Monday May 10 1:34 PM ET
Scientists vaccinate mice against salmonella
NEW YORK, May 10 (Reuters Health) -- Scientists believe they have found a way to alter bacteria genes that could lead to vaccines against salmonella and other infectious diseases.
Researchers at the University of California, Santa Barbara, stripped salmonella bacteria of a gene that controls an enzyme called ''Dam,'' or DNA adenine methylase, and used the mutant bacteria to vaccinate mice against salmonella infection.
The Dam enzyme is a control switch for at least 20 genes necessary to the infection process of salmonella. Bacteria that lack the enzyme ''were effective as live vaccines,'' Douglas Heithoff, lead author of the study, and colleagues report in the May 7th issue of the journal Science.
The investigators found that mice that were injected with the stripped down gene developed a lasting immunity against subsequent exposure to salmonella, even when exposed to 10,000 times the expected lethal levels of bacteria.
The altered gene failed to produce the proteins that would normally make the bacteria virulent, or capable of causing infection, but successfully immunized all 17 mice tested. Analysis revealed that the bacteria were unable to penetrate beyond the intestinal lining of the mice, and the animals did not develop salmonella symptoms.
The scientists believe that their success could lead to a vaccine for salmonella, a potentially lethal infection in animals and humans.
And Heithoff and colleagues suggest that inhibiting Dam in other disease-causing microbes -- such as bacteria that cause meningitis, gastroenteritis, and a form of plague -- could lead to new vaccines and drugs for these infections. They note that this development would be especially welcome in light of the growing resistance to antibiotics seen in many types of bacteria.
SOURCE: Science 1999;284:967-970.
|
