FIG. 4.

Real-Time RT-PCR amplification in the N (A) and L (B) gene assays of serially diluted RNAs of prototype hMPV strains. The values on the x axes indicate the amounts of RNA per reaction, ranging from undiluted (1e+0) to millionfold diluted (1e−6) RNAs. Ct values on the y axes indicate the first PCR cycle at which a positive signal was detected for each sample. Black circles and triangles represent the lineage A1 (NL/1/00) and A2 (NL/17/00) prototype virus strains, respectively. No amplification of viral RNA from lineage B viruses was detected in these experiments. Error bars indicate standard deviations for triplicate samples.