Antiviral activity of a carrageenan from Gigartina skottsbergii against intraperitoneal murine Herpes simplex virus infection

The partially cyclized mu/v-carrageenan 1C3, isolated from the red seaweed Gigartina skottsbergii, was previously shown to be a potent inhibitor of the in vitro replication of Herpes simplex virus types I (HSV-1) and 2 (HSV-2). Here the protective effect of 1C3 in a murine model of intraperitoneal (i.p.) HSV-1 infection was evaluated. OF1 mice were i.p. infected with 5 x 105 PFU of HSV-1 KOS strain, and the effects of different treatments with 1 G were studied. When 30 mg/kg of body weight of 1C3 was administered by the i.p. route immediately after HSV-1 infection, 87.5% survival of the animals was achieved (p < 0.005), associated with a delay in the mean day of death in I G-treated non-surviving mice. Animal survival was not improved when multiple doses of 1C3 were also given in the period 1-48 h post-infection, and no protection was afforded when treatment was started after 24 11 of infection. When virus and compound were injected by different routes, i.p. and intravenous (i.v.), respectively, a still significant protection was achieved (40% survival, p < 0.05). No toxicity of 1C3 for the animals was recorded. The pharmacokinetic properties were analyzed after injection of 10 into the tail vein by monitoring of [H-3]-1C3 in plasma and organs and by a bioassay of the anti-HSV-1 activity remaining in serum after non-radioactive 10 inoculation. A very rapid disappearance of the compound from the blood was observed since only 5.9-0.9% of the radioactivity of the initially administered [H-3]-1C3 appeared in the plasma between 5-300 minutes after administration. A transient peak of radioactivity was detected in the kidney 15 minutes after inoculation. The bioassay confirms the presence of the compound circulating in a biologically active form up to I hour after injection.