Portable biosensor offers promise for rapid detection of avian influenza
The sensor uses a concept called waveguide interferometry to precisely determine how many virus particles attach to the sensor’s surface. Basically, two arms of an interferometer are coated with different antibodies. One arm, which serves as the sensing channel, is coated with antibodies specifically designed to capture the hemagglutinin protein located on the surface of the viral particle. The second arm is coated with non-specific antibodies and serves as a reference channel. When a liquid test sample passes over the waveguide, any antibody-antigen binding that occurs on the top of a sensing channel because of viral particle attachment causes water molecules to be displaced. This causes a relative change in the velocity of the light traveling through the sensing channel compared to the reference channel. By measuring this relative speed of light change based on the interferometry, the concentration of AI can be measured.
According to Jie Xu, research scientist and project director, GTRI’s prototype biosensor holds potential advantages over traditional AI identification methods. It is expected to be inexpensive, portable (so detection can be performed in the field), and is showing it should be able to detect several different avian strains simultaneously and within minutes. Recent experimental results using the prototype indicate it can detect H5 and H7 strains of AI at sensitivities fewer than 100 pfu virus particles in 1 milliliter of sample; in other words, well before symptoms of the virus would appear in infected birds.