ANTIRETROVIRAL ACTIVITIES OF HYPERICIN AND ROSE-BENGAL - PHOTODYNAMICEFFECTS ON FRIEND-LEUKEMIA VIRUS-INFECTION OF MICE

The ability of hypericin to protect mice from splenomegaly resulting f rom infection with Friend leukemia virus (FLV) was re-examined in ligh t of recent evidence showing that light is absolutely required for thi s drug's antiviral activity. FLV-induced splenomegaly was not prevente d or ameliorated in mice injected with 100 mug hypericin, either mixed with the FLV inoculum or administered 1 day p.i., either under normal laboratory light or in the dark. These results contradict previous fi ndings. Both hypericin and rose bengal, however, inactivated the FLV i noculum at low doses (< 11 mug), provided that the mixture was illumin ated for 1 h under a normal fluorescent desk lamp. This procedure prot ected mice completely from FLV-induced splenomegaly, and provided a po ssible explanation for the discrepancy between our results and those r eported previously. We conclude that for FLV, as for other enveloped v iruses studied previously, illumination of hypericin with the virus is absolutely required for hypericin's antiviral (virucidal) effects, th us limiting its potential usefulness as an antiretroviral agent.