Early vascular toxicity induced by Bothrops atrox venom in the chorioallantoic membrane assay: Kinetic profile and translational insights

BACKGROUND: Snakebite envenoming is a neglected tropical disease with significant morbidity and mortality, particularly in areas with limited resources. Bothrops atrox is the most important snake involved in human envenomings in the Amazon. Its venom induces complex vascular damage that contributes to hemorrhage and systemic complications. This study employs the chicken chorioallantoic membrane (CAM) model to illustrate and quantify the acute vascular toxicity of B. atrox venom. METHODOLOGY/PRINCIPAL FINDINGS: Fertilized chicken eggs at embryonic day 9 were exposed to escalating doses of B. atrox venom (1, 50, and 100 µg/egg) for up to 300 seconds. Vascular alterations were assessed using macroscopic imaging, quantitative analysis with ImageJ and AngioTool, and histological examination. Venom exposure resulted in dose- and time-dependent vascular disruption, mainly vascular rupture and hemorrhage. At low doses, we observed minimal hemorrhage without any significant changes in vascular network architecture. At high doses, histopathology revealed endothelial disorganization, vessel dilation, leukocyte infiltration, and microthrombi formation, consistent with direct cytotoxic and inflammatory effects. CONCLUSIONS/SIGNIFICANCE: B. atrox venom rapidly compromises vascular integrity and triggers an inflammatory response in the CAM model, reflecting key pathophysiological features of envenomation. The severity of these effects was proportional to the duration of exposure and the venom dose used. These findings support the use of CAM assay as a translational tool for screening venom-induced vascular toxicity and underscore the imperative of early antivenom administration.