Suppression of EBV release from irradiated B lymphoblastoid cell-lines: superior activity of ganciclovir compared with acyclovir

Keever-Taylor, Carolyn A.; Behn, B.; Konings, Steve; Orentas, Rimas J.; Davies, B.; Margolis, David

doi:10.1080/14653240310002243

Cited by 14 publications

(11 citation statements)

References 22 publications

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“…Our results, as well as those of previous studies (45), also raise the question of whether GCV might be a more effective drug than ACV for treating lytic EBV infection in patients. We found that the IC 50 of ACV for WT EBV was 4.1 M, while the IC 50 of GCV was 1.5 M. Previous studies using Southern blot methods to measure the amount of lytic EBV viral replication also reported that the IC 50 of ACV for WT EBV is considerably higher (7 to 10 M) (71,86) than the IC 50 of GCV (found to be 1.0 M) (11,56).…”

Section: Discussionsupporting

confidence: 84%

The Epstein-Barr Virus (EBV)-Encoded Protein Kinase, EBV-PK, but Not the Thymidine Kinase (EBV-TK), Is Required for Ganciclovir and Acyclovir Inhibition of Lytic Viral Production

Qiao¹,

Hagemeier²,

Fingeroth

et al. 2010

J Virol

142

122

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Ganciclovir (GCV) and acyclovir (ACV) are guanine nucleoside analogues that inhibit lytic herpesvirus replication. GCV and ACV must be monophosphorylated by virally encoded enzymes to be converted into nucleotides and incorporated into viral DNA. However, whether GCV and/or ACV phosphorylation in EpsteinBarr virus (EBV)-infected cells is mediated primarily by the EBV-encoded protein kinase (EBV-PK), the EBV-encoded thymidine kinase (EBV-TK), or both is controversial. To examine this question, we constructed EBV mutants containing stop codons in either the EBV-PK or EBV-TK open reading frame and selected for stable 293T clones latently infected with wild-type EBV or each of the mutant viruses. Cells were induced to the lytic form of viral replication with a BZLF1 expression vector in the presence and absence of various doses of GCV and ACV, and infectious viral titers were determined by a green Raji cell assay. As expected, virus production in wild-type EBV-infected Epstein-Barr virus (EBV) is a human herpesvirus that causes infectious mononucleosis and is associated with a variety of different human tumors (1,47,81). Like all herpesviruses, EBV can infect cells in either the latent or lytic form (13). The lytic form of infection is required for horizontal spread of the virus from cell to cell and from host to host. During the lytic form of viral replication, EBV uses a virally encoded DNA polymerase and the oriLyt replication origin to duplicate its genome (24, 36, 51). The lytic form of EBV replication can be effectively inhibited in vitro by the guanine nucleoside analogues, acyclovir (ACV) and ganciclovir (GCV) (11,16,50,56). Since acyclovir is significantly less toxic than ganciclovir in patients, acyclovir is generally used to treat diseases associated with lytic EBV infection, such as oral hairy leukoplakia (3).GCV and ACV cannot be incorporated into viral or cellular DNA unless they are phosphorylated and converted into nucleotides (17,29). Work in other herpesvirus systems has demonstrated that the first step in GCV or ACV phosphorylation is not performed efficiently by cellular nucleoside kinases but can be carried out by virally encoded enzymes in cells infected with various herpesviruses (6,17,20,25,29,75). Human herpes simplex virus 1 (HSV-1) and HSV-2 encode a viral thymidine kinase (TK) which mediates the first step in GCV and ACV phosphorylation in virally infected cells (20,21,73), and ACV-and GCV-resistant HSV mutants isolated from patients commonly have mutations in the viral thymidine kinase gene (5,14,46,64) and less commonly within the viral DNA polymerase gene (61). In contrast, the human cytomegalovirus (HCMV) does not encode a viral thymidine kinase protein.Instead, in HCMV-infected cells, the virally encoded protein kinase (UL97) mediates the first step of GCV phosphorylation (53, 75) and (albeit much less efficiently) ACV phosphorylation (76). Once made, the triphosphorylated form of ACV (and to a lesser extent GCV) is a much better substrate for herpesvirus-encoded DNA polymerases than...

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Section: Discussionsupporting

confidence: 84%

The Epstein-Barr Virus (EBV)-Encoded Protein Kinase, EBV-PK, but Not the Thymidine Kinase (EBV-TK), Is Required for Ganciclovir and Acyclovir Inhibition of Lytic Viral Production

Qiao¹,

Hagemeier²,

Fingeroth

et al. 2010

J Virol

142

122

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“…The fourth Th2 line was not used in the transformation assay as it was found to be contaminated with LCL, which grew out rapidly and overwhelmed the culture even after sorting. This LCL contamination was probably a result of small amounts of virus released from irradiated LCL-transforming B cells in the cord blood during the induction of the Th2 cells (22). Although undesirable, this result in general supports the conclusion that Th2-polarized conditions favor efficient virus transformation.…”

Section: Effects Of Th1 and Th2 Cells On Virus Transformation To Invsupporting

confidence: 54%

Primary CD4⁺T-Cell Responses Provide both Helper and Cytotoxic Functions during Epstein-Barr Virus Infection and Transformation of Fetal Cord Blood B Cells

MacArthur¹,

Wilson

Birchall³

et al. 2007

J Virol

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“…1d), which is a viral-encoded protein kinase that phosphorylates ganciclovir to its active form (monophosphorylated) [72]. The phosphorylated ganciclovir incorporates with viral and cellular DNA and kills the cells via disrupting replication [73], providing a plausible explanation for the diminished EBV gene expression in response to ganciclovir. However, due to the low level of BGLF4 necessary for converting the ganciclovir into its active form, it cannot independently induce significant cell death.…”

Section: Discussionmentioning

confidence: 99%

Arsenic trioxide inhibits EBV reactivation and promotes cell death in EBV-positive lymphoma cells

Yin

Sides

Parsons³

et al. 2017

Virol J

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BackgroundEpstein-Barr Virus (EBV) is associated with hematopoietic malignancies, such as Burkitt’s lymphoma, post-transplantation lymphoproliferative disorder, and diffuse large B-cell lymphoma. The current approach for EBV-associated lymphoma involves chemotherapy to eradicate cancer cells, however, normal cells may be injured and organ dysfunction may occur with currently employed regimens. This research is focused on employing arsenic trioxide (ATO) as EBV-specific cancer therapy takes advantage of the fact the EBV resides within the malignant cells.Methods and resultsOur research reveals that low ATO inhibits EBV gene expression and genome replication. EBV spontaneous reactivation starts as early as 6 h after re-suspending EBV-positive Mutu cells in RPMI media in the absence of ATO, however this does not occur in Mutu cells cultured with ATO. ATO’s inhibition of EBV spontaneous reactivation is dose dependent. The expression of the EBV immediate early gene Zta and early gene BMRF1 is blocked with low concentrations of ATO (0.5 nM – 2 nM) in EBV latency type I cells and EBV-infected PBMC cells. The combination of ATO and ganciclovir further diminishes EBV gene expression. ATO-mediated reduction of EBV gene expression can be rescued by co-treatment with the proteasome inhibitor MG132, indicating that ATO promotes ubiquitin conjugation and proteasomal degradation of EBV genes. Co-immunoprecipitation assays with antibodies against Zta pulls down more ubiquitin in ATO treated cell lysates. Furthermore, MG132 reverses the inhibitory effect of ATO on anti-IgM-, PMA- and TGF-β-mediated EBV reactivation. Thus, mechanistically ATO’s inhibition of EBV gene expression occurs via the ubiquitin pathway. Moreover, ATO treatment results in increased cell death in EBV-positive cells compared to EBV-negative cells, as demonstrated by both MTT and trypan blue assays. ATO-induced cell death in EBV-positive cells is dose dependent. ATO and ganciclovir in combination further enhances cell death specifically in EBV-positive cells.ConclusionATO-mediated inhibition of EBV lytic gene expression results in cell death selectively in EBV-positive lymphocytes, suggesting that ATO may potentially serve as a drug to treat EBV-related lymphomas in the clinical setting.

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Suppression of EBV release from irradiated B lymphoblastoid cell-lines: superior activity of ganciclovir compared with acyclovir

Cited by 14 publications

References 22 publications

The Epstein-Barr Virus (EBV)-Encoded Protein Kinase, EBV-PK, but Not the Thymidine Kinase (EBV-TK), Is Required for Ganciclovir and Acyclovir Inhibition of Lytic Viral Production

The Epstein-Barr Virus (EBV)-Encoded Protein Kinase, EBV-PK, but Not the Thymidine Kinase (EBV-TK), Is Required for Ganciclovir and Acyclovir Inhibition of Lytic Viral Production

Primary CD4⁺T-Cell Responses Provide both Helper and Cytotoxic Functions during Epstein-Barr Virus Infection and Transformation of Fetal Cord Blood B Cells

Arsenic trioxide inhibits EBV reactivation and promotes cell death in EBV-positive lymphoma cells

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Suppression of EBV release from irradiated B lymphoblastoid cell-lines: superior activity of ganciclovir compared with acyclovir

Cited by 14 publications

References 22 publications

The Epstein-Barr Virus (EBV)-Encoded Protein Kinase, EBV-PK, but Not the Thymidine Kinase (EBV-TK), Is Required for Ganciclovir and Acyclovir Inhibition of Lytic Viral Production

The Epstein-Barr Virus (EBV)-Encoded Protein Kinase, EBV-PK, but Not the Thymidine Kinase (EBV-TK), Is Required for Ganciclovir and Acyclovir Inhibition of Lytic Viral Production

Primary CD4+T-Cell Responses Provide both Helper and Cytotoxic Functions during Epstein-Barr Virus Infection and Transformation of Fetal Cord Blood B Cells

Arsenic trioxide inhibits EBV reactivation and promotes cell death in EBV-positive lymphoma cells

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Product

Resources

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Primary CD4⁺T-Cell Responses Provide both Helper and Cytotoxic Functions during Epstein-Barr Virus Infection and Transformation of Fetal Cord Blood B Cells