Scientists develop listeria vaccine-study

WASHINGTON, Mar 21 (Reuters) Scientists have developed a vaccine for the food-borne disease listeria that they hope to apply to more common illnesses like salmonella and tuberculosis, a researcher said.

The vaccine attacks the listeria bacteria where it lives inside a human or animal cell, but doesn't replicate the disease, said Darren Higgins, associate professor of microbiology at Harvard Medical School said yesterday.

Listeria is a potentially fatal disease that can cause high fever, severe headache and nausea.

Like salmonella or tuberculosis, listeria is an intracellular bacterial pathogen, a bacteria or virus that grows inside a cell, hiding and multiplying within its walls instead of attaching itself to the outside.

''We made a vaccine strain of listeria that can no longer replicate inside a host cell,'' Higgins said.

Instead, it stimulates T-cells, naturally occurring cells that can multiply to identify and kill infected cells, he said in an interview.

''It does not cause disease in the animal models that we tested.

But it stimulates these T-cell responses, so, now, if we come back and challenge that mouse with a disease strain of listeria, that mouse does not get sick,'' said Higgins, whose study appeared yesterday in the Proceedings of the National Academy of Sciences.

Higgins said he and H.G. Archie Bouwer, immunology research scientist at the Portland VA Medical Center, hope to apply the same method to salmonella and tuberculosis, which occur more frequently in the population.

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