Table 4.

Viral loads in brain tissue from 6- to 7-day-old CD1 mice after SC infection with WT or mutant CHIKV strain LR or vaccine strain 181/25

Virus straina	Day 2 postinfection		Day 4 postinfection		Day 6 postinfection		Day 8 postinfection
	No. of animals positive/total no. inoculated	Mean titerb of positive animals ± SD	No. of animals positive/total no. inoculated	Mean titerb of positive animals ± SD	No. of animals positive/total no. inoculated	Mean titerb of positive animals ± SD	No. of animals positive/total no. inoculated	Mean titerb of positive animals ± SD
LR	3/3	3.9 ± 1.3	2/3	2.3 ± 1.3	2/3	3.1 ± 2.1	0/3	≤ 0.9
LR/nsP1	1/2	2.3 ± 2.0	0/2	≤ 0.9	1/2	2.8 ± 2.6	1/2	2.2 ± 1.8
LR/6K	3/3	4.2 ± 0.4	2/3	3.9 ± 2.8	3/3	4.3 ± 1.2	2/3	3.7 ± 2.6
LR/E1	2/3	3.0 ± 1.8	2/3	4.6 ± 3.3	2/3	2.4 ± 1.3	1/3	1.7 ± 1.3
LR/E2-12	0/3	≤ 0.9	1/3	1.8 ± 1.6	0/3	≤ 0.9	0/3	≤ 0.9
LR/E2-82	0/2	≤ 0.9	0/2	≤ 0.9	0/2	≤ 0.9	0/2	≤ 0.9
181/25	0/2	≤ 0.9	1/2	3.7 ± 3.9	0/2	≤ 0.9	0/2	≤ 0.9

^aSee Fig. 1b for strain designations.

^bTiters are in log₁₀ PFU/g of tissue, and the limit of detection of the assay was 0.9 log₁₀ PFU//g of tissue.