realized in has disposition at some time artificially mutated Brucella macrophage - Brucella interaction attenuated disposition mouse - Brucella interaction B. abortus ilvD mutant MUTATION: Of those B abortus mutants with mini-Tn5 insertions in genes predicted to be involved in amino acid biosynthesis and transport, only the ilvD mutant, displayed attenuation in both macrophages and mice. The othre two amino acid biosynthesis mutants [trpB::miniTn5 and pheA::miniTn5] displayed wild-type virulence in mice but attenuated inside macrophages. The studies with B abortus ilvD, trpB, and pheA mutants suggest that tryptophan and phenylalanine are available to the brucellae in their intracellular niche but that other amino acids (eg, leucine, isoleucine, or valine) are not [Ref6485:Alcantara et al., 2004]. See PMID:15271960