As beneficial as science has been for humanity, and even our favored animals, tens of millions of lab rats and guinea pigs pay the ultimate price. That toll is about to fall, however, with the development of an animal-free method for testing neurotoxins. Moreover, the new technique is substantially cheaper and vastly faster, offering its inventors a flood of information likely to lead to life-saving medications, and enhancing our understanding of animal evolution at the same time.
Many of our most important existing medications come from venoms, most famously captopril, which has prevented millions of heart attacks after its predecessor was discovered in Brazilian vipers. From funnel-web spiders offering the potential to limit post-stroke brain damage to coral reef fish dealing opioid-like painkillers, the chemicals in animal venoms are the richest source of potential new medications. However, with the typical venomous animal producing a complex cocktail of molecules, testing to identify those with potential benefits is an enormous challenge.
“The old method, while extremely efficient, is limited in that it’s slow and requires the euthanisation of animals in order to obtain the necessary tissue,” Dr Bryan Fry of the University of Queensland said in a statement. “Our new method uses optical probes dipped into a solution containing the venoms and we measure the binding to these probes – the critical factor – by analyzing changes in the light reflected back.”
“No scientist wants to kill an animal,” Fry told IFLScience. “We like animals, that's why we study them.” He added his alternative “will be adopted not just for ethical reasons, but [because] it's also better science.” In the time he once conducted eight tests on a molecule, Fry can now do 240. As a result, he now has a bunch of “very happy PhD students” with a mountain of data to process.
As if the ethical and scientific benefits weren't enough, Fry estimates the testing process, announced in the journal Toxins, will be considerably cheaper than raising an animal for testing.
Already Fry has announced: “Temple pit viper venom has an unusual cross-reactivity for the human alpha-5 receptor, which is a major target for conditions including colitis and smoking.” He's also using the optical probes to seek out peptides that can be used as “decoys” to stop snake venoms binding to human nerves where anti-venoms don't exist.
Fry expects the process will be expanded beyond neurotoxins to allow the screening of many other molecules for potential medical significance. That doesn't mean the end of animal testing is around the corner – preclinical trials will still require animals to assess the likelihood of side effects, for example.
Fry couldn't estimate the proportion of animal testing the probes will eliminate, but says by pushing back the point where it is necessary in the drug discovery process the reduction will be “significant”.
The opportunity to test much more rapidly across a wider range of organism-specific receptors has already enabled Fry and colleagues to confirm some theories about his specialty of venom evolution. For example, he told IFLScience, he has demonstrated sea snake venom is far more effective on fish than other animals, and king cobra venom affects other snakes more than legged reptiles. Both were expected adaptations to the snake in question's predominant prey, but had been too hard to prove previously.
If that sounds trivial, Fry said the same techniques could also be used to discover whether insecticides such as neonicotinoids really are as targeted in their actions against pest species as their manufacturers claim, or as damaging to bees or even vertebrates as ecologists fear.