Chapter 26 - Regulation of Toxin Production in Clostridium Perfringens

Abstract

This chapter focuses on regulation of toxin production in Clostridium Perfringens. The most significant of these toxins are the α-toxin, θ-toxin, and κ-toxin. The genes encoding these toxins and other extracellular enzymes from C. perfringens have been cloned and sequenced that has greatly facilitated their molecular analysis. The role of α-toxin and θ-toxin in the pathogenesis of C. perfringens infections has been examined using alellic exchange mutagenesis of the chromosomal structural genes. Examination of these isogenic mutants in a mouse myonecrosis model has shown that α-toxin is an essential C. perfringens virulence factor and suggested that α-toxin and θ- toxin act synergistically in vivo. In many bacteria, it has become clear that cell-to-cell communication plays an important role in the regulation of physiological processes or in the expression of virulence factors. In C. perfringens, there have been reports of a diffusible signaling substance, substance A, which is involved in the regulation of toxin production. A model which describes the regulatory network mediated by the virR-virS system has been proposed and subsequently modified.