A murine leukemia virus with Cre-LoxP excisible coding sequences allowing superinfection, transgene delivery, and generation of host genomic deletions

Table 1 Proviral expression and estimated copy numbers in infected GC4 cell populations.

Virus	Infection	time (days)	GFP-Cre+ (%)	GFP-Cre+ EYFP+ (%)	GFP-Cre+ EYFP- (%)	Ratio of intensities^a	Est. # of expressed copies
						(GC4 EYFP)/(NIH/3T3 EYFP)	(GC4 EYFP)/(one expressed EYFP)
Akv-Y	supernatant	5	99.2	78.7	20.5	0.5	1^b
Akv-Y	supernatant	10	99.6	95.7	3.9	0.9	1^b
Akv-Y	supernatant	16	99.1	95.7	3.5	1.2	1^b
Akv-2XY	supernatant	5	99.1	5.4	93.7	1.8
Akv-2XY	supernatant	10	99.6	6.8	92.8	1.7	1^c
Akv-2XY	supernatant	16	99.4	12.7	86.8	1.6
Akv-Y	mixed culture	5	88.5	82.5	6.0	0.9	1^b
Akv-Y	mixed culture	10	93.2	91.8	1.4	0.9	1^b
Akv-Y	mixed culture	16	92.6	91.4	1.2	1.1	1^b
Akv-2XY	mixed culture	5	69.3	46.7	22.7	3.9	2^d
Akv-2XY	mixed culture	10	46.4	45.5	0.9	12.8	8^d
Akv-2XY	mixed culture	16	2.8	2.8	0.0	43.1	20^d

^a For a given virus, the ratio was calculated with fluorescence intensities of that virus to account for differences not related to copy number (see Materials and Methods). ^b One expressed EYFP gene based on unsubcloned NIH/3T3 EYFP fluorescence intensity. ^c One expressed EYFP gene based on the Poisson distribution calculation, using the EYFP- value of non-infected cells. ^d One expressed EYFP gene based on single expressed EYFP fluorescence intensity from supernatant infected culture.

ISSN: 1742-4690