Fig 3.

Impact of fHbp expression of invasive MSM isolates and urethritis isolates on meningococcal pathogenesis (A) Western blotting analysis to detect fHbp. Meningococci from IMD cases in MSM expressing functional fHbp and isolates harboring the fhbp allele 669 (with a pre-mature stop codon) were tested. Meningococcal strain MC58 was used as a positive control (+). (B) Survival of meningococci in transgenic mice expressing human factor H (hfH). Bacterial counts recovered from blood after intraperitoneal challenge with 5x10⁷ colony forming units of meningococcal isolates from urethritis (red) and MSM cases (black). A representative experiment with data representing individual mice is shown. Mice infected with isolates from MSM showed significantly higher bacterial counts 2, 6 and 24 hours after infection compared to those infected with urethritis isolates (p values derived from a Student´s t test are displayed). (C) Flow cytometry analysis of C3b surface deposition on (1) meningococci from IMD cases in MSM expressing fHbp and (2) on meningococci isolated from urethritis cases not expressing fHbp due to an early stop codon. The X axis represents logarithmic scale binding of C3b expressed as the geometric mean of fluorescence. The number of events is displayed on the Y axis. Different coloured lines were used to indicate the isolates for better clarity.