FIG. 1.

Survival curve analyses of mice inoculated with viral clones. (A to D) Mice were inoculated with viral clones BE (n = 24), AE (n = 12), and SA (n = 8) (A), BE-1 (n = 4), BE-2 (n = 31), BE-3 (n = 12), and BE-4 (n = 11) (B), BE-5 (n = 10) and BE-6 (n = 24) (C), and BE-7 (n = 11) and BE-8 (n = 55) (D). IRW mice were infected with 10⁴ focus-forming units of virus within 24 h of birth by intraperitoneal inoculation. Mice were monitored for clinical signs of severe ataxia and seizures. Variant residues encoded between BbsI and EcoRI are shown for all viruses. The amino acid residues encoded by BE (white letters on a black background) and the amino acid residues encoded by Fr54 (black letters on a white background) are indicated. The numbers indicate the amino acid residue positions in the gp70 SU protein.