Characterization of the venom apparatus of Oxyrhopus guibei (Squamata: Colubridae)

Abstract

Oxyrhopus guibei is a conspicuous colubrid snake popular in the exotic pet trade that has been implicated in envenomation cases involving local and systemic clinical manifestations. This study aims to characterize the venom apparatus of O. guibei, including the composition and immunochemical reactivity of its secretion. The maxilla and fangs were examined using scanning electron microscopy, while the histology and histochemistry of the glands were analyzed via hematoxylin-eosin and periodic acid-Schiff (PAS), Alcian Blue pH 2.5, and Gomori´s trichrome staining. Additionally, the protein profile was evaluated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and Tricine-SDS-PAGE, and cross-reactivity with bivalent and tetravalent bothropic antivenoms was assessed by Western blot. Anatomically, recurved teeth were observed in the anterior maxilla, followed by enlarged, deeply grooved posterior teeth (opisthoglyphous dentition). Histologically, Duvernoy´s venom glands exhibited distinct structural and chemical characteristics compared to the supralabial glands; their secretory units are organized into lobules of predominantly serous acini composed of columnar cells with acidophilic cytoplasm and PAS-negative basal nuclei. The venom protein profile displayed bands ranging from ≈8.5 to 65 kDa, with a predominance of proteins migrating within molecular mass ranges consistent with snake venom metalloproteinases, which showed immunoreactivity with both antivenoms tested. In conclusion, O. guibei possesses a specialized venom delivery system consisting of modified anatomical structures designed to deliver a venom containing components reminiscent of bothropic venoms, primarily involved in prey subjugation and with the potential to cause envenomation in humans. This study provides preliminary insights into the venom of this species and underscores the need for further functional characterization to determine its potential toxicological relevance to humans.