Media Release | Nov. 17, 1997

UBC research breakthrough holds promise for E. coli vaccine

A new understanding of how the E. coli bacteria bonds to host cells may lead to the creation of a vaccine against strains of the bacteria that cause potentially fatal diarrhea in children, as well as hamburger disease, salmonella and dysentery.

A research team in UBC's Biotechnology Laboratory, led by Prof. Brett Finlay, has discovered that enteropathogenic Eschericia coli (E. coli), which causes a million infant deaths a year worldwide, inserts a chemical advance party into a host's intestinal cells to prepare a hospitable landing site for the bacteria. Finlay's findings were published in Cell magazine Nov. 14.

Researchers previously believed that the receptor, a protein which allows the E. coli bacteria to adhere to a host's intestinal cell walls, existed within the host cells.

"All our biochemical data said it was a host membrane protein," says Finlay. "We thought the bacteria came in, stuck to the cell, and then sent signals that get the cell warmed up so it can bind properly. But the bacteria are far more devious than that."

Finlay found that rather than making use of a host protein, the bacteria fires a soluble bacterial protein into the host cell membrane. The protein is then modified in the host cell membrane to form a perfect landing site for intimin, a bacterial surface molecule that binds with the host cell surface.

"That's completely unprecedented. We know of no other pathogen that inserts its own receptor," he says, adding that the process, in which a soluble bacterial protein is inserted into a host cell membrane, is "biochemically completely absurd."

Ironically, the bacteria's self-sufficiency may prove its downfall. Having identified the bacterial protein, Finlay says it should take only one or two years to develop vaccines that will prevent the transmission on the bacterial protein to the host cell. This would prevent E. coli from binding to the host cell, forcing it to be passed from the system.

Vaccines, already under development by UBC spin-off company ID Biomedical Corp. and Microbiology Prof. Julian Davies' TerraGen Diversity Inc., could be used to prevent the infection of cows with the bacteria, and thus prevent the transmission of the bacteria to beef consumers. Or, vaccines could be used to inoculate humans.

"What's become apparent is the machinery that E. coli uses to shovel these proteins out is very similar to the machinery used by many other pathogens such as salmonella, shigella, which causes dysentery, and yersinia, which causes bubonic plague and major food poisoning in Vancouver."

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Contact

Prof. Brett Finlay
Biotechnology Laboratory
Tel: 604.822.2210

Stephen Forgacs
UBC Public Affairs
Tel: 604.822.2048