Table 3.

Frequency of SV40 vertical transmission to progeny animals is higher from mothers inoculated with SV40 variants with complex regulatory region structures^a

Type of regulatory region	Strain/variant	No. litters positive/No. tested (%)	No. progeny positive/No. tested (%)b	No. tissues positive/No. tested (%)b
Simple	Baylor-1E SVCPC	0/1 (0) 1/1 (100)	0/12 (0) 2/8 (25)	0/36 (0) 3/14 (21)
Total:		1/2 (50)	2/20 (10)c	3/50 (6)d
Complex	Baylor-2E SVPML-1	1/1 (100) 1/1 (100)	13/14 (93) 6/6 (100)	23/39 (59) 16/18 (89)
Total:		2/2 (100)	19/20 (95)c	39/57 (68)d

^aAnalysis of litters harvested 7 days after birth.

^bThree tissue slices for each of three different organs (spleen, kidney, brain) were analyzed for SV40 DNA for each animal.

^cp<0.001

^dp<0.001.