A “lab on a chip” device for rapidly diagnosing and monitoring HIV infection has been developed by UC Davis biomedical engineer Alexander Revzin and his colleagues. The device could make HIV testing more affordable in the developing world and other resource-poor areas.

The test consists of polymer film imprinted with an array of miniature spots. Each spot contains antibodies specific to the two kinds of T-cells, the white blood cells affected by HIV, and three types of cytokines, the inflammatory proteins released by the T-cells. When blood flows across the antibody spots, CD4 and CD8 T-cells get stuck to them. Cytokines are picked up by other spots on the chip.

A lens-free imaging system developed by Aydogan Ozcan, professor of electrical engineering at UCLA, is used to rapidly count T-cell numbers, CD4/CD8 ratio and measure secreted cytokines.

The test returns results six to 12 times faster than traditional approaches and tests six parameters simultaneously, using a small blood sample.

With further development, the device could be the basis for blood tests in the developing world and resource-poor areas, according to Revzin. He has filed for a patent and is looking for ways to bring his test into clinical use.

“In addition to HIV testing and monitoring, this device will be useful for blood transfusions, where the safety of blood is frequently in question,” he said. It could also be modified to detect HIV and hepatitis B viruses directly.

"We set out to develop a test that could be simple and inexpensive but would provide several parameters based on a single injection of a small blood volume,” Revzin said.

Physicians monitor HIV infection by counting the ratio of two types of T-cells, CD4 and CD8, and by measuring cytokines. Existing technology uses a method called flow cytometry that requires an expensive machine and highly trained specialists. Health care workers and AIDS activists in the developing world have called for less expensive, more easily performed tests.