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Ehrlichia chaffeensis Expresses Macrophage- and Tick Cell-Specific 28-Kilodalton Outer Membrane Proteins
- Singu, Vijayakrishna, Liu, Haijie, Cheng, Chuanmin, Ganta, Roman R.
- Infection and immunity 2005 v.73 no.1 pp. 79-87
- adaptation, genes, hosts, life cycle (organisms), macrophages, membrane proteins, outer membrane proteins, protein synthesis, proteins, proteomics, ticks
- 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.