Caltech researchers develop mobile HIV test

The California Institute of Technology said on Nov. 15 that researchers have developed a "lab-on-a-chip device" to be used with a cell phone to determine molecules, such as HIV RNA molecules, in a sample.

Caltech said this digital approach consistently provides such accurate quantitative information that it can be used in developing nations and rural areas that have limited access to expensive equipment and trained medical professionals.

Researchers Rustem Ismagilov, Ethel Wilson Bowles and Robert Bowles used HIV as context for testing the digital tests. In order to properly treat HIV patients, doctors must know the concentration of HIV RNA viruses in the bloodstream, called a viral load. Testing for viral load require bulky and expensive equipment, a controlled environment, personnel and electricity, which are not always available in rural areas and developing countries.

"The result is like a pregnancy test: either yes or no, positive or negative, for the presence of an HIV RNA molecule," David Selck, a graduate student in Ismagilov's lab and a first author on the study, said. "But by doing a couple of thousand qualitative experiments, you end up getting a numerical, quantitative result: the concentration of HIV RNA molecules in the sample. By calculating the concentration from the number of wells that contain fluorescence -- and therefore HIV -- you're leveraging the robustness of many qualitative 'yes or no' experiments to fulfill the need for a quantitative, numerical result," he says.

Research published by Caltech said the new digital test produces accurate results despite changes in timing, temperature and lighting. The test is completed using cell phone imaging and automated processing, which makes it promising technology for limited-resource settings.

"We believe that our findings of the robustness of digital amplification could signal a major paradigm shift in how quantitative measurements are obtained at home, in the field, and in developing countries," Ismagilov said.

The group said the test has room for improvement, and will develop it for other viruses such as Hepatitis C.