One of the biggest challenges in managing an outbreak of Ebola is quickly identifying who is infected before the virus has a chance to spread.
In a new study, a team of researchers tested a laboratory built onto two microchips that they hope will one day lead to a reliable clinical test of the Ebola virus.
The system is also small enough to be added to a portable device, something that could bring rapid testing to parts of the world most affected by Ebola.
“Lab-on-a-chip approaches for infectious disease diagnostics are very promising and have the potential to bring rapid and simple point-of-care diagnostics into the field,” Dr. Amesh Adalja, an infectious disease physician at the University of Pittsburgh Medical Center and a spokesperson for the Infectious Disease Society of America, told Healthline.
The most recent outbreak of Ebola virus in West Africa has killed more than 11,000 people since 2014. The outbreak is not over yet, with new cases occurring recently in Guinea and Sierra Leone.
Two-Chip System Detects Ebola
In initial tests using prepared samples of Ebola virus, researchers say their two-chip system was highly accurate.
It was also sensitive enough to detect low levels of the virus over a range that would be seen in infected people.
While described as a laboratory, this system actually consists of two small chips.
A virus sample is first added to a microfluidic chip, which contains tiny fluid-filled channels where the sample is processed.
The sample is then passed onto an optofluidic chip that uses fluorescent tags to detect low levels of RNA, the genetic material of the Ebola virus.
The current gold standard for detecting Ebola virus — polymerase chain reaction (PCR) — has to first convert RNA into a DNA copy. The new system eliminates this step.
“Compared to our system, PCR detection is more complex and requires a laboratory setting,” study author Holger Schmidt, Ph.D., a professor of optoelectronics at the University of California, Santa Cruz, said in a press release. “We're detecting the nucleic acids directly and we achieve a comparable limit of detection to PCR and excellent specificity.”
The greater sensitivity of the system was achieved by adding a special step that concentrated the virus sample in the beginning. This also enabled the system to outperform other chip-based approaches.
The results of the study were
Bringing the Test Into the Field
The system, however, is not ready for use in the field. Some of the steps for processing the virus still have to be done in a standard laboratory.
But for the steps carried out on the chips, the results are promising.
“This lab-on-a-chip study provides evidence that such an approach can work for Ebola, providing hope that a simple diagnostic device may come to fruition in the near future,” said Adalja, who was not involved in the study.
The researchers haven’t yet tested the system on raw blood samples. This will require additional preparation of the blood. And because Ebola is highly infectious, these tests would need to be carried out in a special biosafety facility.
The researchers are already moving forward with these plans. They also intend to test the system using less dangerous pathogens.
Other researchers are also working on methods of identifying the Ebola virus quickly and accurately in the field. This global crisis has even attracted the attention of younger scientists.
This year’s Google Science Fair winner, 16-year-old Oliva Hallisey, developed a test for Ebola virus that is fast, cheap, and stable.
Like existing lab-based tests, this one uses antibodies and chemicals to detect the presence of proteins from Ebola virus. Hallisey’s twist was embedding these on card stock using silk fibers.
This eliminated the need for refrigeration, which is often in short supply in the field. This makes the test stable for up to three weeks at room temperature.
To run the test, you add a blood serum sample and water to the paper, where they combine with the chemicals embedded in the paper. A simple color change indicates that the Ebola virus protein is present.
Both of these tests are promising, but the true test will be seeing how well they work in the field.
“The challenge,” said Adalja, “will be ensuring that such a device can be used properly in field conditions — which are vastly different than a lab setting — by minimally trained individuals, while delivering the same precision in diagnosis.”