TABLE 1.

Packaging of lentivirus and nonlentivirus transfer vectors into HIV, SIV, MPMV, and FIV particles produced with the VSV-G Env expression plasmid^a

Transfer vector	Description of transfer vectors	Titers (CFU/ml)b
		HIV proteins	SIV proteins	MPMV proteins	FIV proteins
TR394	Chimeric 5′ FIV LTR,ccis-acting FIV sequencesd and MPMV CTE	185 ± 17	185 ± 56	0	1,664 ± 42
MB74	Same as TR394 except that FIV ψ has been replaced with HIV ψ	391 ± 51	NDe	ND	431 ± 175
MB72	Same as TR394 except that FIV ψ has been replaced with SIV ψ	ND	659 ± 150	ND	343 ± 123
MB87	Same as TR394 with the insertion of HIV vpu, tat, rev, and RRE	ND	ND	ND	7,200 ± 910
MB89	Same as TR394 with the insertion of HIV vpu, tat, rev, and RRE	ND	ND	ND	2,427 ± 318
MB58	cis-acting HIV sequencesd and HIV vpu, tat, rev, and RRE	15,387 ± 3,400	ND	ND	640 ± 97
MB41	cis-acting SIV sequencesd and SIV vpr, tat, rev, and RRE	ND	30,700 ± 8,614	ND	96 ± 14
KAL011	cis-acting MPMV sequencesd and MPMV CTE	ND	ND	32,320f	0
TR174	SV-HYGRO cassette using 3′ SIV LTR as poly(A)sequences	0	0	0	0
MOCK	No DNA control	0	0	0	0

^aNo Hyg^r colonies were observed for any of the vectors when the transfections were performed without the VSV-G Env expression vector, MD.G, or with MD.G by itself, or when mock transfected. 

^bEach value represents a mean of three experiments performed in duplicate except as explained in note f. 

^cIn the chimeric FIV 5′ LTR, the U3 has been replaced by the CMV promoter. 

^dcis-acting sequences include PBS, PPT, ψ, att, 5′ LTR, and 3′ LTR. 

^eND, not done. 

^fValue represents an average of two experiments performed in duplicate; the value for the third experiment was too numerous to count.