TABLE 1.

Composition of the panel of samples artificially contaminated by different amounts of HCV RNA derived from a positive human serum specimen

No. of seminal plasma samples in panel	No. of control samplesa	Concn of HCV RNA (IU/ml)
		Expected	Observedb
2	0	0	<600c
2	0	10	<600c
2	1	20	<600c
2	0	100	<600d
2	1	200	110
2	0	1,000	1,500
2	1	2,000	4,400
2	1	20,000	30,000

^aControls were dilutions of HCV RNA-positive blood plasma in RNase-free distilled water.

^bQuantified in additional serial dilution in RNase-free water by the laboratory preparing the panel before sending the specimens to the other laboratories.

^cNegative by qualitative Cobas Amplicor assay (threshold, 50 IU/ml).

^dPositive by qualitative Cobas Amplicor assay.