Figure 3. Six 6–8-week-old female C57BL/6J wild-type and corresponding SR-A^−/− mice were injected intraperitoneally with 1×10⁵ N. meningitidis MC58 and 10 mg human holo-transferrin per mouse.

At 18-h post-injection a second dose of 10 mg human holo-transferrin was administered i.p. (A) The health of the animals was monitored regularly and scored at each time point according to the symptoms presented as follows: Healthy = 5, ruffled fur = 4, sticky eyes = 3, ruffled fur and sticky eyes = 2, immobile = 1. Scores were then collated for each group at each time point, averaged and plotted. (B) The survival of each group was plotted, and the statistical curve comparison was determined using the Log-rank (Mantel Cox) test (P = 0.0305). (C) Blood was collected from the tail vein at 20 h and by cardiac puncture at termination (48 h), and serial dilutions were plated on bacterial growth medium. Spleen segments were also collected, homogenized, and plated. Plates were incubated at 37°C, 5% CO₂ overnight, and bacterial colonies counted. Counts for six individual animals in each group are plotted. Results were analysed using a two-tailed, unpaired t test, and the star indicates a statistically significant difference (P<0.05). (D) The concentration of interleukin-6 in the plasma from infected animals was measured at termination (48 h) using a standard ELISA assay. Individual measurements from 6 animals in each group are plotted. Results were analysed using a two-tailed, unpaired t test, and the star indicates a statistically significant difference (P<0.05).