FIGURE 1.
IgG degradation activity in culture supernatants of S. suis. A, concentrated (×20) culture supernatants of S. suis strains 10 and 10ΔideSsuis were incubated with 2% porcine plasma for 16 h at 37 °C and analyzed by SDS-PAGE under reducing conditions. A degradation product (*) of ∼32 kDa was observed. B, anti-IgG Western blot analysis of culture supernatant of S. suis strain 10 fractionated by ammonium sulfate precipitation. IgG degradation products (*) were obtained after incubation of 1% porcine plasma with 20–40 and 40–60% ammonium sulfate saturation fractions for 16 h at 37 °C. First lane shows the protein size standard is a photographic image of the membrane before detection of the chemiluminescence signal. C, culture supernatants of S. suis strains of all tested serotypes cleaved IgG. Concentrated (×10) culture supernatants were incubated with 1% porcine plasma for 16 h at 37 °C and analyzed by anti-IgG Western blot. IgG cleavage products (*) at ∼32 kDa of varying intensity were observed in all lanes. Images of different Western blots have been assembled into one figure.