TABLE II.

Key Features of Three NAT Assays Used in This Study

Method	HCV b-DNA 3.0	HCV Monitor 2.0	HCV TaqMan
	Signal amplification	Target amplification (RT-PCR)	Target amplification (RT-QPCR)
Measurement	Fluorescence by luminometry	End-point colorimetry	Real time fluorescence
Sample input volume	50 μl	100 μl	10–140 μl
Linear range	103.0–106.9 IU/ml	102.8–105.9 IU/ml	102.6–106.5 IU/ml
Samples per run	48 (8) duplicates	12	48 (8) duplicates
Approximate cost per sample	$70	$70	$8

The key features of each NAT employed in this study are listed above. The sample input for TaqMan can be adjusted depending on the nature of the sample. The number of duplicate standards and controls per run for b-DNA and TaqMan are shown in parenthesis. TaqMan chemistry allows the detection of amplification in the early stages of PCR, adding precision, whereas end-point measurements are taken at the end of the PCR. Both Monitor and TaqMan require manual total RNA extraction.