TABLE 1.

Analysis of the genetic stability of PV-Luc-EMCV following encapsidation and serial passage at three different temperatures

Passage	37°C		33°C		30°C
	Luciferase activity?b	Genomea	Luciferase activity?	Genome	Luciferase activity?	Genome
Transfection	Yes	Deleted	Yes	Dicis	Yes	Dicis
2	Yes	Deleted	Yes	Dicis	Yes	Dicis
4	No	—	Yes	Deleted	Yes	Mixed
8	—	—	Yes	Deleted	Yes	Deleted

^aDeleted, deleted genome detected by RT-PCR (see Fig. 3 for description of genomes); dicis, starting dicistronic genome sequence detected by RT-PCR; mixed, multiple bands from RT-PCR, including both dicistronic genomes and deleted genomes; —, not done. 

^bLuciferase activity from an infection with replicons from a transfection or designated passages. Yes, 100-fold over background luciferase activity obtained from uninfected HeLa cells; No, background luciferase activity. Loss of the replicon was confirmed by no 3D^pol-related proteins immunoprecipitated from metabolically labeled cells infected with the designated passage. Note that in passages 4 and 8 at 33°C, the levels of luciferase activity were 10⁴- to 10⁶-fold over background. See text for details.