TABLE 4.

Comparison of LD₅₀s of high-fidelity variants and parental RG/B4^a

Virus	Virus amt (TCID50)	Mouse no.	Death rate (%)b	LD50 (TCID50)	Ratio of LD50 to the LD50 of RG/B4
RG/B4	108	6	100	4.3 × 105	1
	107	8	100
	106	9	78 (7/9)
	105	7	0
RG/B4-L123F	108	6	100	1.6 × 107	37
	107	8	37.5 (3/8)
	106	6	0
RG/B4-G64R	109	7	100	4.0 × 107	93
	108	6	83 (5/6)
	107	6	0
RG/B4-G64R/L123F	109	6	83 (5/6)	2.3 × 108	535
	108	6	33 (2/6)
	107	6	0

^aLD₅₀s of all high-fidelity variants were significantly higher than the LD₅₀ of the parental RG/B4.

^bValues in parentheses are the number of mice that died/total number of mice in the group.