Figure 3.

Comparison of LASV NP antigen detection by ELISA versus RNA quantification by qPCR. RNA was prepared from serum samples as outlined in materials and methods. RT-PCR followed by qPCR directed against the GPC gene was performed on days 7-18. A 1:6 dilution series of Josiah strain seed stock was used as a standard to calculate the LASV RNA copy number per milliliter of serum. PCR data were plotted on the second Y axis (LASV RNA copies/mL). Error-bars represent the SEM of two independent experiments. NP Ag ELISA data was plotted on the first Y axis (A₄₅₀) for trend comparison. Trend lines for NP Ag ELISA (power) and qPCR (exponential), and associated R² values are indicated. The limit of detection for antigen by NP Ag ELISA was day 9 (blue arrow), and day 11 for qPCR (red arrow).