TABLE 1.

Plaque formation on NIH 3T3 cells after transfection of the MCMV BAC plasmids in the absence or presence of pBam25^a

Transfection condition	Plaque formation after transfection of BAC plasmid:
	pSM3fr	pSM3frdie3	pSM3frdie3::GFP	pSM3fr-rev
BAC plasmid only	+++	−	−	+++
Cotransfection of BAC plasmid and pBam25b	+++	+	+	++

^aScoring of the transfections was as follows: +++, 10–20 plaques; ++, 5–10 plaques; +, 1–5 plaques; −, no plaques. 

^bPlasmid pBam25 spans the deletion in the ie3-deficient BAC plasmids and encodes the MCMV IE genes ie1 and ie3.