Haemophilus ducreyi transcriptome during human infection

To better understand the molecular mechanisms underlying Haemophilus ducreyi infection in humans, here we determined the transcriptional profile of H. ducreyi in human lesions using RNA-Seq and compared it to that of in vitro growth. We were able to show that the in vivo transcriptome did not resemble that of in vitro growth. Compared to the inoculum, H. ducreyi harvested from pustules differentially expressed ~120 genes, of which 68 were upregulated. A large proportion of the upregulated genes encoded homologs of proteins involved in nutrient transport, alternative carbon pathways, growth arrest response, heat shock response, and DNA recombination. H. ducreyi upregulated few genes or operons (hgbA, flp-tad, and lspB-lspA2) required for human infection; expression of these genes is known to increase under nutrient stress. Homologs of several genes involved in anaerobic metabolism and ascorbate utilization were upregulated in vivo, suggesting that the organism is adjusting its metabolism to anaerobiosis in vivo. RNA from Haemophilus ducreyi infected pustules were collected from four volunteers and performed RNA-Seq.