TORONTO -- University of Toronto researchers are part of an international team which has uncovered a previously unknown mechanism that plays an important role in the spread of listeria, the trigger behind the food-borne disease listeriosis, which caused a deadly outbreak in Canada in the summer of 2008.

Working in collaboration with colleagues from the University of Central Florida and the University of Würzburg in Germany, U of T Prof. Scott Gray-Owen (Department of Molecular Genetics) and his team discovered a previously unknown way in which the disease is carried from cell to cell. Their findings are published in the current edition of Nature Cell Biology.

Listeria monocytogenes is a bacterium linked to food processing plants, and which can be especially debilitating or fatal for people with compromised immune systems and pregnant women. The disease moves swiftly from cell-to-cell via finger-like structures formed as the bacteria pushes out from inside one human cell to pierce into the adjacent cells.

The barrier between most cells would be strong enough to repel that cell-to-cell spread, but Gray-Owen, his PhD student Tina Rajabian, and their colleagues discovered a previously unknown process that accelerates the spread of bacteria between healthy cells. A protein secreted by Listeria, called InlC, softens the junction between cells, making it easier for the adjacent cells to be breached. This effect is caused by InlC inhibiting the function of a human protein known as Tuba. While InlC is unique to Listeria, this work suggests that a similar mechanism may also occur during similar diseases such as Shigellosis.

"These observations show us once again that pathogenic microbes are excellent cell biologists that have learned to disturb even the most basic cellular processes in order to facilitate the infection of their host," said Gray-Owen. "Now, if we can impede the bacteria's capacity to spread between our cells, we should be able to slow the progression of disease by this dangerous bacteria."

"The discovery of this novel protein that helps breach the barrier between cells could lead to new approaches and treatments to block infections caused by Listeria," said Dr. Bhagirath Singh, the Canadian Institutes of Health Research's Scientific Director of the Institute of Infection and Immunity. CIHR provided funding for this research.

Others members of the team involved in this research: Werner Goebel, Stefanie Müller-Altrock and Martin Heisig at the University of Würzburg in Germany, Keith Ireton and Balramakrishna Gavicherla at the University of Central Florida.