Demyelination of the optic nerve in female BALB/c mice infected with different doses of HSV-IL-2. Female BALB/c mice were infected ocularly with 2 × 103, 2 × 104, 2 × 105, 2 × 106, or 2 × 107 PFU/eye of HSV-IL-2 (five mice/group). The optic nerves were dissected 14 days later, fixed, sectioned, and stained with LFB. The presence of focal and/or diffuse demyelination in multiple sections was determined.