To elucidate whether the feo and/or sit genes contribute to growth in vivo, we next incorporated mutations in these loci in the fhuC sst isd background and observed that this mutant was now attenuated (>2 log relative to WT) for proliferation in the kidneys through day 7 of the infection (Fig. 7B). The gene discussed is TNFRSF11A; the disease is infection.