Lab DNA signature tools used to detect naturally occurring food pathogens
Technologies developed by the Laboratory researchers and other scientists
to fight bioterrorism could find another use — detecting naturally
occurring pathogens in food.
Livermore biomedical scientist Paula McCready delivered that message earlier
this week during a session of the American Society for Microbiology at
the Salt Palace Convention Center.
"The tools we use to develop DNA signatures for the detection of
bioterrorist agents could also be used to search out food-borne pathogens,"
McCready said. (DNA signatures are areas or regions of DNA unique to specific
organisms).
"We believe people are going to look at the problem of food-borne
pathogens differently because of the new tools that are becoming available."
Finding the DNA signatures for bacteria that cause food poisoning would
allow laboratories to more rapidly identify their presence in food and
in the environment.
Among the bacteria that could be identified, according to McCready, are
Camphylobacter, a bacterium present in undercooked chicken, or different
types of Salmonella, a bacterium that can be found in eggs, juice, fruit
or vegetables.
Previously, diagnostic tests to identify and type these bacteria normally
required many hours to days to complete because of the need to culture
and prepare samples and conduct analysis.
However, with the rapidly growing development of DNA signatures and new
polymerase chain reaction (PCR)-based DNA analysis systems, the tests
can now be conducted in less than one hour.
"We can also tailor our tests to distinguish harmful forms of different
organisms from the benign forms," McCready said.
Livermore researchers and other biomedical scientists have developed highly
accurate DNA signatures for the bacteria that cause plague and anthrax,
as well as for other organisms.
This work has been done in collaboration with Los Alamos National Laboratory
researchers and the Bioterrorism Rapid Response and Advanced Technology
Laboratory of the Centers for Disease Control in Atlanta.
During the past year, the Livermore DNA assays have been used to test
more than 10,000 complex environmental samples. Individual DNA markers
in these assays have been accurate 99.99 percent of the time and the composite
pathogen test has been 100 percent accurate, McCready said.
Before breakthroughs in DNA sequencing and other advances, it often required
years to find unique DNA signatures to help identify some harmful organisms,
McCready said. DNA signatures can now be found in weeks to months.
"The reason this is important is because if a new bug is identified,
we can quickly develop DNA signatures for new strains of pathogens,"
she said.
The use of DNA signatures to detect food-borne diseases would represent
another application for the emerging technology. Last year, Livermore’s
DNA signatures were used for the first time to detect a public health
disease in the environment when collaborators at Northern Arizona University
(NAU) used them to detect plague.
In the past, tests to confirm whether plague is present in an environment
have usually required seven to 10 days.
Last spring’s finding of plague, in a small rural community northwest
of Flagstaff, Ariz., was confirmed within four hours by a team of researchers
led by NAU microbiology professor and plague expert Paul Keim.
The Livermore DNA signatures were also used in February as part of a detection
system deployed by Los Alamos and Livermore national laboratories at the
Salt Lake City Olympic Games.
Designed to detect the criminal use of biological agents, the system is
called the Biological Aerosol Sentry and Information System, or BASIS.