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

## TL;DR

This study uses a chicken egg model to show how Bothrops atrox snake venom rapidly damages blood vessels, with effects worsening with higher venom doses and longer exposure times.

## Contribution

The study introduces the chorioallantoic membrane (CAM) model as a translational tool for assessing venom-induced vascular toxicity and highlights the importance of early antivenom administration.

## Key findings

- B. atrox venom causes dose- and time-dependent vascular damage, including rupture and hemorrhage.
- High venom doses lead to endothelial disorganization, vessel dilation, and microthrombi formation.
- The CAM model effectively captures inflammatory responses and vascular disruption similar to human envenomation.

## Abstract

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.

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.

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.

Snakebite is a major health problem, especially in tropical regions. Bothrops atrox is a common snake in South America. Its venom can cause significant tissue damage, including vascular injury. We used the chicken egg chorioallantoic membrane (CAM) model, a cost-effective tool, to illustrate the early vascular toxicity induced by B. atrox venom. We exposed the CAM to different amounts of B. atrox venom for short periods. Using imaging techniques, we observed that the venom rapidly damages the blood vessels, causing them to leak and become disorganized. The severity of this damage was proportional to the amount of venom and the time of exposure. We also found evidence of an inflammatory reaction in the affected vessels. These findings demonstrate that the CAM model is helpful in studying the early stages of venom-induced blood vessel damage. This model could be used in future research to compare venom toxicities, test the neutralisation potency of different antivenoms, and explore the specific mechanisms by which B. atrox venom acts.