Table 1.

Comparison of packaging levels of SIN-βgal vector by PCL

Cell line	Vector titer, IU/ml	RCV titer, PFU/ml
S22	1–5 × 106	5–100
F15	1–5 × 106	5–100
987dlneo	1–5 × 108	∼105
987dlsplit	5 × 106—1 × 107	<5*

SIN-βgal vector RNA was transcribed in vitro and electroporated into the indicated PCLs. Culture supernatants were harvested and clarified at 48-hr posttransfection, and titers were determined for SIN-βgal vector particles (IU/ml) and contaminating RCV (PFU/ml). Detection limit of 1 PFU/2 × 10⁶ IU. 

^*RCV also was undetected by blind serial passage in naive BHK cells.