Swallowing Shigella: can bacteria that cause food poisoning deliver oral DNA vaccines?
Shigella flexneri, one of many microorganisms that cause food poisoning, is an unpleasant bug. Fond of invading cells that line the intestines of humans, the bacterium causes gastrointestinal illness marked by diarrhea, stomach cramps, and fever that can last for a week or more. This type of Shigella is also one of the most infectious bugs around: An encounter with as few as 10 of these bacteria is usually enough to infect a person. Nevertheless, Jerald C. Sadoff envisions a future in which adults and children, particularly those in developing countries, swallow a pill containing S. flexneri to ward off infectious diseases ranging from tuberculosis to AIDS. Sadoff, a bacteriologist now at Merck Research Laboratories in West Point, Pa., isn’t crazy. He’s merely one of many researchers pushing the envelope of a radical new form of immunization called DNA vaccines. A number of investigators have recently proclaimed DNA vaccines the third revolution in vaccinology. The first, which celebra
