Fig. 1.

Restricted latency is established upon superinfection of latently infected BL cells. Kem I BL cells were superinfected with wt rEBV, and three resulting cell lines, each derived from an independent infection, were monitored by immunoblotting for the expression of EBV EBNA and LMP1 proteins at approximately 1 month (A) and 12 months (B) postsuperinfection. Detection of EBNA and LMP1 expression in Kem I and Kem III BL cells serves as a positive control for latency I and III, respectively; Mutu⁻ is an EBV-negative BL cell line derived from Mutu I cells. Loading of cell lysates was equivalent within panels A and B as determined by blotting for EBNA1 or β-tubulin (not shown).