Action of Corynebacterium ovis exotoxin on endothelial cells of blood vessels

Abstract

Corynebacterium ovis (C. pseudotuberculosis) causes suppurative infections of sheep, goats and horses and occasional infections in other species². Like C. diphtheriae, it produces a powerful exotoxin in vitro. But unlike the situation with C. diphtheriae, there is no evidence of acute or chronic intoxication, while the lesions are characteristically pyogenic with suppuration and abscess formation at the initial site of infection (usually a skin wound). This is followed frequently by secondary abscess formation in regional lymph nodes and sometimes internal organs. Toxin is produced in vivo as well as in vitro because circulating antitoxin is found in infected animals. The major role of C. ovis toxin in natural infection seems to be facilitation of the spread of the causative bacteria by its action as a permeability factor. It thus causes marked leakage of plasma from small blood vessels at the site of infection which floods lymphatic spaces and increases the risk of bacteria being carried by lymphatic drainage from the site of infection to regional lymph nodes^3,4. We now report experimental evidence that C. ovis toxin is a phospholipase D which attacks the sphingomyelin of endothelial cells of blood vessels.