Global gene expression of B. abortus-infected bovine macrophages

In a time course study, we characterized global gene expression profile of B. abortus-infected macrophages from cattle naturally resistant (R) and susceptible (S) to brucellosis. B. abortus infection causes early down-regulation of transcript levels in Mø from R cattle at 4 h p.i. (22 up- and 126 down-regulated genes) which is reversed by 12 h post-infection (31 up- and 25 down-regulated genes), compared to uninfected control. On the other hand, B. abortus-infected S bovine macrophages exhibited a down-regulated expression profile at 4 (45 up- and 65 down-regulated genes) and 12 h p.i. (47 up- and 193 down-regulated genes). The analysis of the results indicates that B. abortus – infected Mø from cattle naturally R and S to brucellosis display different transcriptional profiles. Specific genes and biological processes identified in this study will further help elucidate how different macrophages from resistant and susceptible animals interact with Brucella during the early infectious process. Keywords: Expression profiling by microarray Microarrays were used to examine the transcriptional profiles of monocytes-derived macrophages from cattle naturally resistant or susceptible to brucellosis that were infected with wild type Brucella abortus S2308. The gene expression of infected macrophages at two time points (4 and 12 hours) was compared with gene expression from non-infected macrophages treated similarly. Experiments were performed in triplicate, generating a total of 24 arrays. Bovine ORFs were double spotted on each microarray. Each replicate was normalized against labeled bovine reference RNA.