TABLE 2.

Biological assessments of the NDV recombinant viruses.

Viruses	MDTa (h)	ICPIb	HAc	EID50d	TCID50e
rLS	134	0.15	2048	3.16 × 109	5.62 × 108
rLS-GFP	140	0.0	2048	3.16 × 109	1.78 × 107
rLS-I-GFP	>150	0.0	512	6.81 × 109	3.16 × 108
rLS-I-RFP-GFP	>150	0.0	256	5.62 × 108	1.78 × 107
rLS-RFP	>150	0.0	512	4.22 × 109	5.62 × 108
rLS-NP-I-RFP	>150	0.0	2048	6.81 × 109	3.16 × 108
rLS-I-GFP-RFP	>150	0.0	256	5.62 × 108	1.78 × 107

^aMean death time assay in embryonating eggs. ^bIntracerebral pathogenicity index assay in day-old chickens. ^cHemagglutination assay. ^dThe 50% egg infective dose assay in embryonated eggs. ^eThe 50% tissue culture infective dose assay on DF-1 cells.