Antiviral agent from lambda-infected Escherichia coli K-12. I. Isolation.

Phagicin, which is an antiviral agent active against deoxyribonucleic acid (DNA) viruses such as vaccinia and herpes simplex, has been identified as a phage internal protein. It was found in infected Escherichia coli lysates, but could also be obtained by disruption of the purified infective particles after incubation with LiCl at 46 C for 15 min or by sonic treatment. After centrifugation at high speed, the antiviral activity was found in the DNA phase and could be separated by chromatography on Sephadex gels with 0.2 M phosphate buffer (pH 7.5) as the eluent. Phagicin present in lysates after removal of infective particles was nondialyzable and was bound to nucleic acids. It could be released during precipitation of nucleic acids by streptomycin sulfate, and in this form it could be easily dialyzed. The antiviral activity of phagicin was specific for herpes simplex and vaccinia viruses.