FIG 3 .

Adult B6 IFNRI^−/− mice immunized with bicistronic LGTVs are protected against lethal challenge with wt LGTV. (A) Survival of B6 IFNRI^−/− mice (n = 5) after immunization. Mice were inoculated i.p. with 10⁵ PFU/mouse of rLGTVs or with diluent alone (mock). (B) Survival of vaccinated mice after i.p. challenge with 10² PFU of wt LGTV. At 31 days postvaccination, animals were challenged with wt LGTV and monitored for neurological signs of disease. (C) Neutralizing antibody titer in the serum of B6 IFNRI^−/− mice at 28 and 56 days postinoculation with bicistronic LGTVs. Neutralizing antibody titer was determined using the 50% plaque reduction neutralization assay (PRNT₅₀) against wt LGTV. (D) Titer of wt LGTV in the serum of mice on days 1 and 4 postinfection. B6 IFNRI^−/− mice immunized with bicistronic LGTVs or mock-infected animals were challenged on day 32 with 10² PFU of wt LGTV. Virus titer in the serum was determined by titration in LLC-MK2 cells. The dashed line indicates the limit of virus detection (1.7 log₁₀ PFU/ml of serum).