Microfluidic immunosensor for rapid and sensitive detection of bovine viral diarrhea virus

We have investigated the utilization of microparticle immunoagglutination assays using forward light scattering measurements in a microfluidic chip towards detecting viral particles. The model viral target was bovine viral diarrhea virus (BVDV). Highly carboxylated polystyrene microparticles (510 nm) were coated with anti-BVDV monoclonal antibodies. This solution was in turn used to detect BVDV in diluted tissue culture media and fetal calf serum. The assay was first performed in a two well slide format for proof of concept and particle stability experiments, then in a simple y-channel microfluidic chip with optical fibers arranged in a close proximity setup. Microparticle immunoagglutination was detected via static forward light scattering measurements taken at 45° to incident light. In the microfluidic chip, BVDV was detected down to a concentration of 10 TCID₅₀ mL^-1. For assay comparison purposes reverse transcriptase polymerase chain reaction (RT-PCR) was performed on serial dilutions of the BVDV sample used in the two well and microfluidic testing. RT-PCR was effective down to a concentration of 10³ TCID₅₀ mL^-1 in detecting the identical BVDV used for microfluidic assays.