Enterotoxigenic Escherichia coli, 1971 to 1979

This chapter provides a review of the work on enterotoxigenic Escherichia coli that was undertaken in Stanley's lab in the 1970s. Stanley's interest in the extrachromosomal nature of enterotoxin genes was undoubtedly a result of the interplay between his clinical microbiology background and his episome work in a lab studying bacterial gastroenteritis (at the Walter Reed Army Institute of Research). Working on enterotoxin plasmids was therefore a natural extension of these interests. The classic approach was to isolate plasmid mutations and then correlate a particular protein with an LT phenotype (the expression or absence of LT in cells harboring a mutated plasmid). The approach was analogous in a way to the one Maggie had used to identify Ent plasmids in mating experiments when a number of plasmids were present. Nature actually did the first cloning experiment by placing the toxin genes on plasmids, and the authors used the knowledge of plasmids gained by previous students to study these virulence determinants; eventually, they did their own recombinant DNA experiments and cloned the genes to smaller plasmids. The transposon work with Tni led to the development of a plasmid to clone the ST gene, and later, the ST gene was shown to be part of a transposon.