Assessment of preclinical efficacy of antivenoms produced in rabbit by immunological methods and neutralization assays

Fatima Zahra Khaddach, Brahim

Abstract

Envenomation by Moroccan vipers (Cerastes cerastes Cc and Macrovipera mauretanica Mm) has caused significant morbidity and mortality. In Morocco, both vipers were increasingly identified as a dangerous and common source of envenomation. The antivenom production in Morocco against poisonous snakes encounters a number of difficulties; unfortunately, there is still no monospecific Moroccan antivenom to date. This study aims to assess the feasibility of monospecific Cc and Mm antivenom production F(ab’)2 prepared under the same immunization protocols in rabbits. SDS-PAGE analysis of both types of antivenoms showed similar serum protein profiles. C.cerastes venom elicited satisfactory titers of anti-Cc F(ab’)2 after immunization as compared to M.mauretanica venom. Both antivenoms, isolated with ammonium sulfate precipitation method, were effective in neutralizing the venom lethality (potency = 49.75 and 39.07 LD50 per ml for anti-Cc and anti-Mm respectively) as well as its hemorrhagic effects induced by 3MHD of the venom. Cross-reactivity studies using Ouchterlony test and indirect ELISA (Enzyme-Linked Immunosorbent Assay) showed that anti-Cc and anti-Mm F(ab’)2 cross-reacted extensively with several venoms, particularly that of viper species (Bitis arietans), presumably due to the presence of venom antigens common to both snakes.