Serological Responses of Patients with Nasopharyngeal Carcinoma to an N-Terminal Epstein-Barr Virus DNA Polymerase Protein Expressed in Prokaryotic Cells.

Abstract

A 1.7-kb cDNA clone, pGEM-cDP, was isolated from a cDNA library of IUdR-induced p3HR1 cells. It contains the upstream nucleotide sequence of the Epstein-Barr virus (EBV) DNA polymerase gene from 156,859 to 155,088, and was subcloned into expression vector pET3cp* by the polymerase chain reaction, giving the plasmid pDP1. Using a T7 RNA polymerase expression system, a 77-kD polypeptide was produced from pDP1 in Escherichia coli and specific hyperimmune serum was generated in mice. The truncated EBV DNA polymerase was shown to possess the authentic antigenicity by an indirect immunofluorescence assay and by immunoblotting using EBV-containing cells as antigens. Serum from nasopharyngeal carcinoma (NPC) patients and healthy donors was examined for antibodies against the 77-kD polypeptide by Western blot analyses and ELISAs. About 70% NPC patients were positive, while less than 15% of healthy persons showed weak reactivities in ELISAs. Copyright 1994 S. Karger AG, Basel