‘Designer Beads’ Capture Viruses

Posted: July 30, 2013 at 5:01 am, Last Updated: August 1, 2013 at 7:16 am

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By Michele McDonald

Kylene Kehn-Hall. Creative Services photo

Kylene Kehn-Hall. Creative Services photo

Forget designer duds — “designer beads” that capture viruses for quick diagnosis are the hot item these days, according to new research by George Mason University.

“There’s a dire need for fast and efficient diagnosis of many viral diseases,” says Kylene Kehn-Hall, an assistant professor with the George Mason-based National Center for Biodefense and Infectious Diseases.

In steps virus-capturing “beads” to help researchers enrich a virus so they can determine what it is. The beads trap viruses ranging from tropical diseases such as Rift Valley Fever to fast-moving respiratory viruses to HIV, according to research published this month in the Public Library of Science (PLOS) Neglected Tropical Diseases.

“We envision it to be a strip-test, like a pregnancy test,” Kehn-Hall says. “With a strip-test you can get an answer in 10 to15 minutes.”

The beads can increase the sensitivity of currently available diagnostic tests. They do this by nabbing the virus during early stages of infection in either a paper strip test done right then or in another version sent to a lab.

“Oftentimes you can’t detect the virus at first because the virus is at such low levels,” Kehn-Hall says. “You take a test because you’re showing symptoms but you may get what’s called a false-negative. We use these beads to capture and concentrate the virus, and now we can see that the virus is there.”

A false-negative can put treatment behind for days.

Kehn-Hall and her team of researchers are building on nanoparticle technology developed by George Mason researchers Lance Liotta and Emmanuel “Chip” Petricoin, co-directors of the Center for Applied Proteomics and Molecular Medicine.

Originally, the nanoparticle technology was developed to isolate the antigens or proteins produced by viruses, but Kehn-Hall’s team wanted to catch the entire virus, not just a piece of it. By ensnaring the entire virus, the beads also give it a protective layer like bubble wrap.

“Biological samples are exposed to all sorts of enzymes in your blood that chop them up and break them down,” Kehn-Hall says. “That’s critical if you’re not in a doctor’s setting. Maybe you’re in a field setting where you need to take a sample and ship it to a diagnostic lab. Now you can ship it without worrying it will degrade in transport, and you can ship it at room temperature. That is very important — you don’t have to worry about what they call cold chains where you have to ship the sample frozen and on ice to make sure it maintains a temperature.”

The beads are tiny — about 800 nanometers, which is smaller than some bacteria but larger than their virus targets. A high-powered microscope is needed to spot them. The team had to prove they caught the entire virus, not just a bit. And they couldn’t pluck off the virus from the bead without destroying the virus. So they added fresh, uninfected cells as bait. The virus left the bead to infect the new cells, proving the research team had the entire virus intact.

The beads could be integrated into collection cup or a syringe. “As you do the collection, the beads automatically capture whatever is in the urine,” Kehn-Hall says.  “Now you have everything protected and captured and you can send it to a diagnostic lab.”

Other Mason researchers included in the study are: Nazly Shafagati, Aarthi Narayanan, Alan Baer, Katherine Fite, Chelsea Pinkham, Charles Bailey and Fatah Kashanchi.

Write to Michele McDonald at mmcdon15@gmu.edu

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