TABLE 2.

Optimal amounts of plasmid DNA required for the production of infectious VLPs^a

Amt of Plasmid DNA (μg) expressing:									Relative efficiency of VLP formationb
L	NP	VP35	VP30	GP	VP40	VP24	T7 Pol	GFP-vRNA
4.0	0.5	0.5	0.3	1.0	1.0	1.0	1.0	1.0	1.0
4.0	0.5	0.5	0.3	1.0	1.0	0.3	1.0	1.0	1.3
4.0	0.5	0.5	0.3	1.0	1.0	0.1	1.0	1.0	1.2
4.0	0.5	0.5	0.3	1.0	1.0	0.03	1.0	1.0	1.6
4.0	0.5	0.5	0.3	1.0	1.0	0	1.0	1.0	1.2
4.0	0.5	0.5	0.3	1.0	0	0.03	1.0	1.0	0
4.0	0.5	0.5	0.3	0	1.0	0.03	1.0	1.0	0

^a293T cells were transfected with plasmids for the expression of seven Ebola Zaire virus structural proteins and with p3E5EGFP and pC-T7Pol. Seventy-two hours later, the supernatants containing Ebola VLPs were harvested and incubated with fresh 293T cells transfected with plasmids expressing L, NP, VP35, and VP30 proteins. Seventy-two hours after infection, the number of GFP-expressing cells (corresponding to the number of infectious VLPs) was determined with a fluorescence microscope.

^bDetermined by counting the number of GFP-expressing cells in all microscopic fields. The sample containing 4.0 μg of plasmid expressing L, 0.5 μg of plasmids expressing NP and VP35, 0.3 μg of plasmid expressing VP30, and 1 μg of plasmids expressing GP, VP40, VP24, p3E5EGFP, and pC-T7Pol (which produced ∼600 infectious VLPs/ml of supernatant) was chosen as the reference (value of 1).