SummaryEpstein-Barr virus (EBV), a human herpes virus with oncogenic potential, persists in B lymphoid tissues and is controlled by virus-specific cytotoxic T lymphocyte (CTL) surveillance. On reactivation in vitro, these CTLs recognize EBV-transformed lymphoblastoid cell lines (LCLs) in an HLA class I antigen-restricted fashion, but the viral antigens providing target epitopes for such recognition remain largely undefined. Here we have tested EBV-induced polyclonal CTL preparations from 16 virus-immune donors on appropriate fibroblast targets in which the eight EBV latent proteins normally found in LCLs (Epstein-Barr nuclear antigen [EBNA] 1, 2, 3A, 3B, 3C, leader protein [LP], and latent membrane protein [LMP] 1 and 2) have been expressed individually from recombinant vaccinia virus vectors. Most donors gave multicomponent responses with two or more separate reactivities against different viral antigens. Although precise target antigen choice was clearly influenced by the donor's HLA class I type, a subset of latent proteins, namely EBNA 3A, 3B, and 3C, provided the dominant targets on a range of HLA backgrounds; thus, 15 of 16 donors gave CTL responses that contained reactivities to one or more proteins of this subset. Examples of responses to other latent proteins, namely LMP 2 and EBNA 2, were detected through specific HLA determinants, but we did not observe reactivities to EBNA 1, EBNA LP, or LMP 1. The bulk polyclonal CTL response in one donor, and components of that response in others, did not map to any of the known latent proteins, suggesting that other viral target antigens remain to be identified. This work has important implications for CTL control over EBu malignancies where virus gene expression is often limited to specific subsets of latent proteins. CTLs can play an important role in controlling virus infections, particularly as effectors of long-term immune surveillance against viruses that persist in the infected host. This is reflected in the frequency with which reactivation of persistent infections is observed in patients whose CTL responses are suppressed (1). Work in model systems first showed that the dominant components of virns-induced CTL populations are CD8 + MHC class I-restricted T cells (2) and that these effectors recognize peptide fragments of endogenously synthesized viral antigens presented on the target cell surface as a complex with MHC class I molecules (3, 4). In seeking to understand viral infections of humans, therefore, it is important in each case to know both the range of viral antigens that can induce effective CTL responses, and the influence of HLA class I polymorphism upon viral target antigen choice.The present study concerns human CTL responses to EBV. This lymphotropic herpes virus has potent cell growth-transforming activity both in vivo and in vitro, is the causative agent of infectious mononucleosis, and is strongly linked to at least three lymphoid malignancies: endemic Burkitt's lymphoma, the immunoblastic B cell lymphomas seen in immunocompromised patien...

Latent Epstein-Barr virus (EBV) infection and growth transformation of B lymphocytes is characterized by EBV nuclear and membrane protein expression (EBV nuclear antigen [EBNA] and latent membrane protein [LMP], respectively). LMP1 is known to be an oncogene in rodent fibroblasts and to induce B-lymphocyte activation and cellular adhesion molecules in the EBV-negative Burkitt's lymphoma cel line Louckes. EBNA-2 is required for EBV-induced growth transformation; it lowers rodent fibroblast serum dependence and specifically induces the B-lymphocyte activation antigen CD23 in Louckes cels. These initial observations are now extended through an expanded study of EBNA-and LMP1-induced phenotypic effects in a different EBV-negative B-lymphoma cell line, BJAB. LMP1 effects were also evaluated in the EBV-negative Blymphoma cel line BL41 and the EBV-positive Burkitt's lymphoma cel line, Daudi (Daudi is deleted for EBNA-2 and does not express LMP). Previously described EBNA-2-and LMPl-transfected Louckes cells were studied in parallel. EBNA-2, from EBV-1 strains but not EBV-2, induced CD23 and CD21 expression in transfected BJAB cells. In contrast, EBNA-3C induced CD21 but not CD23, while no changes were evident in vector control-, EBNA-1-, or EBNA-LP-transfected clones. EBNAs did not affect CD10, CD30, CD39, CD40, CD44, or cellular adhesion molecules. LMP1 expression in all cell lines induced growth in large clumps and expression of the cellular adhesion molecules ICAM-1, LFA-1, and LFA-3 in those cell lines which constitutively express low levels. LMP1 expression induced marked homotypic adhesion in the BJAB cell line, despite the fact that there was no significant increase in the high constitutive BJAB LFA-1 and ICAM-1 levels, suggesting that LMP1 also induces an associated functional change in these molecules. LMP1 induction of these cellular adhesion molecules was also associated with increased heterotypic adhesion to T lymphocytes. The Burkitt's lymphoma marker, CALLA (CD10), was uniformly down regulated by LMP1 in all cell lines. In contrast, LMP1 induced unique profiles of B-lymphocyte activation antigens in the various cell lines. LMP1 induced CD23 and CD39 in BJAB; CD23 in Louckes; CD39 and CD40 in BL41; and CD21, CD40, and CD44 in Daudi. In BJAB, CD23 surface and mRNA expression were markedly increased by EBNA-2 and LMP1 coexpression, compared with EBNA-2 or LMP1 alone. This cooperative effect was CD23 specific, since no such effect was observed on another marker, CD21. Si analyses revealed that BJAB cells express low levels of FcERIIa CD23 mRNA, and FceRIIb CD23 mRNA was not detectable. LMIP1 preferentially increases FceRIIb CD23 mRNA. EBNA-2 expression alone in BJAB increases the constitutively expressed FceRlla CD23 mRNA. However, when coexpressed with LMP1, EBNA-2 increases total CD23 mRNA without altering the high relative abundance of FcpRIIb to FcrRHla CD23 mRNA induced by LMP1. Thus, LMP1 likely activates the FcrRHb CD23 promoter, while EBNA-2 more likely transactivates a regulatory element common to bot...

Wide-spread protozoan parasites carry endosymbiotic dsRNA viruses with uncharted implications to the human host. Among them, Trichomonas vaginalis, a parasite adapted to the human genitourinary tract, infects globally ∼250 million each year rendering them more susceptible to devastating pregnancy complications (especially preterm birth), HIV infection and HPV-related cancer. While first-line antibiotic treatment (metronidazole) commonly kills the protozoan pathogen, it fails to improve reproductive outcome. We show that endosymbiotic Trichomonasvirus, highly prevalent in T. vaginalis clinical isolates, is sensed by the human epithelial cells via Toll-like receptor 3, triggering Interferon Regulating Factor -3, interferon type I and proinflammatory cascades previously implicated in preterm birth and HIV-1 susceptibility. Metronidazole treatment amplified these proinflammatory responses. Thus, a new paradigm targeting the protozoan viruses along with the protozoan host may prevent trichomoniasis-attributable inflammatory sequelae.

Cell surface adhesion molecules are thought to play an important part in establishing the intercellular contacts that are necessary for immunological reactions (1). One such adhesion pathway in man involves the lymphocyte function-associated antigen (LFA-1), ' one of a family of leukocyte cell surface proteins (LFA-1, Mac-1, p150, 95) that are heterodimers with a common (3 chain and distinct though homologous a chains (1, 2). The principal ligand for LFA-1 seems to be the intercellular adhesion molecule ICAM-1, a protein expressed on many differentiated cell types (3) . The LFA-1/ICAM-1 pathway mediates a variety of cell-cell adhesions by T and B lymphocytes, natural killer cells, granulocytes, and macrophages (1-5) and also appears to be responsible for the homotypic cell adhesions shown by certain leukocytederived cell lines in vitro (5).Interactions between cytotoxic T lymphocytes (CTL) and their target cells involve an initial phase of effector/target adhesion, detectable by rapid conjugate formation in vitro, which is independent ofantigen-specific recognition (4). mAb blocking studies indicate that this interaction involves two separate adhesion pathways (4, fi). One is the effector LFA-1/target ICAM-1 pathway described above, the other is mediated via the T cell-specific CD2 antigen (T11, LFA-2) interacting with a widely distributed adhesion protein, LFA-3 (7), on the target cell surface. Both pathways appear to be required for optimal effector/target conjugation, and therefore might be important accessories for CTL formation.One of the best characterized CTL surveillance systems operative in man is that which is specifically directed against Epstein-Barr virus (EBV), an agent with oncogenic potential in vivo (8) and with cell growth transforming ability for human B cells in vitro (9). EBVspecific CTL, reactivated from memory T cells in the blood of virus-immune donors, recognize EBVtransformed B lymphoblastoid cell lines (LCL) in a HLA class I antigen-restricted manner (10) .