A low dose multi-site immunization schedule for raising therapeutic antivenom to the Egyptian cobra naja haje venom

Abstract EN

The production of antibodies (Abs) in response to primary and secondary antigenic challenge of horses with the Egyptian cobra (Naja haje, Nh) venom was investigated.

Horses were immunized with venom (11.5 mg / horse) divided into seven doses over a period of eight months.

Relatively long rest periods, two months each, separate the immunization schedule into three rounds.

The immunization schedule was monitored by determination of the serum potency ‘neutralization of lethality’ in mice.

After the intradermal administration of the first two doses the horses responded differently.

Two weeks from the second intradermal injection, the five horses showed different potencies (30±7 LD50/ml) with two horses suffering from marked signs of toxicity.

Highly potent antivenom (117±53 LD50/ml) was reached by administration of the subsequent venom doses by the subcutaneous route.

The relatively long rest periods seem to be beneficial for raising the potency of the antivenoms in addition to maintaining the animal health.

The results demonstrate the importance of antigen presentation at the initial immunization steps.