Table 1. Contamination of commercial RT-PCR reagents with murine leukemia virus (MLV).¹ .

Manufacturer	Kit/Reagent	RT origin	Lot no.	pro (%, copies/rxn)	gag	Nested pol (%)	mtDNA 2 (copies/rxn)	IAP 2 (copies/rxn)
ABI/Ambion	AgPath One Step RT-PCR kit	MoMLV	1009030	7/16 (44, 1–10)	0/16	6/16 (38)	0/16	0/16
	AgPath One Step RT-PCR kit	MoMLV	909020	1/16 (6, 1–10)	ND3	ND	ND	ND
	AgPath One Step RT-PCR kit	MoMLV	1009025	2/16 (13, 1–10)	ND	ND	ND	ND
	AgPath One Step RT-PCR kit	MoMLV	1003027	0/16	ND	ND	ND	ND
	AgPath One Step RT-PCR kit	MoMLV	1010031	2/16 (13, 1–10)	ND	ND	ND	ND
ABI	AmpliTaq+AgPath enzyme	MoMLV	1009030	7/16 (44, 1–10)	ND	ND	ND	ND
ABI	TaqMan 1-Step Master mix	MoMLV	1006001	4/16 (25, 1–10)	0/16	12/16 (75)	0/16	0/16
ABI	TaqMan RNA to CT kit	MoMLV	802002	4/16 (25, 1–10)	ND	ND	ND	ND
Agilent	Brilliant II QRT-PCR Master mix	MoMLV	6080963	6/16 (38, 1–10)	0/16	15/16 (94)	0/16	0/16
Promega	Access RT-PCR system	AMV	316238	0/16	ND	ND	ND	ND
	AccessQuick RT-PCR system	AMV	313296	0/16	0/16	0/16	0/16	0/16
	AccessQuick RT-PCR system	AMV	316238	0/16	ND	ND	ND	ND
Roche	Transcriptor 1-step RT-PCR kit	AMV	12275200	8/16 (50, 1–10)	0/16	4/16 (25)	0/16	0/16
	Transcriptor 1-step RT-PCR kit	AMV	12513300	2/16 (13, 1–10)	ND	ND	ND	ND
Finnzymes	RobusT I RT-PCR kit	AMV	127	failed	0/16	2/16 (13)	0/16	0/16

¹The reverse transcriptase (RT) enzymes and kits were tested by quantitative protease (pro), polymerase (pol), gag and/or nested pol RT-PCR assays and results shown are number of positive tests out of the total number of replicates. Percentages for replicate testing and copies/reaction (rxn) are in parentheses.

²Mouse DNA contamination was detected using mitochondrial DNA (mtDNA) and intracisternal A particle (IAP) PCR qPCR assays.

³ND, not done.