Figure 4.

Rimantadine protects mice from lethal infection with an influenza virus possessing the 1918 M segment. (a) Survival after infection with the indicated viruses and either mock treatment with PBS or treatment with rimantadine. An uninfected but treated control group was included also. (b) Average weight of mice from the same groups as in a. Average weight is reported for all mice surviving at the indicated time points. Groups of 8 or 9 mice were infected with 10 LD₅₀ of wild-type (WT) WSN virus (circles) or 1918 M virus (squares) or with 10⁶ pfu of Udorn M virus (1 LD₈₀, triangles). The mice then were mock-treated with PBS (filled symbols) or treated with 40 mg/kg of body weight of rimantadine hydrochloride (open symbols). PBS or drug was administered i.p. beginning 6 h postinfection and once daily afterward. One group of mice was left uninfected and treated with rimantadine (filled diamonds).