Inhibition of certain deoxyribonucleic acid viruses by liver extracts.

A proteinaceous substance was detected in the liver of several animal species that inhibited the multiplication of certain deoxyribonucleic acid, but not ribonucleic acid, viruses. Preliminary experiments suggested that its site of action was not extracellular. It did not inhibit virus by interfering with adsorption to cells. It was suggested that this inhibiting substance acts directly upon cells by interfering with viral synthesis.