Abstract
It has been shown by one of us 1 that tetanus toxin is destroyed by a few minutes'exposure to ultra-violet light if toxic broth be diluted to decrease the concentration of protein and reduce the color absorptive factor. Previously, however, it has not been determined whether toxin so treated retains its antigenic potency. Low-enstein's 2 tetanus toxin, treated with 0.2% formalin and subjected to ultra-violet light was atoxic and antigenic, but since it is now well known that formalin alone renders certain toxins atoxic while preserving their antigenic powers, the effect of the irradiation in his experiments is uncertain. An experiment was therefore undertaken using as an immunizing agent tetanus toxin rendered atoxic by ultra-violet light. A mixture of 2 tetanus toxins after titration was diluted to contain 1 M.L.D. in each 1 cc. This was irradiated with “C” carbons (National Carbon Co.) at a distance of 25 cm. in the apparatus described in a previous publication, 3 keeping the toxin below room temperature by a current of cool air.
A 2-minute irradiation period failed to destroy the toxin completely, as about half of the inoculated animals developed late tetanus. A further irradiation of 2 minutes rendered the material atoxic. Using not more than a quantity originally containing 1 M.L.D, 9 guinea pigs were given 5 subcutaneous injections of this irradiated toxin at 6 or 7 day intervals and were inoculated 3 weeks later with freshly titrated tetanus toxin in doses of from 1 to 10 M.L.D.'s. No signs of tetanus developed. The period of observation was 45 days.
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