Studies on the Herpes Simplex Virus Alkaline Nuclease: Detection of Type-common and Type-specific Epitopes on the Enzyme

Abstract

Five monoclonal antibodies to the alkaline nuclease of herpes simplex virus (HSV) types 1 and 2 were used in immunoperoxidase tests to demonstrate the nuclear localization of the enzyme within HSV-1- and HSV-2-infected HEp-2 cells and to purify the enzyme from cells infected with either virus by immunoadsorbant chromatography. Affinity chromatography with a 32P-labeled extract of HSV-2-infected cells has demonstrated that the nuclease eluting from the immunoadsorbant is a phosphoprotein, hence confirming the nuclease to be identical to the phosphorylated polypeptide previously referred to as ICSP 22 (HSV-2) or ICP 19 (HSV-1). The results clearly demonstrate that monoclonal antibodies Q1, CC1 and CH2 are directed against HSV type-common epitopes while V1 and T2T1 antibodies are against HSV-2-specific epitopes on the enzyme. Using the type-specific monoclonal antibodies in an immunoperoxidase test, the enzyme specified in cells infected with intertypic recombinants was typed; correlation of these data with restriction endonuclease maps of the recombinants permitted mapping of the position of the active site of the nuclease gene to map units 0.168-0.184 on the genomes of both HSV-1 and HSV-2. Taken with the data mapping the mRNA encoding this enzyme, the nuclease active site can be mapped to 0.168-0.175 on the genome. The use of monoclonal antibodies in immunofluorescence tests on infected cells has demonstrated that the nuclease is synthesized within 2 h post-infection.