Five murine and 3 human tumor cell lines were transfected with a retroviral vector that carries the EBV encoded
EBNA-1 gene. All cell lines expressed intranuclear
EBNA-1 as detected by
anticomplement immunofluorescence and Western blot assays. The cell lines differed in the level of
EBNA-1 expression and the size of the
protein. The internal major late promoter of adenovirus was efficient in directing the transcription of
EBNA-1 in the human
lymphoma line BJAB, the murine
T-cell lymphoma Tikaut, RBL-5, EL-4 and in the mouse
sarcoma line MSWBS but was less efficient in Ramos, an EBV negative
Burkitt lymphoma line, the human
T-cell leukemia line 1301TK and the P815-X2 mouse
mastocytoma line. All transfected lines except MSWBS contained
EBNA-1 in a truncated form. The truncated
EBNA-1 polypeptide reacted with the conventional human antibody
reagents in an EBNA specific fashion but failed to bind rabbit or human antibody directed against the
glycine-
alanine repeat sequence. MSWBS contained a truncated as well as a full size
EBNA-1 polypeptide. It also reacted with antibody directed against the
glycine-
alanine repeat. This indicates that the repeat sequence is regularly affected by the truncation.