Researchers at the University of Toronto have created a cheap, rapid, easy-to-use testing method for infectious diseases. The test is not yet ready for widespread use, but researchers contend that it can make quick, accurate diagnoses available even in developing countries, speed up detection and response to developing pandemics, and help slow development of drug-resistant disease.
The researchers stated that the science behind the test is not new, but what is new is the way it is being applied. At present, DNA enzymes are used as the bio-sensor and gold nanoparticles are used as the color-changing element in over-the-counter pregnancy tests. According to Kyryl Zagorovsky, a PhD student at the university’s Institute of Biomaterials and Biomedical Engineering (IBBME), the two materials have not been put together before. Zagorovsky and Warren Chan, an IBBME professor and the other lead developer of the test, mixed the gold nanoparticles in solution with linked two-part DNA enzymes that bonded with the nanoparticles, clumping them so they showed a purple color. When a pathogen reaches the DNA enzyme, it causes a change that awakens the enzyme and cuts the chemical links holding the nanoparticles together. Users see this reaction as a change of color from purple to red. A more specific reading of the severity of the infection is done by using a standard TLC plate. Since no special fluorescent equipment or refrigeration is required, this test is ideal for places with poor medical infrastructure.
Zagorovsky explained that there is no limit to the number of diseases the IBBME method can detect through parallel testing, but a different DNA enzyme would be needed for each. He and Chan are focusing first on malaria, HIV, hepatitis, and STDs. Chan compared the IBBE to a quick malaria test called Binax NOW, and showed how the IBBME was quicker and more efficient. Also, Binax NOW costs about $25 per test, which is more than the $3 he estimates for a commercial version of the IBBME.
Chan reasoned that diseases become resistant because many individuals are treated based on symptoms, which may not be an exact indicator of the specific infection. If the drugs do not kill the infection, the infection can mutate and become resistant. With the IBBE, the specific infection can be diagnosed quickly and the right treatment given, thus preventing resistance. Also, rapid test results and centralized data mapping can make it easier to spot developing pandemics. According to Zagorovsky, the test has been tried with genetic imitations of HIV and malaria, but trials in Africa and South Asia with actual disease samples should be completed in summer. After satisfactory completion of the trials and regulatory approval, the researchers will need some type of partnership to produce the tests commercially.