SYNERGY BETWEEN HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 AND EPSTEIN-BARR-VIRUS IN T-LYMPHOBLASTOID CELL-LINES

CR2 (CD21), the EBV receptor, was detected on three of four CD4-positi ve cell lines by indirect fluorescent labeling, and its corresponding mRNA was found by use of the reverse transcription-based polymerase ch ain reaction, To determine whether CR2 on CD4-positive cells was funct ional, their ability to be infected by EBV was analyzed. EBV DNA, EBV nuclear antigen 2 (EBNA-2A), and EBV-encoded small RNA (EBER1) transcr ipts could be detected in CR2-expressing CD4-positive cells following infection by the B95.8 strain of EBV. Analysis of the terminal region showed the EBV genome remained linear following infection, and copy nu mber decreased with time, Since CD4-positive cell lines are targets fo r HIV-1 infection, the effects of EBV infection on HIV-1 expression we re analyzed, HIV-1 replication was upregulated when CD4-positive cells were coinfected with EBV strain B95.8 but not P(3)HR-1K. These result s suggested that EBNA-2 is involved in upregulation of HIV-1 expressio n in T lymphoblastoid cell lines, To test this hypothesis an EBNA-2-ex pression vector was transfected into T lymphoblastoid cell lines and H IV-1 expression measured. First, trans-activation of HIV-1 long termin al repeat (LTR) by Tat was enhanced by EBNA-2 type 1 expression, trans -Activation of the HIV-1 LTR by Tat was also enhanced when CD4-positiv e cells were infected by EBV (strain B95.8) encoding an intact EBNA-2, but not by P(3)HR-1K with a deleted EBNA-2. In addition, CD4-positive cell clones stably expressing EBNA-2 supported enhanced HIV-1 replica tion as measured by accumulation of reverse transcriptase activity and syncytium induction, This provides direct evidence that EBV infection can enhance HIV-1 replication in T cells, Whether this in vitro pheno menon contributes to disease progression in vivo remains to be determi ned.