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About Helicobacter

General information:
Small curved Gram-negative bacteria closely related to Wolinella succinogenes, Campylobacter spp., and Acrobacter spp.
The genus Helicobacter currently comprises 23 validly named species. These can be subdivided into the gastric Helicobacter species, which colonize the mucosa of the stomach of their host organisms, and the enterohepatic Helicobacter species, which colonize the gut and/or the liver.
Isolates are characterized biochemically by the presence of urease, catalase, and oxidase activites.
Many Helicobacter species can colonize the intestines or biliary tracts of humans and other mammals, where they cause an inflammatory response.
Characteristics:
H. pylori is the only recognized bacterial carcinogen.
H. pylori are extraordinary bacteria in their ability to colonize the human gastric mucosa, an inherently inhospitable acidic environment, and to persist in this niche for many decades, despite the development of host immune and inflammatory response. Persistent colonization with has been recognized as a significant risk factor for serious gastroduodenal disease.
H. pylori is a genetically diverse species, with strains differing markedly in virulence.
Disease:
Gastric and duodenal ulcers.
Selected genomes:comparative pathogenomics
H. acinonychis str. Sheeba, 1553927 bp, NC_008229
H. hepaticus ATCC 51449, 1799146 bp, NC_004917
H. pylori 26695, 1667867 bp, NC_000915
H. pylori G27, 1652982 bp, NC_011333
H. pylori HPAG1, 1596366 bp, NC_008086
H. pylori J99, 1643831 bp, NC_000921
H. pylori P12, 1673813 bp, NC_011498
H. pylori Shi470, 1608548 bp, NC_010698
Related publications:
Tomb JF, et al., 1997. The complete genome sequence of the gastric pathogen Helicobacter pylori Nature 388(6642):539-547.
Alm RA, et al., 1999. Genomic-sequence comparison of two unrelated isolates of the human gastric pathogen Helicobacter pylori Nature 397(6715):176-180.
Suerbaum S, et al., 2003. The complete genome sequence of the carcinogenic bacterium Helicobacter hepaticus. Proc. Natl. Acad. Sci. USA. 100(13):7901-7906.
Oh JD, et al., 2006. The complete genome sequence of a chronic atrophic gastritis Helicobacter pylori strain: evolution during disease progression. Proc Natl Acad Sci USA 103(26):9999-10004.
Eppinger M, et al., 2006. Who ate whom? Adaptive Helicobacter genomic changes that accompanied a host jump from early humans to large felines. PLoS Genet 2(7):e120.
Baltrus DA, et al., 2009. The complete genome sequence of Helicobacter pylori strain G27. J Bacteriol 191(1):447-448.
Fischer W, et al., 2010. Strain-specific genes of Helicobacter pylori: genome evolution driven by a novel type IV secretion system and genomic island transfer. Nucleic Acids Res 38(18):6089-6101.
Major virulence factors in Helicobacter:
Adherence
BabA (Blood group antigen binding adhesin)
HopZ (H. pylori outer membrane protein)
SabA (Sialic acid-binding adhesin)
Effector delivery system
CagA (Cytotoxin-associated antigen)
Type IV secretion system
Motility
Flagella
Flagellar glycosylation/Pse biosynthetic pathway
Exotoxin
VacA (Vacuolating cytotoxin A)
Immune modulation
HP-NAP (Neutrophil activating protein)
Lewis antigen
LPS
OipA (Outer inflammatory protein)
Stress survival
Urease

Genomic location of virulence-related genes in Helicobacter:


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