Sequence and Molecular Characterization of a Multicopy Invasion Plasmid Antigen Gene, ipaH, of Shigella flexneri.

摘要

The pathogenesis of bacillary dysentery requires the coordinate expression of a number of components that control the epithelial cell invasion, intracellular replication, and intercellular spreading phenotypes characteristic of the expression of virulence in Shigella species and enteroinvasive Escherichia coli. Genes encoding virulence-associated elements are located on the chromosome and on a 120-to 140-megadalton (MDa) plasmid found in all virulent Shigella and enteroinvasive E. coli strains. At least eight unique polypeptides are encoded by this envasion plasmid; five of these (VirG and invasion plasmid antigens (Ipa) A, B, C, and D) are immunogens consistently recognized by serum and mucosal antibodies in convalescent humans and primates. Molecular cloning and nucleotide sequence determination for Shigella flexneri ipaB, ipaC, ipaD, and virG genes have been previously described. However, phenotypes and functions associated with the expression of these antigens are only broadly defined. (JES)