(A) Dose response for protection from challenge with 2LD50 HSV-2 by UL29 chol-siRNA. Groups of 5 mice were given the indicated dose of UL29 chol-siRNA 2 hr prior and 4 hr following viral challenge. Optimal protection was achieved with 1 and 2.5 mg/kg. (B-D) Groups of 5 mice received no siRNA (B), GFP chol-siRNA (administered 2 hr before and 4 hr after viral challenge) (C) or nectin-1 and/or UL29 chol-siRNA (D) at indicated times. The total siRNA dose for each administration was 1 mg/kg. Mice were scored for disease severity (purple, no signs of disease; blue, slight genital erythema and edema; green, moderate genital inflammation; yellow, purulent genital lesions; orange, hind limb paralysis; 5, death) over 14 days. The UL29 chol-siRNA protected around the time of viral challenge while the nectin-1 siRNA did not become effective until a few days later, but protection persisted for a week. Combining both siRNAs provided protection from challenge at any time during the week. (E) Vaginal histopathology (hematoxylin and eosin staining) 6 days following infection in mice treated as indicated. (Boxes indicate magnified area below). Data are representative of two experiments. Mice treated with a combination of nectin-1 and UL29 chol-siRNAs had essentially no signs of inflammation or cell death.