Characterization and usefulness of a monoclonal antibody against human herpesvirus-7 DNA polymerase processivity factor

A monoclonal antibody (MAb), IK17, was developed and found useful for the analysis of human herpesvirus-7 (HHV7) genome replication. In Western blot analysis, the MAb IK17 specifically detected an HHV7 DNA polymerase subunit, U27protein, expressed in both Escherichia coli (E. Coli) and HHV7-infected cells. Analysis by the same method of truncated U27 proteins expressed in E. Coli demonstrated that the MAb IK17 recognizes an epitope between amino acid1and133of the U27protein. The indirect immunofluorescence (IF) method with MAb IK17detected an unexpected reduction of U27 protein in the infected cells that were treated with a viral DNA polymerase inhibitor, phosphonoacetic acid (PAA), although no reduction of U27 mRNA was observed in the cells by Northern blot analysis.The data suggest the possible usefulness of the MAb IK17 for obtaining clues to characterize an unknown feature of the U27 protein.Immunoprecipitation experiments with the MAb IK17 enabled to detect at least four U27 protein-associated phosphorylated polypeptides in addition to the U27 protein itself. The result indicates the usefulness of the MAb IK17 for qualitative and quantitative analysis of the U27 proteinassociated viral and cellular factors. These analyses contribute to elucidation of the HHV7genome replication system.