Assessment of quality, safety, and pre-clinical toxicity of an equine polyvalent anti-snake venom (Pan Africa): Determination of immunological cross-reactivity of antivenom against venom samples of Elapidae and Viperidae snakes of Africa

Snakebite causes a large amount of morbidities and mortalities in Africa. The safety, efficacy, and homogeneity of anti-snake venoms are crucial for snakebite treatments to be effective with minimal adverse effects. We assessed the homogeneity of preparations of three different batches of Combipack snake venom antiserums (Pan Africa) [CSVAPA] by quantitatively analysing F(ab')(2), IgG, and other contaminating proteins of plasma. LC-MS/MS analysis showed that approximately 92.4% of the proteins from the CSVAPA samples was IgG/F(ab')(2) and the percent composition of contaminating proteins in CSVAPA varied from 0.07 to 4.6%. Batch 1 of the CSVAPA also contained a minor amount of undigested IgG and F(ab')(2) aggregates. CSVAPA contained more than 60% venom specific antibodies, showed moderate complement activation, no IgE contamination, safe level of endotoxin, and also showed pre-clinical safety. The immuno cross-reactivity of CSVAPA against 14 Viperidae and Elapidae snake venoms of Africa was tested by ELISA and immunoblotting, and the neutralization of major enzymatic venom activities, demonstrating that high molecular weight (> 50 kDa) venom proteins are better recognized/neutralized compared to relatively low molecular weight (< 20 kDa) venom proteins. CSVAPA at a dose of 3-12 times higher than the clinical dose did not cause deaths or adverse reaction of treated rabbits. The results suggest the satisfactory quality, safety, and efficacy of CSVAPA.