Advanced influenza diagnostics A timely diagnosis of influenza is the key to prompt treatment. A European consortium worked on developing an innovative diagnostic tool based on microarrays. Health © Thinkstock Over the past years, a number of influenza diagnostic tools have been developed for point-of-care applications. They are based on dipstick lateral flow technology that utilises robust, affordable and easy to perform assays. However, rapid tests have limitations, such as lack of sensitivity, an inability to distinguish among different strains of influenza viruses and little multiplex capacity. New test formats and technologies are required for determining numerous parameters simultaneously. In this context, the EU-funded FLUARRAY (Development and validation of a microarray based automated diagnostic system for the detection of influenza virus types and subtypes at point-of-care) project proposed to develop a microarray-based system for point-of-care influenza diagnosis. This technology would dramatically increase assay throughput while reducing cost. Microarray assays are currently processed manually and require equipment not suitable for the clinical laboratory. FLUARRAY converted the sophisticated microarray technology into a simple and robust diagnostic system. This system can simultaneously process hundreds of assays on a surface area the size of a fingernail. It will be used to distinguish between haemagglutinin (HA) and neuraminidase (NA) variants from major human and animal viruses in biological specimens. The system essentially comprises a miniature immunoassay utilising a microarray of capture antibodies directed against the two influenza virus proteins, HA and NA. The array captures recombinant tracer proteins which are then sandwiched by a secondary fluorescently-labelled antibody. In the presence of influenza virus in the specimen, the tracer proteins are displaced by the viral antigens, causing a reduction in the recorded fluorescence signal. The consortium has produced all the molecular components of the assay including the monoclonal antibodies and assessed its detection sensitivity. Scientists have validated the performance of the system but the desired sensitivity is yet to be achieved. Considerable efforts were dedicated towards the production of a prototype automated microarray reading instrument that can add samples and reagents to the assay device. The instrument contains an optical module to read microarray immunoassays with a sensitivity and dynamic range similar to that of the most sophisticated microarray scanners. FLUARRAYs portable point-of-care diagnostic system will perform hundreds of distinct parallel immunoassays offering high discriminatory capacity in the diagnosis of influenza. Keywords Influenza, diagnosis, microarray, point-of-care, haemagglutinin, neuraminidase, immunoassay, antibodies
