Fig. 7.
Di-galactoside, sialic acid and ChoP have independent and additive effects on bacterial survival in human serum. Bactericidal assays in human serum for lic2A, lgtC and lex2A (R2846 only) phase-on variants (ON) or mutants (−), with or without sialic acid (Neu5Ac) added to growth medium (+). Results are shown for Rd lic1D– (A), a lic1A phase-on variant population of Rd (B), R2846 lic1D– (C) and a lic1A phase-on variant population of R2846 (D). Bactericidal assays were performed at the concentration of normal human serum (NHS) indicated and in the case of lic1A phase-on variants, serum was first depleted of C-reactive protein. Data shown are means and SEM. Statistical analysis (n ≥ 3) was performed by an unpaired t-test; *P < 0.05, **P < 0.01, ***P < 0.001.