Immunochemical analysis of Legionella pneumophila outer membrane vesicles

Abstract

This chapter presents the description of the components of outer membrane (OM) vesicles produced by Legionella pneumophila. The composition of purified vesicles was compared by immumoblot analysis and enzyme-linked immunosorbent assay using the panel of monoclonal antibodies (MAbs) listed. Additional components of the vesicles included the chaperone Hsp60, the amoebal uptake protein (Aup), and the Mip PPIase protein which is necessary for full virulence. The authors assumed that lipid A remains anchored to intravesical structural proteins, whereas carbohydrate moieties of lipopolysaccharide (LPS) are altered, either before or after vesicle formation. The LPS-enriched vesicles are composed of several structural as well as virulence-associated proteins of L. pneumophila, e.g., Mip, Aup, and Hsp60. The detection of particular dot/icm gene products inside the OM vesicles would be one approach to investigate how OM vesicles contribute to L. pneumophila pathogenesis during phagosome formation and maturation, as well as during biofilm establishment and persistence. In addition to growth phase-dependent regulation, the authors demonstrated that the LPS content of OM vesicles varies between L. pneumophila serotypes.