A Cytotoxicity Assay as an Alternative to the Murine Model for the Potency Testing ofVenom and Antivenom: An Intralaboratory Pre-validation Study.

Abstract

Antivenom therapy is the only specific treatment for snakebite envenomation, and antivenom potency determination is key in the efficacy assurance quality control process. Nowadays, this process relies on themurine model - thus, the development of alternativemethods is imperative. In the current study, the principle of the proposed method is the ability ofvenom to induce cytotoxic effects in Vero cells, and the capacity to evaluate the inhibition of this cytotoxicity by the respective antivenom. After exposure to the venom/antivenom, the relative proportions of adherent (viable) cells were evaluated by direct staining with Coomassie Blue. The optical density (OD) of the lysed cell eluate was directly proportional to the number of adherent cells. This cytotoxicity-based alternative method could represent a potential candidate for validation as a replacement for the currenttest. The-determined cytotoxicity of the Brazilianreference venom (expressed as the 50% effective concentration; EC) was 3.61 μg/ml; the-determined 50% inhibitory concentration (IC) of the Brazilianreference antivenom was 0.133 μl/ml. From these two values, it was possible to calculate the potency of the reference antivenom. The results from the assays exhibited a good linear response, indicating that the method could be a potential candidate replacement method for use in antivenom quality control prior to lot release, subject to further validation.