A paper-based test has been developed at Massachusetts Institute of Technology (MIT) to diagnose Zika virus infection within a few hours.
The test can also help distinguish between Zika virus and the very similar dengue virus. It can be stored at room temperature and can also be read with a simple electronic reader.
The outbreak of Zika virus first occurred in Brazil in April last year, and has been connected to microcephaly, a type of birth defect. The test is based on a technology that was earlier developed to detect Ebola virus.
In October 2014, researchers claimed that they could develop synthetic gene networks and embed them on small discs of paper. These gene networks can be programmed to identify a specific genetic sequence that cause the paper to change colour.
Later, the researchers adapted their solution to diagnose Zika virus.
MIT Department of Biological Engineering and Institute for Medical Engineering and Science (IMES) professor and research team leader James Collins said: "In a small number of weeks, we developed and validated a relatively rapid, inexpensive Zika diagnostic platform."
Sensors embedded in the paper discs were developed by Collins and his colleagues for 24 different RNA sequences found in the Zika viral genome, which is composed of RNA instead of DNA.
The paper turns purple from yellow when the target RNA sequence is present and it initiates a series of interactions.
Although the change in colour is visible with naked eye, researchers developed an electronic reader to quantify the change easily, especially in cases where the sensor is used to identify more than one RNA sequence.
The cellular components necessary for this process, including ribosomes, proteins and nucleic acids, can be obtained from living cells and freeze-dried on the paper.
Once rehydrated, components begin functioning as they would inside a living cell.
Using the nucleic acid sequence based amplification (NASBA) system, researchers also integrated a step that boosts the amount of viral RNA in the blood sample before exposing it to the sensor.
This step takes one to two hours, and helps increase the test's sensitivity one million-fold.
They also tested the new device by using synthesised RNA sequences that correspond to the Zika genome, which were then added to human blood serum.
The team demonstrated that the device is capable of detecting very low viral RNA concentrations in those samples and can also distinguish Zika virus from dengue.
Image: The new paper-based test can detect Zika virus. Photo: courtesy of MIT News.