Table 1.

Virulence determinant expression in wild-type strain AM3 and protease-deficient mutants AM3speB and AM3speBΩ

StrainAmt of HA capsule (fg/CFU ± SEM)aM protein dilutionbSLO dilutioncCysteine protease activityd (mm2 ± SEM)
AM334 ± 3.01:41:10129 ± 5.4
AM3speB20 ± 1.71:41:20ND
AM3speBΩ33 ± 3.81:81:10ND
  • a The amount of cell-associated hyaluronic acid (HA) capsule was determined by Stains-All assay. The data shown are mean values derived from three experiments performed in duplicate. Capsule production by AM3speB was significantly less than that by either AM3 or AM3speBΩ (P < 0.05)

  • b Highest dilution of M protein extract that produced a precipitin line in an Ouchterlony immunodiffusion assay with anti-M3 serum. The data shown are from a single representative experiment.

  • c Highest dilution of culture supernatant that lysed 50% of a sheep RBC suspension. The data shown are from a single representative experiment.

  • d Area of protein precipitate surrounding a GAS stab inoculated into agar medium containing casein. The data shown are mean values derived from the measurement of five inoculation sites. ND, not detectable.