Expression profiles of Salmonella typhi inside human macrophages (THP-1) compared to supernatant

Global expression profiles of Salmonella typhi grown in the supernatant of infection and within human macrophages at 0h, 2h, 8h and 24h were obtained. Stringent analytical methods were used to compare Salmonella typhi cDNAs and revealed that known virulence factors, such as the SPI-1 and SPI-2 encoded type III secretion systems, were found to be expressed as predicted during infection by Salmonella. Intracellular Typhi expressed many genes encoding antimicrobial peptides, used the glyoxylate bypass for fatty acid utilization, and, did not induce the SOS response or the oxidative stress response. Genes coding for the flagellar apparatus, chemotaxis and the iron transport system were down-regulated in vivo. The combined use of SCOTS and microarray is an effective way to determine global bacterial gene expression profiling in the context of host infection, without the need of increasing the multiplicity of infection beyond what is seen in nature. Keywords: Time course cDNA was prepared by 3 round of SCOTS from the Supernatant of infection of THP-1 human macrophages and at 0h, 2h, 8h and 24h post-infection. 6 replicates were recorded for each conditions (Supernatant, 0h, 2h, 8h and 24h). Genomic DNA was used as a reference channel on each slide.