"Under appropriate medical care it is not life-threatening. It is just very, very inconvenient," Charles Arntzen, a plant biologist at Arizona State University, told a news conference at a meeting of the American Chemical Society. The U.S. Centers for Disease Control and Prevention estimates that 23 million cases a year of acute gastroenteritis -- stomach and intestinal upset -- are due to norovirus, also known as Norwalk virus. Arntzen and colleagues used a genetically engineered plant virus called the tobacco mosaic virus to start their vaccine. "We force it to make the protein which is the vaccine against norovirus," Arntzen told the news conference. "We call them nanoparticle vaccines because the protein we produce in our tobacco plant self-assembles into a little round ball." The immune system recognizes this ball, called a virus-like particle or a capsid, as if it were a virus and attacks it, Arntzen said. "It is empty. It cannot cause disease," he said. Tests have suggested the vaccine would work better in the nose than taken orally, probably because immune cells in the nasal passages are more inclined to take up the vaccine. ************Read More at: http://news.yahoo.com/s/nm/20090819/hl_nm/us_tobacco_vaccine