General suppression of macrophage gene expression during Leishmania donovani infection

Within the mammalian host, Leishmania donovani is an obligatory intracellul ar protozoan that resides and multiplies exclusively in the phagolysosomes of macrophages, The outcome of this infection is governed by the interactio n between Leishmania and macrophage molecules that ultimately effect the ex pression of genes within bath cells. To explore the effect of this intracel lular infection on macrophage gene expression, a cDNA expression array anal ysis was performed to compare gene expression profiles in noninfected and L , donovani-infected macrophages, In this manner, it was possible to examine the effect of infection on the expression of several hundred well-characte rized host cell genes in an unbiased manner. Interestingly, similar to 40% of the gems whose expression was detected in macrophages were down-regulate d during infection with L, donovani. However, several genes were also induc ed during the infection process, some of which could play a role in recruit ment of additional macrophages to the site of infection. Taken together, th e general suppression of gene expression in addition to the selective induc tion of key genes is likely to play an important role in allowing the paras ite to survive and proliferate within its host macrophage cell.