[The detoxification of Naja naja atra venom and preparation of potent antivenin].

ABSTRACT

The 99.2% toxicity of Naja naja atra venom can be detoxified by treatment with 0.25% GA (glutaraldehyde) solution at pH 6.8 and still remains its antigenicity. Using the GA treated venom incorporated with Freund's complete adjuvant as immunogen, the titer of immune horse sera can be enhanced rapidly. The modified immunization method not only shortened the period of immunization (from 180 to 60 days), but also increased the potency of immune sera (from 75 to 170 units). The method also diminished the mortality rate of the horse during the immunization period (from 37 to 0%) and increased the antibody production rate (from 20 to 100%), as compared to Tanaka's method. With the present method, significant economic effects can be achieved. The neutralization antibody titer of Naja naja atra antivenin could be elevated 3.55 times through purification of the antivenin with the pepsin digestion method. The antivenin recovery rate using the pepsin digestion method was about 55.44%. The solubility of lyophilized antivenin was significantly improved by the addition of 2% glycine. In addition to an increase of antivenin potency and purity, the problem of an inadequate production rate has also been resolved. Now lyophilized antivenin can be supplied even to remote areas, thus providing excellent opportunities for clinical application. This Institute has already adopted this new immunization schedule in lieu of the old Tanaka method.