Bacteria hide out in tiny 'caves' in cells
US scientists have found that bacteria can hijack a cellular structure to get into immune cells and hide from the body's defenses.
The structures, known as "caveolae" because they look like little caves, are normally used to transmit signals within cells, Dr. Soman N. Abraham of Duke University in Durham, North Carolina, told Reuters Health. When bacteria enter cells, they normally enter compartments that later fuse with other cell structures, called lysosomes, which kill the bacteria.
But since caveolae do not fuse with lysosomes, "we've discovered a route of entry of bacteria that avoids the killing activity of the host cell," Abraham said. "So this is a neat way that bacteria can avoid being killed by the very immune cells that are there to kill them. Once they're in here, they can obviously avoid antibiotics, they can avoid other immune cells."
As they report in the August 4th issue of Science, Abraham and colleagues found that E. coli bacteria use the escape route.
"We would like to think that this route of entry of bacteria is more universal than with the bacteria that we've used," Abraham said. He noted that there is some evidence that HIV may use this pathway to avoid the immune system. This system could also be a general way of introducing drugs into cells, he said.
"It appears that the mysterious recesses of caveolae will keep researchers spelunking further into the depths of these fascinating cellular domains for years to come," Drs. Matthew A. Mulvey and Scott J. Hultgren from the Washington University School of Medicine in St. Louis, Missouri, write in an accompanying perspective.
SOURCE: Science 2000;289:732-733, 785-788.
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