Herpes Simplex Virus Non-structural Proteins. IV. Purification of the Virus-induced Deoxyribonuclease and Characterization of the Enzyme Using Monoclonal Antibodies

Department of Microbiology, University of Leeds, Leeds LS2 9JT, U.K. and 1 Department of Virology and Epidemiology, Baylor College of Medicine, Houston, Texas 77030, U.S.A. The alkaline nucleases induced by herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) have been purified from high salt extracts of virus-infected cells. The purification used three types of column chromatography and resulted in apparently homogeneous DNase preparations with good recovery. The enzyme from HSV-2-infected cells has been characterized. It had both exonuclease and endonuclease activity, each with an unusually high pH optimum. The enzyme had an absolute requirement for magnesium which could not be replaced by other divalent cations. Analysis of the sedimentation characteristics and electrophoretic properties of the purified enzyme indicated that it was composed of a single subunit of mol. wt. 85000. The purified HSV-2 enzyme was used as an immunogen to prime BALB/c mice which were used to prepare monoclonal antibodies. Three monoclonal antibodies were shown by several criteria to react with the enzyme. Thus, we were able to confirm that the 85K polypeptide did indeed have nuclease activity. This polypeptide was designated ICSP 22 in earlier studies and is a major polypeptide of virus-infected cells. Keywords: HSV-1 and -2, induced enzyme, nuclease, monoclonal antibodies Received 5 May 1983; accepted 8 July 1983.