Screening Snake Venoms for Toxicity to Tetrahymena Pyriformis Revealed Anti-Protozoan Activity of Cobra Cytotoxins

Abstract

Snake venoms possess lethal activities against different organisms, ranging from bacteria to higher vertebrates. Several venoms were shown to be active against protozoa, however, data about the anti-protozoan activity of cobra and viper venoms are very scarce. We tested the effects of venoms from several snake species on the ciliate Tetrahymena pyriformis. The venoms tested induced T. pyriformis immobilization, followed by death, the most pronounced effect being observed for cobra Naja sumatrana venom. The active polypeptides were isolated from this venom by a combination of gel-filtration, ion exchange and reversed-phase HPLC and analyzed by mass spectrometry. It was found that these were cytotoxins of the three-finger toxin family. The cytotoxins from several cobra species were tested and manifested toxicity for infusorians. Light microscopy revealed that, because of the cytotoxin action, the infusorians’ morphology was changed greatly, from teardrop-like to an almost spherical shape, this alteration being accompanied by a leakage of cell contents. Fluorescence microscopy showed that the fluorescently labelled cytotoxin 2 from cobra N. oxiana was localized mainly at the membrane of killed infusorians, indicating that cytotoxins may kill T. pyriformis by causing membrane rupture. This work is the first evidence of the antiprotozoal activity of cobra venom cytotoxins, as demonstrated by the example of the ciliate T. pyriformis.

The Potassium Channel Blocker β-Bungarotoxin from the Krait Bungarus multicinctus Venom Manifests Antiprotozoal Activity

“…So far, antiprotozoal activity has been found in snake venoms from various families and genera, including Asian elapids, as well as Asian, African and American viperids, and Colubrid [ 3 , 8 ]. Together with recent findings [ 12 , 13 , 14 , 15 ], these data suggest that antiprotozoal activity may be a widespread property of snake venom.…”

“…[ 8 ], Naja nigricollis [ 19 ] and some other species, as well as metalloproteases from the venoms of B. neuwiedi [ 20 ] and B. moojeni [ 21 ]. Non-enzymatic toxins include a lectin from B. leucurus venom [ 22 ], a disintegrin from Cerastes cerastes venom [ 23 ], a small pore-forming myotoxin crotamine from Crotalus venom [ 24 ], cathelicidin-like proteins crotalicidin and batroxicidin from C. durissus terrificus and B. atrox venoms [ 25 , 26 ], a CRiSP crovirin from C. viridis [ 27 ], and cytotoxins from cobra venoms [ 14 ]. It should be noted that the antiprotozoal activity of snake toxins may partially depend on the species of protozoa studied, although such data have not yet been systematized.…”

“…We previously used ciliates T. pyriformis as a model organism for screening snake venoms to search for compounds with antiprotozoal activity [ 14 , 15 ] and found that the cobra venoms were the most toxic among them. They were followed by krait venoms.…”

Variability in the Spatial Structure of the Central Loop in Cobra Cytotoxins Revealed by X-ray Analysis and Molecular Modeling

“…CT13Nn was isolated from N. naja venom and purified essentially as described in [53]. The purification was performed in three steps, including gel-filtration, ion-exchange and reverse-phase high-performance liquid chromatography.…”

Animal Venoms and Their Components: Molecular Mechanisms of Action

“…Several papers describe effects of animal toxins or related peptides on microorganisms. Thus, the screening of snake venoms against protozoan Tetrahymena pyriformis revealed the high activity of cobra venoms [17]. Further analysis of the venoms showed that the active components are cytotoxins of the 3FTX family.…”