Gong of small things


An Irish scientist has captured an important international prize for his research into a common bacterium that can cause serious illness. Research on a disease-causing bacterium has won UCC scientist Roy Sleator the prestigious international award. Dick Ahlstrom reports

Dr Roy Sleator, a researcher at University College Cork's Alimentary Pharmabiotic Centre, captured the 2006 Oxoid W H Pierce Prize for young researchers awarded by the Society for Applied Microbiology, one of the oldest scientific societies of its kind in the world. The prize, instituted in 1984, celebrates the research work and publications of a scientist under the age of 40 who has made a significant contribution to microbiology, as judged by the society.

Sleator received the Pierce Medal and a cheque for £2,000 (€2,887) yesterday before delivering the 2006 Memorial Lecture at the Society's summer conference, held this year in Edinburgh. The title of the lecture was: Understanding a Pathogen's Gut Feelings - the Gastro-Intestinal Phase of Listeria Monocytogenes Infection.

Sleator is conducting intriguing work on how L monocytogenes manages to survive the many defences used by the body's digestive system to kill it off. The bug can cause miscarriage in pregnant women who contract it and severe illness in otherwise healthy people.

"I am looking at the bacterium and how it senses its environment," he explains. "My work is looking at this organism and how it escapes the biochemical defences thrown up by the body. We are looking at the genes that allow it to do that."

The bug first survives the highly acid conditions of the stomach, expressing a selection of genes that allow it to pass safely through. Next it copes with the suddenly drier conditions in the upper bowel, using other genes for this.

It also copes with the detergent-like action of bile which breaks down fats and which should be able to destroy the bug's cell walls but doesn't.

In each case the organism expresses genes in response to its environment that help it survive these changing conditions, explains Sleator. The goal is to understand which genes are essential for survival and find ways of controlling them, either knocking them out to shut down infection or manipulating them for novel forms of medical therapy.

His work was funded for the past two years by the Embark Initiative run by the Irish Research Council for Science, Engineering and Technology and currently by the Health Research Board.

He cited several reasons why listeria is an useful organism, first because its entire genetic blueprint has been sequenced and second because its genome is "very amenable to genetic manipulation".

It is also possible to watch L monocytogenes in action in the gut in real time using a device known as the Ivis Bioilluminator produced by Xenogen.

Each gene has a "promoter" a sequence of DNA which acts like a switch to turn it on and make it work. If the researchers want to know when a gene is switched on, they make a copy of its promoter sequence and connect it to a light emitting substance. This is then stitched into the L monocytogenes genome.

The remarkable bioilluminator is super sensitive to light and can actually read a weak light signal coming from inside a mouse. The genes being switched on and off as L monocytogenes makes its way through the alimentary canal give off a light signal that can be tracked as it moves from acid to dry to bile.

"Our goal is to look at how this knowledge can benefit medicine," says Sleator. "We are studying this for use in vaccines and in drug delivery systems."

It may be possible to have the listeria carry drugs safely past the stomach and further down the digestive system before breaking down and releasing their pharmaceutical cargo.