ANTIVIRAL PROPERTIES OF EXTRACT OF OPUNTIA STREPTACANTHA

An extract of the cactus plant Opuntia streptacantha inhibited intrace llular virus replication and inactivated extracellular virus. Inhibiti on of virus replication also occurred following pre-infection treatmen t - a favourable finding in terms of in-vivo limitation of virus disea se. There was inhibition of both DNA and RNA virus replication, for ex ample, herpes simplex virus, equine herpes virus, pseudorabies virus, influenza virus, respiratory syncytial virus and human immunodeficienc y virus, with normal protein synthesis in uninfected cells at extract concentrations which were 15-fold in excess of 50% viral inhibitory co ncentrations (1 mg/ml). The active inhibitory component(s) of the extr act appeared to be protein in nature and resided mainly in the wall of the plant rather than in the cuticle or inner sap. The extract was no n-toxic on oral administration to mice, horses and human patients; the non-toxicity of intravenous administration of 70 mg to a mouse repres enting at least fifty tissue culture 50% viral inhibitory dosages enco urages clinical trial of this extract in virus disease of human and ve terinary species.