scholarly journals Limiting dilution analysis of Epstein-Barr virus-induced immunoglobulin production by human B cells.

1983 ◽  
Vol 157 (1) ◽  
pp. 1-14 ◽  
Author(s):  
R Yarchoan ◽  
G Tosato ◽  
R M Blaese ◽  
R M Simon ◽  
D L Nelson
Keyword(s):  
B Cells ◽  
B Cell ◽  
Peripheral Blood ◽  
Epstein Barr Virus ◽  
Cell Activation ◽  
B Cell Activation ◽  
Barr Virus ◽  
Human B Cells ◽  
Epstein Barr ◽  
Limiting Dilution

The Epstein-Barr virus (EBV) is a herpes virus that has the capacity to infect human B cells and to induce them to secrete immunoglobulin (Ig). In the current experiments, Poisson analysis of limiting dilution cultures has been used to study the activation of human peripheral B cells by the B95-8 strain of EBV. Under the culture conditions used, 0.2-1% of peripheral blood B cells were activated by EBV to secrete IgM or IgG. In addition, when multiple replicate cultures containing limited numbers of B cells were tested for IgM and for IgG production, the precursors for IgM and IgG segregated independently; thus, individual B cell precursors matured into cells secreting IgM or IgG but not both classes of Ig. Additional experiments using limiting dilutions of EBV were undertaken to study the viral requirements for B cell activation. These studies indicated that B cell activation by EBV to produce Ig was consistent with a "one-hit" model and inconsistent with a "two-hit" model. Taken together, these results indicate that infection by one EBV virion is sufficient to induce a precursor peripheral blood B cell to secrete Ig and that only one isotype of Ig is then secreted.

scholarly journals Early events in Epstein-Barr virus infection provide a model for B cell activation.

1985 ◽  
Vol 162 (1) ◽  
pp. 45-59 ◽  
Author(s):  
D A Thorley-Lawson ◽  
K P Mann
Keyword(s):  
B Cells ◽  
B Cell ◽  
Epstein Barr Virus ◽  
Rna Synthesis ◽  
Cell Activation ◽  
Nuclear Antigen ◽  
Epstein Barr Virus Infection ◽  
B Cell Activation ◽  
Barr Virus ◽  
Epstein Barr

We have used Epstein-Barr virus (EBV) infection in vitro to delineate two distinct stages in B cell activation. Previous studies have shown that the BLAST-2 (EBVCS) (EBV cell surface) activation antigen is expressed on a small fraction of B cells within 24 h of stimulation with a variety of agents, including mitogens and EBV. In this study, we have been able to isolate the BLAST-2 (EBVCS)+ cells early after activation/infection with EBV. These cells are small B cells that are actively synthesizing RNA but not DNA, and are, therefore, clearly distinct from large proliferating lymphoblasts. In addition, they contain multiple copies of the EBV genome, express the viral nuclear antigen (EBNA) and, most importantly, proceed to undergo transformation when placed back in culture. By comparison, the BLAST-2 (EBVCS)- population does not undergo transformation, even though a fraction of these cells are activated for RNA synthesis and express EBNA. Thus, using the EBV system, we have been able to show directly that an activated B cell first expresses the BLAST-2 (EBVCS) antigen concomitant with an increase in RNA synthesis, and then subsequently proceeds to differentiate into a proliferating lymphoblast.

scholarly journals Manipulation of the Toll-Like Receptor 7 Signaling Pathway by Epstein-Barr Virus

2007 ◽  
Vol 81 (18) ◽  
pp. 9748-9758 ◽  
Author(s):  
Heather J. Martin ◽  
Jae Myun Lee ◽  
Dermot Walls ◽  
S. Diane Hayward
Keyword(s):  
Cell Proliferation ◽  
B Cells ◽  
B Cell ◽  
Epstein Barr Virus ◽  
Cell Activation ◽  
B Cell Activation ◽  
Toll Like Receptor ◽  
Barr Virus ◽  
Ebv Infection ◽  
Epstein Barr

ABSTRACT Epstein-Barr virus (EBV) infection of primary B cells causes B-cell activation and proliferation. Activation of B cells requires binding of antigen to the B-cell receptor and a survival signal from ligand-bound CD40, signals that are provided by the EBV LMP1 and LMP2A latency proteins. Recently, Toll-like receptor (TLR) signaling has been reported to provide a third B-cell activation stimulus. The interaction between the EBV and TLR pathways was therefore investigated. Both UV-inactivated and untreated EBV upregulated the expression of TLR7 and downregulated the expression of TLR9 in naive B cells. UV-inactivated virus transiently stimulated naive B-cell proliferation in the presence of the TLR7 ligand R837, while addition of the TLR7 antagonist IRS 661 impaired cell growth induced by untreated EBV. Interferon regulatory factor 5 (IRF-5) is a downstream mediator of TLR7 signaling. IRF-5 was induced following EBV infection, and IRF-5 was expressed in B-cell lines with type III latency. Expression of IRF-5 in this setting is surprising since IRF-5 has tumor suppressor and antiviral properties. B-cell proliferation assays provided evidence that EBV modulates TLR7 signaling responses. Examination of IRF-5 transcripts identified a novel splice variant, V12, that was induced by EBV infection, was constitutively nuclear, and acted as a dominant negative form in IRF-5 reporter assays. IRF-4 negatively regulates IRF-5 activation, and IRF-4 was also present in type III latently infected cells. EBV therefore initially uses TLR7 signaling to enhance B-cell proliferation and subsequently modifies the pathway to regulate IRF-5 activity.

scholarly journals Rheumatoid Factors Induce Signaling from B Cells, Leading to Epstein-Barr Virus and B-Cell Activation

2004 ◽  
Vol 78 (18) ◽  
pp. 9918-9923 ◽  
Author(s):  
Lixin Yang ◽  
Masayuki Hakoda ◽  
Kazuya Iwabuchi ◽  
Tsuyoshi Takeda ◽  
Takao Koike ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Epstein Barr Virus ◽  
Cell Activation ◽  
Mononuclear Cells ◽  
Rheumatoid Factors ◽  
B Cell Activation ◽  
Barr Virus ◽  
Membrane Bound ◽  
Epstein Barr

ABSTRACT B-cell antigen receptor signaling is initiated upon binding of the antigen to membrane-bound immunoblobulin (Ig), and the anti-Ig antibody (Ab) mimics this signaling. In B cells latently infected with Epstein-Barr virus (EBV), the same signals induce virus activation. We examine here whether rheumatoid factors (RFs), autoantibodies directed against the Fc portion of IgG, induce EBV and B-cell activation. As a source of RFs, RF-producing lymphoblastoid cell line (LCL) clones were isolated from peripheral blood mononuclear cells (PBMC) and synovial cells from patients with rheumatoid arthritis (RA) by EBV transformation. Burkitt's lymphoma-derived Akata cells, which are highly responsive to EBV activation by anti-Ig Abs, were used for the assay of EBV activation. Akata cells expressed IgG3 as membrane-bound Ig. RFs from a synovium-derived LCL were directed to IgG3 and induced EBV activation in 16 to 18% of Akata cells, whereas RFs from another synovium-derived LCL were directed to IgG1 and did not induce EBV activation. Pretreatment of RFs with the purified Fc fragment of human IgG completely abolished EBV activation. Furthermore, B-cell activation was assessed by incorporation of [3H]thymidine. RFs from synovium-derived LCLs efficiently induced B-cell activation, and the addition of CD40 ligand had a synergistic effect. On the other hand, RFs from PBMC-derived LCLs were polyreactive, had a lower affinity to IgG, and did not induce EBV and B-cell activation. The present findings imply a possible role for RFs as EBV and B-cell activators.

scholarly journals Rewiring of B cell receptor signaling by Epstein–Barr virus LMP2A

2020 ◽  
Vol 117 (42) ◽  
pp. 26318-26327
Author(s):  
Kamonwan Fish ◽  
Federico Comoglio ◽  
Arthur L. Shaffer ◽  
Yanlong Ji ◽  
Kuan-Ting Pan ◽  
...  
Keyword(s):  
Cell Cycle ◽  
B Cells ◽  
B Cell ◽  
Epstein Barr Virus ◽  
Cell Receptor ◽  
B Cell Receptor ◽  
Barr Virus ◽  
Human B Cells ◽  
Bcr Signaling ◽  
Epstein Barr

Epstein–Barr virus (EBV) infects human B cells and reprograms them to allow virus replication and persistence. One key viral factor in this process is latent membrane protein 2A (LMP2A), which has been described as a B cell receptor (BCR) mimic promoting malignant transformation. However, how LMP2A signaling contributes to tumorigenesis remains elusive. By comparing LMP2A and BCR signaling in primary human B cells using phosphoproteomics and transcriptome profiling, we identified molecular mechanisms through which LMP2A affects B cell biology. Consistent with the literature, we found that LMP2A mimics a subset of BCR signaling events, including tyrosine phosphorylation of the kinase SYK, the calcium initiation complex consisting of BLNK, BTK, and PLCγ2, and its downstream transcription factor NFAT. However, the majority of LMP2A-induced signaling events markedly differed from those induced by BCR stimulation. These included differential phosphorylation of kinases, phosphatases, adaptor proteins, transcription factors such as nuclear factor κB (NF-κB) and TCF3, as well as widespread changes in the transcriptional output of LMP2A-expressing B cells. LMP2A affected apoptosis and cell-cycle checkpoints by dysregulating the expression of apoptosis regulators such as BCl-xL and the tumor suppressor retinoblastoma-associated protein 1 (RB1). LMP2A cooperated with MYC and mutant cyclin D3, two oncogenic drivers of Burkitt lymphoma, to promote proliferation and survival of primary human B cells by counteracting MYC-induced apoptosis and by inhibiting RB1 function, thereby promoting cell-cycle progression. Our results indicate that LMP2A is not a pure BCR mimic but rather rewires intracellular signaling in EBV-infected B cells that optimizes cell survival and proliferation, setting the stage for oncogenic transformation.

Early events in Epstein-Barr virus genome expression after activation: Regulation by second messengers of B cell activation

Virology ◽  
1991 ◽  
Vol 185 (2) ◽  
pp. 922-928 ◽  
Author(s):  
Ingo Mellinghoff ◽  
Masanori Daibata ◽  
Robert E. Humphreys ◽  
Carel Mulder ◽  
Kenzo Takada ◽  
...  
Keyword(s):  
B Cell ◽  
Epstein Barr Virus ◽  
Cell Activation ◽  
Second Messengers ◽  
Virus Genome ◽  
B Cell Activation ◽  
Barr Virus ◽  
Genome Expression ◽  
Epstein Barr

scholarly journals Compatibility of the gH homologues of Epstein–Barr virus and related lymphocryptoviruses

2007 ◽  
Vol 88 (8) ◽  
pp. 2129-2136 ◽  
Author(s):  
Liguo Wu ◽  
Lindsey M. Hutt-Fletcher
Keyword(s):  
B Cells ◽  
Epithelial Cells ◽  
B Cell ◽  
Cell Fusion ◽  
Epstein Barr Virus ◽  
Common Marmoset ◽  
Barr Virus ◽  
Human B Cells ◽  
The Common ◽  
Epstein Barr

Glycoprotein gH, together with its chaperone gL and a third glycoprotein gB, is essential for cell–cell fusion and virus–cell fusion mediated by herpesviruses. Epstein–Barr virus (EBV), the prototype human lymphocryptovirus, requires a fourth glycoprotein gp42 to support fusion with B cells in addition to epithelial cells. Two other lymphocryptoviruses, the rhesus lymphocryptovirus (Rh-LCV) and the common marmoset lymphocryptovirus (CalHV3), have been sequenced in their entirety and each has a gp42 homologue. Combinations of proteins from EBV, Rh-LCV and CalHV3 were able to mediate fusion of epithelial cells, but, even when complexed with EBV gp42, only Rh-LCV and not CalHV3 proteins were able to mediate fusion with human B cells. CalHV3 gL was also unable to function effectively as a chaperone for EBV or Rh-LCV gH. The Rh-LCV gH homologue supported more fusion than EBV gH with an epithelial cell and supported the highest levels of fusion with a B cell. Chimeric constructs made from Rh-LCV gH and EBV gH that have 85.4 % sequence identity should prove useful for mapping the regions of gH that are of importance to fusion as a whole and to B-cell fusion in particular.

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