TABLE 1.

Incidence of polytropic virus in mice transplanted with pseudotyping NSCs

4070A infection of NSCs	NSC viral vector	Serum MCF incidencea
No	None	0/6
Yes	None	1/13
No	CasE	0/7
Yes	CasE	2/21
No	CasES	0/8
Yes	CasES	1/15
No	hrGFP	0/7
Yes	hrGFP	0/17

^aPolytropic virus was detected in the sera using a focus assay with a mixture of MAbs specific for polytropic Env proteins, including MAbs 514, 516, and Hy7 (8). The titers for polytropic virus-positive animals were greater than 10² to 10³ FFU/ml. The incidence values are expressed as the number of mice with detected virus/total number of mice examined.