Toxin Evolution Lab, School of Biological Sciences, University of Queensland, St Lucia, QLD, 4072, Australia.
Monash Venom Group, Department of Pharmacology, Biomedical Discovery Institute, Monash University, Clayton, VIC, 3800, Australia.
Neurotox Res. 2021 Jun;39(3):697-704. doi: 10.1007/s12640-021-00330-4. Epub 2021 Jan 11.
Research into the neurotoxic activity of venoms from species within the snake family Viperidae is relatively neglected compared with snakes in the Elapidae family. Previous studies into venoms from the Bitis genus of vipers have identified the presence of presynaptic phospholipase A neurotoxins in B. atropos and B. caudalis, as well as a postsynaptic phospholipase A in B. arietans. Yet, no studies have investigated how widespread neurotoxicity is across the Bitis genus or if they exhibit prey selectivity of their neurotoxins. Utilising a biolayer interferometry assay, we were able to assess the binding of crude venom from 14 species of Bitis to the neuromuscular α-1 nAChR orthosteric site across a wide range of vertebrate taxa mimotopes. Postsynaptic binding was seen for venoms from B. arietans, B. armata, B. atropos, B. caudalis, B. cornuta, B. peringueyi and B. rubida. To further explore the types of neurotoxins present, venoms from the representatives B. armata, B. caudalis, B. cornuta and B. rubida were additionally tested in the chick biventer cervicis nerve muscle preparation, which showed presynaptic and postsynaptic activity for B. caudalis and only presynaptic neurotoxicity for B. cornuta and B. rubida, with myotoxicity also evident for some species. These results, combined with the biolayer interferometry results, indicate complex neurotoxicity exerted by Bitis species, which varies dramatically by lineage tested upon. Our data also further support the importance of sampling across geographical localities, as significant intraspecific variation of postsynaptic neurotoxicity was reported across the different localities.
与眼镜蛇科的蛇相比，对蝰科蛇类毒液的神经毒性活性的研究相对较少。以前对蝰蛇属的毒液的研究已经确定了在 B.atropos 和 B.caudalis 中存在突触前磷脂酶 A 神经毒素，以及在 B.arietans 中存在突触后磷脂酶 A。然而，还没有研究调查神经毒性在整个 Bitis 属中是多么普遍，或者它们是否表现出对神经毒素的猎物选择性。利用生物层干涉测量法，我们能够评估来自 14 种 Bitis 物种的粗毒液与广泛的脊椎动物分类模拟物的神经肌肉α-1 nAChR 正位点的结合。来自 B.arietans、B.armata、B.atropos、B.caudalis、B.cornuta、B.peringueyi 和 B.rubida 的毒液表现出突触后结合。为了进一步探索存在的神经毒素类型，还在小鸡双脑室颈神经肌肉制备物中测试了代表 B.armata、B.caudalis、B.cornuta 和 B.rubida 的毒液，结果显示 B.caudalis 具有突触前和突触后活性，而 B.cornuta 和 B.rubida 仅具有突触前神经毒性，一些物种也表现出肌毒性。这些结果与生物层干涉测量结果相结合，表明 Bitis 物种具有复杂的神经毒性，其在经过测试的谱系中差异巨大。我们的数据还进一步支持在地理区域内进行采样的重要性，因为不同地点报道的突触后神经毒性存在显著的种内变异。
