GASEOUS LYMPHADENITIS VACCINE DEVELOPMENT - SITE-SPECIFIC INACTIVATION OF THE CORYNEBACTERIUM-PSEUDOTUBERCULOSIS PHOSPHOLIPASE-D GENE

Vaccines for ovine caseous lymphadenitis (CLA) ave currently formulate d using partially purified, formalin inactivated phospholipase D (PLD) derived from Corynebacterium pseudotuberculosis culture supernatants. Chemical treatment has been a common and effective way of inactivatin g bacterial toxins for use in toroid vaccines. Generic inactivation of toxin genes using site-specific mutagenesis has the potential to impr ove this process by providing a safer and more cost-effective product. In the present study amino acid substitutions at the putative catalyt ic site and metal binding domain of the PLD protein had a profound aff ect upon PLD activity and secretion from C. pseudotuberculosis. Two mu tated PLD analogues that were secreted to a level of 40% compared to t he wild-type and retained minimal activity shouted promise for develop ment as recombinant CLA vaccines, Further work will be required to est ablish their suitability for commercialization.