TABLE 2.

LD₅₀s of the wt RC-HL, r RC-HL, Nishigahara, and chimeric R(G) strains in suckling and adult mice

Mouse group	LD50 (FFU) of strain:
	wt RC-HL	r RC-HL	R(G)	Nishigahara
Suckling	3.2 × 10−1	1.8 × 10−1	NDa	ND
Adult	>1.0 × 106	>1.0 × 106	1.0 × 100	6.3 × 10−2

^aND, not determined.