Aquatic bacterium that cause tularemia. Francisella tularensis subsp. tularensis SCHU S4

Francisella tularensis subsp. tularensis strain Schu S4. This subspecies is virulent in humans, and the strain is a clinical isolate that is also virulent in an animal model. Originally isolated from a human case of tularemia in 1951. Genome analysis indicates the presence of a large number of pseudogenes, many that disrupt important metabolic pathways, which is the reason for the exacting nutritional requirements of this organism. There is a duplicated pathogenicity island that has also been detected in strain LVS and mutations in the iglA, iglC, or pdpD genes affect the ability of the pathogen to survive in macrophages. The genome also contains genes for type IV pili production and capsular polysaccharide genes similar to those of Bacillus anthracis as well as numerous ABC transporters. There are a large number of insertion sequences including a mariner element, which is a transposon typically found in eukaryotes and is the first instance of this element to be found in a microbe, which may have acquired it during transit through one of the insect vectors.