The Food and Drug Administration approved certain viruses as food additives, to be sprayed on cold cuts before packaging. The bacteriophages are added to defend the meats from Listeria monocytogenes, a bug that when ingested can cause a nasty bacterial infection in humans. The phages infect the bacteria, binding to the host and ultimately killing it. From the Los Angeles Times:
The FDA spent four years evaluating the safety and effectiveness of the "cocktail" of several phage at the request of Intralytix Inc., a Baltimore, Md., biotechnology company. In presenting its petition, Intralytix referred the government to more than 20 studies documenting the power of phage to fight infection, many of them performed in Russian and Eastern Bloc countries where phage therapies have long been popular in treating certain infections.
Intralytix also conducted studies of its own, trying out its phage mixture (consisting of six different phage that attack the food-poisoning bacterium Listeria monocytogenes) on more than 10 different kinds of deli meats, including sliced turkey, roast beef, bologna, chicken and even raw hot dogs, and found that they effectively killed all strains of listeria.
