RNA extraction and quantitative analysis of viral RNA in ferret nasal washes.

The viral RNA from ferret nasal wash was extracted and quantified using real-time PCR. The real-time primers were provided by the CDC (Atlanta, USA) and were capable of detecting the influenza B virus NS gene. Internal controls with known RNA copy numbers of B/England/598/2014 virus NS transcripts were generated in-house and included for each assay. This was used to correlate cycle threshold (C_T) with the RNA copy number and quantitate viral RNA in nasal wash samples.