Effect of Some Variables on theIn VivoDetermination of Scorpion and Viper Venom Toxicities

Abstract

An adequate assessment of scorpion and snake venom LD50is an important step for accurate evaluation of antivenom sera potencies and the optimization of serotherapy. The LD50variation of Tunisian scorpion (Androctonus australis garzonii: Aag andButhus occitanus tunetanus: Bot) venoms with body weight, sex and strain (Swiss or C57Bl/6) of mice used, the route of venom injection, the venom-milking procedures (manually or electrically) and the venom batches have been studied over a 7-year period (1990–1996). Aag venom is 3–4 times more toxic than Bot venom. However for both venoms, the LD50determined in C57Bl/6 mice, in small body weight animal or by intraperitoneal route were respectively significantly lower than those determined in Swiss mice, in high body weight or by subcutaneous route. Significant LD50variations (25–50%) were also seen from one electrically prepared batch to another. A good correlation (r=0·982) was observed between the concentrations of the crude venom toxic fraction determined by ELISA and LD50values when assessedin vivo.The LD50variation of Tunisian viper (Cerastes cerastes: Cc andVipera lebetina: VI) venoms with the strain (Swiss or BALB/c), sex and body weight of mice used, the season and the year of venom milking were also investigated over a 3-year period (1990–1992). No significant LD50variations were observed with the mouse strain, the sex or the season of venom milking. However, LD50varies significantly with the year of the venom collection and the body weight of mice used. Furthermore, SDS–PAGE analysis shows annual variation for VI venom composition where no such variations were observed for Cc venom. These results stress the need either for the standardization of the venom LD50evaluation or the venom quality used for the development of an efficient antivenom.