Abstract
1. A 1% solution of crude Habu venom was added with formalin initially at 0.2% and then at concentrations increased by 0.2% on the 3rd, 5th, and 7th day. The mixture was kept at 37C and at a constant pH of 7.0. The lethal toxicity and the hemorrhagic activity were determined at certain intervals by intravenous injection into mice and intracutaneous injection into rabbits, respectively. The venom solution treated with formalin became a completely nontoxic within 14 days.
2. To the dialysis residue of the formol-toxoid thus prepared were added a half volume each of 0.1M AlCl3 and 0.1M Na3PO4 in this order listed. The resulting suspension was adjusted to pH 6.0 with sodium hydroxide. The adsorbed formol-toxoid thus prepared was injected subcutaneously into guinea pigs. Individual serum specimens were titrated for antilethal as well as antihemorrhagic (anti-HR 1 and anti-HR 2) potencies.
3. The immunized animals produced antibodies against both HR 1 and HR 2; the titers of which reached to 10 and 7u/ml, respectively, after the 3rd injection. On the other hand, the antilethal titer was below the level of detection.
4. Some of the immunized animals were challenged with the crude venom 6 weeks after the 6th injection, and observed for local symptoms 24 hours later. Control animals showed severe hemorrhage caused by such a small dose of the venom as 30mcg. On the contrary, the immunized animals were protected satisfactorily against the challenge with 300∼1, 000mcg of the venom.
