A nontoxic derivative of Bothrops jararaca venom suitable to generate antibodies against the native venom.

Bothrops jararaca venom was toxoided by stepwise iodination with cold iodine, and doses up to 30 LD50 were non-lethal by i.p. route (BICALHO et al., 1990). Groups of mice injected chronically with the native, or the iodinated venom, have been subjected to histological examination. In the native group, in the spleen, around the white pulp, an acellular, amorphous eosinophilic substance, metachromatic to Methyl Violet, PAS positive, and dichroic to Congo Red under polarized light, was present. Strong congestion in the liver, kidneys and lungs was found. The salivary glands were replenished with an amorphous substance in the serosal acini. The groups injected with the iodinated venom only show discrete alterations, more akin to the control group. The anavenin was immunogenic. Antibody generation in mice and rabbits was detected by ELISA. In mice, active protection against challenge with native venom was presented. The iodinated venom generated a rabbit antiserum with strong lines in gel immunoprecipitation against the lethal venom. A minimum neutralization titer of 2.3 mg ml-1 against the native venom was attained in the first cycle (28 days) of immunization. After 3 cycles (100 days), the protection rose to 5.1 mg ml-1.