Mycobacterium genavense infection in normal and immunodeficient mice

Mycobacterium genavense is a recently described microorganism causing disse minated infections in AIDS patients. In this study, we investigate its path ogenicity in mice and some mechanisms of the host response to this bacteriu m. Following an intravenous challenge of 10(6) organisms, M. genavense grew progressively in the spleens and livers of BALB/c and CBA mice over at lea st an 8-month period. Granulomas were present in the spleens, livers and lu ngs of the animals. The numbers of bacteria recovered from the spleens and livers were higher in BALB/c (Bcg(s)) than in CBA (Bcg(r)) mice from day 30 . The role of the Bcg gene, in the early phase of infection, was supported by the fact that the bacterial load, on day 15, was higher in BALB/c than i n the congenic C.D2 (Bcg(r)) mice. The role of T cells in die host response was suggested by the high susceptibility of nude mice to M. genavense infe ction. In vivo depletion experiments in CBA mice indicated that gamma inter feron and both CD4(+) and CD8(+) T cells participate in the containment of the bacterial load. (C) 2000 Editions scientifiques et medicales Elsevier S AS.