Voice of America (voanews.com)
"Our World" Broadcast
October 27, 2003
Text version of broadcast
In the never-ending battle against bacterial infection, antibiotics have been
the main line of defense, since their discovery more than a half-century ago.
But lately, as more drug-resistant strains of bacteria threaten public health,
doctors are turning to, of all things, viruses. Viruses are best known for
causing diseases like SARS and HIV/AIDS. But as Steve Baragona reports, some
scientists are learning how to enlist their help in curing disease:
Virus researcher Sankar Adhya (SHON-car ODD-hee-ya) flips through a stack of
small plastic dishes at his laboratory at the National Institutes of Health,
just north of Washington, DC. Each dish is covered with a film of bacteria, and
each film is riddled with holes a centimeter or two wide. Mr. Adhya says the
holes are caused by a virus called a bacteriophage (back-TEER-ee-oh-fayj), or
phage (FAYJ) for short.
"Phage infects bacteria and kills them. Each phage particle will kill a
bacterial cell, (it) will disintegrate it. And the new phage particles that are
coming out from (the) first infection invade the neighborhood."
In this way, the phage spreads quickly through the neighborhood bacteria. The
virus hijacks a bacterium's cell machinery, turning it into a tiny virus
factory. Then, the virus disintegrates the bacterium's cell wall, releasing
hundreds, or thousands, of new viruses, which then hijack neighboring bacteria,
and so on. In a few hours, the viruses have wiped out the whole neighborhood,
leaving holes in the bacterial film on Mr. Adhya's dishes.
Virus researcher Carl Merril at the National Institutes of Health says when
Canadian scientist Felix d'Herelle (duh-RELL) discovered bacteriophages in the
early twentieth century, he saw that these bacteria-hunters had potential.
"D'Herelle did realize that these could be used as an antibiotic. He actually
published a paper in 1926 where he reported success in treating all sorts of
animal diseases using bacterial viruses."
Doctors soon used phage therapy to treat skin infections, stomach illnesses,
and many other diseases. But there were problems. Viruses and bacteria were
poorly understood at the time. Each type of virus can only infect one type of
bacteria. So Mr. Merril says phage therapy often did not work because doctors
used the wrong virus. Worse yet, preparations were often contaminated.
"Many of the early preparations may have been as detrimental as the original
bacteria were."
When chemical antibiotics became available in the 1940s, phage therapy fell
out of favor in much of the world. But after decades of exposure to antibiotics,
more and more bacteria are becoming immune to them. Sandro Sulakvelidze (SOO-lock-wah-LEED-zuh)
is chief of research at Intralytix, (in-tra-LIT-ticks) a Maryland-based
biotechnology company. He says antibiotic resistance threatens to roll back the
revolution in medicine that antibiotics have brought about. For example,
surgeons need antibiotics to kill germs like Staph. aureus (staff OR-ee-us) that
would otherwise infect patients getting organ transplants, open-heart surgery,
or other surgical treatments.
"And so if you are no longer able to suppress those infections, you can have
a tremendously successful open hear surgery, but the patient will die because of
an untreatable Staphaureus infection, for example."
Mr. Sulakvelidze remembers a time in the mid-1990s when a doctor friend lost
a patient to a strain of antibiotic-resistant bacteria.
"He couldn't treat him anymore, and was sort-of hopeless at that point. And
without thinking twice, I asked him a very naïve question, I thought. 'How about
bacteriophages, so they didn't work either?' And he looked at me, and I realized
this is the first time he had heard about therapeutic phage uses to treat human
infections."
Mr. Sulakvelidze says he was shocked to discover doctors here had never heard
of phage therapy. He thought his question was naïve because phage therapy is
still commonly used in his native Georgia. That's because antibiotics reached
the Soviet Union much later than in the West. So phage therapy continued, and is
still a mainstay of medical treatment in former Soviet countries. Mr.
Sulakvelidze says in Georgia today, phage preparations are available alongside
antibiotics at the local pharmacy.
One of the major phage research centers is a clinic in Tbilisi, Georgia,
founded by one of phage pioneer Felix d'Herelle's co-workers. Virus researcher
Betty Kutter at Evergreen State University has sent patients to the Tbilisi
clinic to treat infections when antibiotics failed. She says in some ways,
phages are better than antibiotics.
"A lot of times, if you take an antibiotic for an infection it kills off all
the good bacteria, in your gut, for instance. And then you have all sorts of
other problems with other bacteria, bad bacteria, that manage to get in there."
She says phages are much more specific. Each type of phage can only attack
one type of bacteria. So phages that attack disease-causing bacteria leave good
bacteria alone.
They also leave human cells alone. So she says there's no reason to worry
that a virus used to treat a disease will actually make you sick.
Sankar Adhya says in the early days, phage therapy was not tested
scientifically. And regulatory agencies like the U-S Food and Drug
Administration, or FDA, did not exist. So he says advocates of phage therapy
have a lot of work to do to bring it back into the mainstream.
"To make phage therapy acceptable we have to do the basic science, give a
scientific face, to convince not only the FDA type of organization, but also the
medical doctors around the country."
Mr. Sulakvelidze's company, Intralytix, is working on viruses that can rid
livestock of disease-causing bacteria like Salmonella and E. coli. Another
company is developing a gel to treat cuts and burns. Other products are also in
the works. Someday soon, this old idea in medicine may be the newest thing in
your medicine cabinet.
