Enterotoxigenic Escherichia coli (ETEC) is a major cause of diarrhoea, particularly in children in developing countries, and is the most common cause of travellers’ diarrhoea. The ETEC pathotype is defined by the presence of at least one colonisation factor, of which 26 have been identified, and either or both of two toxins, the heat-labile and heat-stable enterotoxins. These two classes of virulence factors have traditionally been described as essential to ETEC pathogenesis, but recent work has uncovered other factors which may also contribute to virulence.
Rns, a transcriptional regulator, is known to activate the transcription of up to 80% of ETEC colonisation factors. In related organisms, Rns homologues activate multiple virulence factors, priming the bacteria for pathogenesis. It is likely that Rns may play a role in the activation of other virulence-related genes, not only those encoding colonisation factors. To determine the extent of the Rns regulon next-generation sequencing techniques were used to identify Rns gene targets. Here, the transcriptomes of ETEC strain H10407 and an isogenic mutant lacking rns were determined by RNA-sequencing and the results analysed by using the programme, Rockhopper. In addition top the operon encoding the colonisation factor CFA/I, Rns was shown to activate the expression of genes encoding putative ETEC virulence factors EtpB, Agn43, and YghJ. This work has generated a wealth of data on the Rns regulon, and shows that Rns contributes to ETEC pathogenesis through the activation of expression of multiple virulence factors.