Strains of the E. coli bacteria are responsible for some of the worst
food poisoning epidemics in recent history. But as this ScienCentral News
video reports, scientists may have found its natural predator, a bacteria-eating
virus.
It’s Just a Phage
These days, the word “virus” brings to mind illnesses like SARS.
But scientists have discovered that a virus called a phage could actually
prevent you from getting sick.
“A phage is a virus that specifically infects bacteria and kills them,
but it has no effect on humans,” explains Andrew Brabban, a microbiologist
at Evergreen State College.
He and fellow microbiologist Betty Kutter found that a phage called CEV-1
kills most harmful strains of E. coli bacteria right at the source
of the problem, in the intestines of livestock. “The problem with this
E. coli is that it gets into food that we as humans eat and it causes
disease,” says Brabban. “So our philosophy is, if you can’t
treat the disease in the humans, stop it before it becomes part of our food.
We’re treating it in the animals so it never ever ends up in human food.”
Researchers at the U.S. Department
of Agriculture (USDA) accidentally discovered CEV-1 while studying sheep.
“The original phage was isolated by one of our students, Peter Varey,
who went down to work at the USDA with some scientists there,” explains
Brabban. “Their job is to try and find methods of removing E.
coli 0157, which caused so many deaths.” The scientists tried
to infect some sheep with E. coli 0157, but to no avail. “Each
time they tried, within two days the sheep were completely absent of the E.
coli and they couldn’t detect it anywhere. Peter made the leap to
realize that this protection could have been caused by a phage living in the
intestines of these sheep. He went out, took some of their feces and isolated
a phage, which we now have in the lab and is proving so successful.”
The phage attacks the bacteria by injecting its DNA into the bacteria cell.
New phages multiply inside and eventually burst through the bacterium, killing
it. “They multiply up as they infect. They reproduce, so they become
more advantageous, they become more concentrated, as opposed to antibiotics
becoming less concentrated,” says Brabban.
The researchers believe that phage
therapy offers another advantage over antibiotics, the usual treatment
for bacterial infections. “The phage are very, very specific,”
says Brabban. “They attack a specific microorganism, unlike taking an
antibiotic, which strips all the microorganisms out of an organism. So they
are much better that way.”
“Clearly, this is part of the natural process of controlling the E.
coli that are living in the guts of the sheep and they work very well,”
adds Kutter. “Phages have probably existed on Earth for about 3 billion
years. There are more phages on earth than there are any other living entity.”
Brabban and Kutter have not yet published their latest work, but they recently
sent a team of students to present their work at the American
Society for Microbiology Conference. The research is being funded by the
National Institutes of Health,
and the USDA.
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