Animal Models of Herpes Skin Infection

Publisher Summary This chapter presents a guinea pig model of herpes skin infection. The animals used in this model are female Hartley outbred albino guinea pigs, of 500 g each. Each of them are injected with about 0.24 ml of 50 mg ketamine/ml plus 10 mg xylazine/ml, subcutaneous (s.c.), high on the back between the shoulder blades, by using a tuberculin syringe with a 25 G 5/8 in needle. After 5–10 minutes, the animals are sedated. The dorsal skin of the anesthetized animals are infected with HSV-1 in four quadrants with 10 well-spaced activations of a vaccination instrument in each quadrant. Ideally, the infection in each quadrant develops over the course of four days into 10 small, well-spaced circles of six lesions in each circle for a total of 60 lesions per area. The virus is harvested from the skin and the amount present is determined in a plaque assay. The clinical parameters for each drug versus placebo pair are total lesion number, total lesion area, and virus titer. Histology of a cutaneous HSV-1 lesion, 72 hours after inoculation of the skin, shows that the infection primarily involves the epidermal layer in the skin with focal epidermal destruction, leukocytic infiltration of the epidermis and adjacent dermis, and cytologic changes in infected epidermal cells typical for HSV. The infection is confined to the skin of the animal's back. Food and water intake are normal and general health is maintained. Any lethargy or abnormal behavior on the part of a guinea pig is usually associated with an overdose of or reaction to anesthesia rather than systemic infection.