Epstein-Barr virus integrates frequently into chromosome 4q, 2q, 1q and 7q of Burkitt's lymphoma cell line (Raji)

Epstein-Barr virus (EBV) integration into a Burkitt's lymphoma (BL) cell line (Raji) was investigated, using polymerase chain reaction (PCR), Southern hybridization, genomic library screening and fluorescence in situ hybridization (FISH). BaMHIW fragments of the EBV genome and DNA sequences of the viral latent membrane protein (LMP)1 and LMP2 genes were detected in Raji cells. BaMHI-digested high-molecular weight DNA from Raji cells generated 4 and 10 kb, 23 kb fragments that hybridized to Probe-1 (EBV genome 13232–16189) and Probe-2 (EBV genome 5–3271). Genomic library for Raji cells was constructed. Plaques (1 × 105) were screened with Probe-2, and four positive clones were obtained. Chromosomal integration of EBV DNA was detected in the Raji cell. The viral integration sites included 1p, 1q, 2q, 3p, 3q, 4q, 5q, 6q, 7p, 7q, 9q, 11p, 14q and 15q. Despite this multiplicity of integration sites, integration showed high frequency only at the sites 4q, 2q, 1q and 7q; 64% of the total signals were found in these four chromosomal bands. No viral integration occurred in chromosomes 16–22 or the sex chromosomes (X, Y). This study is the first comprehensive FISH analysis of EBV integration into the chromosomes of the Raji cell line. The findings support the notion that EBV integrates into the Raji cell genome non-randomly.