Pen-side diagnosis of sheep scab using a paper-based microfluidic device

The traditional diagnosis of P. ovis infestation is based on clinical observations and microscopical detection of mites in skin scrapings. Recently the Moredun Research Institute (MRI) has developed a diagnostic ELISA for the detection of antibodies specific to a mite allergen (Pso o 2) which has proven highly sensitive in the diagnosis of sub-clinical infestation. The main disadvantages of this assay are that it is currently lab-based and also that host antibodies may be present in previously-infested but sucessfully-treated animals for a prolonged period after treatment (3-6 months) potentially leading to false positives. However, a number of serum biomarkers (BMs) for sheep scab have been recently identified, which may overcome the latter limitation as their serum levels increase with disease progression but fall rapidly following successful treatment. At the same time, worldwide interest has grown over the application of microfluidic paper-based analytical devices (µPADs) in the diagnostic field. These devices allow for cheap, point of care, multiplexed analyses to be carried out while maintaining the advantages of conventional microfluidic technology, such as size, speed and reduced sample volumes. The presentation will focus on the preliminary results in transferring the existing sandwich ELISA for detection of a biomarker, haptoglobin, using a laser cut paper device.