Studies on the association of the Epstein-Barr virus genome with chromosomes in human (Burkitt)/mouse hybrid cells

Abstract

We have used somatic-cell hybrids of mouse fibroblast and Burkitt's lymphoblastoid tumour cells to continue our investigation of the association between Epstein-Barr virus (EBV) genome and human chromosomes. A mouse/Burkitt hybrid cell, designated CL1D/HR-1, was cloned in soft agar. Each of 10 clones was assayed for the spontaneous expression of EBV-associated nuclear antigen (EBNA), early antigen (EA) and virus capsid antigen (VCA). Six of 10 clones were EBNA-positive but negative for EA and VCA even after treatment with iododeoxyuridine. One clone, designated M44, contained approximately 90% EBNA-positive cells and 0.3--0.5 EBV genome equivalents per cell. Thirty subclones of clone M44 were obtained and analysed for EBV DNA, EBNA and human chromosomes. Four subclones (three EBNA-positive and one EBNA-negative) were studied in detail. Data obtained thus far indicate that none of the four subclones of clone M44 studied contained any intact human chromosome. Isozyme analysis of these subclones indicated that all four subclones, regardless of the status of the EBV genome, synthesized nucleoside phosphorylase, an enzyme which has been linked to human chromosome number 14.