Development of viper-venom antibodies in chicken egg yolk and assay of their antigen binding capacity

The therapeutic use of specific antibodies is invaluable in certain clinical conditions, such as administration of specific antivenom for snakebite envenomation. The production of antibodies and their purification from mammalian blood has been found low yielding and laborious. Most antivenom is polyvalent whole serum or partially purified immunoglobulin. The side effects of anti-snake-venom therapy include serum sickness and can be reduced by using mono-specific antivenom in sufficiently pure form. We have attempted to standardize a simple method for producing avian antivenom in relatively pure form from eggs. The isolation is very simple and involves only two steps, namely, removal of lipids from the diluted egg yolk followed by gel filtration. Each egg produces 80-100 mg of pure immunoglobulin, and specific antibodies are present for up to 100 days after immunization. Thus, large quantities of the Ig can be obtained in pure form using only small amounts of venom. Antigen binding was shown by Ouchterlony's double diffusion experiments and the avian antivenom neutralizes the thrombin-like activity of equivalent amounts of venom on human plasma. The LD50 of the venom was similar to3 mg/kg body weight in mice and rats but when pre-incubated with equivalent amounts (by weight) of egg IgG injected subcutaneously, all the animals survived. In a similar experiment using a commercial horse IgG, 25% mortality is seen. These results indicate that the antivenom immunoglobulins purified from immunized chicken egg yolk is biologically active and the possibility of their therapeutic use will be investigated further. (C) 2002 Elsevier Science Ltd. All rights reserved.