Laboratory maintenance of Ehrlichia chaffeensis and Ehrlichia canis and recovery of organisms for molecular biology and proteomics studies.

Tick-borne illnesses are emerging as a major concern for human health in recent years. These include the human monocytic ehrlichiosis caused by the Amblyomma americanum tick-transmitted bacterium, Ehrlichia chaffeensis; human ewingii ehrlichiosis caused by Ehrlichia ewingii (also transmitted by A. americanum ticks); and human granulocytic anaplasmosis caused by the Ixodes scapularis tick-transmitted pathogen, Anaplasma phagocytophilum. Likewise, tick-borne rickettsial pathogens are also a major concern to the health of various vertebrates including dogs, cattle, and several wild animals. In vitro-cultured pathogens grown in a vertebrate host cell and a tick cell culture system will be useful in studies to understand the pathogenic differences as well as to perform experimental infection studies and to generate large quantities of purified antigens. In this unit, methods for culturing E. chaffeensis and Ehrlichia canis (a canine monocytic ehrlichiosis pathogen) in cell lines to represent vertebrate and tick hosts are described. The unit also includes methods useful in purifying bacteria from the host cells and to evaluate proteins by 2-D gel electrophoresis and western blotting.