The manufacture of veterinary clostridial vaccines

Abstract

A vaccine is an antigenic preparation used to stimulate the production of antibodies and procure immunity from one or several diseases. Clostridium bacteria are found in soil and in the guts of animals. They are anaerobic (grow in the absence of oxygen), and produce a wide range of toxins leading to disease. Vaccines are required to give animals protection against these diseases. Production of clostridial vaccines involves growing the organism (clostridial bacteria) in a growth medium to produce large amounts of toxins, and altering the toxins so that they are no longer toxic, toxoids. These toxoids become antigens which the immune system recognises and hence produces antibodies to act against genuine toxins. After cultivation the live bacteria in the culture must be deactivated, and the resulting mixture is diluted and mixed with an adjuvant, a substance which improves the immune response to the toxoids. The final vaccine product must pass stringent tests before being released for use on animals. This article is based around the methods used by Mallinckrodt Veterinary Ltd in New Zealand.