title: Ehrlichia chaffeensis expresses macrophage- and tick cell-specific 28-kilodalton outer membrane proteins.
abstract: Ehrlichia chaffeensis, a tick-transmitted rickettsial agent, causes human monocyte/macrophage-tropic ehrlichiosis. In this study, proteomic approaches were used to demonstrate host cell-specific antigenic expression by E. chaffeensis. The differentially expressed antigens include those from the 28-kDa outer membrane protein (p28-Omp) multigene locus. The proteins expressed in infected macrophages are the products of p28-Omp19 and p28-Omp20 genes, whereas in tick cells, the protein expressed is the p28-Omp14 gene product. The differentially expressed proteins are posttranslationally modified by phosphorylation and glycosylation to generate multiple expressed forms. Host cell-specific protein expression is not influenced by growth temperatures and is reversible. Host cell-specific protein expression coupled with posttranslational modifications may be a hallmark for the pathogen's adaptation to a dual-host life cycle and its persistence.
authors.affiliation: Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, 1800 Denison Ave., Manhattan, KS 66506, USA.
authors.forename: Vijayakrishna
authors.initials: V
authors.lastname: Singu
authors.forename: Haijie
authors.initials: H
authors.lastname: Liu
authors.forename: Chuanmin
authors.initials: C
authors.lastname: Cheng
authors.forename: Roman R
authors.initials: RR
authors.lastname: Ganta
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000032:analysis / Q000737:chemistry / Q000235:genetics*; D015153:Blotting, Western; D002460:Cell Line; D004285:Dogs; D018469:Ehrlichia chaffeensis / Q000378:metabolism*; D008264:Macrophages / Q000382:microbiology*; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011499:Protein Processing, Post-Translational; D020543:Proteome; D013696:Temperature; D013987:Ticks / Q000382:microbiology*
chemical_list: D001425:Bacterial Outer Membrane Proteins; D020543:Proteome