Rapid diagnostic biosensors for the detection of respiratory viruses (VIRASENS)

Respiratory syncytial virus (RSV) and others, such as influenza, are widespread and serious infections especially important in the very young and the very old. RSV for example presents in its early stages much like bacterial infections but the treatment required is fundamentally different e.g. anti /viral or anti bacterial. The wrong decision, either way, leads to lost time and complications which can be avoided by early accurate diagnosis. These diseases are thus prime examples of the need for point of care (POC) diagnosis rather than systems which require samples to be sent to a central laboratory. There are a range of approaches to POC including simple lateral flow devices like those used in pregnancy tests. Orla Protein Technologies Ltd is a company using the results from BBSRC funded research to design sensitive surfaces which allow electronic devices to detect biological molecules. These surfaces are used in a variety of systems but for this study they are employing a surface acoustic wave sensor manufactured in collaboration with a leading Japanese wireless communication firm, the Japan Radio Company. The device, a surface acoustic wave (or SAW) sensor is an electronic version of the well known tuning fork with its own defined note or resonant frequency. If small molecules bind to the surface of the device then this characteristic note changes and can be detected electronically. The signal is then sent wirelessly to a central device along with patient information, time, temperature and even a GPS reading. Thus the results are automatically logged and human error is avoided. The physician gets an immediate answer and can prescribe quickly and appropriately.All this depends upon the quality of the detection which relies upon a 5 nm thick layer which recognises characteristic proteins from the virus. Five nanometres is 30,000 times thinner than a sheet of standard A4 paper and the layer is thus an example of molecular scale engineering. Orla uses molecules which self-assemble into an oriented layer due to their design, thus the assembly upon the device are accomplished in a manner easier than painting / imagine painting a room by simply throwing a bucket of silk emulsion on the walls and ending up with a perfect layer that avoids the woodwork, ceiling and floor! The trick to this is in the molecular design of the mixture and much of this is protein engineering. Proteins are the target that we wish to recognise and usually we use other proteins to recognise them. The best examples of these are antibodies, produced in mice, which have been selected to recognise RSV or other viral proteins. The research project in this group will create engineered proteins that will co assemble with the antibodies to create a highly selective monolayer on the SAW device. This involves modifying the self assembling proteins to make very stable and precisely oriented antibody binding arrays, checking the structure of these proteins by biophysical methods, assembly of the proteins on model surfaces like the ones present on the SAW device and measurement of the resulting behaviour of the layers. The company will carry out measurements upon the devices under real life situations in the hands of prospective customers. The Lakey group will thus concentrate on the molecular engineering of the layer and will add value to the project by its access to facilities and expertise in protein engineering. As a preliminary step we will also use our biochemical knowledge to purify viral antigens from sterile materials supplied by VIRATOM. These are essential for quality control purposes and will provide an important resource to calibrate and improve the sensitivity and selectivity of the device. The final result of the project will be a highly selective and sensitive self assembling layer which can be transferred directly into the mass manufacture of the commercial SAW device.