Antiherpetic activities of acidic protein bound polysaccharide isolated from Ganoderma lucidum alone and in combinations with interferons

To investigate antiherpetic activity, an acidic protein bound polysaccharid e (APBP) was isolated from carpophores of Ganoderma lucidum. This brownish APBP was isolated from water soluble substances of the carpophores by activ ity-guided isolation method. APBP was tested for its antiviral activity aga inst herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) by plaque reduc tion assay in tissue culture. APBP showed potent antiviral activity against HSV-1 and HSV-2 in Vero cells at its 50% effective concentration (EC50) of 300 and 440 mu g/ml, respectively. APBP had no cytotoxicity on Vero cells at a concentration of 1 x 10(4) mu g/ml. APBP exhibited a potent antiviral activity with selectivity index (SI) of more than 22.73. The combined antih erpetic effects of APBP with protein antiviral agents, interferon alpha (IF N alpha) and interferon gamma (IFN gamma), were examined on the multiplicat ion of these two strains of herpesviruses in Vero cells by the combination assay. The results of combination assay were evaluated by the combination i ndex (CI) that was calculated by the multiple drug effect analysis. The com binations of APBP with IFN alpha on HSV-1 and HSV-2 showed more potent syne rgistic effects with CI values of 0.30-0.62 for 50-90% effective levels tha n those of APBP with IFN gamma with CI values of 0.65-1.10. These results s uggest the possibility of developing APBP as a new antiherpetic agent. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.