native venom [1] [2] [3]. The venom attenuation induced by irradiation is a result of interaction of the venom components with the free radicals formed by water radiolysis, mainly hydroxyl radical and hidrated electron. These radicals act removing hidrogens, breaking S-S bonds or promoting deamination. As a result of the interaction of these radicals and others lesser known with the venom components, larger molecular weight aggregates are formed, with few if any toxic or enzymatic activity but presenting epitopes that induce a protective response when the irradiated venom is employed as immunogen [3]. These facts point toward venom irradiation as a solution to improve sera production, de Paula et Al [4], when immunizing rabbits with irradiated crotoxin, South American rattlesnake’s main toxin, obtained polyclonal antibodies specific for the Crotalus genus and with high neutralizing capacity. These immunoglobulins proved to be useful as diagnostic and therapeutic agents. C.d.terrificus neurotoxic venom is composed by few protein fractions, mainly crotoxin, while the Brazilian most prevalent snake on what refers to accidents (85%), Bothrops sp, venom has proteolytic and coagulant activities, with several proteins and fractions involved, with phospholipase activity and minor neurotoxicity, serotherapy being the main treatment. These activities generate intense local signs in animals used in antisera production, with losses and low efficiency. In the present work, we detoxified Bothrops jararaca venom by mean of gamma radiation, immunized rabbits with the obtained toxoid and investigated the raised antisera efficiency against toxicity, cross-reactivity with other snake venoms from the Elapid and Crotalid group and neutralization of phospholipase A₂ activity which, as suggested by other authors [5], is an indicator of antisera potency.