Clinical correlation of influenza and respiratory syncytial virus load measured by digital PCR

Hijano, Diego R.; Brazelton de Cardenas, Jessica; Maron, Gabriela; Garner, Cherilyn D.; Ferrolino, Jose A.; Dallas, Ronald H.; Gu, Zhengming; Hayden, Randall T.

Our study is relevant because no studies have been previously published on the use of dPCR to determine viral loads of RSV and influenza virus in pediatric patients with hematologic malignancies, solid tumors, or SCD. Assays reported to date have been performed using real-time PCR. dPCR provides advantages such as endpoint quantitation without the need for calibration curves, improved precision, and reduced likelihood of quantitative bias based on amplification efficiency or inhibition [17, 26, 27] . From 137 samples that were initially positive by BioFire FilmArray1, 19 were negative by dPCR. All 19 samples were collected after completion of antiviral treatment. This might be anticipated due to subsampling error in patients with very low viral load or due to some degree of sample degradation in similarly low load samples (near the assay LOD). These results are in agreement with previous work from our group and others on cytomegalovirus, showing that although dPCR exhibits increased precision over qPCR at higher viral loads, diminished sensitivity can be seen in samples with low viral load values, potentially attributable to reduced input sample volume in the dPCR system [66] [67] [68] .