Project Lead(s): Stephanie Yanow
Access to timely and accurate diagnostic tests has a significant impact in the management of diseases of global concern, such as malaria.
While molecular diagnostics satisfy this need effectively in developed countries, barriers in technology, reagent storage, cost and expertise have hampered the introduction of these methods in developing countries.
The aim of the project was to develop a lab-on-chip polymerase chain reaction (PCR) diagnostic test for malaria.
The platform consists of a disposable plastic chip and a low-cost, portable, real-time PCR machine.
The chip contains a desiccated hydrogel with reagents needed for Plasmodium-specific PCR.
Chips can be stored at room temperature and used on demand by rehydrating the gel with unprocessed blood, avoiding the need for sample preparation.
The chips were run on a custom-built instrument containing a Peltier element for thermal cycling and a laser/camera setup for amplicon detection.
A working prototype of a lab-on-chip device for diagnosis of malaria was developed.
This diagnostic was capable of detecting all Plasmodium species with a limit of detection for Plasmodium falciparum of 2 parasites/μL of blood, which exceeds the sensitivity of microscopy (the current standard for diagnosis in the field) by ten to fifty-fold.
In a blind panel of 188 patient samples from a hyper-endemic region of malaria transmission in Uganda, the diagnostic had high sensitivity (97.4%) and specificity (93.8%) versus conventional, real-time PCR.
The test also distinguished the two most prevalent malaria species in mixed infections, P. falciparum and Plasmodium vivax.
A second blind panel of 38 patient samples was tested on a streamlined instrument with LED-based excitation, achieving a sensitivity of 96.7% and a specificity of 100%.
This platform will be useful in front-line malaria diagnosis, elimination program and clinical trials.
Furthermore, test chips can be adapted to detect other pathogens for a differential diagnosis in the field.
The flexibility, reliability and robustness of this technology hold promise for its use as a novel molecular diagnostic platform in developing countries.
The test has been patented and licensed to Aquila Diagnostic Systems Inc. for commercialization, which provided $550,000.
The work was disseminated in many conferences and a manuscript is being prepared for publication.