Query: NC_003103:266013 Rickettsia conorii str. Malish 7, complete genome
Lineage: Rickettsia conorii; Rickettsia; Rickettsiaceae; Rickettsiales; Proteobacteria; Bacteria
General Information: This strain was isolated from a human in South Africa. Causative agent for Rocky Mountain spotted fever. This genus, like other Rickettsial organisms such as Neorickettsia and Anaplasma, is composed of obligate intracellular pathogens. The latter is composed of two organisms, Rickettsia prowazekii and Rickettsia typhi. The bacteria are transmitted via an insect, usually a tick, to a host organism, in this case humans, where they target endothelial cells and sometimes macrophages. They attach via an adhesin, rickettsial outer membrane protein A, and are internalized where they persist as cytoplasmically free organisms. Transovarial transmission (from mother to offspring) occurs in the invertebrate host. This organism causes Rocky Mountain spotted fever which can cause severe damage to the endothelial layer of major organs, including the lungs, heart, kidneys, and skeletal muscle which can result in death.
Subject: NC_010161:2050816 Bartonella tribocorum CIP 105476, complete genome
Lineage: Bartonella tribocorum; Bartonella; Bartonellaceae; Rhizobiales; Proteobacteria; Bacteria
General Information: This organism was isolated from the blood of wild rats and from fleas obtained from wild rats. Transmission of these organisms is often through an insect vector. Once in a host, this intracellular pathogen is internalized by an actin-dependent mechanism, and primarily targets endothelial cells, although other cells can be infected. The proliferation of the vascular endothelium (bacillary angiomatosis) is characterisitic of Bartonella infection and results in multiplication of the bacterium's host cells. Infected macrophages are stimulated to release vascular endothelial growth factor (VEGF) and interleukin 1 beta, both of which promote angiogenesis. Endothelial cells are also stimulated to grow and divide by direct contact with bacterial cells. In addition, programmed cell death (apoptosis) of endothelial cells is inhibited, combatting a common mechanism eukaryotic cells use to deal with bacterial infection. Other pathogenicity factors include pili and outer membrane adhesins for attachment to host cells. This organism is genetically related to Bartonella elizabethae which was isolated from a case of endocarditis in a human.