Query: NC_012633:1145500 Rickettsia africae ESF-5, complete genome
Lineage: Rickettsia africae; Rickettsia; Rickettsiaceae; Rickettsiales; Proteobacteria; Bacteria
General Information: This organism was isolated from a cattle tick, Amblyomma variegatum, collected in Ethiopia. This organism, a member of the spotted fever group of the Rickettsiales, is found in sub-Saharan Africa and the Caribbean. Rickettsia africae causes a flu-like illness, characterized by a mild fever and severe headache, without the skin rash common to other spotted fever group Rickettsia species. Members of this genus, like other Rickettsial organisms such as Neorickettsia and Anaplasma, are obligate intracellular pathogens. In both groups, the bacteria are transmitted via an insect, usually a tick, to a host organism 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.
Subject: NC_010161:2381195 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.