TABLE 2.

Sensitivity of detection of HIV-1 by the gp41 M/O primer set compared with those of commercial viral load assays

Specimen	Country of origin	Subtype (env/prt)a	Sensitivity of viral load assay (no. of copies/ml)b			Result with gp41 M/O primers
			Chiron	OTC	Roche
301-06	Ghana	A	4 × 103	5 × 103	BLD	Positive
301-07	Ghana	A	5 × 103	2 × 103	BLD	Positive
301-12	Ghana	A	6 × 104	3 × 104	BLD	Positive
301-21	Uganda	A/A	7 × 102	BLD	BLD	Positive
301-24	Uganda	A	BLD	9 × 102	6 × 102	Positive
301-27	Uganda	A/BD	BLD	BLD	BLD	Positive
TIA175	Ivory Coast	A	ND	BLDc	BLDc	Positive
301-14	South Africa	C/B	4 × 103	BLD	7 × 102	Positive
301-16	South Africa	C	3 × 103	9 × 102	BLD	Positive
301-29	Zimbabwe	C	>8 × 105	1 × 103	BLD	Positive
301-44	India	C	4 × 103	BLD	3 × 103	Positive
301-23	Uganda	D	BLD	BLD	BLD	Positive
301-26	Uganda	D/D	2 × 103	BLD	5 × 102	Positive
301-39	Zimbabwe	E/A	4 × 103	BLD	BLD	Positive
301-40	Thailand	E/A	2 × 103	BLD	BLD	Positive
301-47	Argentina	F/B	BLD	BLD	BLD	Positive
301-03	Ghana	G	103	BLD	BLD	Positive
301-08	Ghana	G	1 × 103	7 × 102	BLD	Positive
DAA3671	Ivory Coast	G	ND	BLDc	BLDc	Positive
DAA3760	Ivory Coast	G	ND	BLDc	BLDc	Positive
301-01	Cameroon	O	BLD	BLD	BLD	Positive

^aSubtype was ascribed based on phylogenetic analysis of the env region. In some cases, the protease region (prt) was also sequenced to identify potential dual or recombinant infections. Specimen no. 310-14, 301-27, 301-39, and 301-47 represent dual infection with multiple subtypes or potential recombinants of two different genotypes. 

^bBLD, below limit of detection. The limits of detection of each assay were 500 copies/ml for the Chiron assay and 400 copies/ml for the OTC and Roche assays. ND, not done. 

^cSpecimen still negative by the ultrasensitive versions of the OTC and Roche assays (both with a detection limit of 50 copies/ml).