The HIV pandemic disproportionately affects the poorest regions of the world and, as a result, a large portion of the 34 million individuals living with the virus worldwide do not have access to adequate medical care. One major barrier to proper treatment in these populations is the unavailability of diagnostic instrumentation for monitoring disease progression and assessing the efficacy of antiretroviral therapy. Standard instrumentation is often not practical because of cost, size and the need for a skilled operator, thus low-cost, user-friendly point-of-care diagnostic tests are desperately needed. In particular, technologies are greatly needed for early detection of infection, determination of plasma viral load in individuals undergoing antiretroviral therapy, and measurement of proviral DNA in CD4+ T lymphocytes in infants born to an HIV-positive mother. This project aims to design two lab-on-a-chip biosensor platforms which will be capable of quantification of HIV in blood plasma and provirus in infected CD4+ T cells. These platforms will be the basis for low-cost, user- friendly point-of-care detection devices which analyze a small volume of whole blood input to determine plasma viral load and proviral DNA load for individuals living with HIV. While the current gold standard for plasma viral load is nucleic acid quantification, our approach is to sense whole virus particles in blood plasma by capturing them from a whole blood sample using virus-specific antibodies immobilized on the surface of a microfluidic chamber. After rinsing away blood cells and other debris, the captured viruses will be tagged with liposomes containing concentrated phosphate buffered saline (PBS). The background media will be rinsed away by low conductivity media and leaking of the liposome particles will be triggered by raising the device temperature, stimulating the released of ions which can be quantified by impedance spectroscopy. Virus number will be determined from the change in impedance. Similarly, our approach to provirus detection is to capture CD4+ T lymphocytes in a microfluidic chamber from a whole blood sample. Subsequent lysis with a chemical reagent will wash intracellular contents into a reaction chamber where they can be analyzed. Amplification of viral DNA (provirus) by PCR or will ultimately be detected with electrical sensors which eliminate the need for optical components and serves as an excellent platform for low-cost and rapid detection. These biosensor technologies will change the way HIV is managed around the world, making treatment more informed and frequent diagnostic data more accessible in remote and resource-limited settings.
There is a tremendous need for point-of-care diagnostics for HIV/AIDS applications to enable efficient monitoring of the key indicators of disease progression from initial infection through therapeutic interventions. In this project we are developing lab-on-a-chip biosensors for determination of plasma viral load and cellular proviral load in HIV-positive individuals. These biosensors will provide more accessible testing to individuals living in remote and resource-poor areas for early detection of infection, monitoring the efficacy of antiretroviral therapy and determining HIV status in infants born to HIV-positive mothers.
|Damhorst, Gregory L; Duarte-Guevara, Carlos; Chen, Weili et al. (2015) Smartphone-Imaged HIV-1 Reverse-Transcription Loop-Mediated Isothermal Amplification (RT-LAMP) on a Chip from Whole Blood. Engineering (Beijing) 1:324-335|
|Damhorst, Gregory L; Smith, Cartney E; Salm, Eric M et al. (2013) A liposome-based ion release impedance sensor for biological detection. Biomed Microdevices 15:895-905|