The 120 kDa outer membrane protein of Ehrlichia chaffeensis: Preferential expression on dense-core cells and gene expression in Escherichia coli associated with attachment and entry

The immunodominant 120 kDa protein (p120) of Ehrlichia chaffeensis was demo nstrated to be exposed on the surface of purified whole ehrlichial cells ex amined by immunoelectron microscopy with a rabbit antibody against a portio n of the domain containing tandem repeat units. In the intracellular locati on, the 120 kDa protein was detected by immunoelectron microscopy in the ou ter membrane of the cell wall of dense-core forms of the ehrlichiae in infe cted canine macrophagelike cells and as a component of the intramorular fib rillary matrix. No 120 kDa protein was detected in the cell wall of ehrlich ial reticulate cells. Recombinant Escherichia coli with a plasmid containing the entire 120 kDa p rotein gene, but no bacteria with non-recombinant plasmid, attached to the surface of HeLa cells as visualized by electron microscopy. Some of the rec ombinant 120 kDa protein expressing E. coil invaded the HeLa cells as deter mined by gentamicin protection assays and by intravacuolar localization ult rastructurally. (C) 2000 Academic Press.