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Portable device detects HIV with push of a button

CALTECH (US) — A device that is small enough to stow in a backpack and as simple to operate as a DVD player may speed the diagnosis of HIV, AIDS, and other diseases in remote parts of the world.

Researchers hope the portable device will make rapid molecular diagnostic techniques and the resulting health-care benefits available and affordable to those who need them.

An inexpensive, portable, easy-to-use device, built by a team of Caltech engineers and biologists, promises to speed the diagnosis of HIV/AIDS and other diseases—and improve treatment—in even the most far-flung corners of the world. (Credit: Caltech)

The device is the result of nearly 10 years of research at California Institute of Technology (Caltech). In 2004, Axel Scherer and George Maltezos—then Scherer’s graduate student and now a senior scientist—were investigating how to manipulate biological fluids on a chip.

While this was an interesting engineering problem, Maltezos began to wonder whether he could apply the microfluidic techniques that he was perfecting to real-world problems. Then the H5N1 bird flu pandemic erupted in Asia, and he and his colleagues had their real-world problem.

The best tool for diagnosing H5N1 is a PCR machine, which, in this case, takes small amounts of viral material and makes a large number of copies so that the virus can be identified. In 2005, a polymerase chain reaction (PCR) machine cost about $50,000—too expensive for most health clinics in the developing world.

That summer, Maltezos built a prototype of a far less expensive PCR machine that went on to perform well in field tests in Thailand, where H5N1 was rampant. Still, it was far from a commercially viable product, in part because it didn’t give results quickly enough.

To improve the performance of the device, Maltezos and Scherer thought that they needed a better handle on the biology behind infectious diseases, so they then teamed up with David Baltimore, professor of biology. If they could build something to detect H5N1, they figured, it would be equally useful for detecting other viruses or diseases, like HIV/AIDS.

By the end of 2006, a newer version of the instrument could evaluate a sample in just 94 seconds—compared to 45 minutes with standard PCR machines—and a company, Helixis, was formed to manufacture and sell the technology.

Helixis’s first product, a pathogen-detection PCR instrument called the Eco, sold for $13,000. But while the Eco is fast and relatively cheap, it’s still the size of a microwave oven—not something that you want to lug up a mountain trail or through a rainforest to reach a village with sick people.

Maltezos teamed up with Baltimore’s and Scherer’s labs to help build a new-generation PCR machine specifically for use in remote areas of the developing world. With such a simple PCR machine, doctors in an African village, for example, would be able to almost immediately diagnose people suffering from hard-to-diagnose diseases like tuberculosis, or determine whether a patient’s AIDS medications are effective against the virus.

To bring a portable PCR machine to a point-of-care setting in a remote area, Scherer says, “it has to be inexpensive, it has to be robust, and we also have to automate as much as possible.”

The newest prototype, which runs off a rechargeable battery and operates at the push of a button, consists of a chip that can analyze a blood sample to spot different pathogens. In addition to tuberculosis and HIV, the machine can diagnose acute lower-respiratory diseases, diarrheal diseases, malaria, and other conditions.

The goal is to bring the machine’s cost below $1,000 and each test under $5. The preliminary results from clinical tests show that the device is working well, Maltezos says. “Now we need to get it out of the lab and to the people who need it.”

Source: Caltech

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