Enzymatic activity and brine shrimp lethality of venom from the large brown spitting cobra (Naja ashei) and its neutralization by antivenom

Abstract

Objective: Naja ashei is a snake of medical importance in Kenya, Ethiopia, Somalia, Uganda, and Tanzania. Little is known about the enzymatic (snake venom phospholipases A 2 ; svPLA 2 's) and toxic (lethal) activities of N. ashei venom and crucially, the safety and capacity of available antivenom to neutralize these effects. This study aimed to determine the enzymatic and toxic activities of N. ashei venom and the capacity of Indian and Mexican manufactured antivenoms to neutralize these effects. The protein content of the venom and the test antivenoms were also evaluated. A 12-point log concentration-response curve (0.5-22.5 µg/mL) was generated on an agarose-egg yolk model to predict the svPLA 2 activity of the venom. The toxicity profiles of the venom and antivenoms were evaluated in the brine shrimp lethality assay. Lowry's method was used for protein estimation. Results: Low and intermediate concentrations of the venom exhibited similar svPLA 2 activities. The same was true for concentrations > 15 µg/mL. Intermediate and high doses of the venom exhibited similar mortalities in brine shrimp and test antivenoms were generally non-toxic but poorly neutralized svPLA 2 activity. Mexican manufactured antivenom had lower protein content but neutralized venom-induced brine shrimp lethality much more effectively than Indian manufactured antivenom.

Effects of 3FTx Protein Fraction from Naja ashei Venom on the Model and Native Membranes: Recognition and Implications for the Mechanisms of Toxicity

“…A final measurement related to the determination of the effect of 3FTx on cell lines was to determine the safety of administration of venom components by determining the LD50. Studies conducted by Okumu et al [ 60 ] have shown a dose-dependent and time-dependent variable toxicity of the components of the Naja ashei venom. The LC50 for this snake venom was 63.02 μg/mL.…”

“…Based on preliminary results, isotherms for single lipid components were obtained for 10 and 40 ng/mL 3FTx. The cholesterol and phospholipid (PL) ratio for the membrane mimicking system of used human cell lines were 0.35 for HL- 60…”

Development of an Inhibition Enzyme-Linked Immunosorbent Assay (ELISA) Prototype for Detecting Cytotoxic Three-Finger Toxins (3FTxs) in African Spitting Cobra Venoms

“…As is the case with the other African spitting cobras, the venom of N. ashei is known to induce mainly cytotoxic effects caused by the predominant presence of 3FTx proteins and phospholipases A 2 [ 5 , 6 ]. N. ashei is a medically important snake species in Kenya, Ethiopia, Uganda, Somalia, and Tanzania, and thus, is implicated in snakebites and associated morbidity, mortality, and disability [ 7 ].…”

Evaluation of lethality and cytotoxic effects induced by Naja ashei (large brown spitting cobra) venom and the envenomation-neutralizing efficacy of selected commercial antivenoms in Kenya

“…However, Inoserp™ antivenom consist of venoms of a wider variety of Naja snakes including N. pallida , N. nubiae and N. senegalensis , which are not covered in the specific VINS™ antivenom under review. Nevertheless, according to Okumu and colleagues ( Okumu et al, 2020 ), the venom of N. ashei does not form part of the immunizing mixtures of commercially available antivenoms as of yet. Thus, whereas the neutralizing efficacy of Mexican and Indian-made antivenoms against N. ashei venom phospholipase A 2 activity and venom-induced lethality in the brine shrimp model has been demonstrated ( Okumu et al, 2020 ), the efficacy of these antivenoms to neutralize N. ashei -induced lethal and cytotoxic effects in mice model is not known.…”