Table 2.

Role of rsT3D^F/T3D^C S1 gene products in viremia^a

Strain and day postinfection	Viremia (no. of positive mice/total no. of mice)
T3DF
1	1/5
2	0/5
4	0/5
rsT3DF/T3DCS1
1	7/8
2	6/8
4	4/8
rsT3DF/T3DCS1 σ1s-null
1	3/5
2	3/5
4	1/5

^aCBA/J mice were inoculated intranasally with 10⁷ PFU T3D^F, rsT3D^F/T3D^CS1, or rsT3D^F/T3D^CS1 σ1s-null. Blood was collected by heart puncture at the indicated times postinoculation, and viral titers were determined by plaque assay using L929 cells. Results are expressed as the number of mice with detectable virus in the blood (limit of detection, 10 PFU/ml).