Characterization of Shigella type 1 fimbriae: expression, FimA sequence, and phase variation.
This study documents the presence of type 1 fimbriae on Shigella and confirms these mannose-sensitive adherence structures to be bona fide components of the Shigella surface. While laboratory-passaged Shigella strains and lyophilized clinical isolates failed to express type 1 fimbriae, 6 of 20 recent clinical isolates, including 4 Shigella flexneri strains, 1 Shigella boydii strain, and 1 Shigella dysenteriae strain, produced type 1 fimbriae as detected by mannose-sensitive hemagglutination (MSHA) and electron microscopy. Optimal production of a predominantly Fim+ population required serial passage every 48 to 72 h in unshaken brain heart infusion broth at 37 degrees C. Fim+ Shigella cultures were capable of reversibly switching to a non-MSHA, afimbriated phase during serial aerobic cultivation on tryptic soy agar plates. The amino acid sequence of S. flexneri type 1 FimA contained 18 substitutions compared to that of Escherichia coli fimbrillin. Indirect immunoelectron microscopy suggested the presence of both shared and unique epitopes on E. coli and S. flexneri type 1 fimbriae. Random phase variation between fimbriated and afimbriated states in Shigella was accompanied by the genomic rearrangement associated with phase variation in E. coli.
Snellings
N J
NJ
Division of Communicable Diseases and Immunology, Walter Reed Army Institute of Research, Washington, D.C. 20307-5100, USA.
Tall
B D
BD
Venkatesan
M M
MM
D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry*; D036781:Fimbriae Proteins; D010861:Fimbriae, Bacterial / Q000502:physiology / Q000648:ultrastructure*; D006168:Guinea Pigs; D006384:Hemagglutination; D006801:Humans; D008969:Molecular Sequence Data; D012760:Shigella / Q000648:ultrastructure*
D001426:Bacterial Proteins; C063055:fimbrillin; D036781:Fimbriae Proteins