The purification and nature of an antiviral protein from Cuscuta reflexa plants

An antiviral substance, showing highly significant virus inhibiting property, has been isolated from the aqueous extract of Cuscuta reflexa plants. The biologically active virus inhibitor was purified by fractionation with organic solvents followed by precipitation with a saturated solution of ammonium sulphate, dialysis, ultracentrifugation and filtration through a Sephadex G-200 column. It shows characteristics of proteins with a molecular weight around 14,000-18,000 daltons. The antiviral activity of the purified material was increased several folds. It has prevented the infection of several unrelated isometric as well as anisometric viruses in their hypersensitive and systemic hosts. Systemic resistance induced in lower treated as well as upper nontreated leaves of host plants, whose lower leaves had been treated with inhibitor, was significantly reversed in presence of Actinomycin D.