PNEUMOLYSIN - A MULTIFUNCTIONAL PNEUMOCOCCAL VIRULENCE FACTOR

Pneumolysin (PLY) is a multifunctional pneumococcal virulence factor t hat appears to augment intrapulmonary growth and dissemination during the early pathogenesis of Streptococcus pneumoniae infection. Through its cytotoxicity to respiratory epithelium and endothelium, PLY disrup ts pulmonary tissue barriers that serve as mechanical pulmonary defens es, thus facilitating S. pneumoniae growth and dissemination. Through direct inhibitory effects on immune and inflammatory cells and by acti vating complement, PLY inhibits bacterial clearance from the pulmonary interstitium and the blood. Because PLY stimulates local and systemic immune responses and enhances the immunogenicity of S. pneumoniae pol ysaccharide (PS), PLY-PS conjugates may form the basis for vaccines th at not only induce protective and durable immune responses to pneumoco ccal PS but also generate neutralizing anti-PLY antibodies that can pr otect the respiratory mucosa from toxin-induced injury.