RSPO2 and colitis: While some strains (e.g. C57BL/6) infected with C. rodentium present self-limiting mild colitis, others (e.g. C3H derivates and FVB) present severe symptoms, including signs of discomfort, diarrhoea and weight loss, which is fatal.3,10 Differences in host genetics such as R-spondin 2 expression and the composition of the gut microbiota have been previously identified as factors, which determine colitis severity upon C. rodentium infection.11–13