Recombinant human growth hormone protects thermally injured mice infected with herpes simplex virus

As a promoter of wound healing and skeletal muscle function, growth hormone (GH) has been used clinically in thermally injured patients. In the present study, an antiviral efficacy of GH in thermally injured mice infected with herpes simplex virus type 1 (HSV) was investigated, because the protective effect of GH in rats infected with Salmonella typhimurium has been recently reported. Recombinant GH was provided from Genentech, Inc., South San Francisco, CA. BALB/c mice were subjected to a flame burn (3rd degree, 30% of total body surface area), and designated as thermally injured mice (TI-mice). A 5LD₅₀ dose of HSV (KOS strain) grown in Vero cells was challenged i.p. to TI-mice. IFN was measured by a plaque reduction assay and IFNγ was detected by an ELISA assay. When GH (4 mg/kg, s.c.) was administered to TI-mice every other day for 5 times beginning just after the bum, a 38% survival rate was obtained, as compared with 0% survival of TI-mice treated with saline. Protection of TI-mice infected with the same dose of HSV was also demonstrated when GH was injected to them prophylactically (1, 2 and 3 days before burn). IFN (153 IU/ml) was detected in serum specimens from mice 12 hrs after treatment with GH (10 mg/kg, s.c.), and 84 IU/ml of IFNγ was detected in these sera. These results suggest that GH administered exogenously may have a potential to protect TI-mice infected with HSV. IFN may play a role on this protective response.