A toxoid prepared from cholera toxin by iodination

A cholera toxoid was prepared by iodinating purified cholera toxin having an activity of 25 Limit of blueing (Lb) doses/l ug with 0.8 umol of iodine monochloride per mg toxin, and the residual lesion capacity was tested in mice. The Blueing Dose (BD) test was strongly positive for the native toxin, and co0mpletely abolished in the iodinated toxoid when tested at up to 25 times one Lb dose. The dermal microscopic lesions with intradermal doses of 1 ug virulent toxin presented intense leucocyte infiltration, proteinaceous edema and active hypertemia, whereas none of these effects was observed with the same amount of toxoid. To determine antigenicity, two groups of micereceived toxin or toxoid, 8.5 ug adsorbed to aluminum hydroxide, followed by a booster of 17 ug in saline 21 days later. Measurement of antibodies by ELISA at day 28 indicated that the toxoid was 2.5 times more antigenic than the toxin. These data show iodination converts cholera toxin to an effective toxoid

Iodinated soluble adult worm protein preparations of Schistosoma mansoni do not induce immediate hypersensitivity reactions but retain other immunogenic properties

Samples of Schistosoma mansoni soluble adult worm proteins (SWAP) were iodinated with 4-15 µmolI/mg protein using iodine monochloride. The capacity to elicit immediate hypersensitivity reactions of the iodinated derivatives was compared to that of the native SWAP preparations. The degranulation of mast clls from infected mice decreased with increasing iodine incorporation and was absent in fully iodinated samples containing 15 µmol I/mg protein. The response of guinea pigs and humans to the intradermal test with iodinated SWAP also decrease in proportion to iodine incorporation, and no responses were obtained with fully iodinated samples. No false-positive tests were observed. Antibodies to the folly iodinated extracts generated in C57BL/10 mice reacted by ELISA with the unmodified proteins and by immunoprecipitation on agar gel. The immunoprecicpitation pattern suggested that some epitopes were altered by iodination

Generation of protective immune sera by Crotalus durissus terrificus venom detoxified by controlled iodination

1. Whole soluble venom from the snake Crotalus durissus terrificus was detoxified by controlled iodination. Doses equivalent to 100 LD50 of the native venom were administerd to mice, without signs of intoxication. 2. The non-toxic iodinated derivative were able to stimulate antibodies in rabbits and horses within a short period (6 months) of inmunization. Horse antisera attained titers of 0.5 to 0.9 mg/ml for protection aginst native venom. 3. Horse antisera obrained in horses from native and iodinated venom were run against both native and iodinated venoms, as antigens, in gel immunodiffusion. The precipitation lines showed total identity of the types of sera