Spoligotype patterns evolve through the deletion of spacer sequences that cannot be recovered and have provided Dr Mark Tanaka with a rich source of data with which to understand the transmission of disease.
Molecular Evolution of E. coli Causing Extraintestinal Infections
E. Coli is a highly variable species. Most strains are commensal in the large intestine of mammals or birds, but a small proportion are pathogenic, and fall into discrete pathovars, each with a particular mode of pathogenesis, of which at least 8 are now recognised. They include enteropathogenic enterohaemorrhagic, enterotoxigenic, enteroaggregative and enteroinvasive E. coli (EIEC). A range of serotypes, based on both O and H antigens, is found in each pathovar. Most serotypes are clones and the variety of serotypes gives a good indication of the diversity of pathogenic forms. However the serogroup, based on O antigen only, often does not reflect clonal relatedness.
We have in collaboration with 3 other laboratories developed a multilocus sequence typing (MLST) scheme and is being used to study E. coli population structure and evolution of the pathogenic forms. MLST is a method based on sequencing of 7 house keeping genes from each strain and use the variation revealed to determine the relationships and study global epidemiology. We have used MLST to study the origins of Shigella and EIEC. In this project we will extend our study to E. coli causing extraintestinal infections. We will identify SNPs from the MLST data and use them for typing. We will also determine variation in virulence genes. The project involves PCR, sequencing, and bioinformatic analysis.
Selected references (available upon request)
- Lan, R., M. C. Alles, K. Donohoe, M.B. Matinez and P.R. Reeves 2004. Evolutionary relationships of enteroinvasive E. coli and Shigella. Infection and Immunity 72 5080-5088.
- Wirth T, Falush D, Lan R, Colles F, Mensa P, Wieler LH, Karch H, Reeves PR, Maiden MC, Ochman H, Achtman M. 2006 Sex and virulence in Escherichia coli: an evolutionary perspective. Molecular Microbiology 60:1136-1151.
BABS personnel that are responsible for this project