An international team of researchers has developed a low-cost and portable product for detecting the Zika Virus. After using their device to test for the Zika virus in monkeys, the researchers are looking to product development as their next step.
The test is nucleic-acid based and has three steps: amplification, Zika detection, and CRISPR-Cas9-aided strain identification. Amplification is necessary because the viral load in samples such as saliva is significantly smaller than the viral load present in samples like urine.
Once the sample has been amplified, it goes into an RNA sensor called a toehold switch. The team’s research paper states that the switch can “be designed to bind and sense virtually any RNA sequence.” The RNA sensors are deployed via a paper disc that provides a sterile and abiotic environment for them. The paper changes color from yellow to purple if positive.
In the final step, the gene-editing mechanism, CRISPR-Cas9, searches the whole gene sequence for genetic markers. According to the Harvard Gazette, this step allows it to differentiate between strains of the Zika Virus.
This process improves upon previous tests which performed serum analyses that tested for the antibodies to certain viruses. In the past, this led to false positives, as the tests were unable to differentiate between the Zika Virus and close relatives like the dengue virus that share a geographical range.
Similarities between the targeted Zika Virus genomic sequences and those of the dengue virus range between 51 to 59 percent.
To ensure the accuracy of their test, Keith Pardee, a faculty member of the University of Toronto, told ResearchGate that the researchers exposed their test to low and high concentrations of the dengue virus, as well as “off-target regions of the Zika genome.” It differentiated between the target genome and everything else successfully.
All three components of the test can be freeze-dried for storage and distribution without damaging their effectiveness, which allows them to be sent to rural clinics for use. This means that even low-resource areas could have access to faster and more accurate tests for the Zika Virus. Previously, Pardee said, people needed to travel to urban areas for such accurate tests.
In an interview with ResearchGate, Pardee noted numerous potential benefits of the team’s test. It could potentially track the Zika Virus outbreak, and it would help physicians to more quickly identify and treat the infected. Physicians can also then take precautions to ensure the virus doesn’t spread.
– Anastazia Vanisko
Photo: National Cancer Institute