Publications by authors named "Selmir Avdic"

25 Publications

  • Page 1 of 1

Prophylactic antigen-specific T-cells targeting seven viral and fungal pathogens after allogeneic haemopoietic stem cell transplant.

Clin Transl Immunology 2021 15;10(3):e1249. Epub 2021 Mar 15.

Sydney Medical School University of Sydney Sydney NSW Australia.

Objectives: Adoptive immunotherapy using donor-derived antigen-specific T-cells can prevent and treat infection after allogeneic haemopoietic stem cell transplant (HSCT).

Methods: We treated 11 patients with a prophylactic infusion of 2 × 10 cells per square metre donor-derived T-cells targeting seven infections (six viral and one fungal) following HSCT. Targeted pathogens were cytomegalovirus (CMV), Epstein-Barr virus (EBV), adenovirus, varicella zoster virus, influenza, BK virus (BKV) and .

Results: T-cell products were successfully generated in all patients with 10 products responsive to 6 or 7 infections. T-cell infusions were associated with increases in antigen-experienced activated CD8 T-cells by day 30. CMV, EBV and BKV reactivation occurred in the majority of patients and was well controlled except where glucocorticoids were administered soon after T-cell infusion. Three patients in that circumstance developed CMV tissue infection. No patient required treatment for invasive fungal infection. The most common CMV and EBV TCR clonotypes in the infusion product became the most common clonotypes seen at day 30 post-T-cell infusion. Donors and their recipients were recruited to the study prior to transplant. Grade III/IV graft-versus-host disease developed in four patients. At a median follow-up of 390 days post-transplant, six patients had died, 5 of relapse, and 1 of multi-organ failure. Infection did not contribute to death in any patient.

Conclusion: Rapid reconstitution of immunity to a broad range of viral and fungal infections can be achieved using a multi-pathogen-specific T-cell product. The development of GVHD after T-cell infusion suggests that infection-specific T-cell therapy after allogeneic stem cell transplant should be combined with other strategies to reduce graft-versus-host disease.
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http://dx.doi.org/10.1002/cti2.1249DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7960021PMC
March 2021

Profiling the Blood Compartment of Hematopoietic Stem Cell Transplant Patients During Human Cytomegalovirus Reactivation.

Front Cell Infect Microbiol 2020 8;10:607470. Epub 2021 Jan 8.

Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.

Human cytomegalovirus (HCMV) is a widespread pathogen establishing a latent infection in its host. HCMV reactivation is a major health burden in immunocompromised individuals, and is a major cause of morbidity and mortality following hematopoietic stem cell transplantation (HSCT). Here we determined HCMV genomic levels using droplet digital PCR in different peripheral blood mononuclear cell (PBMC) populations in HCMV reactivating HSCT patients. This high sensitivity approach revealed that all PBMC populations harbored extremely low levels of viral DNA at the peak of HCMV DNAemia. Transcriptomic analysis of PBMCs from high-DNAemia samples revealed elevated expression of genes typical of HCMV specific T cells, while regulatory T cell enhancers as well as additional genes related to immune response were downregulated. Viral transcript levels in these samples were extremely low, but remarkably, the detected transcripts were mainly immediate early viral genes. Overall, our data indicate that HCMV DNAemia is associated with distinct signatures of immune response in the blood compartment, however it is not necessarily accompanied by substantial infection of PBMCs and the residual infected PBMCs are not productively infected.
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http://dx.doi.org/10.3389/fcimb.2020.607470DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7820775PMC
January 2021

Successful treatment of CMV, EBV, and adenovirus tissue infection following HLA-mismatched allogeneic stem cell transplant using infusion of third-party T cells from multiple donors in addition to antivirals, rituximab, and surgery.

Transpl Infect Dis 2020 Nov 24:e13528. Epub 2020 Nov 24.

Department of Haematology, Westmead Hospital, Sydney, NSW, Australia.

Viral infections, principally cytomegalovirus, Epstein Barr virus (EBV) and adenovirus, are a leading cause of morbidity and mortality after allogeneic stem cell transplantation. The use of systemic antivirals is limited by limited efficacy and organ toxicities. Inability to clear infection is exacerbated by transplant-related immunosuppression and prophylaxis or treatment of acute graft versus host disease. We report the first patient to clear three serious viral infections after stem cell transplant using third-party donor partially human leukocyte antigen (HLA) matched virus-specific cytotoxic T cells. The patient, a 53 year old female with transplanted for relapsed leukemia, with severe graft versus host disease received five T cell infusions from three separate donors that ultimately cleared serious systemic infections with cytomegalovirus and adenovirus, and an EBV-driven lymphoma. Systemic antivirals had resulted in failed clinical responses. Use of repeated infusions of partially HLA matched virus-specific T cells from banks containing cryopreserved cells should be strongly considered in transplant recipients with single or multiple refractory viral infections.
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http://dx.doi.org/10.1111/tid.13528DOI Listing
November 2020

Rapidly expanded partially HLA DRB1-matched fungus-specific T cells mediate in vitro and in vivo antifungal activity.

Blood Adv 2020 07;4(14):3443-3456

Westmead Institute for Medical Research, Sydney, NSW, Australia.

Invasive fungal infections are a major cause of disease and death in immunocompromised hosts, including patients undergoing allogeneic hematopoietic stem cell transplant (HSCT). Recovery of adaptive immunity after HSCT correlates strongly with recovery from fungal infection. Using initial selection of lymphocytes expressing the activation marker CD137 after fungal stimulation, we rapidly expanded a population of mainly CD4+ T cells with potent antifungal characteristics, including production of tumor necrosis factor α, interferon γ, interleukin-17, and granulocyte-macrophage colony stimulating factor. Cells were manufactured using a fully good manufacturing practice-compliant process. In vitro, the T cells responded to fungal antigens presented on fully and partially HLA-DRB1 antigen-matched presenting cells, including when the single common DRB1 antigen was allelically mismatched. Administration of antifungal T cells lead to reduction in the severity of pulmonary and cerebral infection in an experimental mouse model of Aspergillus. These data support the establishment of a bank of cryopreserved fungus-specific T cells using normal donors with common HLA DRB1 molecules and testing of partially HLA-matched third-party donor fungus-specific T cells as a potential therapeutic in patients with invasive fungal infection after HSCT.
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http://dx.doi.org/10.1182/bloodadvances.2020001565DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7391149PMC
July 2020

Varicella zoster virus encodes a viral decoy RHIM to inhibit cell death.

PLoS Pathog 2020 07 10;16(7):e1008473. Epub 2020 Jul 10.

Discipline of Infectious Diseases and Immunology, School of Medical Sciences, The University of Sydney, NSW, Australia.

Herpesviruses are known to encode a number of inhibitors of host cell death, including RIP Homotypic Interaction Motif (RHIM)-containing proteins. Varicella zoster virus (VZV) is a member of the alphaherpesvirus subfamily and is responsible for causing chickenpox and shingles. We have identified a novel viral RHIM in the VZV capsid triplex protein, open reading frame (ORF) 20, that acts as a host cell death inhibitor. Like the human cellular RHIMs in RIPK1 and RIPK3 that stabilise the necrosome in TNF-induced necroptosis, and the viral RHIM in M45 from murine cytomegalovirus that inhibits cell death, the ORF20 RHIM is capable of forming fibrillar functional amyloid complexes. Notably, the ORF20 RHIM forms hybrid amyloid complexes with human ZBP1, a cytoplasmic sensor of viral nucleic acid. Although VZV can inhibit TNF-induced necroptosis, the ORF20 RHIM does not appear to be responsible for this inhibition. In contrast, the ZBP1 pathway is identified as important for VZV infection. Mutation of the ORF20 RHIM renders the virus incapable of efficient spread in ZBP1-expressing HT-29 cells, an effect which can be reversed by the inhibition of caspases. Therefore we conclude that the VZV ORF20 RHIM is important for preventing ZBP1-driven apoptosis during VZV infection, and propose that it mediates this effect by sequestering ZBP1 into decoy amyloid assemblies.
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http://dx.doi.org/10.1371/journal.ppat.1008473DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7375649PMC
July 2020

Mass cytometry reveals immune signatures associated with cytomegalovirus (CMV) control in recipients of allogeneic haemopoietic stem cell transplant and CMV-specific T cells.

Clin Transl Immunology 2020 2;9(7):e1149. Epub 2020 Jul 2.

Faculty of Medicine and Health The University of Sydney Camperdown NSW Australia.

Objectives: Cytomegalovirus (CMV) is known to have a significant impact on immune recovery post-allogeneic haemopoietic stem cell transplant (HSCT). Adoptive therapy with donor-derived or third-party virus-specific T cells (VST) can restore CMV immunity leading to clinical benefit in prevention and treatment of post-HSCT infection. We developed a mass cytometry approach to study natural immune recovery post-HSCT and assess the mechanisms underlying the clinical benefits observed in recipients of VST.

Methods: A mass cytometry panel of 38 antibodies was utilised for global immune assessment (72 canonical innate and adaptive immune subsets) in HSCT recipients undergoing natural post-HSCT recovery ( = 13) and HSCT recipients who received third-party donor-derived CMV-VST as salvage for unresponsive CMV reactivation ( = 8).

Results: Mass cytometry identified distinct immune signatures associated with CMV characterised by a predominance of innate cells (monocytes and NK) seen early and an adaptive signature with activated CD8 T cells seen later. All CMV-VST recipients had failed standard antiviral pharmacotherapy as a criterion for trial involvement; 5/8 had failed to develop the adaptive immune signature by study enrolment despite significant CMV antigen exposure. Of these, VST administration resulted in development of the adaptive signature in association with CMV control in three patients. Failure to respond to CMV-VST in one patient was associated with persistent absence of the adaptive immune signature.

Conclusion: The clinical benefit of CMV-VST may be mediated by the recovery of an adaptive immune signature characterised by activated CD8 T cells.
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http://dx.doi.org/10.1002/cti2.1149DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7332355PMC
July 2020

Whole-Genome Approach to Assessing Human Cytomegalovirus Dynamics in Transplant Patients Undergoing Antiviral Therapy.

Front Cell Infect Microbiol 2020 15;10:267. Epub 2020 Jun 15.

MRC-University of Glasgow Centre for Virus Research, Glasgow, United Kingdom.

Human cytomegalovirus (HCMV) is the most frequent cause of opportunistic viral infection following transplantation. Viral factors of potential clinical importance include the selection of mutants resistant to antiviral drugs and the occurrence of infections involving multiple HCMV strains. These factors are typically addressed by analyzing relevant HCMV genes by PCR and Sanger sequencing, which involves independent assays of limited sensitivity. To assess the dynamics of viral populations with high sensitivity, we applied high-throughput sequencing coupled with HCMV-adapted target enrichment to samples collected longitudinally from 11 transplant recipients (solid organ, = 9, and allogeneic hematopoietic stem cell, = 2). Only the latter presented multiple-strain infections. Four cases presented resistance mutations ( = 6), two (A594V and L595S) at high (100%) and four (V715M, V781I, A809V, and T838A) at low (<25%) frequency. One allogeneic hematopoietic stem cell transplant recipient presented up to four resistance mutations, each at low frequency. The use of high-throughput sequencing to monitor mutations and strain composition in people at risk of HCMV disease is of potential value in helping clinicians implement the most appropriate therapy.
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http://dx.doi.org/10.3389/fcimb.2020.00267DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7308726PMC
June 2020

Single cell analysis reveals human cytomegalovirus drives latently infected cells towards an anergic-like monocyte state.

Elife 2020 01 22;9. Epub 2020 Jan 22.

Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel.

Human cytomegalovirus (HCMV) causes a lifelong infection through establishment of latency. Although reactivation from latency can cause life-threatening disease, our molecular understanding of HCMV latency is incomplete. Here we use single cell RNA-seq analysis to characterize latency in monocytes and hematopoietic stem and progenitor cells (HSPCs). In monocytes, we identify host cell surface markers that enable enrichment of latent cells harboring higher viral transcript levels, which can reactivate more efficiently, and are characterized by reduced intrinsic immune response that is important for viral gene expression. Significantly, in latent HSPCs, viral transcripts could be detected only in monocyte progenitors and were also associated with reduced immune-response. Overall, our work indicates that regardless of the developmental stage in which HCMV infects, HCMV drives hematopoietic cells towards a weaker immune-responsive monocyte state and that this anergic-like state is crucial for the virus ability to express its transcripts and to eventually reactivate.
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http://dx.doi.org/10.7554/eLife.52168DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7039680PMC
January 2020

Human Cytomegalovirus Latency and Reactivation in Allogeneic Hematopoietic Stem Cell Transplant Recipients.

Front Microbiol 2019 28;10:1186. Epub 2019 May 28.

Discipline of Infectious Diseases and Immunology, Sydney Medical School, Charles Perkins Centre, University of Sydney, Sydney, NSW, Australia.

Human cytomegalovirus (HCMV) reactivation is a major infectious cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HSCT). HCMV is a ubiquitous beta-herpesvirus which asymptomatically infects immunocompetent individuals but establishes lifelong latency, with the potential to reactivate to a life-threatening productive infection when the host immune system is suppressed or compromised. Opportunistic HCMV reactivation is the most common viral complication following engraftment after HSCT and is associated with a marked increase in non-relapse mortality, which appears to be linked to complex effects on post-transplant immune recovery. This minireview explores the cellular sites of HCMV latency and reactivation in HSCT recipients and provides an overview of the risk factors for HCMV reactivation post-HSCT. The impact of HCMV in shaping post-transplant immune reconstitution and its relationship with patient outcomes such as relapse and graft-versus-host disease will be discussed. Finally, we survey current and emerging strategies to prevent and control HCMV reactivation in HSCT recipients, with recent developments including adoptive T cell therapies to accelerate HCMV-specific T cell reconstitution and new anti-HCMV drug therapy for HCMV reactivation after HSCT.
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http://dx.doi.org/10.3389/fmicb.2019.01186DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6546901PMC
May 2019

Restriction of Human Cytomegalovirus Infection by Galectin-9.

J Virol 2019 02 17;93(3). Epub 2019 Jan 17.

Discipline of Infectious Diseases and Immunology, University of Sydney, Camperdown, New South Wales, Australia

Human cytomegalovirus (HCMV) is a ubiquitous human herpesvirus. While HCMV infection is generally asymptomatic in the immunocompetent, it can have devastating consequences in those with compromised or underdeveloped immune systems, including transplant recipients and neonates. Galectins are a widely expressed protein family that have been demonstrated to modulate both antiviral immunity and regulate direct host-virus interactions. The potential for galectins to directly modulate HCMV infection has not previously been studied, and our results reveal that galectin-9 (Gal-9) can potently inhibit HCMV infection. Gal-9-mediated inhibition of HCMV was dependent upon its carbohydrate recognition domains and thus dependent on glycan interactions. Temperature shift studies revealed that Gal-9 specific inhibition was mediated primarily at the level of virus-cell fusion and not binding. Additionally, we found that during reactivation of HCMV in hematopoietic stem cell transplant (HSCT) patients soluble Gal-9 is upregulated. This study provides the first evidence for Gal-9 functioning as a potent antiviral defense effector molecule against HCMV infection and identifies it as a potential clinical candidate to restrict HCMV infections. Human cytomegalovirus (HCMV) continues to cause serious and often life-threatening disease in those with impaired or underdeveloped immune systems. This virus is able to infect and replicate in a wide range of human cell types, which enables the virus to spread to other individuals in a number of settings. Current antiviral drugs are associated with a significant toxicity profile, and there is no vaccine; these factors highlight a need to identify additional targets for the development of anti-HCMV therapies. We demonstrate for the first time that secretion of a member of the galectin family of proteins, galectin-9 (Gal-9), is upregulated during natural HCMV-reactivated infection and that this soluble cellular protein possesses a potent capacity to block HCMV infection by inhibiting virus entry into the host cell. Our findings support the possibility of harnessing the antiviral properties of Gal-9 to prevent HCMV infection and disease.
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http://dx.doi.org/10.1128/JVI.01746-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6340044PMC
February 2019

Mass Cytometry for the Assessment of Immune Reconstitution After Hematopoietic Stem Cell Transplantation.

Front Immunol 2018 26;9:1672. Epub 2018 Jul 26.

University of Sydney, Sydney, NSW, Australia.

Mass cytometry, or Cytometry by Time-Of-Flight, is a powerful new platform for high-dimensional single-cell analysis of the immune system. It enables the simultaneous measurement of over 40 markers on individual cells through the use of monoclonal antibodies conjugated to rare-earth heavy-metal isotopes. In contrast to the fluorochromes used in conventional flow cytometry, metal isotopes display minimal signal overlap when resolved by single-cell mass spectrometry. This review focuses on the potential of mass cytometry as a novel technology for studying immune reconstitution in allogeneic hematopoietic stem cell transplant (HSCT) recipients. Reconstitution of a healthy donor-derived immune system after HSCT involves the coordinated regeneration of innate and adaptive immune cell subsets in the recipient. Mass cytometry presents an opportunity to investigate immune reconstitution post-HSCT from a systems-level perspective, by allowing the phenotypic and functional features of multiple cell populations to be assessed simultaneously. This review explores the current knowledge of immune reconstitution in HSCT recipients and highlights recent mass cytometry studies contributing to the field.
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http://dx.doi.org/10.3389/fimmu.2018.01672DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6070614PMC
September 2019

Modulation of the Host Environment by Human Cytomegalovirus with Viral Interleukin 10 in Peripheral Blood.

J Infect Dis 2017 03;215(6):874-882

Department of Biology, University of San Francisco, California, USA.

Background: Human cytomegalovirus (HCMV) is a herpesvirus with both lytic and latent life cycles. Human cytomegalovirus encodes 2 viral cytokines that are orthologs of human cellular interleukin 10 (cIL-10). Both cytomegalovirus interleukin 10 (cmvIL-10) and Latency-associated cytomegalovirus interleukin 10 (LAcmvIL-10) (collectively vIL-10) are expressed during lytic infection and cause immunosuppressive effects that impede virus clearance. LAcmvIL-10 is also expressed during latent infection of myeloid progenitor cells and monocytes and facilitates persistence. Here, we investigated whether vIL-10 could be detected during natural infection.

Methods: Plasma from healthy blood donors was tested by enzyme-linked immunosorbent assay for anti-HCMV immunoglobulin G and immunoglobulin M and for cIL-10 and vIL-10 levels using a novel vIL-10 assay that detects cmvIL-10 and LAcmvIL-10, with no cross-reactivity to cIL-10.

Results: vIL-10 was evident in HCMV+ donors (n = 19 of 26), at levels ranging 31-547 pg/mL. By comparison, cIL-10 was detected at lower levels ranging 3-69 pg/mL. There was a strong correlation between vIL-10 and cIL-10 levels (P = .01). Antibodies against vIL-10 were also detected and neutralized vIL-10 activity.

Conclusions: vIL-10 was detected in peripheral blood of healthy blood donors. These findings suggest that vIL-10 may play a key role in sensing or modifying the host environment during latency and, therefore, may be a potential target for intervention strategies.
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http://dx.doi.org/10.1093/infdis/jix043DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5853888PMC
March 2017

Cytomegalovirus Restructures Lipid Rafts via a US28/CDC42-Mediated Pathway, Enhancing Cholesterol Efflux from Host Cells.

Cell Rep 2016 06 16;16(1):186-200. Epub 2016 Jun 16.

Baker IDI Heart and Diabetes Institute, Melbourne, VIC 3004, Australia. Electronic address:

Cytomegalovirus (HCMV) contains cholesterol, but how HCMV interacts with host cholesterol metabolism is unknown. We found that, in human fibroblasts, HCMV infection increased the efflux of cellular cholesterol, despite reducing the abundance of ABCA1. Mechanistically, viral protein US28 was acting through CDC42, rearranging actin microfilaments, causing association of actin with lipid rafts, and leading to a dramatic change in the abundance and/or structure of lipid rafts. These changes displaced ABCA1 from the cell surface but created new binding sites for apolipoprotein A-I, resulting in enhanced cholesterol efflux. The changes also reduced the inflammatory response in macrophages. HCMV infection modified the host lipidome profile and expression of several genes and microRNAs involved in cholesterol metabolism. In mice, murine CMV infection elevated plasma triglycerides but did not affect the level and functionality of high-density lipoprotein. Thus, HCMV, through its protein US28, reorganizes lipid rafts and disturbs cell cholesterol metabolism.
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http://dx.doi.org/10.1016/j.celrep.2016.05.070DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5389417PMC
June 2016

Human Cytomegalovirus-Encoded Human Interleukin-10 (IL-10) Homolog Amplifies Its Immunomodulatory Potential by Upregulating Human IL-10 in Monocytes.

J Virol 2016 Apr 28;90(8):3819-3827. Epub 2016 Mar 28.

Discipline of Infectious Diseases and Immunology, University of Sydney, Sydney, New South Wales, Australia

Unlabelled: The human cytomegalovirus (HCMV) gene UL111A encodes cytomegalovirus-encoded human interleukin-10 (cmvIL-10), a homolog of the potent immunomodulatory cytokine human interleukin 10 (hIL-10). This viral homolog exhibits a range of immunomodulatory functions, including suppression of proinflammatory cytokine production and dendritic cell (DC) maturation, as well as inhibition of major histocompatibility complex (MHC) class I and class II. Here, we present data showing that cmvIL-10 upregulates hIL-10, and we identify CD14(+)monocytes and monocyte-derived macrophages and DCs as major sources of hIL-10 secretion in response to cmvIL-10. Monocyte activation was not a prerequisite for cmvIL-10-mediated upregulation of hIL-10, which was dose dependent and controlled at the transcriptional level. Furthermore, cmvIL-10 upregulated expression of tumor progression locus 2 (TPL2), which is a regulator of the positive hIL-10 feedback loop, whereas expression of a negative regulator of the hIL-10 feedback loop, dual-specificity phosphatase 1 (DUSP1), remained unchanged. Engagement of the hIL-10 receptor (hIL-10R) by cmvIL-10 led to upregulation of heme oxygenase 1 (HO-1), an enzyme linked with suppression of inflammatory responses, and this upregulation was required for cmvIL-10-mediated upregulation of hIL-10. We also demonstrate an important role for both phosphatidylinositol 3-kinase (PI3K) and STAT3 in the upregulation of HO-1 and hIL-10 by cmvIL-10. In addition to upregulating hIL-10, cmvIL-10 could exert a direct immunomodulatory function, as demonstrated by its capacity to upregulate expression of cell surface CD163 when hIL-10 was neutralized. This study identifies a mechanistic basis for cmvIL-10 function, including the capacity of this viral cytokine to potentially amplify its immunosuppressive impact by upregulating hIL-10 expression.

Importance: Human cytomegalovirus (HCMV) is a large, double-stranded DNA virus that causes significant human disease, particularly in the congenital setting and in solid-organ and hematopoietic stem cell transplant patients. A prominent feature of HCMV is the wide range of viral gene products that it encodes which function to modulate host defenses. One of these is cmvIL-10, which is a homolog of the potent immunomodulatory cytokine human interleukin 10 (hIL-10). In this study, we report that, in addition to exerting a direct biological impact, cmvIL-10 upregulates the expression of hIL-10 by primary blood-derived monocytes and that it does so by modulating existing cellular pathways. This capacity of cmvIL-10 to upregulate hIL-10 represents a mechanism by which HCMV may amplify its immunomodulatory impact during infection.
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http://dx.doi.org/10.1128/JVI.03066-15DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4810557PMC
April 2016

Abrogation of the interferon response promotes more efficient human cytomegalovirus replication.

J Virol 2015 Jan 12;89(2):1479-83. Epub 2014 Nov 12.

Discipline of Infectious Diseases and Immunology, Sydney Medical School, University of Sydney, Camperdown, NSW, Australia

The effect of abrogating the interferon (IFN) response on human cytomegalovirus (HCMV) replication was investigated using primary human cells engineered to block either the production of or the response to type I IFNs. In IFN-deficient cells, HCMV produced larger plaques and spread and replicated more rapidly than in parental cells. These cells demonstrate the vital role of IFNs in controlling HCMV replication and provide useful tools to investigate the IFN response to HCMV.
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http://dx.doi.org/10.1128/JVI.02988-14DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4300662PMC
January 2015

Latency-associated viral interleukin-10 (IL-10) encoded by human cytomegalovirus modulates cellular IL-10 and CCL8 Secretion during latent infection through changes in the cellular microRNA hsa-miR-92a.

J Virol 2014 Dec 24;88(24):13947-55. Epub 2014 Sep 24.

Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom

Unlabelled: The UL111A gene of human cytomegalovirus encodes a viral homologue of the cellular immunomodulatory cytokine interleukin 10 (cIL-10), which, due to alternative splicing, results in expression of two isoforms designated LAcmvIL-10 (expressed during both lytic and latent infection) and cmvIL-10 (identified only during lytic infection). We have analyzed the functions of LAcmvIL-10 during latent infection of primary myeloid progenitor cells and found that LAcmvIL-10 is responsible, at least in part, for the known increase in secretion of cellular IL-10 and CCL8 in the secretomes of latently infected cells. This latency-associated increase in CCL8 expression results from a concomitant LAcmvIL-10-mediated suppression of the expression of the cellular microRNA (miRNA) hsa-miR-92a, which targets CCL8 directly. Taking the data together, we show that the previously observed downregulation of hsa-miR-92a and upregulation of CCL8 during HCMV latent infection of myeloid cells are intimately linked via the latency-associated expression of LAcmvIL-10.

Importance: HCMV latency causes significant morbidity and mortality in immunocompromised individuals, yet HCMV is carried silently (latently) in 50 to 90% of the population. Understanding how HCMV maintains infection for the lifetime of an infected individual is critical for the treatment of immunocompromised individuals suffering with disease as a result of HCMV. In this study, we analyze one of the proteins that are expressed during the "latent" phase of HCMV, LAcmvIL-10, and find that the expression of the gene modulates the microenvironment of the infected cell, leading to evasion of the immune system.
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http://dx.doi.org/10.1128/JVI.02424-14DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4249158PMC
December 2014

Modulation of dendritic cell functions by viral IL-10 encoded by human cytomegalovirus.

Front Microbiol 2014 4;5:337. Epub 2014 Jul 4.

Human Cytomegalovirus Research Group, Discipline of Infectious Diseases and Immunology, University of Sydney Camperdown, NSW, Australia ; Centre for Virus Research, Westmead Millennium Institute Westmead, NSW, Australia.

Human cytomegalovirus (HCMV), a clinically important β-herpesvirus, is a master of evasion and modulation of the host immune system, including inhibition of a number of dendritic cell (DC) functions. DCs play a central role in co-ordination of the immune response against pathogens and any disturbance of DCs functions can result in a cascade effect on a range of immune cells. Recently, the HCMV gene UL111A, which encodes viral homologs of human interleukin 10, has been identified as a strong suppressor of a number of DCs functions. In this mini review, we focus on HCMV-encoded viral IL-10-mediated inhibitory effects on DCs and implications for the development of an effective HCMV vaccine.
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http://dx.doi.org/10.3389/fmicb.2014.00337DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4081832PMC
July 2014

Human cytomegalovirus upregulates expression of the lectin galectin 9 via induction of beta interferon.

J Virol 2014 Sep 9;88(18):10990-4. Epub 2014 Jul 9.

Discipline of Infectious Diseases and Immunology, Sydney Medical School, University of Sydney, Sydney, NSW, Australia Centre for Virus Research, Westmead Millennium Institute, Sydney, NSW, Australia

Regulation of the lectin galectin 9 (Gal-9) was investigated for the first time during human cytomegalovirus (HCMV) infection. Gal-9 transcription was significantly upregulated in transplant recipients with reactivated HCMV in vivo. In vitro, Gal-9 was potently upregulated by HCMV independently of viral gene expression, with interferon beta (IFN-β) identified as the mediator of this effect. This study defines an immunoregulatory protein potently increased by HCMV infection and a novel mechanism to control Gal-9 through IFN-β induction.
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http://dx.doi.org/10.1128/JVI.01259-14DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4178876PMC
September 2014

Human cytomegalovirus interleukin-10 polarizes monocytes toward a deactivated M2c phenotype to repress host immune responses.

J Virol 2013 Sep 17;87(18):10273-82. Epub 2013 Jul 17.

Centre for Virus Research, Westmead Millennium Institute, Westmead, New South Wales, Australia.

Several human cytomegalovirus (HCMV) genes encode products that modulate cellular functions in a manner likely to enhance viral pathogenesis. This includes UL111A, which encodes homologs of human interleukin-10 (hIL-10). Depending upon signals received, monocytes and macrophages become polarized to either classically activated (M1 proinflammatory) or alternatively activated (M2 anti-inflammatory) subsets. Skewing of polarization toward an M2 subset may benefit the virus by limiting the proinflammatory responses to infection, and so we determined whether HCMV-encoded viral IL-10 influenced monocyte polarization. Recombinant viral IL-10 protein polarized CD14(+) monocytes toward an anti-inflammatory M2 subset with an M2c phenotype, as demonstrated by high expression of CD163 and CD14 and suppression of major histocompatibility complex (MHC) class II. Significantly, in the context of productive HCMV infection, viral IL-10 produced by infected cells polarized uninfected monocytes toward an M2c phenotype. We also assessed the impact of viral IL-10 on heme oxygenase 1 (HO-1), which is an enzyme linked with suppression of inflammatory responses. Polarization of monocytes by viral IL-10 resulted in upregulation of HO-1, and inhibition of HO-1 function resulted in a loss of capacity of viral IL-10 to suppress tumor necrosis factor alpha (TNF-α) and IL-1β, implicating HO-1 in viral IL-10-induced suppression of proinflammatory cytokines by M2c monocytes. In addition, a functional consequence of monocytes polarized with viral IL-10 was a decreased capacity to activate CD4(+) T cells. This study identifies a novel role for viral IL-10 in driving M2c polarization, which may limit virus clearance by restricting proinflammatory and CD4(+) T cell responses at sites of infection.
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http://dx.doi.org/10.1128/JVI.00912-13DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3754025PMC
September 2013

Human cytomegalovirus encoded homologs of cytokines, chemokines and their receptors: roles in immunomodulation.

Viruses 2012 Oct 25;4(11):2448-70. Epub 2012 Oct 25.

Discipline of Infectious Diseases and Immunology, University of Sydney, Australia.

Human cytomegalovirus (HCMV), the largest human herpesvirus, infects a majority of the world's population. Like all herpesviruses, following primary productive infection, HCMV establishes a life-long latent infection, from which it can reactivate years later to produce new, infectious virus. Despite the presence of a massive and sustained anti-HCMV immune response, productively infected individuals can shed virus for extended periods of time, and once latent infection is established, it is never cleared from the host. It has been proposed that HCMV must therefore encode functions which help to evade immune mediated clearance during productive virus replication and latency. Molecular mimicry is a strategy used by many viruses to subvert and regulate anti-viral immunity and HCMV has hijacked/developed a range of functions that imitate host encoded immunomodulatory proteins. This review will focus on the HCMV encoded homologs of cellular cytokines/chemokines and their receptors, with an emphasis on how these virus encoded homologs may facilitate viral evasion of immune clearance.
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http://dx.doi.org/10.3390/v4112448DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3509658PMC
October 2012

Viral interleukin-10 expressed by human cytomegalovirus during the latent phase of infection modulates latently infected myeloid cell differentiation.

J Virol 2011 Jul 18;85(14):7465-71. Epub 2011 May 18.

Westmead Millennium Institute, Centre for Virus Research, P.O. Box 412, Westmead, New South Wales, Australia 2145.

The human cytomegalovirus UL111A gene is expressed during latent and productive infections, and it codes for homologs of interleukin-10 (IL-10). We examined whether viral IL-10 expressed during latency altered differentiation of latently infected myeloid progenitors. In comparison to infection with parental virus or mock infection, latent infection with a virus in which the gene encoding viral IL-10 has been deleted upregulated cytokines associated with dendritic cell (DC) formation and increased the proportion of myeloid DCs. These data demonstrate that viral IL-10 restricts the ability of latently infected myeloid progenitors to differentiate into DCs and identifies an immunomodulatory role for viral IL-10 which may limit the host's ability to clear latent virus.
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http://dx.doi.org/10.1128/JVI.00088-11DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3126599PMC
July 2011

Inhibition of 2',5'-oligoadenylate synthetase expression and function by the human cytomegalovirus ORF94 gene product.

J Virol 2011 Jun 30;85(11):5696-700. Epub 2011 Mar 30.

Centre for Virus Research, Westmead Millennium Institute, and the University of Sydney, Westmead, NSW, Austalia.

The human cytomegalovirus (HCMV) ORF94 gene product has been reported to be expressed during both productive and latent phases of infection, although its function is unknown. We report that expression of pORF94 leads to decreased 2',5'-oligoadenylate synthetase (OAS) expression in transfected cells with and without interferon stimulation. Furthermore, the functional activity of OAS was inhibited by pORF94. Finally, we present evidence of OAS modulation by pORF94 during productive HCMV infection of human fibroblasts. This study provides the first identification of a function for pORF94 and identifies an additional means by which HCMV may limit a critical host cell antiviral response.
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http://dx.doi.org/10.1128/JVI.02463-10DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3094971PMC
June 2011

Human cytomegalovirus latent infection and associated viral gene expression.

Future Microbiol 2010 Jun;5(6):883-900

Centre For Virus Research, Westmead Millennium Institute & University of Sydney, Westmead Millennium Institute, PO Box 412, New South Wales 2145, Australia.

Human cytomegalovirus (HCMV) is a clinically important and ubiquitous herpesvirus. Following primary productive infection the virus is not completely eliminated from the host, but instead establishes a lifelong latent infection without detectable virus production, from where it can reactivate at a later stage to generate new infectious virus. Reactivated HCMV often results in life-threatening disease in immunocompromised individuals, particularly allogeneic stem cell and solid organ transplant recipients, where it remains one of the most difficult opportunistic pathogens that complicate the care of these patients. The ability of HCMV to establish and reactivate from latency is central to its success as a human pathogen, yet latency remains very poorly understood. This article will cover several aspects of HCMV latency, with a focus on current understanding of viral gene expression and functions during this phase of infection.
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http://dx.doi.org/10.2217/fmb.10.58DOI Listing
June 2010

The role of the human cytomegalovirus UL111A gene in down-regulating CD4+ T-cell recognition of latently infected cells: implications for virus elimination during latency.

Blood 2009 Nov 25;114(19):4128-37. Epub 2009 Aug 25.

Centre for Virus Research, Westmead Millennium Institute and University of Sydney, Westmead, NSW 2145, Australia.

The capacity of human cytomegalovirus (HCMV) to establish and maintain a latent infection from which it can later reactivate ensures its widespread distribution in the population, but the mechanisms enabling maintenance of latency in the face of a robust immune system are poorly understood. We examined the role of the HCMV UL111A gene, which encodes homologs of the immunosuppressive cytokine interleukin-10 in the context of latent infection of myeloid progenitor cells. A UL111A deletion virus was able to establish, maintain, and reactivate from experimental latency in a manner comparable with parental virus, but major histocompatibility complex class II levels increased significantly on the surfaces of cells infected with the deletion virus. Importantly, there was an increase in both allogeneic and autologous peripheral blood mononuclear cells and CD4(+) T-cell responses to UL111A deletion virus-infected myeloid progenitors, indicating that loss of the capacity to express viral interleukin-10 during latency results in latently infected cells becoming more readily recognizable by a critical arm of the immune response. The detection of a viral gene that suppresses CD4(+) T-cell recognition of latently infected cells identifies an immune evasion strategy that probably enhances the capacity of HCMV to persist in a latent state within the human host.
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http://dx.doi.org/10.1182/blood-2008-12-197111DOI Listing
November 2009

Virus-encoded homologs of cellular interleukin-10 and their control of host immune function.

J Virol 2009 Oct 29;83(19):9618-29. Epub 2009 Jul 29.

Centre for Virus Research, Westmead Millennium Institute and University of Sydney, Sydney, Australia.

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http://dx.doi.org/10.1128/JVI.01098-09DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2747999PMC
October 2009