Survival analysis and clinical score of WNV Eg101 and WNV NY99 infected mice. (A) Eight-week old C57BL/6J mice were inoculated subcutaneously with 1000 or 100 PFU of WNV Eg101 or WNV NY99. A group of mice were also inoculated with PBS (Mock). All mice were observed for 21 days. Data are combined of two independent studies (n = 16 per group). (B) Animals were monitored for clinical scores twice a day. The designation for the clinical scores is as follows: 1, ruffled fur/hunched back; 2, paresis/difficulty walking; 3, paralysis; 4, moribund/euthanized; and 5, dead. Error bars represent SEM. * p < 0.001, ** p < 0.0001.