Tetanus Toxoid and its Use for Active Immunization*
D. T. FRASER, M.C., M.B., D.P.H.; D. L. MACLEAN, M.B., D.P.H.†; M. D. ORR, B.A.; H. C. PLUMMER, PH.D.; AND
F. O. WISHART, M.D., D.P.H.
Connaught Laboratories and School of Hygiene, University of Toronto Toronto
THIS study records the antitoxin response to tetanus toxoid in young adults.
The first part of the study deals with the results obtained following two doses of toxoid as compared with three doses of an identical antigen. The second part has to do with the response to three doses of a combined antigen, made up of typhoid, paratyphoid A and B vaccine, suspended in tetanus toxoid.
PREPARATION OF TOXOID
In the preparation of the toxoid used in these studies, the following details are relevant. Upon the outbreak of war large quantities of tetanus toxin were prepared in anticipation of the requirements of toxoid for the armed forces. The broth used for this purpose was a veal infusion base with 1.5 per cent Witte's peptone added. With this medium the potency of the toxin obtained varied between 20,000 and 150,000 m.l.d. (guinea pig) per ml. Detoxification was carried out in the usual manner with formalin and storage at 37°C. The com- parison of the antitoxin response to two doses and to three doses of antigen was based upon the results obtained with toxoid thus prepared. For convenience of expression and reference, toxoid made in that manner is designated Toxoid A. Experience with this toxoid, used under field conditions, showed that reactions of an anaphylactic character were occasionally encountered (1). In consequence of this, the use of Witte's peptone in the medium for the preparation of toxin was discontinued in the spring of 1940, and hog stomach autolysate plus veal infusion was substituted, Toxoid B. Later, the medium used for the production of toxin was one adopted for the purpose by E. M. Taylor (2), the basis of which was half veal infusion and half hog stomach autolysate treated with calcium chloride in order to reduce the iron content to a fixed level. A small amount of nicotinic acid was added, and the pH set at about 7.0. The strain of Clostridium tetani used throughout for the production of toxin was obtained in 1929 from the New York State Health Department, and used in these Laboratories continuously since that time. Incubation was carried out at between 35°C. and 36°C. for 10 or 11 days. The yield of toxin with this medium has been satisfactory. Dur-
* Presented at a joint session of the Health Officers, Laboratory, and Epidemiology Sections of the American Public Health Association at the seventy-first annual meeting in St. Louis, Mo., October 27, 1942, and published in this issue by kind permission of the Association.
† Lieut.-Col., Royal Canadian Army Medical Corps.