Detection of H3N2 canine influenza virus using a Quartz Crystal Microbalance.

Label-free technology-based Quartz Crystal Microbalance (QCM) is an emerging tool in biological research. In this study, QCM was applied successfully for the rapid diagnosis of H3N2 canine influenza virus (CIV) infection. ProLinker™ B, a calixcrown derivative, enables antibodies to be attached to a gold-coated quartz surface and positioned in a regular pattern with the correct orientation. The ProLinker-coated quartz-based assay detected H3N2 CIV at lower concentrations (2(2) HA unit) than a commercial immunochromatography Ag kit (2(3) HA unit). Three independent experiments in which H3N2 CIV-positive reference samples were applied to an anti-CIV nucleoprotein (NP) monoclonal antibody immobilized on a quartz surface yielded standard deviations (SD) of ≤5%, indicating high reproducibility. In addition, the QCM assay with a cut-off value (-140 Hz) showed 97.1% (34/35) sensitivity and 94.7% (36/38) specificity in testing 73 field saliva samples, respectively. Thus, the QCM assay described herein will be a valuable tool for the rapid diagnosis of H3N2 CIV infection with high sensitivity and specificity, and should overcome several of the disadvantages and limitations inherent in the commercial immunochromatography Ag kit.