n. Medical therapy that uses bacteriophage viruses to kill the bacteria that are causing an illness or infection.
Could phage therapy be the answer to our prayers? It certainly has its attractions. Unlike most antibiotics, phages are "smart weapons" specific to individual bacterial species — their tail-fibre enzymes, called adhesins, will only interact with particular molecules on the surface of bacteria, unique to each species. That means they do little harm to the "good" bacteria in our guts, which antibiotics can decimate.
As even the most potent antibiotics lose the upper hand against bacteria, researchers are again exploring the potential of these virulent invaders, with several biotechnology companies in the U.S. and Canada developing phage therapies.
Working with farm animals, Williams Smith and Michael Huggins have found that phages work extremely well against bacteria inside the body—a finding that will give veterinarians a new, probably better method of treating rapidly spreading intestinal diseases in livestock. More important, phage therapy could prove equally effective for humans. Diseases such as cholera are caused by related bacteria, and while antibiotics are now used for such diseases, more and more frequently the drugs are ineffective because the bacteria concerned are resistant.
The word phage is short for bacteriophage, a virus that invades a bacterial cell and hijacks the cell's genetic machinery to make copies of itself. Eventually these replicated viruses fill the cell until it bursts open and releases the viruses. Of course, this kills the host cell, which is the whole point of phage therapy: using phages to target and kill specific bacteria cells that cause certain diseases. As the first example citation points out, this should enable scientists to develop treatments that target only the "bad" bacteria while leaving the body's "good" bacteria alone. Not only that, but bacteria find it much harder to render phages ineffective by mutation, a tactic that does work well against antibiotics, which is becoming a big problem in the medical community.