CBS and infection: The macrophage infection studies above clearly show decreased bacillary growth in H2S-deficient Cbs+/− cells and that Mtb growth could be chemically complemented with H2S. To more clearly establish the role of H2S in Mtb virulence and pathogenicity, we infected WT and Cbs+/− mice with Mtb and observed that Cbs+/− mice survived significantly longer than WT mice (median time to death 286 days vs. 211 days for WT mice (Fig. 1g)).