A team of nine researchers at the University of Illinois at Urbana-Champaign and Harvard Medical School recently developed a biosensor that can measure the amount of the human immunodeficiency virus (HIV) present in an infected person's body. The biosensor offers an early and direct way of monitoring how widespread the infection is (the viral load) and how well treatment is working.
Findings of the study were published recently in the Nature.com journal Scientific Reports. The published work is the culmination of two years of research led by Brian Cunningham, director of the Micro and Nanotechnology Laboratory and professor of Bioengineering and of Electrical and Computer Engineering at Illinois, and Utkan Demirci, assistant professor of Medicine and Health Sciences and Technology, Harvard Medical School. Second author on the research paper is Erich Lidstone, M.D./Ph.D. student in Bioengineering at Illinois and a trainee in the National Science Foundation's Integrative Graduate Education and Research Traineeship (IGERT) program.
The researchers believe their development may be the first biosensor that can perform a direct test of viral load. Early, more acute detection is important because it can help forecast a patient's ability to respond to antiretroviral therapy, a drug regimen that can suppress the disease and allow patients to live longer, healthier lives.
Erich Lidstone, M.D./Ph.D. student in Bioengineering, shows photonic crystal sensor material.
The sensor itself has been in use for more than a decade, says Cunningham. "What is new and exciting is using (the sensor) to detect the HIV virus."
The published results were measured with a lab-based detection instrument, but the new approach demonstrates a system that will enable point-of-care testing after the team takes it through the next steps. With further research, the biosensor would be contained in a cartridge that slides into a cradle and interacts with a smartphone to generate and display results. The research team is also developing the software that runs on the phone.
Cunningham and his group have previously used the biosensor to test for contaminants in water. Then they started talking about using it as a pathogen (infectious microorganism) detector, and they chose to test for the HIV virus because it is a prevalent problem.
Demirci and Cunningham are both friends and colleagues who share similar research interests, so their collaboration was a natural for the project. In addition, Harvard's experience with microfluidics — specifically, filtering viruses from white blood cells — and Demirci's access to Harvard labs presented the opportunity for the group to test their research directly with the live virus.
Feeding his interests in detecting and sensing, Lidstone was able to experience the crux of the lab work firsthand by traveling to Boston for the experiments. The team shipped its biosensor detection equipment to the lab at Harvard, since it has an approved facility for safely handling live HIV. Lidstone set up the detection system and taught the students in the Demirci group how to use it. He was there for about two weeks to help develop the approach for preparing the biosensors to selectively capture the HIV, establish good experimental controls, and start testing the sensor by exposing it to different concentrations of HIV. When he returned to Champaign, the Harvard group continued performing experiments, and Lidstone was involved in interpreting the data, suggesting improvements to the team's methods, and preparing the text and figures for the manuscript.
In another project in Cunningham's research group, which also includes Lidstone, the team showed that a smartphone can perform the readout of the same photonic crystal biosensors used for the laboratory-based testing at Harvard. The group is working toward a portable, handheld system for easily performing HIV viral load measurement, the next step in the progression of the published research. The use of an optical biosensor for this purpose results in a test that is very simple to perform because it only requires exposing the sensor to the test sample, without a need for additional reagents, and the test can be performed in less than an hour. A simple, accurate, and quantitative HIV viral load test would be very helpful, as it would allow patients to monitor the effectiveness of antiviral therapy themselves, especially significant for people without easy access to a hospital or clinic. The method the research team developed can be applied to many other types of viruses, and for applications such as monitoring for the presence of pathogens in water used for irrigation, detecting viral contamination in food, or diagnosing infections in animals.
The work of this study has promise for the creation of biosensors that also could detect several viruses at once. Sensors in the published study are prepared to recognize only HIV by grafting specific antibodies that selectively recognize proteins that are displayed on the outer surface of the virus. For the sensor to detect other types of virus, the team would simply substitute another antibody that recognizes the new pathogen instead. And a future sensor could have multiple regions within it, with each region prepared to capture a different type of virus, so that a single test could be performed for several common viruses at the same time.
READ MORE: Published article in Scientific Reports