Pilus-Mediated Clearance of Salmonella Typhimurium by the Perfused Mouse Liver

Abstract

Most Salmonella isolated from animal hosts are piliated. While data are available to suggest that pili do not play a major role in the disease process per se (1), the role of these organelles in adherence of organisms to intestinal mucosa or deep tissue endothelium has not been systematically explored. For several years our laboratory has utilized a perfused liver model to explore the basic mechanisms involved in the early trapping and killing of selected microorganisms. We have established that the liver can trap Salmonella typhimurium and Candida albicans equally well in the presence and absence of plasma (2,3). Plasma is a requirement for the bactericidal activity of this organ and, at least for S. typhimurium, killing is dependent on a functional alternate pathway of complement (4). The results presented here describe the importance of type 1 pili in the trapping of S. typhimurium by liver. Type 1 pili are characterized as those which can agglutinate guinea pig red blood cells in a reaction which is sensitive to mannose. Both in vitro and in vivo data suggest that, while probably not the only surface antigen involved in trapping, pili are certainly one of the main adherence factors on the bacterial surface.