Finding Zika one paper disc at a time in 2 to 3 hours

A novel, inexpensive method for detecting the Zika virus could help slow spread of outbreak, and potentially other future pandemic diseases

An international, multi-institutional team of researchers led by synthetic biologist James Collins, Ph.D., at the Wyss Institute for Biologically Inspired Engineering at Harvard University, has developed a low-cost, rapid paper-based diagnostic system for strain-specific detection of the Zika virus, with the goal that it could soon be used in the field to screen blood, urine, or saliva samples.

“The growing global health crisis caused by the Zika virus propelled us to leverage novel technologies we have developed in the lab and use them to create a workflow that could diagnose a patient with Zika, in the field, within 2-3 hours,” said Collins, who is a Wyss Core Faculty member, and Termeer Professor of Medical Engineering & Science and Professor of Biological Engineering at the Massachusetts Institute of Technology (MIT)’s Department of Biological Engineering.

Building off previous work done at Harvard’s Wyss Institute by Collins and his team, along with collaborators from Massachusetts Institute of Technology (MIT), the Broad Institute of Harvard and MIT, Harvard Medical School (HMS), University of Toronto, Arizona State University (ASU), University of Wisconsin-Madison (UW-Madison), Boston University (BU), Cornell University, and Addgene, joined their efforts to quickly prototype the rapid diagnostic test and describe their methods in a study published online May 6 in the journal Cell, all within a matter of six weeks. Collins is the paper’s corresponding author.

Emerging innovation during the Ebola health crisis

In October 2014, Collins’ team developed a breakthrough method for embedding synthetic gene networks — which could be used as programmable diagnostics and sensors – on portable, small discs of ordinary paper.

Stirred by the then-ongoing Ebola outbreak in Africa, they demonstrated a proof-of-concept color-changing diagnostic that could screen for Ebola by embedding in paper a novel kind of synthetic biomolecular sensor designed to screen for specific RNA sequences. These RNA sequences can mark not only the genetic signatures of Ebola but also other RNA viruses including Zika, SARS, measles, influenza, hepatitis C, and West Nile fever. The team believed that one day, the method could be applied in the field to identify viruses with blood, urine, or saliva samples.

However, until recently, the team’s paper-based technology has been challenged by the extremely low concentration of virus that is normally found in blood, urine, and saliva. Now, using blood samples from monkeys infected with Zika virus as well as virus recovered from cells infected in the laboratory, the team has validated a next generation technique that overcomes this problem.

A leap for paper-based diagnostics, urged by the Zika outbreak

“The vivid images in the news stemming from the ongoing Zika crisis are heartbreaking,” said Keith Pardee, Ph.D., one of the study’s co-first authors and an Assistant Professor in the Leslie Dan Faculty of Pharmacy at University of Toronto, who was formerly a Postdoctoral Fellow at the Wyss Institute and BU. “We hope a tool like this can help reduce the impact of the outbreak until a vaccine can be developed.”

With field use in mind, Collins’ team designed a simple modular workflow comprising three steps: amplification, Zika detection, and CRISPR-Cas9-aided strain identification. CRISPR-Cas9, a gene editing mechanism derived from the immune systems of bacteria, can be used to search entire sequences to find exclusive genetic markers. Leveraging CRISPR-Cas9’s talent for sequence recognition, the third part of the team’s system uses a CRISPR-Cas9-aided paper-based diagnostic to discriminate between strains whose genetic profiles differ by as little as one nucleotide.

Learn more: Finding Zika one paper disc at a time