Relationship between infectivity and genomic RNA copies.

Data are sumarized as mean ± SD (3 to 6 determinations). Drug treatments used: 10 mM NH4Cl, 10 nM Concanamycin A, or 25 µM furin inhibitor. Control indicates that no drug was added to the culture medium. The PFUs in the sample were determined by standard titration [35] at 24 h.p.i. The amount of genomic RNA copies was measured by quantitative RT-PCR (24 h. p.i.) using previously titrated samples, and expressed as genomic equivalents to PFU/ml [40], [41].