RSV RNA synthesis in human and mouse cell lines. A-D) Positive and negative sense viral RNA were monitored by strand-specific QPCR from A549 and KLN205 cells treated with RSV A2 at MOIs of A) 1 × 10-3, B) 1 × 10-2 C) 1 × 10-1 or D) 1. Copy numbers were determined from strand-specific RNA standard curves. RSV RNA was not detected in KLN205 cells treated with RSV at MOI = 1 × 10-3. E-F) Beta actin, expressed as arbitrary copy number, was measured by QPCR from E) A549 or F) KLN205 cells treated with RSV A2 at the MOIs shown. Means ± SEM (n = 2) are plotted.