In a worst-case scenario, 1.4 million people in Liberia and Sierra Leona could be infected with Ebola by late January, according to the US Centers for Disease Control and Prevention.
The CDC warns that those countries could now have 21,000 cases of the virus, which kills 70 percent of people infected.
One of the big problems hindering the containment of Ebola is the cost and difficulty of diagnosing the disease when a patient is first seen. Conventional fluorescent label-based virus detection methods require expensive lab equipment, significant sample preparation, transport and processing times, and extensive training to use.
A rapid, label-free photonic device that can provide affordable, simple, and accurate on-site detection could be a potential solution. The device could be used to diagnose Ebola and other hemorrhagic fever diseases in resource-limited countries.
Diagnosis in an hour
A team, led by Selim Ünlü, a professor of biomedical engineering, electrical and computer engineering, and materials science and engineering at Boston University, in collaboration with physics professor Bennett Goldberg, showed the ability to pinpoint and size single H1N1 virus particles.
Researchers reported the first demonstrated of the concept in Nano Letters in 2010.
Now, after four years of refining the instrumentation with collaborators including John Connor, a School of Medicine associate professor of microbiology, the team has demonstrated the simultaneous detection of multiple viruses in blood serum samples—including viruses genetically modified to mimic the behavior of Ebola and the Marburg virus.
The device identifies individual viruses based on size variations resulting from distinct genome lengths and other factors. Funded by the National Institutes of Health, the research appears in the May 2014 ACS Nano.
“Others have developed different label-free systems, but none have been nearly as successful in detecting nanoscale viral particles in complex media,” says Ünlü, referring to typical biological samples that may have a mix of viruses, bacteria, and proteins.
“Leveraging expertise in optical biosensors and hemorrhagic fever diseases, our collaborative research effort has produced a highly sensitive device with the potential to perform rapid diagnostics in clinical settings.”
Whereas conventional methods can require up to an hour for sample preparation and two hours or more for processing, the current prototype requires little to no sample preparation time and delivers answers in about an hour.
“By minimizing sample preparation and handling, our system can reduce potential exposure to health care workers,” says Connor, a researcher at Boston University’s National Emerging Infectious Diseases Laboratories (NEIDL).
“And by looking for multiple viruses at the same time, patients can be diagnosed much more effectively.”
How it works
The shoebox-sized prototype diagnostic device, known as the single particle interferometric reflectance imaging sensor (SP-IRIS), detects pathogens by shining light from multicolor LED sources on viral nanoparticles bound to the sensor surface by a coating of virus-specific antibodies.
Interference of light reflected from the surface is modified by the presence of the particles, producing a distinct signal that reveals the size and shape of each particle. The sensor surface is very large and can capture the telltale responses of up to a million nanoparticles.
In collaboration with BD Technologies and NexGen Arrays, a start-up based at the Photonics Center and run by longtime SP-IRIS developers David Freedman and postdoctoral fellow George Daaboul, the research team is now working on making SP-IRIS more robust, field-ready, and fast—ideally delivering answers within 30 minutes—through further technology development and preclinical trials.
SP-IRIS devices are now being tested in several labs, including a Biosafety Level-4 (BSL-4) lab at the University of Texas Medical Branch, which is equipped to work with hemorrhagic viruses.
Other tests will be conducted at the university’s NEIDL once the facility is approved for BSL-4 research. Based on the team’s current rate of progress, a field-ready instrument could be ready to enter the medical marketplace in five years.
Source: Boston University