FIG. 1.

Typical amplification patterns for 10-fold serially diluted fecal RNA extracts containing NLV-2 by using RT-PCR (lanes 2 to 5) and one-tube nested RT-PCR (lanes 6 to 13), showing a 100-fold increase in sensitivity with the latter method. See Table 1 for primers; RT-PCR was performed with NLV-2-OF and NLV-2-OR to produce a 326-bp product. Nested RT-PCR was performed with NLV-2-OF and NLV-2-OR priming the RT and primary PCR steps and with NLV-2-IF and NLV-2-IR priming the secondary nested amplification to produce a 210-bp nested product. The lanes are marked with the RNA extract dilution; “−1” means “10⁻¹,” etc. Note also in the latter method the presence of an intermediate-length product produced by amplification from inner and outer primer pairs.