Epstein-Barr-virus-infected human T-cell line with a unique pattern of viral-gene expression.

Epstein-Barr-virus(EBV)-gene expression was analyzed in clonal sub-lines of the human T-cell line MT-2 that are persistently infected by the virus with a positive selection marker. Immunoblot analyses showed the expression of EBV proteins associated with the latent viral cycle, including the EBV nuclear antigen 1 (EBNA1) and the latent membrane protein 1 (LMP1), whereas EBNA2 was not detected. RT-PCR further demonstrated the expression of LMP2A, EBV-encoded small RNA 1 (EBER1), and complementary-strand transcripts from the BamHI-A fragment. EBNA2 mRNA was detected at a very low level. In addition to these latent viral functions, the BZLF1 protein, a transcription factor that activates a cascade of replicative-gene expression in EBV-infected B cells, was detected in these MT-2 clones by immunoblot analysis and immuno-enzymatic staining. Moreover, mRNA from other genes of the early virus-replicative cycle, such as BRLF1, BSMLF1, and BALF2, as well as BZLF1 was detected by Northern-blot analysis. Since sub-lines of the human B-cell lines BJAB and Louckes infected with similar recombinant EBV did not express these early genes, these data suggest that MT-2 cells are relatively permissive for expression of early EBV-replicative functions.