By breaking the molecular code used by listeria bacteria to invade human cells, French scientists have created an animal model that opens a new frontier in the fight against the deadly germs that cause food poisoning and other diseases. Because the lock opened by the bacterial protein is found on human cells, but not on cells of rats and mice, the French researchers created a strain of transgenic mice with a human version of the receptor.
Listeria can contaminate raw vegetables and poorly preserved processed foods.
About 2,500 cases of listeriosis occur in the United States each year. The death rate is above 20 percent, mostly among newborns, older adults and persons with weakened immune systems. The disease occurs when listeria from contaminated food moves from the stomach into the bloodstream, then into the central nervous system. Until now, the molecular events that allow the invasion have been a mystery. The French researchers identified a protein they call internalin on the listeria surface membrane as the key.