Enterotoxigenic E. coli (ETEC) causes watery diarrhea with the help of a group of adhesins known as colonization factors (CFs). These CFs enable the bacteria to attach the intestinal cells, where they can colonize the intestine and produce the toxins that result in diarrhea. As external structures essential to the development of disease, CFs have frequently been selected as candidate vaccine targets. However, as many as 50% of investigated ETEC strains are lacking the any of the 22 known colonization factors, suggesting the presence of unknown CFs, and making it difficult to develop effective vaccine formulations.
A recent paper, with contributions by Dave Rasko, used bioinformatics techniques to identify previously undescribed CF loci. Large-Scale BLAST Score Ratio (LS-BSR) analyses allowed for the identification of CF homologs in ETEC strains that were thought to be CF-negative based on previous methods. These homologs, some of which belong to pili classes previously unknown in ETEC virulence, increase the understanding of the structural diversity of ETEC adhesins. Further characterization of these adhesins may determine their usefulness as vaccine targets.
Del Canto, F. et al. (2016) Chaperone-Usher Pili Loci of Colonization Factor-Negative Human Enterotoxigenic Escherichia coli. Front Cell Infect Microbiol 6:200. doi: 10.3389/fcimb.2016.00200