Abstract
We have isolated mutants of Epstein-Barr virus (EBV) which carry a dominant selectable marker inserted into the third exon of the gene encoding two membrane proteins, TP1 and TP2 (or LMP2A and LMP2B), which are expressed in latently infected, growth-transformed B cells. One of the mutants also acquired a 260-bp deletion beginning in the first intron a few base pairs from the terminal repeats and removing most of the second TP exon, including the initial coding sequences of TP2. These EBV mutants transform human B cells in culture, and the transformed B-cell clones carrying them release EBV at approximately normal frequencies.