Consistency in potency assay of tetanus toxoid in mice.

The use of mice for the assay of tetanus toxoids would offer considerable advantages over the use of guinea-pigs, but mice cannot readily be immunized with the fluid tetanus toxoid at present designated as the International Standard. This study shows, however, that the mouse is a very suitable laboratory animal for the comparison of adsorbed tetanus toxoids, and that an AlPO(4)-adsorbed vaccine, which is stable at 4 degrees C, is a satisfactory reference preparation. The log-dose-response lines of toxoids adsorbed on different quantities of AlPO(4) and on various quantities of another adsorbent ran parallel to those of the reference vaccine. The 95% confidence limits for the potencies of tetanus vaccines, diphtheria-tetanus vaccines, and diphtheria-pertussis-tetanus vaccines, determined by assay against the reference vaccine in mice, showed a high degree of reproducibility of the results.