RAPGEF5 and infection: The ΔgfrB, ΔgfrD, ΔgfrE, ΔgfrF, and Δgfr mutant strains were attenuated by about 3‐ to 10‐fold (C.I. ≈ 0.1) on Day 1 p.i. and either remained at this level of attenuation (ΔgfrB, ΔgfrE, ΔgfrF, Δgfr) or declined further to a C.I. of 0.1–0.01 (ΔgfrD) by Day 4 p.i. These data suggest that the gfr operon provides S. Tm with a competitive advantage during initial growth in LCM mice, as the Δgfr and the individual gfr subunit mutants, except for the ΔgfrA mutant, were primarily attenuated during the first 2 days of infection.