Skip to main content
Advertisement

< Back to Article

Virulence of Group A Streptococci Is Enhanced by Human Complement Inhibitors

Fig 3

Phagocytosis of GAS AP1 is reduced in the presence of hu-C4BP and hu-FH.

(A) Binding of hu-FH and hu-C4BP decreases opsonophagocytosis of GAS strain AP1 in vitro. Strain AP1 was incubated with bone marrow derived macrophages from wild-type BALB/c mice in the presence of wild type, heat inactivated wild type (BALB/c HI), hu-C4BP, hu-FH or hu-C4BPxFH tg serum. Uptake of AP1 in BALB/c (wild type) serum was set to 100%. (B) and (C). Binding of hu-FH and hu-C4BP decreases opsonophagocytosis of AP1 in vivo. BALB/c and hu-C4BPxFH tg mice were injected i.p. with Carboxyfluorescein succinimidyl ester (CFSE)-labeled GAS strain AP1 (B; 5 BALB/c and 8 hu-C4BPxFH tg mice) or its isogenic mutant GAS strain BM27.6 that lacks expression of M protein (and therefore protein H) and neither binds hu-FH or hu-C4BP (C; 6 BALB/c and 5 hu-C4BPxFH tg mice). Phagocytic index was calculated as the product of the % of neutrophils in the peritoneal cavity and % of those neutrophils containing CFSE labeled GAS (see also S3 Fig where these measurements are shown separately). Results are expressed as Mean ± SEM of at least three independently performed experiments. Statistical analysis: 1way ANOVA with Dunnetts post-test (A) and students t-test (B-C).

Fig 3

doi: https://doi.org/10.1371/journal.ppat.1005043.g003