FIG. 3.

Morbidity, mortality, and viral titers in infected mice. B6 mice were infected intranasally with 1,000 PFU of protein 6 variant viruses or controls and monitored daily for mortality (A and B) and weight loss (C and D). (A and C) Mortality (A) and weight loss (C) after infection with rJ2.2.6 (n = 35), rJ2.2.6^KO (n = 31), or viruses expressing protein 6 with mutated sorting motifs [rJ2.2.6^0(DxE) (n = 19) or rJ2.2.6^1(DxE)] (n = 26). (B and D) Mortality (B) and weight loss (D) after infection with rJ2.2.6, rJ2.2.6^KO, or viruses expressing 6 protein with hydrophobic domain deletions (rJ2.2.6^Δ3-10 [n = 10], rJ2.2.6^Δ11-18 [n = 10], or rJ2.2.6^Δ3-18 [n = 18]). (E and F) Viral titers in brain homogenates from infected mice were determined by plaque assay on HeLa-MHVR cells. (E) Virus titers in mice infected with rJ2.2.6 (n = 5), rJ2.2.6^1(DxE) (n = 5), or rJ2.2.6^0(DxE) (n = 5) were greater than those infected with rJ2.2.6^KO (n = 5) (P < 0.01) at day 3 p.i. Titers for rJ2.2.6^1(DxE)-infected mice (n = 7) were greater than those infected with rJ2.2.6 (n = 5), rJ2.2.6^KO (n = 5), or rJ2.2.6^0(DxE) (n = 10) at day 5 p.i. (P < 0.05). (F) Titers in the brains of mice infected with rJ2.2.6^Δ3-18 (n = 4) were significantly lower than those found for mice infected with rJ2.2.6 (n = 5), rJ2.2.6^Δ3-10 (n = 6), or rJ2.2.6^Δ11-18 (n = 4) at day 7 p.i. (P < 0.01).