Genome analysis of gene expression by THP-1 macrophage during Brucella abortus wild type and mutant strains infection

Brucella abortus (B. abortus), an intracellular bacterium, is the causative agent of Brucellosis. This organism invades into macrophages and then survives through its abilities to modulate host cells functions. The biggest problem caused by B. abortus is that it prevents macrophage elimination and makes it difficult to remove B. abortus from the host body. Therefore, it is essential to identify the bacterial genes involved in virulence factor as a first step to understanding the bacterial pathogenicity and controlling Brucellosis. To identify these genes, B. abortus mutant strains were generated using transposon mutagenesis and transcriptomic profile during macrophage infection were analyzed. The gene expression level was analyzed using total RNA obtained from THP-1 cells infected with B. abortus wild type and mutant strains and cellular immunity during the infections were compared to wild type infected cell to identify the role of genes in B. abortus pathogenicity. Transcriptomic profiling showed that two mutant strains having disrupted genes related to 4-hydrobenzoate 3-monooxygenase (PHBH) of C1 strain and heme exporter protein cytochrome C (CcmC) of C10 strain, induced suppression of cytokine expression during infection in human macrophages. Conversely, two other mutant strains of exopolyphosphatase (PPX)of C27 and Peptidase M24 of C32 induced activation of cytokine expression in the THP-1 macrophage cells. Total RNA obtained from THP-1 cells after stimulation with B. abortus mutant strains was compared to RNA from THP-1 cells infected with B. abortus wild type. All of RNA was obtained at 24 hours after stimulation.