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Science Online
N E W S F O C U S 25 OCTOBER 2002 VOL 298 SCIENCE
www.sciencemag.org
Bacteriophage therapy, pioneered in Stalin-era Russia, is
attracting renewed attention in the West as a potential weapon
against drug-resistant bugs and hard-to-treat infections
Stalin’s Forgotten Cure
TBILISI—Last December, three woodsmen in the mountains of
Georgia stumbled upon a pair of canisters that were, oddly, hot
to the touch. The men lugged the objects back to their campsite
to warm themselves on a bitterly cold night. That turned out to
be a terrible mistake: The canisters, Soviet relics once used to
power remote generators, were intensely radioactive and burned
two of the men severely. The victims were rushed to the capital,
Tbilisi, where doctors plied them with antibiotics but failed to
prevent staphylococcus bacteria from invading the deep wounds.
Septic shock seemed just around the corner. Then a kinder legacy
of the Soviet Union came to the rescue.
Georgian doctors turned to a therapy virtually unknown in the
West: They unleashed the bacteria’s natural predators. The
doctors covered the open wounds with novel biodegradable patches
impregnated with bacteriophages, viruses that infect bacteria.
The business card–sized PhageBioDerm patches, recently licensed
for sale in Georgia, eliminated the infection, and within a few
weeks the woodsmen were stable enough to go abroad for treatment
to replace the lost skin.
The episode shows that a unique brand of medicine from the
Stalin era is alive and well in this remote corner of the world.
More surprisingly, phage therapy might be about to stage a
comeback in the West. After a brief fling with phages before
World War II, when the use of penicillin became widespread,
Western physicians ignored the therapy for more than half a
century. “Phages were relegated to the dustbin of history,” says
Richard Carlton, president of Exponential Biotherapies Inc. (EBI),
a firm based in Port Washington, New York, that is one of more
than two dozen racing to reclaim phages from that dustbin.
Driving phage therapy’s potential rehabilitation is the
accelerating crisis of antibiotic resistance. Some cases are
particularly chilling: Last July, for example, U.S. health
authorities reported the first instance in which a stalker of
hospital wards, methicillinresistant Staphylococcus aureus, had
also acquired full resistance to vancomycin, often used as a
last-ditch treatment. “The window of opportunity for new
antibiotics is rapidly closing,” asserts Janakiraman (“Ram”)
Ramachandran, a former president of AstraZeneca India who 2
years ago launched GangaGen Inc., a phage-therapy start-up in
Bangalore.
Although phages offer hope against drugresistant bacteria and
could soon find a role as a treatment for burns, diabetic
ulcers, and other open wounds, experts concur that these viral
breeds are unlikely to knock antibiotics off their pedestal for
most infections. “Phages are certainly not going to replace
chemicals,” says Alexander Sulakvelidze of Intralytix, a company
in Baltimore, Maryland, that’s exploring a potential market for
PhageBioDerm or similar products in the United States. Nor is it
evident how the U.S. Food and Drug Administration will regulate
phage products, or if it will be permissible to alter phage
strains after FDA approval to counter bacterial resistance. For
these reasons, many experts expect that phage concoctions for
livestock and food-borne pathogens will find their way to market
first (see sidebar).
Despite the uncertainties, proponents say that as a medicine,
bacteriophages have a lot going for them. “They are the most
abundant life forms on Earth,” notes phage biologist Elizabeth
Kutter of Evergreen State College in Olympia, Washington. A drop
of seawater or sewage teems with millions of phages; any exposed
surface of our bodies, not to mention our digestive tracts, is
carpeted with them. “Mother nature gives you an endless source
of phages,” says Sulakvelidze. And unlike most antibiotics, they
are very specific, Kutter says: “Phages can kill off a small
fraction of the microbial population and leave the rest intact.”
Phages are like minuscule smart bombs that home in on
particular bacterial strains. Anecdotal evidence from decades of
Soviet practice suggests that this results in far fewer side
effects than use of antibiotics. And whereas drugs lose
effectiveness as they are metabolized, phages replicate in their
hosts, gaining strength in numbers and thus increasing potency.
EBI, the fastest company off the blocks, has completed safety
testing in healthy volunteers of a phage against vancomycin-resistant
enterococci and plans to launch a clinical trial in patients
with VRE in the middle of next year. “We really are living in a
brave new world,” says Toney Ilenchuk, vice president of
Biophage Pharma in Montreal, Canada. He and others are watching
EBI closely, because its experiences could determine how quickly
the first phage therapies against human diseases reach the
market—or whether the approach slips back into obscurity in the
Western world.
Many are rooting for a comeback. “We need to do something,
have some alternative to antibiotics,” says Diane Schaak of the
Rowland Institute for Science at Harvard University. “Phage
therapy could be a wonderful way to go.”
Top of Page
A checkered past
The first whiff of the microscopic predators came in 1896,
when British chemist E. H. Hankin reported that water straight
from the sewage-ridden Ganges and Jumma rivers could kill the
cholera pathogen. It wasn’t until 2 decades later that a pair of
scientists, working independently, concluded that the bacteria
slayers must be microbes themselves. In 1915, British
bacteriologist Frederick W. Twort described an “ultramicroscopic
virus” that somehow killed bacteria in solution. But it was
noted biologist Félix d’Herelle of the Pasteur Institute in
Paris who made the critters famous: He and his wife coined the
term bac-teriophage in 1916 after d’Herelle isolated an
“anti-Shiga” microbe from the feces of patients with dysentery
and grew it in the bacterium that causes the disease.
D’Herelle was also the first to comprehend the promise that
phages held as a disease treatment. In 1919, he and his
colleagues made a phage preparation for a 12- year-old boy with
severe dysentery. After guzzling 100 times the intended dose to
check its safety—“the first clinical safety trial,” jokes
Sulakvelidze—they gave the diluted preparation to the boy, who
recovered fully within a few days.
Over the next several years, d’Herelle helped set up
phage-therapy trials across the globe. “He would go to villages
and observe who was recovering on their own from an illness,
isolate phages from these people, and grow them in the lab,”
says Ramachandran. Phage therapy was off to a flying start, and
it gained in popularity after the 1925 publication of Arrowsmith,
a novel by Sinclair Lewis in which a doctor deploys phages
against an outbreak of bubonic plague in the West Indies.
Back then, “phages seemed like a miracle answer to many
devastating infectious diseases,” says Kutter. The drug giant
Eli Lilly and a plethora of entrepreneurs piled into the phage
business, but their record was spotty. In some patients the
concoctions worked well, whereas in many others they had no
effect. The mixed results were grist for a damning critique of
phage therapy from the American Medical Association in 1934.
Phage enthusiasts are quick to disassociate modern approaches
from the field’s early days. Little was known then about phages
or bacteria, so patients often took phages that were not suited
to their infections. In addition, says EBI’s Carlton, “they
didn’t purify these products well enough.” Preparations were
often loaded with endotoxins produced by bacteria in the
suspensions used to cultivate phages, and they were rarely
tested before use to see if the phages were viable. But whereas
Western physicians abandoned the fickle medicine, Soviet
scientists kept the faith.
Stalin’s antibiotic alternative
Sunlight streams through a picture window into an office
suffused with the yeasty smell of agar as Amiran Meipariani
removes a logbook from a desk drawer. The silver-haired and -moustached
bacteriologist scrolls down a record in cramped Cyrillic
handwriting of the last batches of medicinal bacteriophages
shipped abroad by the Eliava Institute here in Tbilisi. On the
wall behind him is a 1930s photograph of the man who started it
all in Georgia, a dashing young scientist with oiled black hair
and deep-set eyes. Under Giorgi Eliava’s intense gaze,
Meipariani, who has worked here for 45 years, puts a finger on
the most recent entries in his log: 88,600 phage tablets for
intestinal illnesses and 497,000 tablets for prophylaxis against
Salmonella, both shipped to Central Asia in 1989. That was the
beginning of the end of the Eliava Institute’s golden era.
The Soviet enterprise got under way in 1923, when Eliava, who
had spent 5 years with d’Herelle in Paris, founded a
bacteriological research center with the blessing of Soviet
dictator Josef Stalin. Eliava’s phage program got a big boost in
1933, when d’Herelle left Yale University to join his protégé in
Tbilisi. He stayed until tragedy struck a few years later:
Eliava fell into disfavor with the dreaded Lavrenty Beria, later
head of the KGB, and was executed. The devastated institute
eventually recovered and continued its pioneering work,
including the development in the 1940s of phages against
anaerobic infections such as gangrene. Soviet authorities placed
a high value on the Eliava Institute’s work. When it came to
ordering new equipment and supplies of enzymes, says
microbiologist Mzia Kutateladze, who joined the institute in the
late 1980s, “we got whatever we wanted.”
The Soviet military was perhaps the biggest consumer of phage
preparations, many of which were produced in Russia— and still
are—according to Georgian techniques. “Antibiotics were
expensive, while phage preparations were very cheap,” explains
Meipariani. The military’s enthusiasm did not ebb after the
Soviet meltdown. During the civil war in the early 1990s,
Georgian soldiers fighting in the breakaway Abkhazia region
carried spray cans filled with phages against five bugs:
Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa,
Streptococcus pyogenes, and Proteus vulgaris. Phage preparations
were also widely available in many Russian cities alongside
antibiotics. And in a handful of towns such as Tolyatti, an
auto-manufacturing center, clinics “rarely used antibiotics,”
instead relying almost exclusively on phages, says Zemphira
Alavidze, a microbiologist at the Eliava.
By the time the Soviet Union dissolved in 1991, the Eliava
had only the means to produce phages for a stillthriving
domestic market in newly independent Georgia. This minimal
production, says Meipariani, has helped “preserve the
tradition.” Cooking up phages means more than following a
recipe, he says: “You need a good mind and good hands.” Visitors
concur. “There is really no substitute for their collective
experience over the past 70 years,” says Tony Smithyman,
managing director of SPS, a phage-therapy company in Sydney,
Australia. He’s one of many Westerners who have made a
pilgrimage to Tbilisi to learn the art of phage therapy.
The Eliava Institute was not alone in pursuing such
therapies, as phage centers sprang up elsewhere in Eastern
Europe. Perhaps the most important data in the English
literature on the therapy’s effectiveness come from the
Institute of Immunology and Experimental Therapy in Wrocl–aw,
Poland. Researchers there compiled a detailed report on the
successful treatment of more than 500 patients with bacterial
infections in the mid-1980s, but the results appeared in the
obscure Archivum Immunologiae et Therapiae Experimentalis and
only recently were excavated for wider dissemination. The Wrocl–aw
institute is itself experiencing a renaissance, busily culturing
medicinal phages and forging ties with Western labs.
Top of Page
Promises and perils
Whereas antibiotics relegated phage therapy to a historical
footnote in the West, bacteriophages themselves, particularly
the lunar lander–shaped T4 that infects E. coli, became the
darlings of biologists. Beginning with Max Delbrück’s famous
“phage group” in the early 1940s, molecular biologists exploited
the simplicity and ease of handling of a few lab phages to do
the following: confirm that DNA is the genetic material, show
that messenger RNA is involved in its translation, reveal that
the unit of recombination is the nucleotide, and clarify how
genes are turned on and off. But the mainstream view on phage
therapy was summarized in a passage from Gunther Stent’s classic
1963 textbook Molecular Biology of Bacterial Viruses: “Just why
bacteriophages, so virulent in their antibacterial action in
vitro, proved to be so impotent in vivo has never been
adequately explained.”
Stent suggested that the therapy failed because antibodies
mop up phages infused into the body. In the early 1970s, a young
researcher at the U.S. National Institutes of Health (NIH), Carl
Merril, tested that notion on a germ-free colony of mice using a
common lab phage, lambda. His group discovered that before the
mice could even develop antibodies, the phages were cleared from
the bloodstream, primarily by the spleen.
Several years later, Merril and NIH colleague Sankar Adhya
wondered whether some particularly hardy strains might evade
clearance. If so, these could be harvested and studied and
perhaps serve as the basis for an improved therapy. To find out,
the researchers proposed injecting mice with billions of lambda
phages and seeing if any persisted hours later. Teaming up with
EBI’s Carlton, they found that phage mutants that were around
many hours longer than run-ofthe- mill phages were much more
effective at rescuing mice from otherwise lethal infections.
Their 1996 report, in the Proceedings of the National Academy of
Sciences (Vol. 93, p. 3188), was widely hailed as a basis for
selecting promising phage strains. For the first time in more
than half a century, Western experts were taking the disparaged
approach seriously again.
In a sign of the changing times, the Cold Spring Harbor
Laboratory in New York, once a powerhouse in basic research on
bacteriophages, will hold its first-ever Banbury meeting on
phage therapy next month. However, there are still big gaps in
our understanding of how phages work: Exquisite studies of phage
genetics have revealed little about how these viruses behave in
their natural environments or when introduced into the human
body. “Decades of neglect of phage biology have left us woefully
unprepared to take rapid steps in such uses as therapeutics,”
says Ry Young, a phage biologist at Texas A&M University in
College Station.
What is known is that phages come in two flavors. “Lytic”
phages infect a bacterium, hijack its DNA, and replicate madly
until the bacterium’s cell wall gives out and it expires: the
killing mechanism common for all phages. Lytic phages are ideal
for therapy. But half of all phages, it is thought, are
“temperate,” meaning that they often integrate their DNA into
that of their host. “You wouldn’t know the phage is there,” says
Adhya, because they hibernate in the form of genetic code before
the viral DNA tears itself free again and the virus begins
replicating— sometimes taking some of the host DNA with it. At
the same time, temperate phages can protect their host from
attack by other phages. And they can abet pathogens: Certain
temperate phages carry the genes for the toxins released by
bacteria that cause diphtheria and cholera, for example.
One serious concern is that a temperate phage could make off
with host genes connected with virulence or resistance. These
phages could, in principle, wreak havoc by integrating such
genes into a new host. “I would worry about the transference of
such genes,” says Harvard’s Schaak. After all, she asks, “Why
would a phage wipe out its host?” Schaak speculates that some
phages that are lytic in the test tube could acquire the genes
to turn temperate in the body. Although most experts discount
that possibility, Sulakvelidze in informal conversations with
FDA officials understood that firms must guarantee that their
phages are stably lytic. “We’re doing much more rigorous
characterizations of phages than has been done in the past,” he
says, including DNA sequencing.
Another hurdle that could make or break phage therapy is that
bacteria inevitably develop resistance to phage strains just as
they do to antibiotics. The problem might not be as severe for
would-be phage therapists: A study from the early 1980s found
that mutations conferring resistance in E. coli occurred less
frequently following phage therapy than they did following
antibiotic therapy. And proponents say it’s much easier to
tackle resistance with phages than with drugs. “You can generate
a new phage variant in a week” by selecting those that don’t
lose virulence in culture, says Ramachandran, who envisions a
regulatory process in which panels of phages are put through
clinical trials for FDA approval. Adhya’s team, meanwhile, is
developing a “master” phage that could undergo rigorous FDA
review. Such a master phage could be subtly tinkered with, for
example by altering a single gene that affects host
susceptibility. Modified strains presumably would take less time
and money to approve, Adhya says.
Some scientists hope to bypass these issues altogether by
extracting the active components from phages. For example,
Vincent Fischetti and his team at Rockefeller University in New
York City describe in the 22 August issue of Nature how they
used a phage’s lytic enzyme to kill the anthrax bacterium in the
test tube. In a similar vein, Young’s lab at Texas A&M reported
last year in Science (22 June 2001, p. 2326) that one type of
phage makes peptides that act like penicillin, blocking
cell-wall synthesis in bacteria and causing the cell to explode
when it tries to divide.
Some companies are trying to exploit such eccentricities of
phages in their quest for new drugs. For instance, PhageTech in
St. Laurent, Canada, is studying a myriad of phage “killer”
proteins that derail the host metabolism to make it easier for
the phages to reproduce. It is now screening libraries of small
molecules for killer protein analogs that could act as
antibiotics. And Schaak is taking a novel tack. Earlier this
year, she and a few colleagues launched MicroStealth
Technologies, which aims to use phages as delivery vehicles for
antimicrobial peptides that are only active inside bacterial
cells.
Top of Page
Phage futures?
Although the experiences in Georgia and elsewhere in Eastern
Europe have helped establish sound methods for selecting and
cultivating phages, it’s unclear how much of that data will be
useful to companies intending to bring phage therapy to the
West. “I’m not knocking the work in the East,” asserts EBI’s
Carlton, “but the FDA pretty much has to discount it.” That’s
not a universal view. Kutter, for one, argues that Eastern
European findings on the use of phages to treat conditions such
as diabetic ulcers and osteomyelitis, in which poor circulation
can render antibiotics toothless, “are particularly impressive
and incontrovertible. They have excellent cure rates.” But it
seems that message isn’t reaching the right ears. “We just get a
blank stare when we talk to regulators,” says Ilenchuk, who says
his firm, Biophage Pharma, will target “compartments” such as
the mouth or intestines rather than dive into injectibles.
FDA has not yet issued written guidance on how it intends to
regulate phage therapy. But many unknowns will be cleared up as
EBI takes its VRE phage through trials. “They are blazing the
trail for us,” says Asher Wilf, who last year founded Phage
Biotech Ltd. in Rehovot, Israel. Navigating through the
regulatory waters will be “a big challenge,” says Ilenchuk. “It
would take just one of us to screw it up,” he says, recalling
the troubles encountered in the early days of bringing blood
substitutes to the market. FDA’s emerging stance could also
determine if and when large pharmaceutical companies get into
the game. “Big pharma is waiting to see proof of concept before
they do deals,” says PhageTech co-founder Michael DuBow, now at
the Université Paris- Sud XI in Orsay, France.
In addition to regulatory and scientific uncertainties, phage
enthusiasts might face one more hurdle: public acceptance. The
time is ripe to start educating the public about phages, says
Ilenchuk. “We have to get the message across that phages are
everywhere.” He and others assiduously avoid the “v” word.
Rather than refer to them as viruses, says Schaak, “I call
phages a natural delivery system.” Others prefer a
straight-shooting approach. “Phages are viruses, and if they are
to be used as therapeutic agents, we need to respect their
origin and use our modern scientific methods to assure that they
are safe,” says NIH’s Merril.
No matter how it’s sold, most experts believe that in light
of the increasing perils of antibiotic resistance, the
once-scorned Soviet therapy will ultimately find a niche in
modern Western medicine. A half-century of antibiotics usage has
taught us that “you cannot win the war against bacteria,” says
Sulakvelidze. But with phages, he says, “at least you can try to
shift the ecological balance in our favor.”
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