McDevitt Lab HIV Research and Monitoring Initiatives

Infectious diseases remain the leading killers of human beings worldwide. This HIV immune function program targets the development of powerful microchip sensors suitable for detection and monitoring of infectious diseases. Here a novel combination of bio-medical methodologies, nano-chemistry, microfluidics, imaging, software and communication algorithms has led to the development of these membrane-based microchip sensor systems. This technology enables cellular analysis to be completed at the point of care.

The microchip systems cover all bases of sample collection, processing, and analysis within the confines of a practical and inexpensive structure. These advances allow for the chips to get out of the lab thereby eliminating the expensive and inconvenient clinical laboratory infrastructure. A true " lab on a chip" structure is thus created. The key to getting the "chips out of the lab" lies in the development of new microfluidics methodologies. Reagents, buffers, visualization cocktails, and bio-waste are all contained within the confines of a disposable credit card-sized plastic cartridge. Whole blood is processed directly within the microchip ensemble where by white blood cells are collected and separated from their more numerous red blood cell counterparts.

Portable Point-of-Care Testing

Like a computer that serves as a universal work tool for us these days, the microchip-reader combination is designed to serve as a universal detector system. The same core technology can be modified and customized readily for new tasks in a manner like a computer can be adapted for alternative applications by installing new software modules. Molecular-level code is included into new customized microchip cartridge sets. Different analytes are readily detected with such an approach. The use of this point of care clinical analyzer is very simple. A microchip cartridge containing the sample is inserted into the reader unit and all other manipulations are completed by the reader-microchip combination. The entire unit is portable and suitable for point of care clinical measurements in remote settings.

For the HIV immune function monitoring application, it is necessary to process whole blood, separate out the white blood cells from the other cellular components and then provide an accurate accounting of the number of various important lymphocyte cells. The final part of this sequence, the data analysis, is completed using an imaging system and automated pixel analysis methodology. The data analysis method is shown in the images below collected from a whole blood sample as processed by the microchip system. Here a cocktail of labeled antibodies is used to color-code the relevant sub-populations of lymphocytes. The proprietary pixel analysis protocol is able to recognize the authentic cells and eliminate the undesirable background signals. Then the various types of lymphocytes are classified and counted. Absolute CD-4 counts and ratios of CD-4 to CD-8 positive lymphocytes are readily obtained with these methodologies.

Using only finger prick quantities of whole blood, the microchip instrumentation provides laboratory quality results for a number of important tests within 5-8 minutes for biomarkers that currently are not available on other Point of Care systems. For example, the microchip counts CD4+, CD8+ cells as needed for HIV immune function assessment. The system uses whole blood directly and thus eliminates the time-consuming sample preparation steps. The lymphocyte counting system has been validated in US hospital settings as well as in HIV reference laboratory in Botswana, Africa. The new system compares nicely with the gold standard method of flow cytometry.