Fig. 7.

C4 is a virulence factor. BALB/c mice (n = 5) were infected intranasally with the indicated viruses and their weights and signs of illness were measured daily (Methods). (a) Weights. Data (means±sd) are expressed as a percentage of the mean weight of the same group of animals on day 0. (b) Signs of illness. The mean ±sem score of each group of animals is shown. □, Mock; •, vC4; ○, vΔC4; ▴, vC4-Rev. The horizontal bars indicate days on which the weight loss or signs of illness induced by vΔC4 was statistically different (P<0.05) from both vC4 and vC4-Rev.