C3AR1 and infection: Here, we compared the roles of all three ATRs during mouse nasal colonization, intraperitoneal infection and human whole blood infection with Nme. Deficiency of complement or ATRs did not alter nasal colonization, but significantly affected invasive disease: Compared to WT mice, the disease was aggravated in C3ar−/- mice, whereas C5ar1−/- and C5ar2−/- mice showed increased resistance to meningococcal sepsis.