Hypomethylation of Epstein-Barr virus DNA in the nonproducer B-cell line EBR

The conversion of the Epstein-Barr virus-negative Ramos cell line has previously been shown to result in an Epstein-Barr virus-positive non-virus-producer cell line, EBR. We report here that Epstein-Barr virus DNA from EBR alone among several cell lines examined was totally unmethylated at three of four sites containing guanine plus cytosine which were tested. This is in direct contrast to reports of high degrees of methylation in the DNAs of other animal viruses, including herpesviruses, isolated from cells in which the viral genome is expressed at a low level.