Rapid, Point-of-Care Host-Based Gene Expression Diagnostics Using Giant Magnetoresistive Biosensors

Host-based gene expression analysis is a promising toolfor a broadrange of clinical applications, including rapid infectious diseasediagnostics and real-time disease monitoring. However, the complexinstrumentation requirements and slow turnaround-times associatedwith traditional gene expression analysis methods have hampered theirwidespread adoption at the point-of-care (POC). To overcome thesechallenges, we have developed an automated and portable platform thatutilizes polymerase chain reaction (PCR) and giant magnetoresistive(GMR) biosensors to perform rapid multiplexed, targeted gene expressionanalysis at the POC. As proof-of-concept, we utilized our platformto amplify and measure the expression of four genes (HERC5, HERC6, IFI27, and IFIH1) that were previously shown to be upregulated in hosts infectedwith influenza viruses. The compact instrument conducted highly automatedPCR amplification and GMR detection to measure the expression of thefour genes in multiplex, then utilized Bluetooth communication torelay results to users on a smartphone application. To validate theplatform, we tested 20 cDNA samples from symptomatic patients thathad been previously diagnosed as either influenza-positive or influenza-negativeusing a RT-PCR virology panel. A non-parametric Mann-Whitneytest revealed that day 0 (day of symptom onset) gene expression wassignificantly different between the two groups (p < 0.0001, n = 20). Hence, we preliminarily demonstratedthat our platform could accurately discriminate between symptomaticinfluenza and non-influenza populations based on host gene expressionin & SIM;30 min. This study not only establishes the potential clinicalutility of our proposed assay and device for influenza diagnosticsbut it also paves the way for broadscale and decentralized implementationof host-based gene expression diagnostics at the POC.