The effect of chlortetracycline on the immune response.

Chlortetracylcine was incorporated in the diet of mice preceding immunization with an avirulent live culture of Erysipelothrix rhusiopathiae, an organism susceptible to the antibiotic. The antibiotic was fed continuously for 2 weeks, and was removed from the ration 1 week prior to challenge. It was shown in two studies that a definite interference with development of immunity occurred. The quantitative nature of this interference was calculated by dose-effect determinations. Implications of this interference in some current methods of livestock vaccination were discussed.