The effect of topical and systemic treatment with 9-(1,3-dihydroxy-2-propoxymethyl)guanine on the evolution of herpes simplex virus-induced skin infection in hairless mice was investigated. Systemic (subcutaneous) treatment with a 10-mg/kg dose and topical-applications with a 5% cream started up to 48 h after infection prevented the development of severe skin lesions and a fatal outcome. However, the establishment of latent infections was prevented only by topical treatment started at 6 h after infection. Systemic (50 mg/kg) and topical treatments started 48 h after infection reduced virus titers in the skin and ganglia and promoted rapid clearance of virus from these sites. The clearance of infectious virus from ganglia during the acute phase of infection was followed by early establishment of latency. 9-(1,3-Dihydroxy-2-propoxymethyl)guanine (0.03 ,ug/ml) significantly inhibited the synthesis of infectious virus in explant cultures of latently infected ganglia, and at concentrations higher than 8 ,Lg/ml no infectious virus was detectable in ganglia explant cultures.The acyclic nucleoside 9-(1,3-dihydroxy-2-propoxymethyl)guanine (DHPG), synthesized by the procedures described by Ogilvie and Gillian (20), Martin et al. (19a), and Ashton et al. (1) has been shown to be an effective inhibitor of herpes simplex virus (HSV) and cytomegalovirus replication in cell cultures (1, 2, 4, 5,19,23,26). DHPG proved to be superior to acyclovir (ACV) in the treatment of HSV-induced encephalitis and vaginitis in mice (1, 5, 6, 8,26) and was effective in reducing the severity of primary and recrudescent lesions induced by genital infection of guinea pigs (9) and by eye infections in rabbits (27). Although 4 to 35 times more DHPG is required to inhibit cytomegalovirus in cell cultures than is necessary to inhibit HSV (26). DHPG is a more potent inhibitor of cytomegalovirus than is ACV. DHPG is an efficient substrate for HSV-induced thymidine kinase (1, 2,26) and is more rapidly converted to the corresponding triphosphate derivative in virus-infected cells than is ACV (1, 10). The triphosphate of DHPG competitively inhibits incorporation of dGTP into DNA catalyzed by the DNA polymerase specified by HSV (7,25).In this study we have investigated the effect of DHPG on experimental HSV-induced skin infections in hairless mice and have examined the ability of the drug to prevent the colonization of sensory ganglia and the establishment of latency by the virus. In addition we have determined the concentration of DHPG required to prevent the reactivation of HSV in explant cultures of latently infected mouse trigeminal ganglia. stock virus, and the quantification of inocula have been described in a previous publication (16).
MATERIALS AND METHODSInoculation of mice. Female hairless mice of the fully immunocompetent HRS/J strain were obtained from Jackson Laboratories, Bar Harbor, Maine, and used in the experiments at the age of 6 to 8 weeks. The mice were inoculated percutaneously on a triangular area of the snout by rubbing a virus susp...