Rapid, Sample-to-Answer Host Gene Expression Test to Diagnose Viral Infection

Abstract

<jats:title>Abstract</jats:title> <jats:sec> <jats:title>Background</jats:title> <jats:p>Distinguishing bacterial, viral, or other etiologies of acute illness is diagnostically challenging with significant implications for appropriate antimicrobial use. Host gene-expression offers a promising approach although no clinically useful tests have yet been developed to accomplish this. Here, Qvella’s FAST™ HR process was developed to quantify previously identified host gene-expression signatures in whole blood in <45 minutes.</jats:p> </jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>Whole blood was collected from 128 human subjects (mean age 47, range 18-88) with clinically adjudicated, microbiologically confirmed viral infection, bacterial infection, non-infectious illness, or healthy controls. Stabilized mRNA was released from cleaned and stabilized RNA-surfactant complexes using e-lysisTM, an electrical process providing a qRT-PCR-ready sample. Threshold cycle values (CT) for 10 host response targets were normalized to HPRT1 expression, a control mRNA. The transcripts in the signature were specifically chosen to discriminate viral from non-viral infection (bacterial, non-infectious illness, or healthy). Classification accuracy was determined using cross-validated sparse logistic regression.</jats:p> </jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>Reproducibility of mRNA quantification was within 1 cycle as compared to the difference seen between subjects with viral vs. non-viral infection (up to 5.0 normalized CT difference). Classification of 128 subjects into viral or non-viral etiologies demonstrated 90.6% overall accuracy compared to 82.0% for procalcitonin (p=0.06). FASTTM HR achieved rapid and accurate measurement of the host response to viral infection in less than 45 minutes.</jats:p> </jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>These results demonstrate the ability to translate host gene expression signatures to clinical platforms for use in patients with suspected infection.</jats:p> </jats:sec>