For absolute viral nucleoprotein quantification, RNA was extracted from 1 x 107 PFU PR8 using the ISOLATEII RNA kit according to the manufacturer’s instructions (Bioline) and 100 ng reverse-transcribed with the Tetro cDNA synthesis Kit using IAV nucleoprotein specific primers [39 (link)]. Following amplification, the 216 bp cDNA product was gel purified using a Gel Extraction kit (Sigma Aldrich) and total copy number determined based on size and yield of product. A standard curve was generated to determine absolute viral nucleoprotein mRNA copy number among sample mRNA.
All quantitative reverse-transcriptase PCR (qRT-PCR) was performed using SYBR NoROX master mix (Bioline) on a Roche LightCycler480. Forward and reverse qRT-PCR primers are listed in