Table 1.

Expression of motility affects Y. enterocolitica invasion of HEp-2 cells

Strain genotypeaPlasmidb% Relative invasion of HEp-2 cellsc:
Without centrifugationWith centrifugation
Wild type100115
Wild type (LB medium)16138
Wild typepTM1006988
Wild typepGY104060
Wild typepGY10* 117177
flhDC 588
flhDC pTM1007106
flhDC pGY106536
fliA 6195
fliA pTM1005203
fliA pJB222117278
inv 83
  • a Strains represented are JB580v (wild type) (12), GY460v (flhDC) (21), VK1v (fliA) (11), and JP273v (inv) (17). A “v” designation indicates the presence of the virulence plasmid.

  • b Plasmids represented include pTM100, which served as the cloning vector (14); pGY10, which is a clone of flhDC in pTM100 (21); and pGY10*, which is aflhDC::TnMax2 derivative of pGY10 (this study) (9).

  • c Invasion assays were done in duplicate as described previously, but with or without centrifugation to bring the bacteria into contact with the HEp-2 cells (15). Except where indicated, all cultures were grown overnight in T medium at 26°C. Values for invasion were calculated as described previously (15) and normalized to the wild-type strain JB580v, which was arbitrarily set at 100. The actual percent invasion for the wild-type strain, JB580v, was 24 ± 5% when grown in T medium and assayed for invasion under conditions without centrifugation.