TABLE 1.

Comparison of four different assays for HIV-1 RNA^a

No. of copies/ml predicted by VQA (control)	No. of copies/ml
	AMPLICOR ultrasensitive assay						Modified AMPLICOR ultrasensitive assay						Single-copy assay
	Run 1	Run 2	Run 3	Run 4	Mean	SD	Run 1	Run 2	Run 3	Run 4	Mean	SD	Run 1	Run 2	Run 3	Run 4	Mean	SD
200	173	176	170	127	162	23	190	149	140	199	170	29	187	200	189	232	202	30
100	90	137	150	90	117	31	87	45	107	88	82	26	85	84	75	139	96	29
50	24	70	60	59	53	20	69	27	61	44	50	19	32	33	39	62	42	14
25	31	28	Negb	Neg	30	2.1	27	18	28	17	23	5.8	15	25	11	30	20	8.8
12.5	Neg	Neg	Neg	Neg	Neg	Neg	9	11	15	11	12	2.5	11	8	10	12	10	1.7
6.25	Neg	Neg	Neg	Neg	Neg	Neg	17	12	5	7	10	5.4	2	9	8	8	6.8	3.2
3.125	Neg	Neg	Neg	Neg	Neg	Neg	10	Neg	Neg	Neg	10	0	2	5	4	3	3.5	1.3
1.56	Neg	Neg	Neg	Neg	Neg	Neg	Neg	Neg	Neg	Neg	Neg	Neg	2	1	1	6	2.5	2.4
0.78	Neg	Neg	Neg	Neg	Neg	Neg	Neg	Neg	Neg	Neg	Neg	Neg	0.3	1	0.8	NDc	0.7	0.4

^aAn amount of preassayed virus with the corresponding number of copies of RNA indicated was mixed with normal plasma.

^bNeg, the OD was not above background.

^cND, not determined (due to RCAS value <15,000 copies/reaction mixture).