Mechanisms of human cytomegalovirus (HCMV) (re)activation and its impact on organ transplant patients

Human cytomegalovirus degrades DMXL1 to inhibit autophagy, lysosomal acidification, and viral assembly

Human cytomegalovirus (HCMV) is an important human pathogen that regulates host immunity and hijacks host compartments, including lysosomes, to assemble virions. We combined a quantitative proteomic analysis of HCMV infection with a database of proteins involved in vacuolar acidification, revealing Dmx-like protein-1 (DMXL1) as the only protein that acidifies vacuoles yet is degraded by HCMV. Systematic comparison of viral deletion mutants reveals the uncharacterized 7 kDa US33A protein as necessary and sufficient for DMXL1 degradation, which occurs via recruitment of the E3 ubiquitin ligase Kip1 ubiquitination-promoting complex (KPC). US33A-mediated DMXL1 degradation inhibits lysosome acidification and autophagic cargo degradation. Formation of the virion assembly compartment, which requires lysosomes, occurs significantly later with US33A-expressing virus infection, with reduced viral replication. These data thus identify a viral strategy for cellular remodeling, with the potential to employ US33A in therapies for viral infection or rheumatic conditions, in which inhibition of lysosome acidification can attenuate disease.

Opportunistic Infections Post-Lung Transplantation: Viral, Fungal, and Mycobacterial

Opportunistic infections are a leading cause of lung transplant recipient morbidity and mortality. Risk factors for infection include continuous exposure of the lung allograft to the external environment, high levels of immunosuppression, impaired mucociliary clearance and decreased cough reflex, and impact of the native lung microbiome in single lung transplant recipients. Infection risk is mitigated through careful pretransplant screening of recipients and donors, implementation of antimicrobial prophylaxis strategies, and routine surveillance posttransplant. This review describes common viral, fungal, and mycobacterial infectious after lung transplant and provides recommendations on prevention and treatment.

Opportunistic Infections Post-Lung Transplantation: Viral, Fungal, and Mycobacterial

Opportunistic infections are a leading cause of lung transplant recipient morbidity and mortality. Risk factors for infection include continuous exposure of the lung allograft to the external environment, high levels of immunosuppression, impaired mucociliary clearance and decreased cough reflex, and impact of the native lung microbiome in single lung transplant recipients. Infection risk is mitigated through careful pretransplant screening of recipients and donors, implementation of antimicrobial prophylaxis strategies, and routine surveillance posttransplant. This review describes common viral, fungal, and mycobacterial infectious after lung transplant and provides recommendations on prevention and treatment.

Transcriptomic analysis of human cytomegalovirus to survey the indirect effects on renal transplant recipients

Post-transplant human cytomegalovirus (HCMV) viremia has been linked to adverse "indirect effects" among transplant patients. HCMV-created immunomodulatory mechanisms could be associated with the indirect effects.

OBJECTIVE

In the present study, the RNA-Seq whole transcriptome of renal transplant (RT) patients was analyzed to seek the underlying pathobiologic pathways associated with the long-term indirect effects of HCMV.

METHODS

To investigate the activated biological pathways in HCMV infection, total RNA was extracted from PBMCs of 2 RT patients with active HCMV and 2 RT patients without infection and then were sequenced using RNA-Seq. The resulted raw data were analyzed by conventional RNA-Seq software to determine the Differentially Expressed Genes (DEGs). Afterward, Gene Ontology (GO) and pathway enrichment analyses were conducted to determine the enriched pathways and biological processes by DEGs. Eventually, the relative expressions of some significant genes were validated in the twenty external RT patients.

RESULT

The analysis of RNA-Seq data related to RT patients with HCMV active viremia led to the identification of 140 up-regulated and 100 down-regulated DEGs. KEGG pathway analysis revealed the enrichment of DEGs in IL18 signaling, AGE-RAGE signaling pathway in diabetic complications, signaling by GPCR, Platelet activation, signaling and aggregation, Estrogen signaling pathway and signaling by Wnt due to HCMV infection. The expression levels of six genes involved in enriched pathways including F3, PTX3, ADRA2B, GNG11, GP9, HBEGF were then verified using RT-qPCR. The results were in consistent with RNA-Seq resultsoutcomes.

CONCLUSION

This study specifies some pathobiological pathways which are activated in HCMV active infection and could be linked to the adverse indirect effects caused by HCMV infection in transplant patients.

Family Herpesviridae and neuroinfections: current status and research in progress

This article addresses the relationship between human herpesviruses (HHVs) and neuroinfections. Alphaherpesviruses, betaherpesviruses and gammaherpesviruses are neurotropic viruses that establish latency and exhibit reactivation capacity. Encephalitis and meningitis are common in cases of HHV. The condition promoted by HHV infection is a purported trigger for certain neurodegenerative diseases. Ongoing studies have identified an association between HSV-1 and the occurrence of Alzheimer's disease, multiple sclerosis and infections by HHV-6 and Epstein-Barr virus. In this review, we highlight the importance of research investigating the role of herpesviruses in the pathogenesis of diseases that affect the nervous system and describe other studies in progress.

The Human Cytomegalovirus β2.7 Long Non-Coding RNA Prevents Induction of Reactive Oxygen Species to Maintain Viral Gene Silencing during Latency

Human cytomegalovirus (HCMV) is a significant source of disease for the immunosuppressed and immunonaive. The treatment of HCMV is made more problematic by viral latency, a lifecycle stage in which the virus reduces its own gene expression and produces no infectious virus. The most highly expressed viral gene during HCMV latency is the viral β2.7 long non-coding RNA. Although we have recently shown that the β2.7 lncRNA lowers levels of reactive oxygen species (ROS) during infection in monocytes, how this impacts latency is unclear. We now show that β2.7 is important for establishing and maintaining HCMV latency by aiding the suppression of viral lytic gene expression and that this is directly related to its ability to quench reactive oxygen species (ROS). Consistent with this, we also find that exogenous inducers of ROS cause reactivation of latent HCMV. These effects can be compensated by treatment with an antioxidant to lower ROS levels. Finally, we show that ROS-mediated reactivation is independent of myeloid differentiation, but instead relies on NF-κB activation. Altogether, these results reveal a novel factor that is central to the complex process that underpins HCMV latency. These findings may be of particular relevance in the transplant setting, in which transplanted tissue/organs are subject to very high ROS levels, and HCMV reactivation poses a significant threat.

Viral infections in lung transplantation

Viral infections account for up to 30% of all infectious complications in lung transplant recipients, remaining a significant cause of morbidity and even mortality. Impact of viral infections is not only due to the direct effects of viral replication, but also to immunologically-mediated lung injury that may lead to acute rejection and chronic lung allograft dysfunction. This has particularly been seen in infections caused by herpesviruses and respiratory viruses. The implementation of universal preventive measures against cytomegalovirus (CMV) and influenza (by means of antiviral prophylaxis and vaccination, respectively) and administration of early antiviral treatment have reduced the burden of these diseases and potentially their role in affecting allograft outcomes. New antivirals against CMV for prophylaxis and for treatment of antiviral-resistant CMV infection are currently being evaluated in transplant recipients, and may continue to improve the management of CMV in lung transplant recipients. However, new therapeutic and preventive strategies are highly needed for other viruses such as respiratory syncytial virus (RSV) or parainfluenza virus (PIV), including new antivirals and vaccines. This is particularly important in the advent of the COVID-19 pandemic, for which several unanswered questions remain, in particular on the best antiviral and immunomodulatory regimen for decreasing mortality specifically in lung transplant recipients. In conclusion, the appropriate management of viral complications after transplantation remain an essential step to continue improving survival and quality of life of lung transplant recipients.

Update in Viral Infections in the Intensive Care Unit

The advent of highly sensitive molecular diagnostic techniques has improved our ability to detect viral pathogens leading to severe and often fatal infections that require admission to the Intensive Care Unit (ICU). Viral infections in the ICU have pleomorphic clinical presentations including pneumonia, acute respiratory distress syndrome, respiratory failure, central or peripheral nervous system manifestations, and viral-induced shock. Besides de novo infections, certain viruses fall into latency and can be reactivated in both immunosuppressed and immunocompetent critically ill patients. Depending on the viral strain, transmission occurs either directly through contact with infectious materials and large droplets, or indirectly through suspended air particles (airborne transmission of droplet nuclei). Many viruses can efficiently spread within hospital environment leading to in-hospital outbreaks, sometimes with high rates of mortality and morbidity, thus infection control measures are of paramount importance. Despite the advances in detecting viral pathogens, limited progress has been made in antiviral treatments, contributing to unexpectedly high rates of unfavorable outcomes. Herein, we review the most updated data on epidemiology, common clinical features, diagnosis, pathogenesis, treatment and prevention of severe community- and hospital-acquired viral infections in the ICU settings.

Human cytomegalovirus protein pUL36: A dual cell death pathway inhibitor

Human cytomegalovirus (HCMV) is an important human pathogen and a paradigm of intrinsic, innate, and adaptive viral immune evasion. Here, we employed multiplexed tandem mass tag-based proteomics to characterize host proteins targeted for degradation late during HCMV infection. This approach revealed that mixed lineage kinase domain-like protein (MLKL), a key terminal mediator of cellular necroptosis, was rapidly and persistently degraded by the minimally passaged HCMV strain Merlin but not the extensively passaged strain AD169. The strain Merlin viral inhibitor of apoptosis pUL36 was necessary and sufficient both to degrade MLKL and to inhibit necroptosis. Furthermore, mutation of pUL36 Cys¹³¹ abrogated MLKL degradation and restored necroptosis. As the same residue is also required for pUL36-mediated inhibition of apoptosis by preventing proteolytic activation of procaspase-8, we define pUL36 as a multifunctional inhibitor of both apoptotic and necroptotic cell death.

Cytomegalovirus Latency and Reactivation: An Intricate Interplay With the Host Immune Response

CMV is an ancient herpesvirus that has co-evolved with its host over millions of years. The 236 kbp genome encodes at least 165 genes, four non-coding RNAs and 14 miRNAs. Of the protein-coding genes, 43-44 are core replication genes common to all herpesviruses, while ~30 are unique to betaherpesviruses. Many CMV genes are involved in evading detection by the host immune response, and others have roles in cell tropism. CMV replicates systemically, and thus, has adapted to various biological niches within the host. Different biological niches may place competing demands on the virus, such that genes that are favorable in some contexts are unfavorable in others. The outcome of infection is dependent on the cell type. In fibroblasts, the virus replicates lytically to produce infectious virus. In other cell types, such as myeloid progenitor cells, there is an initial burst of lytic gene expression, which is subsequently silenced through epigenetic repression, leading to establishment of latency. Latently infected monocytes disseminate the virus to various organs. Latency is established through cell type specific mechanisms of transcriptional silencing. In contrast, reactivation is triggered through pathways activated by inflammation, infection, and injury that are common to many cell types, as well as differentiation of myeloid cells to dendritic cells. Thus, CMV has evolved a complex relationship with the host immune response, in which it exploits cell type specific mechanisms of gene regulation to establish latency and to disseminate infection systemically, and also uses the inflammatory response to infection as an early warning system which allows the virus to escape from situations in which its survival is threatened, either by cellular damage or infection of the host with another pathogen. Spontaneous reactivation induced by cellular aging/damage may explain why extensive expression of lytic genes has been observed in recent studies using highly sensitive transcriptome analyses of cells from latently infected individuals. Recent studies with animal models highlight the potential for harnessing the host immune response to blunt cellular injury induced by organ transplantation, and thus, prevent reactivation of CMV and its sequelae.

Heterologous Cytomegalovirus and Allo-Reactivity by Shared T Cell Receptor Repertoire in Kidney Transplantation

Cytomegalovirus (CMV) infection is associated with allograft rejection but the mechanisms behind are poorly defined yet. Although cross-reactivity of T cells to alloantigen and CMV has been hypothesized, direct evidence in patients is lacking. In this observational cohort study, we tested the pre-transplant effector/memory T cell response to CMV peptide pools and alloantigen in 78 living donor/recipient pairs using the interferon-gamma Enzyme-Linked ImmunoSpot (ELISPOT) assay. To prove the hypothesis of cross-reactivity, we analyzed by applying next-generation sequencing the T cell receptor ß (TCR- ß) repertoire of CMV- and alloantigen-reactive T cells enriched from peripheral pre-transplant blood of 11 CMV-seropositive and HLA class I mismatched patients. Moreover, the TCR-repertoire was also analyzed in the allograft biopsies of those patients. There was a significant association between the presence of pre-transplant CMV immediate-early protein 1 (IE-1)-specific effector/memory T cells and acute renal allograft rejection and function (p = 0.01). Most importantly, we revealed shared TCR-ß sequences between CMV-IE1 and donor alloantigen-reactive T cells in all pre-transplant peripheral blood samples analyzed in CMV-seropositive patients who received HLA class I mismatched grafts. Identical TCR sequences were also found in particular in post-transplant allograft biopsies of patients with concomitant CMV infection and rejection. Our data show the presence of functional, cross-reactive T cells and their clonotypes in peripheral blood and in kidney allograft tissue. It is therefore likely that CMV-donor cross-reactivity as well as CMV specific T cell elicited inflammation is involved in the processes that affect allograft outcomes.

A live-attenuated RhCMV/SIV vaccine shows long-term efficacy against heterologous SIV challenge

Previous studies have established that strain 68-1-derived rhesus cytomegalovirus (RhCMV) vectors expressing simian immunodeficiency virus (SIV) proteins (RhCMV/SIV) are able to elicit and maintain cellular immune responses that provide protection against mucosal challenge of highly pathogenic SIV in rhesus monkeys (RMs). However, these efficacious RhCMV/SIV vectors were replication and spread competent and therefore have the potential to cause disease in immunocompromised subjects. To develop a safer CMV-based vaccine for clinical use, we attenuated 68-1 RhCMV/SIV vectors by deletion of the Rh110 gene encoding the pp71 tegument protein (ΔRh110), allowing for suppression of lytic gene expression. ΔRh110 RhCMV/SIV vectors are highly spread deficient in vivo (~1000-fold compared to the parent vector) yet are still able to superinfect RhCMV+ RMs and generate high-frequency effector-memory-biased T cell responses. Here, we demonstrate that ΔRh110 68-1 RhCMV/SIV-expressing homologous or heterologous SIV antigens are highly efficacious against intravaginal (IVag) SIVmac239 challenge, providing control and progressive clearance of SIV infection in 59% of vaccinated RMs. Moreover, among 12 ΔRh110 RhCMV/SIV-vaccinated RMs that controlled and progressively cleared an initial SIV challenge, 9 were able to stringently control a second SIV challenge ~3 years after last vaccination, demonstrating the durability of this vaccine. Thus, ΔRh110 RhCMV/SIV vectors have a safety and efficacy profile that warrants adaptation and clinical evaluation of corresponding HCMV vectors as a prophylactic HIV/AIDS vaccine.

HCMV modulation of cellular PI3K/AKT/mTOR signaling: New opportunities for therapeutic intervention?

Human cytomegalovirus (HCMV) remains a major public health burden domestically and abroad. Current approved therapies, including ganciclovir, are only moderately efficacious, with many transplant patients suffering from a variety of side effects. A major impediment to the efficacy of current anti-HCMV drugs is their antiviral effects are restricted to the lytic stage of viral replication. Consequently, the non-lytic stages of the viral lifecycle remain major sources of HCMV infection associated with transplant recipients and ultimately the cause of morbidity and mortality. While work continues on new antivirals that block lytic replication, the dormant stages of HCMV's unique lifecycle need to be concurrently assessed for new therapeutic interventions. In this review, we will examine the role that the PI3K/Akt/mTOR signaling axis plays during the different stages of HCMV's lifecycle, and describe the advantages of targeting this cellular pathway as an antiviral strategy. In particular, we focus on the potential of exploiting the unique modifications HCMV imparts on the PI3K/Akt/mTOR pathway during quiescent infection of monocytes, which serve an essential role in the dissemination strategy of the virus.

The level of intracellular tacrolimus in T cell is affected by CD44+ABCB1+activities triggered by inflammation

Rejection is an important issue in kidney transplant. Although with adequate trough level of tacrolimus, acute rejection occurs, and we are focused on these cases. We hypothesized that the lower concentration of tacrolimus in the peripheral blood mononuclear cell would be a cause of rejection; in this regard, we describe ABCB1, which regulates intracellular concentration of tacrolimus. The effect of inflammation on the intracellular concentration of tacrolimus was evaluated, as was the association between that concentration and ABCB1 and CD44 activities. Seven kidney recipients experiencing acute rejection were prospectively enrolled. Both the whole blood concentration of tacrolimus and intracellular concentration of tacrolimus were measured at the time of enrollment and after stabilization. A human T lymphoblastoid cell line (Jurkat T cell) was treated with various concentrations of tacrolimus for 21 h and then stimulated for 3 h. The levels of mRNA interleukin-2, interleukin-8, and interferon-γ decreased dose dependently by tacrolimus. Furthermore, a fluorescence-activated cell sorter was used to count cells expressing CD44 and ABCB1; changes in intracellular concentration of tacrolimus were explored after tacrolimus treatment and stimulation. Also, B6 splenocytes were tested in the same manner as previous Jurkat T cell experiments. The tacrolimus ratio of three patients was lower at the time of acute rejection than when patients were stabilized. In vitro, the intracellular concentration of tacrolimus decreased after stimulation. Under the same conditions, CD44+ABCB1+cells increased in proportion on tacrolimus treatment and stimulation. This work supports the hypothesis that inflammation reduces the intracellular tacrolimus level, possibly via drug efflux mediated by CD44+ABCB1+and inflammation could lead to acute rejection.

Simultaneous Detection of Beta and Gamma Human Herpesviruses by Multiplex qPCR Reveals Simple Infection and Coinfection Episodes Increasing Risk for Graft Rejection in Solid Organ Transplantation

Herpesviruses are common components of the human microbiome that become clinically relevant when a competent immunosurveillance is compromised, such as in transplantation. Members of the beta and gamma subfamilies are associated with a wide diversity of pathologies, including end-organ disease and cancer. In this study, we developed a multiplex qPCR technique with high specificity, sensitivity, efficiency and predictability that allowed the simultaneous detection and quantification of beta and gamma human herpesviruses. The technique was tested in a cohort of 34 kidney- or liver-transplanted pediatric patients followed up for up to 12 months post-transplant. Viral load was determined in 495 leukocyte-plasma paired samples collected bi-weekly or monthly. Human herpesvirus (HHV) 7 was the herpesvirus most frequently found in positive samples (39%), followed by Epstein-Barr virus (EBV) (20%). Also, EBV and HHV7 were present in the majority of coinfection episodes (62%). The share of positive samples exclusively detected either in leukocytes or plasma was 85%, suggesting that these herpesviruses tended to take a latent or lytic path in an exclusive manner. Infection by human cytomegalovirus (HCMV) and HHV6, as well as coinfection by EBV/HHV7 and EBV/HHV6/HHV7, were associated with graft rejection (RR = 40.33 (p = 0.0013), 5.60 (p = 0.03), 5.60 (p = 0.03) and 17.64 (p = 0.0003), respectively). The routine monitoring of beta and gamma herpesviruses should be mandatory in transplant centers to implement preventive strategies.

Cytomegalovirus prophylaxis in seropositive renal transplant recipients receiving thymoglobulin induction therapy: Outcome and risk factors for late CMV disease

BACKGROUND

Anti-thymocyte globulin (ATG) therapy is a risk factor for cytomegalovirus (CMV) disease in renal transplant (RTx) recipients and therefore antiviral prophylaxis is commonly used. We evaluated the outcome of our current policy of 90 days of CMV prophylaxis in seropositive recipients given ATG and the risk factors for the occurrence of CMV disease after prophylaxis.

METHODS

We studied a retrospective cohort of 423 RTx (2010-2014) CMV-seropositive adults given ATG induction therapy.

RESULTS

54 (13%) patients developed CMV disease at a median of 163 days after transplant, of which 29 (54%) had viral syndrome and 25 (46%) had invasive disease. Median prophylaxis time (94 days) and immunosuppressive drugs were similar between groups (CMV vs no-CMV). Those with CMV disease had more deceased donors and higher donor age, lower lymphocyte count, and lower median eGFR at day 90. Multivariable logistic regression analysis at day 90 and 180 found that eGFR ≤40 ml/min/1.73 m² (but not acute rejection) was associated with late CMV disease. In a separate validation cohort of 124 patients with 8% late CMV disease, eGFR ≤45 and lymphocyte count ≤800 cells/mm³ at the end of prophylaxis remained predictive of late CMV disease occurrence.

CONCLUSIONS

These data indicate that antiviral prophylaxis adequately prevented CMV in seropositive recipients given ATG, but late disease still occurred. Low eGFR and low lymphocyte count at the end of prophylaxis may help identify patients at higher risk of CMV disease.

Nuclear domain 10 components upregulated via interferon during human cytomegalovirus infection potently regulate viral infection

Human cytomegalovirus (HCMV) is a ubiquitous betaherpesvirus that causes life-threatening disease in immunocompromised and immunonaïve individuals. Type I interferons (IFNs) are crucial molecules in the innate immune response to HCMV and are also known to upregulate several components of the interchromosomal multiprotein aggregates collectively referred to as nuclear domain 10 (ND10). In the context of herpesvirus infection, ND10 components are known to restrict gene expression. This raises the question as to whether key ND10 components (PML, Sp100 and hDaxx) act as anti-viral IFN-stimulated genes (ISGs) during HCMV infection. In this study, analysis of ND10 component transcription during HCMV infection demonstrated that PML and Sp100 were significantly upregulated whilst hDaxx expression remained unchanged. In cells engineered to block the production of, or response to, type I IFNs, upregulation of PML and Sp100 was not detected during HCMV infection. Furthermore, pre-treatment with an IFN-β neutralizing antibody inhibited upregulation of PML and Sp100 during both infection and treatment with HCMV-infected cell supernatant. The significance of ND10 components functioning as anti-viral ISGs during HCMV infection was determined through knockdown of PML, Sp100 and hDaxx. ND10 knockdown cells were significantly more permissive to HCMV infection, as previously described but, in contrast to control cells, could support HCMV plaque formation following IFN-β pre-treatment. This ability of HCMV to overcome the potently anti-viral effects of IFN-β in ND10 expression deficient cells provides evidence that ND10 component upregulation is a key mediator of the anti-viral activity of IFN-β.

Safety and Efficacy of Antiviral Therapy for Prevention of Cytomegalovirus Reactivation in Immunocompetent Critically Ill Patients: A Randomized Clinical Trial

IMPORTANCE

Latent cytomegalovirus (CMV) infection is present in more than half the adult population, and a viral reactivation (ie, when the virus becomes measurable in body fluids such as blood) can occur in up to one-third of these individuals during episodes of critical illness.

OBJECTIVE

To determine whether antiviral therapy is safe and effective for preventing CMV reactivation in a general population of critically ill patients.

DESIGN, SETTING, AND PARTICIPANTS

A single-center, open-label, randomized, controlled clinical trial recruited 124 CMV-seropositive patients undergoing mechanical ventilation for at least 24 hours in the intensive care unit between January 1, 2012, and January 31, 2014. The mean baseline Acute Physiology and Chronic Health Evaluation II score of all patients was 17.6.

INTERVENTIONS

Patients were randomized to receive anti-CMV prophylaxis with valacyclovir hydrochloride (n = 34) or low-dose valganciclovir hydrochloride (n = 46) for up to 28 days to suppress viral reactivation, or to a control group with no intervention (n = 44).

MAIN OUTCOMES AND MEASURES

Time to first CMV reactivation in blood within the 28-day follow-up period following initiation of the study drug.

RESULTS

Among the 124 patients in the study (46 women and 78 men; mean [SD] age, 56.9 [16.9] years), viral reactivation in the blood occurred in 12 patients in the control group, compared with 1 patient in the valganciclovir group and 2 patients in the valacyclovir group (combined treatment groups vs control: hazard ratio, 0.14; 95% CI 0.04-0.50). Although this trial was not powered to assess clinical end points, the valacyclovir arm was halted prematurely because of higher mortality; 14 of 34 patients (41.2%) had died by 28 days, compared with 5 of 37 (13.5%) patients in the control arm at the point of the decision to halt this arm. Other safety end points showed similar outcomes between groups.

CONCLUSIONS AND RELEVANCE

Antiviral prophylaxis with valacyclovir or low-dose valganciclovir suppresses CMV reactivation in patients with critical illness. However, given the higher mortality, a large-scale trial would be needed to determine the clinical efficacy and safety of CMV suppression.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01503918.

Impact of Desensitization on Antiviral Immunity in HLA-Sensitized Kidney Transplant Recipients

Viral infections represent significant morbidity and mortality factors in kidney transplant recipients, with CMV, EBV, and BKV infections being most common. Desensitization (DES) with IVIg and rituximab with/without plasma exchange followed by kidney transplantation with alemtuzumab induction increased successful transplant rates in HLA-sensitized patients but may represent an increased risk for viral infections due to severe lymphocyte depletion. Here, we report on the posttransplant viral infection status in 372 DES versus 538 non-DES patients. CMV and EBV viremia were significantly lower in DES patients, while BKV viremia was similar. This trend was observed primarily in CMV sero(-), EBV sero(+), and sero(-) patients. No patient developed PTLD. The incidence of BKAN, allograft, and patient survival was similar in both groups. These viral infections were not associated with subsequent allograft rejection which occurred within 6 months after the infection. Conclusions. The IVIg + rituximab desensitization combined with alemtuzumab induction with triple immunosuppression maintenance does not increase the risk for CMV, EBV, and BKV infections. Possible factors include, in addition to posttransplant antiviral prophylaxis and PCR monitoring, presence of memory T cells and antibodies specific to CMV and likely EBV, NK cell-mediated ADCC despite lymphocyte depletion, elimination of EBV and CMV reservoirs by rituximab and alemtuzumab, and use of IVIg with antiviral properties.

Functional screening for anti-CMV biologics identifies a broadly neutralizing epitope of an essential envelope protein

The prototypic β-herpesvirus human cytomegalovirus (CMV) establishes life-long persistence within its human host. The CMV envelope consists of various protein complexes that enable wide viral tropism. More specifically, the glycoprotein complex gH/gL/gO (gH-trimer) is required for infection of all cell types, while the gH/gL/UL128/130/131a (gH-pentamer) complex imparts specificity in infecting epithelial, endothelial and myeloid cells. Here we utilize state-of-the-art robotics and a high-throughput neutralization assay to screen and identify monoclonal antibodies (mAbs) targeting the gH glycoproteins that display broad-spectrum properties to inhibit virus infection and dissemination. Subsequent biochemical characterization reveals that the mAbs bind to gH-trimer and gH-pentamer complexes and identify the antibodies' epitope as an 'antigenic hot spot' critical for virus entry. The mAbs inhibit CMV infection at a post-attachment step by interacting with a highly conserved central alpha helix-rich domain. The platform described here provides the framework for development of effective CMV biologics and vaccine design strategies.

Activation of Langerhans-Type Dendritic Cells Alters Human Cytomegalovirus Infection and Reactivation in a Stimulus-Dependent Manner

Oral mucosal Langerhans cells (LC) are likely to play important roles in host defense against infection by human cytomegalovirus (CMV). We previously showed that in vitro-differentiated immature LC (iLC) populations contain smaller amounts of infected cells but produce higher yields than mature LC (mLC) cultures, obtained by iLC stimulation with fetal bovine serum (FBS), CD40 ligand (CD40L) and lipopolysaccharide (LPS). Here, we sought to determine if exposure to select stimuli can improve LC permissiveness to infection, if specific components of the mLC cocktail are responsible for lowering viral yields, if this is due to defects in progeny production or release, and if these restrictions are also effective against reactivated virus. None of the stimuli tested extended the proportion of infected cells to 100%, suggesting that the block to infection onset cannot be fully removed. While CD40L and FBS exerted positive effects on viral progeny production per cell, stimulation with LPS alone or in combination with CD40L was detrimental. Reductions in viral titers were not due to defects in progeny release, and the permissive or restrictive intracellular environment established upon exposure to each stimulus appeared to act in a somewhat similar way toward lytic and latent infections.

The risk factors for cytomegalovirus reactivation following stem cell transplantation

Objective:

Opportunistic infections like cytomegalovirus (CMV) are among the primary causes of morbidity and mortality in patients undergoing hematipoetic stem cell transplantation (HSCT). This infection is frequently seen in early postengraftment period. So we determined to find the risk factors associated with CMV reactivation.

Methods:

We retrospectively evaluated the medical records of 126 consecutive patients who underwent allogenic-HSCT from peripheral blood stem cells from August 2011 to February 2013 in Shariati Hospital. We included HSCT patients with 15 years of age or older, who survived at least 100 days after transplantation. CMV reactivation was detected based on the weekly PP65 assessment. Patients with 10 or more positive cells per 50,000 cells were defined as having high-level antigenemia.

Findings:

From 126 patients which included in this study, 76 were male (60%). CMV antigenemia was documented in 43 patients (34%). The median time to CMV infection was 40 days (range: 3–77) after transplantation. The incidence of high-level antigenemia during the first 100 days following HSCT was 11%.

Conclusion:

We found that the significant risk factor for CMV antigenemia in multivariate analysis was prior graft-versus-host disease (GVHD) experience and higher donor age. For high-level antigenemia, GVHD or duration of its treatment was significant determinant.

Cytotoxic T-lymphocyte antigen 4 gene polymorphism influences the incidence of symptomatic human cytomegalovirus infection after renal transplantation

BACKGROUND

The role of CTLA4 gene polymorphisms in T-cell-mediated immunity in association with human cytomegalovirus (HCMV) infection after transplantation is poorly understood. In the present study, we have made an attempt to investigate the impact of CTLA4 single nucleotide polymorphisms (SNPs) (rs231775, rs5742909, rs11571317, rs16840252, rs4553808, rs3087243) and dinucleotide (AT)n repeat polymorphism on the incidence of symptomatic HCMV infection (disease) among 270 renal allograft recipients.

MATERIALS AND METHODS

Genotyping of CTLA4 SNPs was performed by a PCR, followed by a restriction fragment length polymorphism assay. The detection of the dinucleotide (AT)n repeat polymorphism was carried out by PCR-polyacrylamide gel electrophoresis.

RESULTS

An almost three-fold increased risk was observed for the incidence of symptomatic HCMV infection in mutant genotype carriers of rs231775 and rs3087243 SNPs under additive and recessive models, respectively. The mutant haplotype carriers of six studied SNPs (rs231775, rs5742909, rs11571317, rs16840252, rs4553808 and rs3087243) showed an almost two-fold higher risk for symptomatic HCMV cases, whereas wild-type haplotype combinations of these six SNPs showed a protective effect. Subsequently, no correlation was observed in the promoter region SNPs of CTLA4, namely, rs5742909, rs11571317, rs16840252 and rs4553808 in symptomatic HCMV cases at the genotypic/allelic level. Survival analysis showed that the mutant genotypes of rs231775 and rs3087243 SNPs were associated with the lowest HCMV disease-free survival compared with heterozygous and wild genotypes. The crude and adjusted hazard ratios showed an almost three-fold and 2.5-fold increased risk in univariate and multivariate Cox regression models, respectively, for HCMV disease-free survival against mutant genotypes of rs231775 and rs3087243 SNPs. CTLA4 dinucleotide (AT)n repeat analysis showed that the smaller allele (102 bp) was associated with a protective effect, whereas the longer (110 and 116 bp) alleles showed a susceptible effect for symptomatic HCMV cases.

CONCLUSION

These results suggested that CTLA4 variants might be involved in the clinical manifestation of HCMV diseases.

Immunologic Monitoring of T-Lymphocyte Subsets and Hla-Dr-Positive Monocytes in Kidney Transplant Recipients: A Prospective, Observational Cohort Study

The clinical significance of circulating T-lymphocyte subsets and human leukocyte antigen (HLA)-DR-positive monocytes in the peripheral blood of kidney transplant recipients (KTRs) remains unclear. We examined the efficacy of enumerating these cells for the immunologic monitoring of KTRs.Blood samples were obtained before transplantation, 2 weeks after transplantation and at diagnosis, and 2 weeks after treating biopsy-proven acute cellular rejection and cytomegalovirus (CMV) infection. Serial flow cytometric analysis was performed using peripheral blood obtained from 123 patients to identify the frequencies of HLA-DR, CD3, CD4, CD8, and CD25 T-lymphocytes and HLA-DR-positive monocytes.Frequencies of CD4CD25/CD4 T cells, CD8CD25/CD8 T cells, and HLA-DR-positive monocytes were significantly lower at 2 weeks after transplantation than before transplantation (all P < 0.001). This decrease was not correlated with clinical parameters. The frequency of CD4CD25/CD4 T cells was significantly higher in KTRs with acute rejection than in KTRs at 2 weeks after transplantation (9.10% [range 4.30-25.6%] vs 5.10% [range 0.10-33.3%]; P = 0.024). However, no significant differences were observed between stable KTRs and KTRs with CMV infection. Analysis of the receiver operating characteristic curve adjusted by covariates showed that acute rejection could be predicted with 75.0% sensitivity and 68.4% specificity by setting the cutoff value of CD4CD25/CD4 T cell frequency as 5.8%.Circulating T-lymphocyte and monocyte subsets showed significant and consistent changes in their frequencies after immunosuppression. Of the various immune cells examined, circulating levels of CD4CD25 T cells might be a useful noninvasive immunologic indicator for detecting acute rejection.

Viral surveillance and subclinical viral infection in pediatric kidney transplantation

The more potent immunosuppressive therapy that has successfully reduced the incidence of acute rejection and improved graft outcomes has also resulted in a higher incidence of viral complications. Sensitive molecular methods now allow for the detection of subclinical viral infection, which is increasingly recognized due to the adoption of routine post-transplant viral surveillance protocols. The goal of viral surveillance is the detection of subclinical viral infection that triggers an intervention; one that either prevents progression to viral disease or leads to early diagnosis of viral disease, which is associated with improved outcomes. Knowledge of the epidemiology and natural history of subclinical viral infection and viral disease, as well as patient-specific risk factors, is required to establish the optimal surveillance schedule which achieves the goal of early diagnosis. Evidence that detection of subclinical viral infection can impact viral disease is variable depending on the virus. This review will summarize the current data on the role of viral surveillance for BK virus (BKV), cytomegalovirus (CMV), and the Epstein-Barr virus (EBV) in the pediatric kidney transplant population.

Cytomegalovirus, and possibly Epstein-Barr virus, shedding in breast milk is associated with HIV-1 transmission by breastfeeding

OBJECTIVE

Postnatal HIV-1 mother-to-child transmission (MTCT) occurs in spite of antiretroviral therapy. Co-infections in breast milk with cytomegalovirus (CMV) and Epstein-Barr virus (EBV) are associated with increased HIV-1 shedding in this compartment. We investigated CMV levels and EBV detection in breast milk as potential risk factors for MTCT of HIV-1 via breastfeeding.

METHODS

Cell-free HIV-1 RNA, cell-associated HIV-1 DNA, CMV and EBV DNA were quantified in breast milk from 62 HIV-infected mothers and proven postnatal MTCT of HIV-1 via breastfeeding. Controls were 62 HIV-positive mothers with HIV-uninfected infants.

RESULTS

Median (interquartile range) CMV DNA viral load was significantly higher in cases [88,044 (18,586-233,904)] than in controls [11,167 (3221-31,152)] copies/10 breast milk cells (P < 0.001). Breast milk CMV DNA level correlated positively with breast milk HIV-1 RNA level in cases and controls. EBV DNA was detectable in a higher proportion of breast milk samples of cases (37.1%) than controls (16.1%; P = 0.009). HIV-1 MTCT was strongly associated with HIV-1 RNA shedding in breast milk and plasma. In multivariable analysis, every 1 log10 increase in breast milk CMV DNA was associated with a significant 2.5-fold greater odds of MTCT of HIV-1, independent of breast milk and plasma HIV-1 levels; the nearly three-fold increased risk of HIV-1 MTCT with breast milk EBV DNA detection did not reach significance.

CONCLUSION

We provide the first evidence of an independent association between CMV in breast milk, and postnatal MTCT of HIV-1. This association could fuel persistent shedding of HIV-1 in breast milk in women receiving antiretroviral therapy. EBV DNA detection in breast milk may also be associated with MTCT of HIV-1, but only marginally so.

Impaired CD8(+) T cell immunity after allogeneic bone marrow transplantation leads to persistent and severe respiratory viral infection

RATIONALE

Bone marrow transplant (BMT) recipients experience frequent and severe respiratory viral infections (RVIs). However, the immunological mechanisms predisposing to RVIs are uncertain. Therefore, we hypothesized that antiviral T cell immunity is impaired as a consequence of allogeneic BMT, independent of pharmacologic immunosuppression, and is responsible for increased susceptibility to RVI.

METHODS

Bone marrow and splenocytes from C57BL/6(H2(b)) mice were transplanted into B10.BR(H2(k)) (Allo) or C57BL/6(H2(b)) (Syn) recipients. Five weeks after transplantation, recipient mice were inoculated intranasally with mouse parainfluenza virus type 1 (mPIV-1), commonly known as Sendai virus (SeV), and monitored for relevant immunological and disease endpoints.

MAIN RESULTS

Severe and persistent airway inflammation, epithelial injury, and enhanced mortality are found after viral infection in Allo mice but not in control Syn and non-transplanted mice. In addition, viral clearance is delayed in Allo mice as evidenced by prolonged detection of viral transcripts at Day 15 post-inoculation (p.i.) but not in control mice. In concert with these events, we also detected decreased levels of total and virus-specific CD8(+) T cells, as well as increased T cellexpression of inhibitory receptor programmed death-1 (PD-1), in the lungs of Allo mice at Day 8 p.i. Adoptive transfer of CD8(+) T cells from non-transplanted mice recovered from SeV infection into Allo mice at Day 8 p.i. restored normal levels of viral clearance, epithelial repair, and lung inflammation.

CONCLUSIONS

Taken together these results indicate that allogeneic BMT results in more severe RVI based on the failure to develop an appropriate pulmonary CD8(+) T cell response, providing an important potential mechanism to target in improving outcomes of RVI after BMT.

Multifocal bacterial osteomyelitis in a renal allograft recipient following urosepsis

Non-tubercular bacterial osteomyelitis is a rare infection. We report on a renal allograft recipient with osteomyelitis complicating urosepsis, manifesting as a multifocal infection poorly responsive to appropriate antibiotics and surgical intervention and culminating in graft loss.

CMV Viremia is associated with a decreased incidence of BKV reactivation after kidney and kidney-pancreas transplantation

BACKGROUND

Cytomegalovirus (CMV) and BK virus (BKV) infections can cause significant morbidity after kidney and kidney-pancreas transplant. There are limited data on the epidemiology and interactions between these two viral pathogens.

METHODS

We prospectively screened 609 kidney or kidney-pancreas transplant recipients from January 2007 to June 2011 for BKV and/or CMV viremia. This included 7453 quantitative BKV polymerase chain reaction and 15,496 quantitative CMV polymerase chain reaction tests. We evaluated risk factors and timing of these infections and the impact of treatment of one infection on the other.

RESULTS

Among 609 recipients, 108 (17.7%) developed CMV viremia, of which 95 (88%) were asymptomatic, 5 (5%) had CMV syndrome, and 8 (7%) developed CMV tissue invasive disease at a median of 5.6 months after transplantation. Risk factors for CMV infection using multivariable analysis were D+R- serogroup (P≤0.0001), donor age >50 years (P=0.013), and higher mean tacrolimus (P=0.0009) and mycophenolate mofetil (P=0.01) blood levels. The incidence of BKV infection in the total population was 163 of 609 (26.7%), of which 150 (92%) occurred in patents without antecedent CMV viremia. Such patients demonstrated a higher rate of subsequent BKV viremia than patients with antecedent CMV viremia (P=0.003; hazard ratio, 2.05; 95% confidence interval, 1.2-3.4). Moreover, we found that only symptomatic CMV viremia had a significant negative impact on graft survival when compared with asymptomatic CMV viremia and those without CMV viremia (relative risk, 3.5; 95% confidence interval, 1.06-8.9; P=0.04).

CONCLUSION

CMV viremia may indirectly protect against subsequent BK viremia possibly due to a reduction of intensity of immunosuppression after diagnosis of CMV viremia.

Late onset epstein barr virus seropositive posttransplant lymphoproliferative disorder in two renal transplant receivers

Posttransplant malignancy is one of the most important complications of organ transplantation. Immunosuppressive drugs, viral infections such as human herpes virus 8 or Epstein-Barr virus, exposure to carcinogenic factors such as sun, and host factors can be etiologic factors in the development of malignant disease. In this paper we report 2 cases of late posttransplant lymphoproliferative disorder with malign behavior.

Conflict of interest:None declared.

Circulating dendritic cells isolated from healthy seropositive donors are sites of human cytomegalovirus reactivation in vivo

Primary infection with human cytomegalovirus (HCMV) is generally asymptomatic in healthy individuals and results in a lifelong infection of the host. In contrast, in immunosuppressed transplant recipients and late-stage AIDS patients, HCMV infection and reactivation can result in severe disease or death. In vivo, latency is established in bone marrow CD34(+) progenitor cells with reactivation linked with their differentiation to macrophages and dendritic cells (DCs). However, previous analyses have relied on ex vivo differentiation of myeloid progenitor cells to DCs in culture. Here, we now report on the isolation and analysis of circulating blood myeloid DCs, resulting from natural differentiation in vivo, from healthy HCMV-seropositive carriers. We show that these in vivo-differentiated circulating DCs are fully permissive for HCMV and exhibit a phenotype similar to that of monocyte-derived DCs routinely used for in vitro studies of HCMV. Importantly, we also show that these DCs from healthy HCMV-seropositive donors carry HCMV genomes and, significantly, are typically positive for viral immediate-early (IE) gene expression, in contrast to circulating monocytes, which carry genomes with an absence of IE expression. Finally, we show that HCMV reactivation from these circulating DCs is enhanced by inflammatory stimuli. Overall, these data argue that the differentiation in vivo of myeloid progenitors to circulating DCs promotes the reactivation of HCMV lytic gene expression in healthy individuals, thereby providing valuable confirmation of studies performed using in vitro generation of DCs from myeloid precursors to study HCMV reactivation.

Epigenetic control of cytomegalovirus latency and reactivation

Cytomegalovirus (CMV) gene expression is repressed in latency due to heterochromatinization of viral genomes. In murine CMV (MCMV) latently infected mice, viral genomes are bound to histones with heterochromatic modifications, to enzymes that mediate these modifications, and to adaptor proteins that may recruit co-repressor complexes. Kinetic analyses of repressor binding show that these repressors are recruited at the earliest time of infection, suggesting that latency may be the default state. Kidney transplantation leads to epigenetic reprogramming of latent viral chromatin and reactivation of immediate early gene expression. Inflammatory signaling pathways, which activate transcription factors that regulate the major immediate early promoter (MIEP), likely mediate the switch in viral chromatin.

Subclinical Epstein-Barr virus viremia among adult renal transplant recipients: incidence and consequences

The natural history and clinical significance of posttransplant Epstein-Barr virus (EBV) infection remain largely unknown. The aims of this study are to describe the incidence, risk factors and consequences of EBV infection after kidney transplantation. A total of 383 consecutive patients having received a kidney transplant between January 2002 and December 2010 were included. EBV polymerase chain reaction (PCR) was performed every 2 weeks for 3 months, and every 4 weeks for the next 9 months. A total of 155 of the 383 patients (40%) had at least one positive viremia during the first year posttransplant. The median time to viremia was day 31 posttransplant (14-329). A total of 73 (47%) had EBV viremia > 10(3) log and 23 (15%) had positive viremia for more than 6 months. EBV D+/R- patients (12/18 (67%) versus 143/365 (39%), p = 0.02) and those having received antithymocyte globulins (ATG) (54% vs. 35%; p<0.001) were more likely to develop EBV infection. EBV infection (hazard ratio [HR], 3.03; 95% confidence interval [CI], 1.72-8.29; p = 0.01) was associated with the occurrence of opportunistic infections. A positive EBV PCR during the first 6 months posttransplant was associated with graft loss (HR, 3.04; 95% CI, 1.36-6.79; p = 0.014). EBV reactivation is frequent after transplantation and reflects overimmunosuppression. Prospective studies should examine the association between EBV and graft loss.

Relevance of maintenance triple-drug immunosuppression to bridle the amplification of rat cytomegalovirus infection after experimental lung transplantation

Immunosuppressive therapy required to treat rejection after lung transplantation (LTx) contributes significantly to the pathogenesis of cytomegalovirus (CMV) infection and disease. In a weak allogeneic left LTx model in the rat (Fisher 344 [F344] to Wistar Kyoto [WKY] rats) we analyzed the influence of acute CMV infection on postoperative day (POD) 3, with application of standard triple-drug immunosuppression (TD-IS) (cyclosporin A, azathioprine, prednisolone) on late outcome after LTx. Native right lungs and syngeneic grafts (WKY to WKY) served as controls. Rats were sacrificed on POD 15, 30, 60, and 100. TD-IS completely prevented acute and chronic rejection in non-infected rats. Allografts of CMV-infected rats treated with TD-IS showed only mild perivascular infiltrations in 6/10 rats (POD 15 and 30), which persisted up to POD 100 in 4/10 rats. In the long-term course, mild isolated interstitial and alveolar changes were found in 40% of these animals. In conclusion, rat CMV infection partially neutralized the immunosuppressive effect of TD-IS. However, an amplification of CMV infection under TD-IS can be controlled and does not result in fatal outcome.

Cytomegalovirus-specific regulatory and effector T cells share TCR clonality--possible relation to repetitive CMV infections

Cytomegalovirus (CMV) infections have a major impact on morbidity and mortality of transplant patients. Among the complex antiviral T-cell response, CMV-IE-1 antigen-specific CD8+ cells are crucial for preventing CMV disease but do not protect from recurring/lasting CMV reactivation. Recently, we confirmed that adoptive transfer of autologous IE-1/pp65-specific T-cell lines was able to combat severe CMV disease; however, the control of CMV infection was only temporary. We hypothesized that CMV-induced regulatory T cells (iTreg) might be related to recurring/lasting CMV infection. In fact, kidney transplant patients with recurring CMV infections expressed enhanced suppression on CMV response. Analysis of in vitro expanded CD4+ epitope-specific cells revealed that CMV-specific CD4+CD25(high) Treg cells functionally suppress CD25(low) effector T cells (Teff) upon epitope-specific reactivation. Their phenotype is similar to iTreg - CD39(high) /Helios-/IL-2(low) /IFNγ(high) /IL-10±/TGFß-LAP±/FOXP3+ and methylated foxp3 locus. Remarkably, in vitro expanded CD4+CD25(high) iTreg share the same dominant TCR-Vβ-CDR3 clones with functionally distinct CD4+CD25(low) Teff. Moreover, the same clones were present in freshly isolated CD4+CD25(high) and CD4+CD25(low) T cells suggesting their in vivo generation. These findings directly demonstrate that Teff and iTreg can differentiate from one "mother" clone with specificity to the same viral epitope and indicate that peripheral iTreg generation is related to frequent antigen appearance.

Consensus on the role of human cytomegalovirus in glioblastoma

The human cytomegalovirus (HCMV) and glioma symposium was convened on April 17, 2011 in Washington, DC, and was attended by oncologists and virologists involved in studying the relationship between HCMV and gliomas. The purpose of the meeting was to reach a consensus on the role of HCMV in the pathology of gliomas and to clarify directions for future research. First, the group summarized data that describe how HCMV biology overlaps with the key pathways of cancer. Then, on the basis of published data and ongoing research, a consensus was reached that there is sufficient evidence to conclude that HCMV sequences and viral gene expression exist in most, if not all, malignant gliomas, that HCMV could modulate the malignant phenotype in glioblastomas by interacting with key signaling pathways; and that HCMV could serve as a novel target for a variety of therapeutic strategies. In summary, existing evidence supports an oncomodulatory role for HCMV in malignant gliomas, but future studies need to focus on determining the role of HCMV as a glioma-initiating event.

The impact of prophylactic antiviral agents and statin administration on graft longevity in kidney allograft recipients

CONTEXT

In an earlier study, we compared the duration of kidney graft survival between two groups of recipients; one on triple (cyclosporine, prednisone and mycophenolate mofetil) and the other on quadruple (cyclosporine, prednisone, mycophenolate mofetil, and sirolimus) immunosuppressive therapy.

OBJECTIVE

The aim of this study was to examine the impact of antiviral and statin therapy on graft longevity.

MATERIALS AND METHODS

One hundred five kidney allograft recipients were preoperatively assessed for serological markers of infection with various viral agents. All patients were on a prophylactic antiviral regimen of acyclovir and gancyclovir. Seventeen patients were on a statin. Patients were monitored for viral infections and graft rejection or loss for period of 3 years posttransplantation.

RESULTS

We detected a high preoperative prevalence rate of IgG immunoglobulins versus the latency-establishing Herpesviridae viruses. Two patients who were preoperatively IgG positive for CMV had cytomegalovirus disease after transplantation. One patient who was preoperatively IgG positive for VZV had shingles after the surgery. No other confirmed viral infections were reported. Thirteen of 88 patients (14.77%) whose treatment regimen did not include a statin suffered a rejection episode or lost the graft whereas 1 of 17 patients (5.88%) on a statin had a rejection episode.

CONCLUSIONS

The low rate of viral infections observed in our study population supports the utility of prophylactic administration of antiviral agents to transplant recipients. However, statins seem to have a protective effect on graft longevity (odds ratio [OR] = 0.361, 95% confidence interval [CI] = 0.044-2.957).

Inhibition of inflammatory interleukin-6 activity via extracellular signal-regulated kinase-mitogen-activated protein kinase signaling antagonizes human cytomegalovirus reactivation from dendritic cells

Human cytomegalovirus (HCMV) remains a major cause of viral disease in immunosuppressed transplant patients. The ability of HCMV to establish lifelong infection in humans and reactivate with devastating clinical consequences underscores the importance of understanding the triggers of HCMV reactivation in mature myeloid cells. Dendritic cell (DC) differentiation is concomitant with the activation of cellular signaling pathways and inflammatory gene expression and also HCMV reactivation. Here, we show a major role for interleukin-6 (IL-6) through extracellular signal-regulated kinase-mitogen-activated protein kinase (ERK-MAPK) signaling upon DC differentiation to promote HCMV reactivation. IL-6 drives reactivation by transcriptional upregulation of the major immediate-early (IE) genes, resulting in efficient progression of the virus life cycle and, ultimately, higher titers of infectious virus. Furthermore, the interception of IL-6 signaling with biological inhibitors significantly abrogated HCMV reactivation from experimental latency. Crucially, using cells derived from healthy seropositive donors, we observed a key role for IL-6 during reactivation from natural latency ex vivo in interstitial DCs. Clinically, HCMV reactivation occurs in highly inflammatory environments (i.e., transplantation); thus, the implications of this study could potentially provide novel approaches for therapeutic intervention.

Human cytomegalovirus and kidney transplantation: a clinician's update

Infection with human cytomegalovirus (CMV) is an important cause of morbidity and mortality in kidney transplant recipients. CMV disease is diagnosed based on the detection of viral replication by phosphoprotein 65 antigenemia or CMV DNA polymerase chain reaction in combination with typical signs and symptoms. Risk factors include CMV-seronegative recipients receiving a CMV-seropositive transplant, older donor age, exposure to cyclosporine and/or antilymphocyte antibody, rejection episodes, and impaired transplant function. Current preventive strategies in kidney transplant recipients include pre-emptive therapy with valganciclovir or intravenous ganciclovir and universal prophylaxis with valacyclovir, valganciclovir, or ganciclovir for 3-6 months after kidney transplantation and for 1-3 months after treatment with antilymphocyte antibody. Established disease should be treated using either intravenous ganciclovir or oral valganciclovir until CMV replication can no longer be detected. In addition to direct effects, CMV infection also induces a wide range of indirect effects, such as decreased transplant and recipient survival and susceptibility to rejection and opportunistic infections. In this review, we highlight the most relevant topics on CMV and kidney transplantation based on current evidence and guidelines.

Cytomegalovirus-specific T cell immunity is maintained in immunosenescent rhesus macaques

Although CMV infection is largely benign in immunocompetent people, the specific T cell responses associated with control of this persistent virus are enormous and must be maintained for life. These responses may increase with advanced age and have been linked to an "immune risk profile" that is associated with poor immune responsiveness and increased mortality in aged individuals. Based on this association, it has been suggested that CMV-specific T cell responses might become dysfunctional with age and thereby contribute to the development of immune senescence by homeostatic disruption of other T cell populations, diminished control of CMV replication, and/or excess chronic inflammation. In this study, we use the rhesus macaque (RM) model of aging to ask whether the quantity and quality of CMV-specific T cell responses differ between healthy adult RMs and elderly RMs that manifest hallmarks of immune aging. We demonstrate that the size of the CD4(+) and CD8(+) CMV-specific T cell pools are similar in adult versus old RMs and show essentially identical phenotypic and functional characteristics, including a dominant effector memory phenotype, identical patterns of IFN-γ, TNF-α, and IL-2 production and cytotoxic degranulation, and comparable functional avidities of optimal epitope-specific CD8(+) T cells. Most importantly, the response to and protection against an in vivo CMV challenge were identical in adult and aged RMs. These data indicate that CMV-specific T cell immunity is well maintained in old RMs and argue against a primary role for progressive dysfunction of these responses in the development of immune senescence.

Impact of CMV infection on acute rejection and long-term renal allograft function: a systematic analysis in patients with protocol biopsies and indicated biopsies

BACKGROUND

Higher rates of acute rejection (AR) and reduced graft survival have been reported in patients with cytomegalovirus (CMV) infection, but an association between these factors remains controversial.

METHODS

In this study, serial protocol biopsies (PBs) and clinically indicated biopsies (IBs) from a large cohort of renal allograft recipients (n &frac14; 594) were analyzed to examine the relation between CMV and AR.

RESULTS

Patients with CMV were more likely to receive IB (85 of the 153 patients; 56%) compared to patients without CMV (138 of 441 patients; 32%; P = 0.003). However, this did not translate into a greater number of patients with episodes of acute cellular rejection on histopathology in IBs. Analysis of PBs revealed a significantly higher number of episodes of rejection per patient with CMV infection (P = 0.04), but only in a subgroup of patients with triple immunosuppression. Long-term graft function post-transplantation was analyzed in four different subgroups according to CMV infection and/or AR. Differences in renal function were apparent within the first 6 weeks after transplantation and persisted during follow-up, with the best renal function in patients without AR or CMV, whereas patients with both AR and CMV had the worst (P < 0.012 at 1 year; P < 0.001 at 2 years). On average, the latter group had significantly older donors and more often delayed graft function.

CONCLUSIONS

Our data suggests that the link between CMV and AR is far less significant than previously thought. Outcome in patients with CMV may be more determined by coexisting conditions like high donor age and delayed graft function.

Clinical relevance of cytomegalovirus viraemia(*,†)

BACKGROUND

Using new sensitive quantitative polymerase chain reaction (PCR) assays, cytomegalovirus (CMV) DNA is often detectable in the plasma of immunosuppressed patients. We investigated the prognostic value of a positive CMV DNA test for the development of CMV end-organ disease, other AIDS-defining events and mortality.

METHODS

A survival analysis was performed, using the Kaplan-Meier method and Cox proportional hazards models, for patients prospectively followed in the Swiss HIV Cohort Study, from January 1996 to December 2007, who were CMV-seropositive, had a CD4 count of ≤ 100 cells/μL, and had a plasma sample available for the measurement of baseline CMV DNA with an ultrasensitive PCR. The outcome analysed was an AIDS-defining event, including CMV end-organ disease, or death. Variables analysed at the time of CMV measurement were demographic variables, CD4 cell counts, HIV-1 RNA loads, and use and type of highly active antiretroviral therapy (HAART).

RESULTS

Of 1128 patients, 208 (18%) presented an AIDS-defining event and 246 (22%) died. A total of 368 patients (34% of samples) had detectable CMV DNA at baseline, with DNA concentrations of up to 38 800 copies/mL. In the multivariate analysis, CMV DNA predicted evolution not only towards CMV end-organ disease [hazard ratio (HR) 12.6; 95% confidence interval (CI) 4.27-37.41], but also towards other AIDS-defining events (HR 2.6; 95% CI 1.60-4.33) and death (HR 1.9; 95% CI 1.10-3.34).

CONCLUSION

Quantitative CMV DNA detected in the plasma of HIV-infected patients with CD4 counts ≤ 100 cells/μL is a predictor for HIV disease progression, CMV disease and death. A single low value of 80 copies/mL identifies patients at low but significantly increased risk during the following months, after the measurement.

Strategies for managing cytomegalovirus in transplant recipients

IMPORTANCE OF THE FIELD

Cytomegalovirus (CMV) is the most important pathogen that affects transplant recipients, by directly causing clinical disease and by indirectly reducing patient and allograft survival.

AREAS COVERED IN THIS REVIEW

This review provides a brief overview of the direct and indirect effects of CMV disease and the traditional and newly described factors that increase the risk of disease after transplantation. Newly acquired data in the diagnostics, prevention and treatment of CMV infection are discussed, with emphasis on guidelines for management as recently endorsed by the American Society of Transplantation and the Transplantation Society.

WHAT THE READER WILL GAIN

The reader will gain up-to-date insights into the contemporary management of CMV after solid organ transplantation. Practical aspects of its diagnosis, prevention and treatment are discussed. Emerging concerns of late-onset CMV disease and antiviral resistance are also highlighted to emphasize the need to optimize CMV-prevention strategies.

TAKE HOME MESSAGE

Prevention of CMV disease is an important goal in the management of solid organ transplant recipients. The efficacy of CMV prevention should be measured not only by the significant reduction in CMV incidence but, as importantly, by the improvement in long-term allograft and patient survival.

Is HCMV a tumor promoter?

Human cytomegalovirus (HCMV) is a beta-herpesvirus that causes persistent infection in humans and can cause severe disease in fetuses and immunocompromised individuals. Although HCMV is not currently causally implicated in human cancer, emerging evidence suggests that HCMV infection and expression may be specifically associated with human malignancies including malignant glioma, colon, and prostate cancer. In addition, multiple investigators have demonstrated that HCMV can dysregulate signaling pathways involved in initiation and promotion of malignancy, including tumor suppressor, mitogenic signaling, inflammatory, immune regulation, angiogenesis and invasion, and epigenetic mechanisms. This review highlights some of the recent evidence that HCMV might play a role in modulating the tumor microenvironment as well as in the initiation and promotion of tumor cells themselves.

Subclinical viremia increases risk for chronic allograft injury in pediatric renal transplantation

The impact of subclinical viral infection on chronic allograft injury in the pediatric renal transplant population is not well defined. We prospectively assessed cytomegalovirus (CMV) and Epstein-Barr virus (EBV) DNAemia by monthly PCR in 55 pediatric renal transplant recipients for the first 2 years after transplantation. Subclinical CMV and EBV infection occurred in 22 and 36%, respectively. Multivariable linear regression analysis suggested that both subclinical CMV and EBV infection independently associate with significant declines in GFR during the first 2 years after transplantation. CMV seronegativity associated with a significantly greater decline in GFR than seropositivity (P < 0.01). Subclinical CMV infection and subclinical EBV infection each associated with approximately fourfold greater odds of histologic evidence of chronic allograft injury (odds ratio 4.61 [95% confidence interval 1.18 to 18.07] and odds ratio 4.33 [95% confidence interval 1.34 to 14.00], respectively). An increase in viral load of CMV or EBV also associated with increased risk for moderate to severe chronic allograft injury. Taken together, these results demonstrate an association between subclinical CMV and EBV infections, which occur despite standard antiviral prophylaxis, and chronic allograft injury in pediatric renal transplant recipients.