C57bl 6

All mice used in the current study were housed in the same rooms in Emory’s animal facility during the course of the experiment, with one room designated for animal breeding and maintenance and an adjacent room solely for SE experiments. The lights were on a 12-h on/off cycle, and mice were fed and watered ab libitum. In Ccr2^rfp/rfp KO mice, the Ccr2 open reading frame was disrupted with a cDNA encoding red fluorescent protein (RFP)^{20 (link)}. The Ccr2^rfp/rfp mice originally obtained were maintained on the C57BL/6 (Jackson Laboratories) inbred genetic background, and we subsequently backcrossed the mice to C57BL/6 (Charles River) for over 11 generations. To generate heterozygous Ccr2^+/rfp mice, in which Ccr2-expressing monocytes are marked by RFP expression, male Ccr2^rfp/rfp mice were bred to female C57BL/6 mice from Charles River.
After backcrossing for over 11 generations we submitted genetic material obtained from a Ccr2^rfp/rfp mouse to Charles River Laboratories for strain background characterization. A total of 128 single nucleotide polymorphisms (SNPs) spread across the genome was analyzed to generate an allelic profile for comparison between the Jackson Laboratories and Charles River C57BL/6 substrains. Our Ccr2^rfp/rfp mice were a 99.6% match to C57BL/6 inbred mice from Charles River Laboratories, making the mouse strain essentially congenic.

6–8 week old C57BL/6 (Charles River, Margate, UK), and age and weight-matched C57BL/6 C5^-/- and C57BL/6 C3^-/-/C5^-/- female mice were challenged intra-muscularly with 1×10⁸ GAS, and quantitative endpoints compared at 3 hours post infection. Mice were euthanized, blood taken by cardiac puncture and infected thigh muscle, spleen, liver, and draining inguinal lymph nodes dissected. All organs were plated to quantify bacterial cfu and systemic dissemination. Additional C57BL/6 mice were challenged intra-muscularly with 1×10⁸ GAS. Whole thighs were formalin-fixed, and paraffin-embedded for histopathology imaging as described previously [24 (link)], or homogenized and prepared for western blotting as described above. No animals were excluded from the study and randomization was not necessary as mice were genetically identical and age, weight and sex matched. No blinding was carried out as mice were caged separately to prevent contamination with different GAS strains.