FIG. 5.

BRLF1 interaction with CBP is important for activation of the early SM gene in Raji cells. (A) Latently infected, EBV-positive Raji cells were transfected with a control vector or expression vectors for BZLF1 or BRLF1. Cell extracts were harvested 1 day later and immunoblotted with antibodies directed against the BMRF1 or SM early EBV proteins. BMRF1 protein was detected using a monoclonal antibody (Capricorn; 1:100 dilution) and SM protein was detected using a rabbit polyclonal antibody (1:400 dilution) provided by Sankar Swaminathan. (B) Raji cells were transfected with 2 μg of the BRLF1 expression vector (pRTS15) or control vector (SG5) in the presence or absence of the CBP expression vector (5 μg) (keeping the total DNA level constant). Cell extracts were harvested at 24 h posttransfection and immunoblotted for SM early protein. (C) Raji cells were transfected with the BRLF1 expression vector (2 μg), control vector (2 μg), wild-type E1A (10 μg), or mutant E1A (Δ2-36) (10 μg), keeping the total DNA level constant. Cell extracts were harvested at 24 h posttransfection and immunoblotted for SM early protein. (D) The same extracts shown in panel C were immunoblotted using an antibody which recognizes BRLF1.