Pre_GI: SWBIT SVG BLASTN

Query: NC_016913:24000 Rickettsia rickettsii str. Brazil chromosome, complete genome

Lineage: Rickettsia rickettsii; Rickettsia; Rickettsiaceae; Rickettsiales; Proteobacteria; Bacteria

General Information: This genus, like other Rickettsial organisms such as Neorickettsia and Anaplasma, are obligate intracellular pathogens and is composed of two groups, the spotted fever group, and the typhus group. 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. This organism was first identified by Dr. Howard Rickets as the causative agent of Rocky Mountain Spotted Fever, which was originally named for its geographic distribution at the time, it is now known to be widespread throughout the North American continent. This bacterium is an obligate intracellular pathogen that infects primarily the vascular endothelium, and occasionally smooth muscle tissue. This bacterium is an obligate intracellular pathogen that infects primarily the vascular endothelium, and occasionally smooth muscle tissue. It is passed to the human host from a tick bite, and the tick acts as both a natural reservoir and a vector for disease transmission. Once the organism is endocytosed by the host cell, it quickly escapes the phagozome, and replicates intracellularly, causing cell death and tissue damage. The disease is characterized by a spotted rash and has a high mortality rate if left untreated.

Subject: NC_006368:3211998 Legionella pneumophila str. Paris, complete genome

Lineage: Legionella pneumophila; Legionella; Legionellaceae; Legionellales; Proteobacteria; Bacteria

General Information: This serogroup I strain is endemic in France. Causes Legionnaire's disease. This organism is a non-marine bacterium usually found growing inside other organisms such as protozoans in aquatic environments. They can also be found in soil, freshwater, and in biofilms. The first outbreak of Legionnaire's disease occurred in 1976 at an American Legion convention and the resulting pneumonia-like disease resulted in 34 deaths. The cause of the disease was traced to Legionella bacteria. Once the bacteria are brought into the lungs they make contact with alveolar macrophages and are internalized where they can cause severe respiratory distress. Internalization occurs through specialized vacuoles (replicative phagosomes) that allow the bacteria to grow and replicate prior to escape from the macrophage. Formation of the replicative phagosome, which requires reprogramming of the normal phagosome maturation pathway, requires a type IV secretion system called the Dot/Icm system. This type IV system is closely related to the conjugative system of plasmid ColIb-P9, and is involved in the secretion of numerous protein components that aid in formation of the replicative phagosome. Other virulence determinants include a set of multidrug transporters and other efflux pumps for toxic compounds that may allow the organism to persist in its habitat, a set of LPS phase variable genes that enhance immune evasion, and a type II secretion system for transport of hydrolases.