Mice immunized with the HSV-1 R2 mutant are protected from HSV-1 neuroinvasion and periocular skin disease.

(A) Mice were vaccinated by inoculating the left cornea with 7 μl of the HSV-1 R2 mutant stock (R2; 9 x 10⁷ PFU/ml). Sham vaccinated animals received an equivalent volume of conditioned media. At 14 days post vaccination mice were challenged with 7 μl of wild-type HSV-1 strain F (1.0 x 10⁸ PFU/ml) in the right eye. Mice were euthanized at 4 days post infection and the viral load in the whole ipsilateral trigeminal ganglia and brain were determined. The mean titer of each data set is indicated by a red bar (n.d., not detected). (B) Mice were vaccinated as described in (A), at 14 days post vaccination mice were challenged with 5 μl of wild-type HSV-1 McKrae (6.0 x 10⁸ PFU/ml) in the right eye and monitored for survival. (C) Mice were vaccinated as described in (A), and at 14 days post vaccination mice were challenged in the right eye with wild-type HSV-1 (either strain F or McKrae as indicated). The right eye of vaccinated animals was scored for periocular skin disease at the indicated day post challenge. Scoring was based on previous published criteria [56]: 0, no lesions; 1, minimal eyelid swelling; 2, moderate eye lid swelling; 3, severe eye lid swelling with no periocular hair loss; 4, eyes swollen shut with minimal ocular discharge and periocular hair loss; 5 eyes swollen shut with severe periocular hair loss and skin lesions. Values are mean disease scores ± s.d. * Mice were euthanized at 5 days post challenge due to pronounced neurological symptoms.