anti-CMV Effect Research Articles

Virus-Specific CD8+ Stem Memory T Lymphocytes Display Enhanced Anti-Virus Responses

Virus specific memory CD8+ T cells can be divided into three subsets, stem memory (T SCM), central (T CM) and effector (T EM), but their lineage relationships and their ability to persist and confer protective immunity against virus infection are not well understood. Our results show that virus-specific CD8+T SCM have a greater capacity than T CM and T EM to persist in vivo and in vitro and are more efficient in mediating protective immunity against CMV infection and EBV infection because of their increased self-renew potential whether in transcriptome or in epigenome. We firstly expanded virus-specific T cells containing CD8+TSCM and CD8+TCM cells in vitro by stimulating healthy human PBMCs with cytokines and CMV (pp65 and IE1) and EBV (LMP2a and EBNA1) virus peptides. Then we fully evaluated the phenotypic and functional differences of diverse virus-specific memory T subsets and found that CD8+TSCM cells are a subset of low exhaustion, high migration and high secretion of IL-2. However, the expression of IFN-γand TNF-a and CD107a were lower compared with TEM cells, although comparable to CD8+TCM cells. We then evaluated the self-renewal and differentiation capacity of CD8+TSCM cells, compared with TCM or TEM cells. The results showed after stimulated with a-CD3/CD2/CD28 for 5 days, that CD8+TSCM cells possess around 50% of CD45RA+CD62L+ subpopulation cells. Meanwhile, CD8+TSCM cells constantly keep a higher expression of CD45RA+ cells than TCM and TEM cells in different proliferation generations. Notably, around 20% of TCM cells,5% of TEM cells and 10% of TEFF cells were found, suggesting that TSCM cells can reconstitute the whole memory T subsets. By contrast, the TCM cells mainly retained a central memory phenotype or differentiated into effector memory T cells and the TEM cells maintained its original phenotype. We also used the stem cell index to evaluate the stemness of different subgroups, and the results confirmed that the stemness evaluation of TSCM cells were significantly higher than TCM and TEM subsets. In vivo rein-fusion of different virus-specific T cell into irradidated NPG mice also showed that CD8+TSCM cells in vivo can differentiate into all memory T subsets in vivo while TCM cells mainly retained TEM and TCM subgroups at 4W post T cell infusion in mouse liver,lung and spleen(Figure 1A-G). To explore whether the antiviral ability of TSCM cells lasted longer than that of TCM and TEM cells. We first evaluated the apoptosis of different T cell subsets stimulated by AD169 virus and found less apoptosis rate was lower than TCM and TEM cells, suggesting persistent virus infection leads to damage to T cells and CD8+TSCM cells have a strong ability to resist virus damage, which may potentially lead to stronger and longer lasting antiviral effects. Based on this, we also evaluated the apoptosis level of virus-infected MRC-5 cells to evaluate whether CD8+TSCM cells exert a stronger anti-virus effect. The result showed that AD-169 infected MRC-5 cells co-incubated with CD8+TSCM had a higher proportion of apoptotic level than CD8+TCM cells. We also used the 5day-long-term infection model in vitro to evaluate the effect of virus infection on T cell differentiation and evaluated the change of virus copy number after long-term co-culture of different cell subsets. We found that sorted CD8+TSCM system can significantly reduce the virus copy number compared with the control group, while there is no significant difference among TCM and TEM cells (Figure1H,). Further analysis into survival ability of T cell subpopulations found that the proportion of CD3+ T cells in TSCM group were significantly higher and the CD8+TSCM group was dominated by TCM and TEM cells after 5-day stimulation but still kept about 22 percentage of TSCM phenotype. (Figure1I). In summary, CD8+ TSCM cells have a sustainable ability against CMV than TCM and TEM. To examine the in vivo activity of virus-specific CD8+TSCM cells. We used Raji-HLA*A0201-pp65-luciferase cells to construct tumor infiltration mouse model. The result showed that in contrast to control mice, we observed a reduction in bioluminescence over three weeks in mice treated with CD8+TSCM cells. Although mice treated with CD8+TCM and CD8+TEM cells retained a lower tumor size in the early two weeks post adoptive T infusion, they showed a rapid tumor progresses and event lead to shorter survival compared with CD8+TSCM group, indicating a sustained anti-CMV effect of CD8+TSCM cells.

Distinct activities of Vδ1+ T-cells upon different cytomegalovirus reactivation status after haematopoietic transplantation.

Cytomegalovirus (CMV) reactivation is the most frequent viral infectious complication correlating to non-relapse mortality after allogeneic haematopoietic cell transplantation (alloHCT). The intrinsic anti-CMV immunity has not been completely elucidated. γδ T-cells have drawn increasing attentions due to their distinct biological features and potential ability against viral infections. Previous studies reported a general association of γδ T-cells or Vδ2-negative γδ T-cells with CMV reactivation. Whereas researches for the direct responses and specific functions of γδ T subsets remain limited, especially in the scenario of alloHCT. Herein, we initially demonstrated that Vδ1+ T-cells directly and independently recognized cell-free CMV and CMV-infected target cells, and inhibited CMV replication in vitro. The anti-CMV effect of Vδ1+ T-cells was partially through TCRγδ, TLR2 and NKG2D receptor pathways. Further investigation about the anti-CMV characteristics of Vδ1+ T-cells was performed in a clinical cohort with different CMV reactivation status after alloHCT. We found that occasional CMV reactivation remarkably increased the recovery levels and stimulated the functional activity of Vδ1+ T-cells. Whereas disability of Vδ1+ T-cells was observed upon refractory CMV reactivation indicating the differential responses of Vδ1+ T-cells under different CMV reactivation status. CXCL10 and IFN-β that were dramatically induced by occasional CMV reactivation could re-activate the deficient Vδ1+ T-cells from recipients with refractory CMV reactivation. These findings unveiled the distinct activities of Vδ1+ T-cells in anti-CMV immunity after alloHCT and may help develop novel strategies for the treatment of CMV infectious diseases.

Effect of Sirolimus vs. Everolimus on CMV-Infections after Kidney Transplantation-A Network Meta-Analysis.

(1) Background: Following renal transplantation, infection with cytomegalovirus (CMV) is a common and feared complication. mTOR-inhibitor (mTOR-I) treatment, either alone or in combination with calcineurininhibitors (CNIs), significantly reduces the CMV incidence after organ transplantation. As of now, there is no information on which mTOR-I, sirolimus (SIR) or everolimus (ERL), has a stronger anti-CMV effect. (2) Methods: The current literature was searched for prospective randomized controlled trials in renal transplantation. There were 1164 trials screened, of which 27 could be included (11,655 pts.). We performed a network meta-analysis to analyze the relative risk of different types of mTOR-I treatment on CMV infection 12 months after transplantation compared to CNI treatment. (3) Results: Four different types of mTOR-I treatment were analyzed in network meta-analyses—SIR mono, ERL mono, SIR with CNI, ERL with CNI. The mTOR-I treatment with the strongest anti-CMV effect compared to a regular CNI treatment was ERL in combination with a CNI (relative risk (RR) 0.27, confidence interval (CI) 0.22–0.32, p < 0.0001). The other mTOR-I therapy groups showed a slightly decreased anti-CMV efficacy (SIR monotherapy (mono): RR 0.35, CI 0.22–0.57, p < 0.001; SIR with CNI: RR 0.43, CI 0.29–0.64, p < 0.0001; ERL mono: RR 0.46, CI 0.22–0.93, p = 0.031). (4) Conclusions: The anti-CMV effect of both mTOR-Is (SRL and ERL) is highly effective, irrespective of the combination with other immunosuppressive drugs. Certain differences with respect to the potency against the CMV could be found between SRL and ERL. Data gained from this analysis seem to support that a combination of ERL and CNI has the most potent anti-CMV efficacy.

Comparative Study of Mizoribine and Mycophenolate Mofetil Combined with a Calcineurin Inhibitor-Based Immunosuppressive Regimen in Patients with Alternative Donor Hematopoietic Cell Transplantation.

Cytomegalovirus (CMV) infection and graft-versus-host disease (GVHD) remain the major causes of nonrelapse mortality (NRM) in patients following alternative donor hematopoietic stem cell transplantation (HCT). Mizoribine (MZR) showed an anti-CMV effect in addition to its immunosuppressive effect in patients with renal transplantation. In this study, we aimed to evaluate the efficacy and safety of MZR combined with a calcineurin inhibitor (CNI) as a method of prophylactic immunosuppression in recipients following alternative donor HCT. Eighty patients were enrolled in the study and randomized to the MZR (n=40) or MMF (n=40) cohort before transplantation conditioning. Analyses involved a comparison of the outcomes between the 2 cohorts, as well as risk analyses of early nonrelapse mortality (NRM) and severe CMV infection. In contrast to MMF, MZR was associated with a lower but statistically nonsignificant median CMV DNA peak load (P=.075), significantly fewer episodes of persistent/refractory infection (odds ratio [OR], .12), and a lower failure rate of CMV treatment (OR, .82), but a significantly higher rate of hyperuricemia (OR, 2.75). Transplantation efficacy was comparable in the 2 cohorts regarding engraftment, the development of secondary poor graft function and GVHD, and the estimated OS and PFS. The 1-year NRM of the MZR cohort did not differ from that of the MMF cohort, whereas the rate of 1-year NRM caused by viral infections was reduced in the MZR cohort and was of borderline statistical significance (P=.05). In the multivariate analysis, lower doses of CD34+ cells in grafts (hazard ratio [HR], 3.65) and persistent/refractory CMV infections (versus no CMV infection: HR, 7.31; versus CMV infection that was not persistent/refractory: HR, 4.46) were predictors of increased 1-year NRM. The use of MMF (versus MZR cohort: OR, 11.54) and grade II-IV acute GVHD (OR, 15.32) were independent risk factors for developing persistent/refractory CMV infection. When combined with CNIs, MZR functioned well in terms of both immunosuppression and reduced severity of CMV infection; however, further studies are warranted to verify its use as a potential immunosuppressant for alternative donor HCT.

Direct and Indirect Effects of Cytomegalovirus-Induced γδ T Cells after Kidney Transplantation.

Despite effective anti-viral therapies, cytomegalovirus (CMV) is still associated with direct (CMV disease) and indirect effects (rejection and poor graft survival) in kidney transplant recipients. Recently, an unconventional T cell population (collectively designated as Vδ2neg γδ T cells) has been characterized during the anti-CMV immune response in all solid-organ and bone-marrow transplant recipients, neonates, and healthy people. These CMV-induced Vδ2neg γδ T cells undergo a dramatic and stable expansion after CMV infection, in a conventional “adaptive” manner. Similarly, as CMV-specific CD8+ αβ T cells, they exhibit an effector/memory TEMRA phenotype and cytotoxic effector functions. Activation of Vδ2neg γδ T cells by CMV-infected cells involves the γδ T cell receptor (TCR) and still ill-defined co-stimulatory molecules such as LFA-1. A multiple of Vδ2neg γδ TCR ligands are apparently recognized on CMV-infected cells, the first one identified being the major histocompatibility complex-related molecule endothelial protein C receptor. A singularity of CMV-induced Vδ2neg γδ T cells is to acquire CD16 expression and to exert an antibody-dependent cell-mediated inhibition on CMV replication, which is controlled by a specific cytokine microenvironment. Beyond the well-demonstrated direct anti-CMV effect of Vδ2neg γδ T cells, unexpected indirect effects of these cells have been also observed in the context of kidney transplantation. CMV-induced Vδ2neg γδ T cells have been involved in surveillance of malignancy subsequent to long-term immunosuppression. Moreover, CMV-induced CD16+ γδ T cells are cell effectors of antibody-mediated rejection of kidney transplants, and represent a new physiopathological contribution to the well-known association between CMV infection and poor graft survival. All these basic and clinical studies paved the road to the development of a future γδ T cell-based immunotherapy. In the meantime, γδ T cell monitoring should prove a valuable immunological biomarker in the management of CMV infection.

Is Cytomegalovirus Prophylaxis Dispensable in Patients Receiving an mTOR Inhibitor–Based Immunosuppression? A Systematic Review and Meta-Analysis

Cytomegalovirus (CMV) is a common opportunistic infection after solid organ transplantation. Cytomegalovirus causes increased morbidity, mortality, and reduced allograft survival. Prophylaxis may help control the virus but is associated with substantial side effects and does not completely prevent virus reactivation; relapses after cessation of the prophylaxis are frequent. Experimental and clinical data suggest that mTOR inhibitors may have an anti-CMV effect. Here, we present a meta-analysis of clinical trials after solid organ transplantation and describe potential mechanisms involved in the anti-CMV effect of mTOR-inhibitors. The current literature was reviewed for randomized controlled trials in solid organ transplantation comparing an mTOR-I with a non-mTOR-I (CNI based) treatment. The scientific quality of the trials was assessed by the Jadad score, the use of an effective allocation concealment (AC) and the existence of an intention-to-treat (ITT) analysis. Cytomegalovirus incidence was assessed in studies comparing 1) an mTOR-I-based with a CNI-based immunosuppression (10 trials, n=3,100 patients) and 2) an mTOR-I/CNI combination therapy with a CNI-based immunosuppression (15 trials, n=7,100 patients). In the first meta-analysis, CMV events after solid organ transplantation occurred significantly more often under CNIs (RR=2.27). The second meta-analysis comparing the mTOR-I + CNI combination with a CNI treatment in 15 trials of kidney, heart, and liver transplantation showed again a higher CMV incidence when patients received an mTOR-I free immunosuppression (RR=2.45). mTOR-inhibitor treatment either alone or in combination with CNIs reduces significantly the CMV incidence after organ transplantation. With the use of an mTOR-inhibitor, CMV prophylaxis may be dispensible.

Effect of maintenance immunosuppressive drugs on virus pathobiology: evidence and potential mechanisms

Recent evidence suggesting a potential anti-CMV effect of mTORis is of great interest to the transplant community. However, the concept of an immunosuppressant with antiviral properties is not new, with many accounts of the antiviral properties of several agents over the years. Despite these reports, to date, there has been little effort to collate the evidence into a fuller picture. This manuscript was developed to gather the evidence of antiviral activity of the agents that comprise a typical immunosuppressive regimen against viruses that commonly reactivate following transplant (HHV1 and 2, VZV, EBV, CMV and HHV6, 7, and 8, HCV, HBV, BKV, HIV, HPV, and parvovirus). Appropriate immunosuppressive regimens posttransplant that avoid acute rejection while reducing risk of viral reactivation are also reviewed. The existing literature was disparate in nature, although indicating a possible stimulatory effect of tacrolimus on BKV, potentiation of viral reactivation by steroids, and a potential advantage of mammalian target of rapamycin (mTOR) inhibition in several viral infections, including BKV, HPV, and several herpesviruses.

MTOR-Inhibitors and CMV Infection after Solid Organ Transplantation - Is CMV Prophylaxis Still Necessary?

Introduction: CMV infection remains one of the most threatening conditions in the immunocompromised patient. CMV related mortality in the transplant patient used to be substantial. Recently, several drugs could show satisfactory efficacy against CMV. However, irrespective of (Val-)Ganciclovir prophylaxis or preemptive therapy CMV disease still occurs in up to 20% of all solid organ transplant patients. The mTOR-inhibitor treatment was shown to have anti-CMV efficacy. The aim of this study was to analyze the anti-CMV effect of mTOR-inhibitors and to clarify if mTOR-Is alone may be enough as anti-CMV treatment/prophylaxis in selected patients thus making an expensive (V)GCV prophylaxis dispensable. Methods: The most recent prospective randomized trials on solid organ transplantation were reviewed. Trials were required to have at least one mTOR-I treatment arm which was compared to a “non”-mTOR-I group and sufficient reporting on the data of interest (CMV incidence). The scientific quality of the trials was assessed by the Jadad-score, allocation concealment (AC) and Intention-to-treat (ITT) analysis. Two different analyses were performed: 1. mTOR-I treatment without CNI vs. CNI. 2. mTOR-I treatment with CNI vs. CNI. A metaanalysis was performed using the latest edition of the software “R”. Results: Ten prospective randomized trials on solid organ transplantation comparing an mTOR-I based- with a CNI-based treatment group were included (n=3100 pts.). The metaanalysis of these trials showed a cumulative risk of 2.27 when pts. were not treated with mTOR-Is. Early mTOR-I treatment seemed beneficial vs. late mTOR-I introduction. The second analysis included 15 trials comparing a combination therapy of mTOR-Is and CNIs vs. CNIs alone (n=7100 pts). The ensuing metaanalysis showed again a beneficial effect of the mTOR-I treatment (cumulative risk for a CMV infection was 2,5 without mTOR-I). Conclusion: Considering the high percentage of “early” CMV infection under preemptive and “late” CMV infection under prophylaxis an mTOR-I based treatment may have advantages in selected patients.

172 Everolimus Treatment Reduces the Need for Anti-CMV Prophylaxis in De Novo Heart Transplant Recipients

Cytomegalovirus (CMV) is the most clinically relevant infectious agent in heart transplant (HT) recipients. Although antiviral agents used in a prophylaxis strategy seem superior to a pre-emptive approach to reduce CMV burden and its consequences, the impact of the additional anti-CMV effect of everolimus (EVE) on the benefit of antiviral prophylaxis is currently unexplored. In this study we analyzed the interaction of anti-CMV strategy and the use of EVE or mycophenolate (MMF) on the occurrence of CMV events in de novo HT recipients.

Novel Anticytomegalovirus Activity of Immunosuppressant Mizoribine and Its Synergism with Ganciclovir

Cytomegalovirus (CMV) infection is a prominent infection in transplant recipients. The immunosuppressive drug mizoribine was shown to have anti-CMV activity in vitro and was reported to have an anti-CMV effect in renal transplantation. This study characterized the anti-CMV activity of mizoribine in vitro and its synergistic activity with ganciclovir. Mizoribine suppressed replication and at the EC(50) for plaque inhibition of 12.0 microg/ml. Mizoribine and ganciclovir exerted a strong synergism in anti-CMV activity. Mizoribine depletes guanosine nucleotides by inhibiting inosine monophosphate dehydrogenase and may increase the ratio of ganciclovir to guanosine in treated cells, resulting in a strong synergistic augmentation of the anti-CMV activity of ganciclovir. Two clinical isolates with UL97 mutations were less susceptible to mizoribine than the Towne strain but were equally susceptible in the presence of guanine. Two mizoribine-resistant strains were isolated after culture for 3 months with 100 microg/ml mizoribine, but they were as sensitive to ganciclovir as the parent Towne strain. The anti-CMV activity of mizoribine was antagonized by 2'-deoxyguanosine. Mizoribine inhibited CMV replication directly, and the sequence of mizoribine-resistant mutants of UL97 and UL54 was identical to that of the parent Towne strain, indicating the different anti-CMV action from ganciclovir, foscarnet, and maribavir. Mizoribine as an immunosuppressive and anti-CMV drug in the clinical regimen was suggested to suppress replication of CMV in vivo and control CMV infection in transplant recipients in combination with ganciclovir.

Delayed resistance to Cucumber mosaic virus mediated by 3’UTR-derived hairpin RNA

RNA silencing has been shown to function in the plant antivirus defense response, leading to viral RNA degradation induced by vsiRNA-containing RISC cleavage activity. Cucumber mosaic virus (CMV) 3’UTR sequences share a high conservation of nucleotide sequence and secondary structures that are important for CMV replication. Here, in an attempt to simultaneously target the multiple genomic and subgenomic RNAs of CMV for degradation, CMV 3’UTR were used to design hairpin RNA (hpRNA) to transform tobacco (Xanthi. nc) so as to constitutively produce viral siRNAs. Most of the transgenic plants expressing CMV Q strain (Q-CMV, subgroup II strain) RNA3 3’UTR-derived hpRNA showed delayed resistance to Q-CMV infection and exhibited recovery phenotypes. Compared with Q-CMV-inoculated leaves, the upper leaves showed weak or no disease symptoms and a reduced accumulation level of viral RNAs. Together with transient assays, our results indicate that the 3’UTR-derived siRNAs were biologically active in targeting viral RNA for degradation. Recovery resistance in transgenic plants was also observed against subgroup IB strain SD-CMV infection, indicating a broad-spectrum anti-CMV effect of the 3’UTR-based antiviral silencing. Northern blot assays indicated that there was no strong correlation between the degree of resistance and the accumulation level of 3’UTR-derived siRNAs, suggesting that to target a highly structured RNA, such as the CMV 3’UTR, the quantity of siRNAs may not be the only determinant of silencing efficiency. Target RNA secondary structures may also affect target accessibility, siRNA-containing RISC-target recognition and the consequent antiviral effect.

Artificial MicroRNA-Mediated Virus Resistance in Plants

RNA silencing in plants is a natural defense system against foreign genetic elements including viruses. This natural antiviral mechanism has been adopted to develop virus-resistant plants through expression of virus-derived double-stranded RNAs or hairpin RNAs, which in turn are processed into small interfering RNAs (siRNAs) by the host's RNA silencing machinery. While these virus-specific siRNAs were shown to be a hallmark of the acquired virus resistance, the functionality of another set of the RNA silencing-related small RNAs, microRNAs (miRNAs), in engineering plant virus resistance has not been extensively explored. Here we show that expression of an artificial miRNA, targeting sequences encoding the silencing suppressor 2b of Cucumber mosaic virus (CMV), can efficiently inhibit 2b gene expression and protein suppressor function in transient expression assays and confer on transgenic tobacco plants effective resistance to CMV infection. Moreover, the resistance level conferred by the transgenic miRNA is well correlated to the miRNA expression level. Comparison of the anti-CMV effect of the artificial miRNA to that of a short hairpin RNA-derived small RNA targeting the same site revealed that the miRNA approach is superior to the approach using short hairpin RNA both in transient assays and in transgenic plants. Together, our data demonstrate that expression of virus-specific artificial miRNAs is an effective and predictable new approach to engineering resistance to CMV and, possibly, to other plant viruses as well.

Maribavir Antagonizes the Antiviral Action of Ganciclovir on Human Cytomegalovirus

The cytomegalovirus (CMV) UL97 kinase inhibitor maribavir antagonized the anti-CMV effect of ganciclovir, increasing the ganciclovir 50% inhibitory concentration against a sensitive strain by up to 13-fold. Antiviral activities of foscarnet and cidofovir were unaffected by maribavir.

Role of interferon alpha (IFN-alpha) and interferon gamma (IFN-gamma) in the control of the infection of monocyte-like cells with human cytomegalovirus (HCMV).

The role of cytokines in the control of HCMV infection has been studied in THP-1 cells, a macrophage-like cell model and in MRC-5 cells. HCMV replication was studied by immune detection of viral immediate-early antigens (IEA) and virus yield was evaluated in MRC-5 cells by immunoperoxidase staining. Pretreatment of MRC-5 and phorbol 12-myristate 13-acetate (PMA)-treated THP-1 cells with IFN-alpha or IFN-gamma for 24 hr prior to the infection reduced the number of infected cells and virus yield. A synergistic anti-CMV activity in synthesis of early proteins was obtained with these cytokines in combination with TNF-alpha in differentiated THP-1 cells only. Treatment of HCMV-infected differentiated THP-1 cells or MRC-5 cells with IFN-alpha or IFN-gamma alone had no inhibitory effect on virus replication, however the virus yield was reduced with ganciclovir. A synergistic anti-CMV activity in virus yield was obtained only when infected differentiated THP-1 cells were treated with ganciclovir in combination with IFN-gamma. The current study shows that IFN-alpha and IFN-gamma can play a role in the reduction of HCMV replication in macrophage-like cells and in the efficiency of therapies with ganciclovir in this cell type and that the anti-CMV effect of cytokines may be different in fibroblasts and in macrophage-like cells.

Effect of natural human interferon-beta on the replication of human cytomegalovirus.

The antiviral effect of natural human interferon-beta (HuIFN-beta) against human cytomegalovirus (CMV) was evaluated in human embryonic lung fibroblasts (HEL). Natural HuIFN-beta, like other HuIFNs, inhibited the replication of CMV. Pretreatment of the cells with natural HuIFN-beta inhibited the appearance of immediate-early antigen (IEA) or pre-early nuclear antigen (PENA) as well as the production of infectious CMV. After a single treatment with natural HuIFN-beta, intracellular 2', 5'-oligoadenylate (2-5A) synthetase activity was induced and maintained at a high level for several days. The anti-CMV effect of natural HuIFN-beta correlated with the intracellular 2-5A synthetase activity.