Escherichia coli–expressed near full length HIV-1 envelope glycoprotein is a highly sensitive and specific diagnostic antigen

Table 4 Evaluation of different TRF assays using anti-HIV-1 low titer performance panel (PRB 108)

Member ID #	Abbott HIV 1/2^a	Gen. Sys. HIV 1/2^a	Org. Tek. HIV 1^a	Bio-Rad HIV-1 Western Blot Result^b	Roche PCR HIV-1 RNA test copies/ml^c	TRF assays^d
Member ID #	Abbott HIV 1/2^a	Gen. Sys. HIV 1/2^a	Org. Tek. HIV 1^a	Bio-Rad HIV-1 Western Blot Result^b	Roche PCR HIV-1 RNA test copies/ml^c	r-Δgp160 two-step	r-Δgp160 one-step	r-HIV-1env two-step
1	5.5	>8.9	1.4	+	3x10⁴	1.9 (+)	1.8 (+)	2.0 (+)
2	0.2	0.3	0.3	-	BLD	0.8 (−)	0.6 (−)	0.7 (−)
3^e	NA	NA	1.8	IND	5x10¹*	3.4 (+)	3.0 (+)	0.8 (−)
4^e	11.9	>8.9	6.3	+	9x10⁴	7.0 (+)	5.2 (+)	3.4 (+)
5	3.4	>8.9	3.2	+	5x10¹*	2.2 (+)	1.2 (+)	3.6 (+)
6	NA	NA	1.2	IND	6x10³	1.8 (+)	1.1 (+)	5.9 (+)
7^f	5.3	>8.9	1.3	+	3x10³	2.7 (+)	1.6 (+)	3.9 (+)
8^f	8.0	>8.9	2.8	+	7x10³	3.8 (+)	2.8 (+)	4.8 (+)
9	8.5	>8.9	0.7	+	2x10³	1.9 (+)	1.1 (+)	7.2 (+)
10	8.6	>8.9	0.6	IND	3x10⁵	1.7 (+)	1.2 (+)	13.2 (+)
11	NA	NA	3.8	+	8x10³	3.2 (+)	2.0 (+)	5.4 (+)
12	1.7	2.0	0.3	-	5x10⁵	1.1 (+)	0.6 (−)	0.9 (−)
13	NA	NA	0.9	IND	2x10⁵	4.9 (+)	2.7 (+)	18.2 (+)
14^g	NA	NA	0.4	-	3x10⁵	1.4 (+)	1.0 (+)	1.1 (+)
15^g	14.2	>8.9	1.8	IND	>7x10⁵	5.9 (+)	3.0 (+)	8.0 (+)

^aValues indicate S/Co ratios, provided by the panel supplier using the indicated commercial EIA kits. S/Co values ≥ 1.0 are considered as positive. (Gen. Sys., Genetic Systems; Org.Tek., Organon Teknika). ‘NA’ indicates data ‘not available’ from the panel supplier.
^bResult provided by the panel supplier using the indicated commercial test. ‘+’ and ‘–’ indicate the presence and absence, respectively, of antigen bands in the Western blot assay. ‘IND’ indicates indeterminate result.
^CResult provided by the panel supplier using the indicated commercial test. ‘BLD’ indicates that the RNA level is below the limit of detection. *Ultrasensitive method was used (50–75,000 copies/ml).
^dValues indicate S/Co ratios obtained in this study, using the in-house TRF assays. The results are indicated in parentheses. Samples with S/Co values < 1.0 are designated as negative (−) and those with values ≥ 1.0 are designated as positive (+).
^ePRB 108–4 is a bleed from the same donor as PRB 108–3 collected 17 months later.
^fPRB 108–8 is a bleed from the same donor as PRB 108–7 collected 6 days later.
^gPRB 108–15 is a bleed from the same donor as PRB 108–14 collected 7 days later.

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