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Food Safety Research: Streamlining the Pathogen-Identification Process

In the time it takes to test a potential pathogen-turned-weapon and determine its source, the harmful agent may already have done its damage. With current technology, it can take up to 8 hours to prepare a sample, identify the agent, and administer help.

Researchers at APL are working to streamline the process. Developing a way to quickly prepare samples to be run through biosensors is a critical issue for many detection communities.," says Charles Young, of the National Security Technology Department. "If we are successful, our work could help revolutionize the field of food safety, bioterrorism protection, and health care."

Charles Young (back), Emily Seay, and Alex
Proescher examine an electrophoresis system.

Each year an estimated 76 million cases of foodborne illness occur in the United States, ultimately leading to 9,000 deaths, according to the Centers for Disease Control and Prevention. And that's just the natural stuff; terrorists could intentionally contaminate food supplies with known pathogens, leading to widespread illness and death.

Detecting biological agents early is a cornerstone of the Department of Homeland Security's (DHS) defense of food. However, inadequate detection methods make it hard to identify foodborne outbreaks.

Within APL's Applied Biology, Chemistry, and Nuclear Sciences Group, staff members Emily Seay and Alex Proescher are working to develop detection, decontamination, and inactivation technologies by researching the fundamental behaviors of select chemical or biological agents in food. Funding for the research comes from DHS through its National Center for Food Protection and Defense (NCFPD).

Clean Samples

A second grant from NCFPD is allowing Young to build on research begun in 2008 under an APL Independent Research and Development (IRAD) award to use isotachophoresis—a technique used to separate charged particles—as a way to simultaneously purify and then concentrate nucleic acids and proteins from soil. "A biosensor uses biological elements—such as antibodies, proteins or nucleic acids—to detect chemicals or other biological molecules," explains Young. "The biological sensing element can determine whether the test sample contains a suspected molecule."

Detecting biological weapons and pathogens is a tricky business because of interference by natural compounds, such as soil or naturally occurring substances in foods. So a sample must be cleaned before running a suspected agent through a sensor.

But preparing the sample depends on which of two technologies is used to power a biosensor: antibodies that selectively bind to target molecules, or polymerase chain reaction tests. The latter relies on the power of DNA-making enzymes called DNA polymerase to selectively amplify genetic fragments of infectious agents to make billions of copies, which can then be observed by one of several different methods.

"We wanted to be able to run the same sample on both platforms," Young explains. His IRAD-funded work allowed researchers to copurify DNA and protein in humic acids found in dirt. "We combined the humic acid, the protein, and the DNA and separated them out, and the interference that was caused by the humic acid was removed."

Once Young's team was able to prove, in principle, that it could remove this humic acid interference, it turned to the NCFPD to continue its research. "The first year of the grant expanded the number of matrices we tested to prove functionality of the method over a broad range of sample types," Young says.

In the second year of the grant, the team will address the gaps identified during the first phase and improve the chemistry to deal with food matrices that the initial approach could not overcome.

"This idea of having a universal sample is relatively new," Young says. "And it's not just a biodefense issue. There is a lot at stake here for clinical diagnostics, which is where the field of biosensors really developed."