TABLE 3.

Infectious center assay for env vector transmission by gpgpt-based packaging NSCs

NSC type	Mean ± SD		IC efficiency (%)c
	IC focia	Mean plating efficiency (%)b
gpgpt	<0.05d	NDe	ND
CasE-gpgpt	15.3 ± 2.1	17.8 ± 2.0	86.0
FE-gpgpt	10.3 ± 3.8	12.2 ± 2.0	83.3

^aMitomycin C-treated and trypsin-EDTA-resuspended engineered NSCs were seeded with 10⁵ naive Mus dunni cells at different ratios. The numbers of Env-expressing foci were evaluated when target cells reached confluence. Numbers are expressed as IC foci/100 NSCs seeded.

^bTo determine the efficiency of plating, mitomycin C-treated NSCs were seeded alone, and the vector-expressing cells present on these plates were assessed at the same time as those seeded with targets. Plating efficiency indicates the percentage of seeded cells that attached.

^cIC efficiency is the number of foci/100 NSCs seeded divided by the plating efficiency and is expressed as a percentage.

^dNo retroviral Env-positive cells were detected with both virus-specific and broadly reactive antiviral antibodies in assays where 2,000 NSCs were seeded into each assay.

^eND, not determined.