Abstract
Venoms are complex mixtures of biologically active molecules that impact multiple physiological systems. Manufacture of antivenoms (AVs) therefore requires potency testing using in vivo models to ensure AV efficacy. As part of ongoing research to replace small animals as the standard model for AV potency testing, we developed an alternate in vivo method using the embryonated egg model (EEM). In this model, the survival of chicken embryos envenomated in ovo is determined prior to 50% gestation, when they are recognized as animals by animal welfare legislation. Embryos were found to be susceptible to a range of snake, spider, and marine venoms. This included funnel-web spider venom for which the only other vertebrate, non-primate animal model is newborn mice. Neutralization of venom with standard AV allowed correlation of AV potency results from the EEM to results from animal assays. Our findings indicate that the EEM provides an alternative, insensate in vivo model for the assessment of AV potency. The EEM may enable reduction or replacement of the use of small animals, as longer-term research that enables the elimination of animal use in potency testing continues.
Highlights
Venoms are complex mixtures of biologically active molecules, that have the potential to impact multiple physiological systems
The current study investigates the feasibility of testing in an insensate in vivo model, the embryonated egg model (EEM)
Injection using this side envenomation method reduced the potential for trauma to the chorioallantoic membrane (CAM) compared to the top envenomation method, reducing the background mortality in control eggs injected with PBS or AV alone in triplicate comparison assays
Summary
Venoms are complex mixtures of biologically active molecules, that have the potential to impact multiple physiological systems. In the field of venomics, Sells et al developed a method for testing the hemorrhagic effect of snake venoms on chick embryos, as an alternative to the WHO-approved rodent intradermal skin test for assessing venom neutralization [24,25,26] In this assay, paper discs loaded with venom (with or without incubation with AV) were placed onto yolk sac vitelline veins of 6-day old shell-less, ex-ovo chick embryos, which were observed up to 6 h postenvenomation for cessation of heartbeat. Paper discs loaded with venom (with or without incubation with AV) were placed onto yolk sac vitelline veins of 6-day old shell-less, ex-ovo chick embryos, which were observed up to 6 h postenvenomation for cessation of heartbeat This assay was found to correlate well with rodent assays for testing the potency and neutralization of non-neurotoxic snake venoms [24,25]. The current study details the development of an alternate in ovo assay for assessing venom and AV potency
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