Characterization of a cDNA of Epstein-Barr Virus DNase Gene

A complementary DNA (cDNA) library of mRNAs obtained from P3HR1 cells treated with IUDR was constructed in λgt10 and screened with radiolabeled B95–8 EBV DNA Bam HI fragment B and G probes. One clone, designated BG9, containing a 1.7 kb cDNA was further studied. Results of complete DNA sequencing revealed that BG9 emcompassed the B95–8 EBV DNA sequences from 120,747 to 122,412 base pairs and corresponded to the BGLF5 open reading frame of EBV DNase gene. A detailed comparison of the sequences of BG9 with those of published B95–8 EBV DNA indicated that there were 14 different base pairs which may result in 7 amino acid residue changes.. The products of in vitro transcription and translation of a subclone, pGEM3–BG9, appeared to contain EBV DNase activity and a 52 kd protein was immunoprecipitated with a NPC patient’s serum containing high level of antibody to this enzyme activity.