Cytomegalovirus hepatitis in normal and immune compromised hosts

Upregulation of Nrf2 expression by human cytomegalovirus infection protects host cells from oxidative stress

NF-E2 related factor 2 (Nrf2) is a transcription factor that plays a key role(s) in cellular defence against oxidative stress. In this study, we showed that the expression of Nrf2 was upregulated in primary human foreskin fibroblasts (HFFs), following human cytomegalovirus (HCMV/HHV-5) infection. The expression of haem oxygenase-1, a downstream target of Nrf2, was also increased by HCMV infection, and this induction was suppressed in HFFs expressing a small hairpin RNA (shRNA) against Nrf2. The HCMV-mediated increase in Nrf2 expression was abolished when UV-irradiated virus was used or when the activity of casein kinase 2 was inhibited. Host cells infected by HCMV had higher survival rates following oxidative stress induced by buthionine sulfoximine compared with uninfected control cells, but this cell-protective effect was abolished by the use of Nrf2 shRNA. Our results suggest that HCMV-mediated activation of Nrf2 might be beneficial to the virus by increasing the host cell's ability to cope with oxidative stress resulting from viral infection and/or inflammation.

Measuring T-cell responses against LCV and CMV in cynomolgus macaques using ELISPOT: potential application to non-clinical testing of immunomodulatory therapeutics

A number of immunomodulatory therapeutics increase the risk of disease associated with latent herpesviruses such as cytomegalovirus (CMV) and Epstein-Barr virus (EBV), a member of the lymphocryptovirus (LCV) family that infects humans. The diseases associated with loss of immunity to these viruses can have major impacts on patients as well as on the commercial viability of the immunomodulatory therapeutics. In an effort to develop non-clinical methods for measuring effects on anti-viral immunity, we have developed an interferon (IFN)-γ enzyme-linked immunosorbent spot (ELISPOT) assay to quantify the number of CMV or LCV-reactive T-cells in peripheral blood of cynomolgus macaques. After optimization of various parameters, the IFN-γ ELISPOT assay was characterized for specificity, intra-assay, monkey-to-monkey, and longitudinal variability and sensitivity to immunosuppression. The results show that nearly all animals have detectable responses against both CMV and LCV and responses were derived from T-cells specific to the virus of interest. Analyses of variability show assay reproducibility (≤23% CV), and that variability over time in anti-viral responses in individual animals (larger for LCV than for CMV) was ∼2-fold in most animals over a 3-month time period, which is predicted to allow for detection of drug-induced changes when using group sizes typical of non-clinical studies. In addition, the IFN-γ ELISPOT assay was capable of detecting decreases in the numbers of CMV and LCV reactive T-cells induced by immunosuppressive drugs in vitro. This assay may allow for non-clinical assessment of the effects of immunomodulatory therapeutics on anti-viral T-cell immunity in monkeys, and may help determine if therapeutics increase the risk of reactivating latent viral infections.

Cytomegalovirus disease in nonimmunocompromised, human immunodeficiency virus-negative adults with chronic kidney disease

BACKGROUND/PURPOSE(S)

To identify the clinical characteristics of cytomegalovirus (CMV) disease in chronic kidney disease (CKD) patients.

METHODS

Patients from two sources were reviewed: (1) a retrospective study of hospitalized patients admitted between January 1990 and February 2009 was performed at a tertiary hospital in Taiwan; (2) the English literature from 1990 to 2009 was reviewed for additional cases, and adults with CKD and histopathologically documented cytomegalovirus disease were included.

RESULTS

Seven CKD patients from our hospital and seven from the literature were included. Nine (64.3%) patients were males, and the mean age was 66 years. Histopathologically proven CMV disease was present in the gastrointestinal (GI) tract of 13 (92.9%) and in the skin of one (7.1%) patient. GI symptoms included bleeding (78.6%), abdominal pain (35.7%), and diarrhea (28.6%).The most common comorbidities were diabetes mellitus (7, 50%) and hypertension (8, 57.1%). Thirteen patients had CMV GI disease. The endoscopic gross features of the GI tract lesions included single or multiple ulcers and a large polypoid or uneven surface mass. Of the seven cases with available data, a low body mass index (22.3 ± 1.3 kg/m(2)) and hypoalbuminemia (25 ± 7.0 g/L) were noted. Twelve patients had received ganciclovir or valganciclovir therapy. Five (35.7%) patients died, and the death of two patients was directly related to bowel perforation caused by CMV colitis.

CONCLUSION

CMV disease may occur in CKD patients without the presence of overt immunodeficiency. The gastrointestinal tract is the most common site of involvement. Clinicians should be aware of this possibility in CKD patients who have GI symptoms.

Effects of intrapulmonary viral tropism and cytokine expression on the histological patterns of cytomegalovirus pneumonia

Pulmonary cytomegalovirus (CMV) infection causes fatal CMV pneumonia (CMVp) in Immunocompromised patients; however, the mechanisms underlying CMV-Infection-Induced pulmonary lesion development remain largely unknown. We examined the relationship between CMVp patterns and Intrapulmonary viral tropism, Including expression of Inflammatory cytokines and related molecules. Double Immunohistochemistry of CMV antigen and cellular markers showed that epithelial tropism was associated with a diffuse alveolar damage (DAD) pattern (CMVp-DAD) while stromal tropism was associated with a predominantly interstitial inflammation/fibrosis (IIF) (CMVp-IIF) or a combination of DAD and IIF (CMVp-complex). Transforming growth factor (TGF)-β1 expression was relevant to CMV-induced tissue injury, and its expression was higher in CMVp-complex and CMVp-IIF than in CMVp-DAD. Expression of integrin β6 (ITGB6), an adhesion molecule and important activator of TGF-β1 in interstitial pneumonia, was lost in CMV-infected pneumocytes, especially CMVp-DAD, whereas CMV-negative pneumocytes in CMVp-complex and CMVp-IIF showed overexpression. Diffuse interleukin (IL)-8 up-regulation and strong expression were present in both CMV-infected pneumocytes and stromal cells only in CMVp-IIF cases with marked interstitial neutrophilic infiltration. On the basis of viral tropism and the expression of TGF-β1, ITGB6, and IL-8, we conclude that CMV-Infected pulmonary cells play an Important role in the development of diverse CMVp patterns.

Quantification of cytomegalovirus DNA by a fully automated real-time PCR for early diagnosis and monitoring of active viral infection in solid organ transplant recipients

BACKGROUND

Quantification of cytomegalovirus (CMV) DNA by real-time PCR is currently considered an alternative diagnostic approach for the evaluation of active infection in transplant patients. The pp65 antigenemia assay has been used as reference test for monitoring active CMV infection and guiding preemptive therapy in transplant recipients. However, this assay suffers from some limitations: need for immediate processing of the samples, labour-intensive process, lack of standardization and subjective result interpretation.

OBJECTIVES

The aim of this study was to evaluate the performance of a new commercially available real-time PCR assay coupled with a fully automated DNA extraction system (COBAS Ampliprep/COBAS Taqman CMV Test, Roche Diagnostics) for the detection of CMV-DNA in plasma comparing it with pp65 antigenemia assay for monitoring active CMV infection in solid organ transplant recipients (SOTRs).

STUDY DESIGN

A total of 266 consecutive samples from 45 SOTRs were monitored with pp65 antigenemia and in parallel with CMV-DNA quantitation by real-time PCR assay.

RESULTS

Fifty-eight samples resulted PCR-positive, 163 negative and for 45 samples the CMV-DNA values obtained were below the lower limit of quantification (<150 copies/ml); pp65 antigen was detected in 47 samples and resulted negative in 219 specimens. Concordance between the two evaluations was 76.7%; also a good correlation was observed (r=0.718). Considering the existing treatment criteria based on pp65 antigenemia evaluation corresponding to pp65 levels≥20 positive cells/200,000, preemptive therapy was administered to four asymptomatically infected patients. The corresponding cut-off value of CMV-DNA load calculated for discrimination between self-clearing infections and those requiring therapy was 2500 copies/ml (or 2275 IU/ml).

CONCLUSION

The fully automated real-time PCR from Roche provided specific and sensitive results and represented a rapid and simple assay for the evaluation and monitoring of CMV infection in SOTRs. Further studies are required to validate the threshold level for the initiation of preemptive therapy.

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

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

The genome of murine cytomegalovirus is shaped by purifying selection and extensive recombination

The herpesvirus lifestyle results in a long-term interaction between host and invading pathogen, resulting in exquisite adaptation of virus to host. We have sequenced the genomes of nine strains of murine cytomegalovirus (a betaherpesvirus), isolated from free-living mice trapped at locations separated geographically and temporally. Despite this separation these genomes were found to have low levels of nucleotide variation. Of the more than 160 open reading frames, almost 90% had a dN/dS ratio of amino acid substitutions of less than 0.6, indicating the level of purifying selection on the coding potential of MCMV. Examination of selection acting on individual genes at the codon level however indicates some level of positive selection, with 0.03% of codons showing strong evidence for positive selection. Conversely, 1.3% of codons show strong evidence of purifying selection. Alignments of both genome sequences and coding regions suggested that high levels of recombination have shaped the MCMV genome.

Human cytomegalovirus infection dysregulates the canonical Wnt/β-catenin signaling pathway

Human Cytomegalovirus (HCMV) is a ubiquitous herpesvirus that currently infects a large percentage of the world population. Although usually asymptomatic in healthy individuals, HCMV infection during pregnancy may cause spontaneous abortions, premature delivery, or permanent neurological disabilities in infants infected in utero. During infection, the virus exerts control over a multitude of host signaling pathways. Wnt/β-catenin signaling, an essential pathway involved in cell cycle control, differentiation, embryonic development, placentation and metastasis, is frequently dysregulated by viruses. How HCMV infection affects this critical pathway is not currently known. In this study, we demonstrate that HCMV dysregulates Wnt/β-catenin signaling in dermal fibroblasts and human placental extravillous trophoblasts. Infection inhibits Wnt-induced transcriptional activity of β-catenin and expression of β-catenin target genes in these cells. HCMV infection leads to β-catenin protein accumulation in a discrete juxtanuclear region. Levels of β-catenin in membrane-associated and cytosolic pools, as well as nuclear β-catenin, are reduced after infection; while transcription of the β-catenin gene is unchanged, suggesting enhanced degradation. Given the critical role of Wnt/β-catenin signaling in cellular processes, these findings represent a novel and important mechanism whereby HCMV disrupts normal cellular function.

A large percentage of the world population is infected with HCMV. As a leading viral cause of birth defects in the developed world, HCMV represents a significant public health burden. For the first time, we report that HCMV infection dysregulates the canonical Wnt/β-catenin signaling pathway which is essential in regulating a diverse range of biological functions. We demonstrate that HCMV infection leads to sequestration and degradation of β-catenin protein, the effector transcription factor in the pathway, thus preventing its downstream signaling activities. Since this pathway is essential in regulating mammalian development and homeostasis, the finding that HCMV impairs this pathway becomes globally important for understanding viral pathogenesis, particularly that related to HCMV disease.

Prevention of cellular suicide by cytomegaloviruses

As intracellular parasites, viruses rely on many host cell functions to ensure their replication. The early induction of programmed cell death (PCD) in infected cells constitutes an effective antiviral host mechanism to restrict viral spread within an organism. As a countermeasure, viruses have evolved numerous strategies to interfere with the induction or execution of PCD. Slowly replicating viruses such as the cytomegaloviruses (CMVs) are particularly dependent on sustained cell viability. To preserve viability, the CMVs encode several viral cell death inhibitors that target different key regulators of the extrinsic and intrinsic apoptosis pathways. The best-characterized CMV-encoded inhibitors are the viral inhibitor of caspase-8-induced apoptosis (vICA), viral mitochondrial inhibitor of apoptosis (vMIA), and viral inhibitor of Bak oligomerization (vIBO). Moreover, a viral inhibitor of RIP-mediated signaling (vIRS) that blocks programmed necrosis has been identified in the genome of murine CMV (MCMV), indicating that this cell death mode is a particularly important part of the antiviral host response. This review provides an overview of the known cell death suppressors encoded by CMVs and their mechanisms of action.

Live or let die: manipulation of cellular suicide programs by murine cytomegalovirus

Cytomegaloviruses (CMVs) are large double-stranded DNA viruses that replicate slowly and cause life-long persisting infections in their hosts. To achieve this, the CMVs had to evolve numerous countermeasures against innate and adaptive immune responses. Induction of programmed cell death is one important host defense mechanism against intracellular pathogens such as viruses. For a multicellular organism, it is advantageous to let infected cells die in order to thwart viral replication and dissemination. For a virus, by contrast, it is better to inhibit cell death and keep infected cells alive until the viral replication cycle has been completed. As a matter of fact, the CMVs encode a number of proteins devoted to interfering with different forms of programmed cell death: apoptosis and necroptosis. In this review, we summarize the known functions of the four best characterized cell death inhibitors of murine cytomegalovirus (MCMV), which are encoded by open reading frames, M36, m38.5, m41.1, and M45. The viral proteins interact with key molecules within different cell death pathways, namely caspase-8, Bax, Bak, and RIP1/RIP3. In addition, we discuss which events during MCMV infection might trigger apoptosis or necrosis and how MCMV's countermeasures compare to those of other herpesviruses. Since both, MCMV and its natural host, are amenable to genetic manipulation, the mouse model for CMV infection provides a particularly suitable system to study mechanisms of cell death induction and inhibition.

Cytomegalovirus colitis following azacitidine therapy

The present report describes the first recognized case of cytomegalovirus (CMV) colitis following azacitidine therapy. A 66-year-old woman with myelodysplastic syndrome developed CMV colitis, which responded to treatment with ganciclovir. Currently, patients receiving azacitidine do not undergo CMV testing, or receive prophylaxis or CMV-free blood products; however, this policy needs to be revised.

HLA-DR and HLA-DP restricted epitopes from human cytomegalovirus glycoprotein B recognized by CD4+ T-cell clones from chronically infected individuals

Purpose

Helper CD4⁺ T cells presumably play a major role in controlling cytomegalovirus (CMV) by providing help to specific B and CD8⁺ cytotoxic T cells, as well as through cytotoxicity-mediated mechanisms. Since CMV glycoprotein B (gB) is a major candidate for a subunit vaccine against CMV, we searched for gB-epitopes presented by human leukocyte antigen (HLA)-class II molecules.

Methods

Dendritic cells obtained from CMV-seropositive donors were loaded with a recombinant gB and co-cultured with autologous CD4⁺ T cells. Microcultures that specifically recognized gB were cloned by limiting dilution using autologous Epstein-Barr virus (EBV)-immortalized B cells pulsed with gB as antigen-presenting cells. To pinpoint precisely the region encoding the natural epitope recognized by a given CD4⁺ clone, we assessed the recognition of recombinant Escherichia coli expressing gB-overlapping polypeptides after their processing by autologous EBV-B cells.

Results

We isolated several gB-specific CD4⁺ T-cell clones directed against peptides gB_190-204, gB_396-410, gB_22-36 and gB_598-617 presented by HLA-DR7, HLA-DP10 and HLA-DP2. While their precise role in controlling CMV infection remains to be established, gB-specific CD4⁺ T cells are likely to act by directly targeting infected HLA-class II cells in vivo, as suggested by their recognition of EBV-B cells infected by the Towne CMV strain.

Conclusions

The characterization of such gB-epitopes presented by HLA-class II should help to understand the contribution of CD4⁺ T-cell responses to CMV and may be of importance both in designing a vaccine against CMV infection and in immunomonitoring of subjects immunized with recombinant gB or with vectors encoding gB.

Overview of the diagnosis of cytomegalovirus infection

Cytomegalovirus (CMV) is recognized as the most common congenital viral infection in humans and an important cause of morbidity and mortality in immunocompromised hosts. This recognition of the clinical importance of invasive CMV disease in the setting of immunodeficiency and in children with congenital CMV infection has led to the development of new diagnostic procedures for the rapid identification of CMV. Diagnosis of acute maternal CMV infection by the presence of immunoglobulin (Ig)M and low-avidity IgG requires confirmation of fetal infection, which is typically performed using polymerase chain reaction (PCR) assays for CMV on amniotic fluid. Viral culture of the urine and saliva obtained within the first two weeks of life continues to be the gold standard for diagnosis of congenitally-infected infants. PCR assays of dried blood spots from newborns have been shown to lack sufficient sensitivity for the identification of most neonates with congenital CMV infection for universal screening purposes. However, saliva PCR assays are currently being assessed as a useful screening method for congenital CMV infection. In the immunocompromised host, newer rapid diagnostic assays, such as phosphoprotein 65 antigenemia and CMV real-time PCR of blood or plasma have allowed for preemptive treatment, reducing morbidity and mortality. However, lack of standardized real-time PCR protocols hinders the comparison of data from different centers and the development of uniform guidelines for the management of invasive CMV infections in immunocompromised individuals.

The immune response to human CMV

This review will summarize and interpret recent literature regarding the human CMV immune response, which is among the strongest measured and is the focus of attention for numerous research groups. CMV is a highly prevalent, globally occurring infection that rarely elicits disease in healthy immunocompetent hosts. The human immune system is unable to clear CMV infection and latency, but mounts a spirited immune-defense targeting multiple immune-evasion genes encoded by this dsDNA β-herpes virus. Additionally, the magnitude of cellular immune response devoted to CMV may cause premature immune senescence, and the high frequencies of cytolytic T cells may aggravate vascular pathologies. However, uncontrolled CMV viremia and life-threatening symptoms, which occur readily after immunosuppression and in the immature host, clearly indicate the essential role of immunity in maintaining asymptomatic co-existence with CMV. Approaches for harnessing the host immune response to CMV are needed to reduce the burden of CMV complications in immunocompromised individuals.

A critical role for STAT3 transcription factor signaling in the development and maintenance of human T cell memory

STAT3 transcription factor signaling in specific T helper cell differentiation has been well described, although the broader roles for STAT3 in lymphocyte memory are less clear. Patients with autosomal-dominant hyper-IgE syndrome (AD-HIES) carry dominant-negative STAT3 mutations and are susceptible to a variety of bacterial and fungal infections. We found that AD-HIES patients have a cell-intrinsic defect in the number of central memory CD4(+) and CD8(+) T cells compared to healthy controls. Naive T cells from AD-HIES patients had lower expression of memory-related transcription factors BCL6 and SOCS3, a primary proliferation defect, and they failed to acquire central memory-like surface phenotypes in vitro. AD-HIES patients showed a decreased ability to control varicella zoster virus (VZV) and Epstein-Barr virus (EBV) latency, and T cell memory to both of these viruses was compromised. These data point to a specific role for STAT3 in human central memory T cell formation and in control of certain chronic viruses.

Human cytomegalovirus tegument proteins (pp65, pp71, pp150, pp28)

Human cytomegalovirus (HCMV), a member of the Betaherpesvirinae sub-family of Herpesviridae family, is a widespread pathogen that infects a majority of the world's population by early adulthood. In individuals whose immune systems are immature or weakened, HCMV is a significant pathogen causing morbidity and mortality. There is no effective vaccine and only limited antiviral treatments against HCMV infection to date. A possible target for novel antiviral treatments is the HCMV proteins that localize to the tegument of the virion, since they play important roles in all stages of the viral life cycle, including, viral entry, gene expression, immune evasion, assembly, and egress. The most likely tegument protein candidates are pp65 (immune evasion), pp71 (gene expression), and pp150 and pp28 (assembly and egress). Although the subcellular localization of these proteins has been identified during HCMV infections in vitro, their localization patterns have not been determined when each protein is expressed individually in living cells. Thus, the objective of this review is elucidate the HCMV tegument as well as present current research findings concerning the subcellular localization of the tegument proteins pp65, pp71, pp150, and pp28 as fusions to one of several fluorescent proteins.

Cytomegalovirus reactivation in critically ill immunocompetent hosts: a decade of progress and remaining challenges

Human cytomegalovirus (HCMV) is an undisputed pathogen in humans with severe immune compromise, which has historically been thought to carry little consequence in immunocompetent hosts. During the past decade, however, accumulating data suggest that significant numbers of immunocompetent humans reactivate HCMV during critical illness, and that these reactivation episodes are associated with worsened outcomes. Because most people are infected with this ubiquitous virus by adulthood, confirming pathogenicity has now become a clinical priority. In this article, we will review the incidence and implications of reactivation, the relevant immune responses and reactivation triggers relevant to the immunocompetent host. We will summarize the progress made during the past ten years, outline the work ongoing in this field, and identify the major gaps remaining in our emerging understanding of this phenomenon.

Pathogenesis and treatment of human immunodeficiency virus-associated cytomegalovirus retinitis

In the era of HAART, human cytomegalovirus (HCMV) retinitis remains the leading opportunistic ocular infection and the major cause of blindness in patients with AIDS. The virus has been subjected to selection and presented with the opportunity to occupy a niche to which it is highly adapted in order to escape from host immune recognition and establish persistent infection in the retina. The imbalance between host immune protection and viral immune evasion results in retinitis progression. Moreover, a synergistic interaction between HCMV and HIV in the pathogenesis of retinitis has been proposed. HAART has had a major beneficial impact on the prognosis for HIV-infected individuals. Both HAART and specific anti-HCMV treatment contribute to therapeutic success against HCMV retinitis in AIDS patients. The improved prognosis for AIDS patients with respect to the development of HCMV retinitis has been welcomed; however, we should bear in mind the occurrence of HIV drug resistance, relapse of retinitis and immune recovery uveitis after treatment, which mean that this complication of HIV infection remains a threat.

Role of tegument proteins in herpesvirus assembly and egress

Morphogenesis and maturation of viral particles is an essential step of viral replication. An infectious herpesviral particle has a multilayered architecture, and contains a large DNA genome, a capsid shell, a tegument and an envelope spiked with glycoproteins. Unique to herpesviruses, tegument is a structure that occupies the space between the nucleocapsid and the envelope and contains many virus encoded proteins called tegument proteins. Historically the tegument has been described as an amorphous structure, but increasing evidence supports the notion that there is an ordered addition of tegument during virion assembly, which is consistent with the important roles of tegument proteins in the assembly and egress of herpesviral particles. In this review we first give an overview of the herpesvirus assembly and egress process. We then discuss the roles of selected tegument proteins in each step of the process, i.e., primary envelopment, de-envelopment, secondary envelopment and transport of viral particles. We also suggest key issues that should be addressed in the near future.

Post-Cervical Decompression Parsonage-Turner Syndrome Represents a Subset of C5 Palsy: Six Cases and a Review of the Literature: Case Report

BACKGROUND:

Approximately 5% of cervical decompression cases are complicated by postoperative weakness. Parsonage-Turner syndrome (PTS) or neuralgic amyotrophy is known to be precipitated by surgery and unrelated to technical or structural issues. Our practice has seen a number of cases of PTS after cervical decompression surgery. In this case report, we discuss a series of such patients, highlighting the commonalities with the more frequently diagnosed C5 palsy. We conclude with our management algorithm.

CLINICAL PRESENTATION:

Six patients with post-cervical decompression PTS were referred to our institution during a 32-month period. All patients were examined physically, radiographically, and electromyographically and were followed for up to 2 years or until symptoms resolved. Conservative management was the rule, and surgical intervention, including nerve releases and nerve reconstruction, was undertaken in select circumstances. In the majority of patients (4 of 6 patients), pain management and physical therapy alone were used and achieved eventual resolution of pain and recovery of motor strength. The other 2 patients required adjunctive surgical procedures to maximize their outcomes.

CONCLUSION:

PTS accounts for a subset of patients experiencing postoperative weakness after cervical decompression operations. Although it is at times difficult to arrive at this diagnosis, an understanding of the history of PTS, among other causes of postoperative weakness, allows a structured approach to these patients. An evidence-based approach to management helps provide the best outcome for a given patient.

War and peace between microbes: HIV-1 interactions with coinfecting viruses

HIV-1 disrupts the homeostatic equilibrium between the host and coinfecting microbes, facilitating reactivation of persistent viruses and invasion by new viruses. These viruses usually accelerate HIV disease but occasionally create conditions detrimental for HIV-1. Understanding these phenomena may lead to anti-HIV-1 strategies that specifically target interactions between HIV-1 and coinfecting viruses.

Influence of human cytomegalovirus infection on the NK cell receptor repertoire in children

Human cytomegalovirus (hCMV) infection is usually asymptomatic but may cause disease in immunocompromised hosts. It has been reported that hCMV infection may shape the NK cell receptor (NKR) repertoire in adult individuals, promoting a variable expansion of the CD94/NKG2C+ NK cell subset. We explored the possible relationship between this viral infection and the expression pattern of different NKR including CD94/NKG2C, CD94/NKG2A, immunoglobulin-like transcript 2 (ILT2, CD85j), KIR2DL1/2DS1, KIR3DL1, and CD161 in peripheral blood lymphocytes from healthy children, seropositive (n=21) and seronegative (n=20) for hCMV. Consistent with previous observations in adults, a positive serology for hCMV was associated with increased numbers of NKG2C+ NK and T cells as well as with ILT2+ T lymphocytes. Moreover, the proportions of CD161+ and NKG2C+CD56-CD3- NK cells also tended to be increased in hCMV+ individuals. Excretion of the virus was associated with higher proportions of NKG2C+ NK cells. Altogether, these data reveal that hCMV may have a profound influence on the NKR repertoire in early childhood.

Antiviral prevention of sepsis induced cytomegalovirus reactivation in immunocompetent mice

INTRODUCTION

Immunocompetent patients can reactivate latent cytomegalovirus (CMV) during critical illness and reactivation is associated with significantly worse outcomes. Prior to clinical trials in humans to prove causality, we sought to determine an optimal antiviral treatment strategy.

METHODS

Mice latently infected with murine CMV (MCMV) received a septic reactivation trigger and were randomized to receive one of four ganciclovir regimens or saline. Lungs were evaluated for viral transcriptional reactivation and fibrosis after each regimen. Influences of ganciclovir on early sepsis-induced pulmonary inflammation and T-cell activation were studied after sepsis induction.

RESULTS

All ganciclovir regimens reduced measurable MCMV transcriptional reactivation, and 10mg/day for 7 or 21 days was most effective. Lower dose (5mg/kg/day) or delayed therapy was associated with significant breakthrough reactivation. Higher doses of ganciclovir given early were associated with the lowest incidence of pulmonary fibrosis, and delay of therapy for 1 week was associated with significantly worse pulmonary fibrosis. Although bacterial sepsis induced activation of MCMV-specific pulmonary T-cells, this activation was not influenced by ganciclovir.

CONCLUSION

These results suggest that antiviral treatment trials in humans should use 10mg/kg/day ganciclovir administered as early as possible in at-risk patients to minimize reactivation events and associated pulmonary injury.

The aging of the immune system

An age-related decline in immune functions, referred to as immunosenescence, is partially responsible for the increased prevalence and severity of infectious diseases, and the low efficacy of vaccination in elderly persons. Immunosenescence is characterized by a decrease in cell-mediated immune function as well as by reduced humoral immune responses. Age-dependent defects in T- and B-cell function coexist with age-related changes within the innate immune system. In this review, we discuss the mechanisms and consequences of age-associated immune alterations as well as their implications for health in old age.

The flexible loop of the human cytomegalovirus DNA polymerase processivity factor ppUL44 is required for efficient DNA binding and replication in cells

Phosphoprotein ppUL44 of the human cytomegalovirus (HCMV) DNA polymerase plays an essential role in viral replication, conferring processivity to the DNA polymerase catalytic subunit pUL54 by tethering it to the DNA. Here, for the first time, we examine in living cells the function of the highly flexible loop of ppUL44 (UL44-FL; residues 162 to 174 [PHTRVKRNVKKAP(174)]), which has been proposed to be directly involved in ppUL44's interaction with DNA. In particular, we use a variety of approaches in transfected cells to characterize in detail the behavior of ppUL44Deltaloop, a mutant derivative in which three of the five basic residues within UL44-FL are replaced by nonbasic amino acids. Our results indicate that ppUL44Deltaloop is functional in dimerization and binding to pUL54 but strongly impaired in binding nuclear structures within the nucleus, as shown by its inability to form nuclear speckles, reduced nuclear accumulation, and increased intranuclear mobility compared to wild-type ppUL44. Moreover, analysis of cellular fractions after detergent and DNase treatment indicates that ppUL44Deltaloop is strongly reduced in DNA-binding ability, in similar fashion to ppUL44-L86A/L87A, a point mutant derivative impaired in dimerization. Finally, ppUL44Deltaloop fails to transcomplement HCMV oriLyt-dependent DNA replication in cells and also inhibits replication in the presence of wild-type ppUL44, possibly via formation of heterodimers defective for double-stranded DNA binding. UL44-FL thus emerges for the first time as an important determinant for HCMV replication in cells, with potential implications for the development of novel antiviral approaches by targeting HCMV replication.

Prevalence of human cytomegalovirus co-infection in patients with chronic viral hepatitis B and C: a comparison of clinical and histological aspects

BACKGROUND

Human cytomegalovirus (HCMV) is a common pathogen of severe disease in patients with impaired immune functions. Reactivation of HCMV in immunocompetent host is usually asymptomatic, but may deteriorate the prognosis of patient with chronic illness.

OBJECTIVES

This study was conducted to detect HCMV infection in patients with chronic hepatitis B virus (HBV) and chronic hepatitis C virus (HCV) infections and to point out the effects of HCMV-HBV and HCMV-HCV co-infections on liver histology.

STUDY DESIGN

Expression of HCMV DNA was determined in liver tissue biopsies by real-time quantitative polymerase chain reaction (qPCR) method. There were 44 chronic HBV, and 25 chronic HCV patients within the study group. Control group consisted of 36 patients with hepatologic malignancies.

RESULTS

HCMV infection was demonstrated in 52.3% of chronic HBV, and 36% of chronic HCV patients. Although alanine aminotransferase (ALT) levels of HCMV-infected HBV patients were decreased slightly, they were increased in HCV patients. Histologic activity scores (necroinflammation and fibrosis) of HCMV-positive patients were higher than that of HCMV-negatives in both HBV and HCV groups. Intrahepatic HBV DNA or HCV RNA loads of the corresponding study groups were decreased in HCMV-infected patients.

CONCLUSION

We conclude that HCMV infection is common in chronic HBV and HCV patients, who can be regarded as patients at high risk for HCMV disease. Though the histological changes were more marked in liver, replication of HBV and HCV were inhibited in HCMV-positive cases.

Highly quantitative serological detection of anti-cytomegalovirus (CMV) antibodies

Background

Human cytomegalovirus infection is associated with a variety of pathological conditions including retinitis, pneumonia, hepatitis and encephalitis that may be transmitted congenitally, horizontally and parenterally and occurs both as a primary infection and as reactivation in immunocompromised individuals. Currently, there is a need for improved quantitative serological tests to document seropositivity with high sensitivity and specificity.

Methods

Here we investigated whether luciferase immunoprecipitation systems (LIPS) would provide a more quantitative and sensitive method for detecting anti-CMV antibodies. Four protein fragments of immunodominant regions of CMV antigens pp150 and pp65 were generated as Renilla luciferase (Ruc) fusion proteins and used in LIPS with two cohorts of CMV positive and negative sera samples previously tested by ELISA.

Results

Analysis of the antibody responses to two of these antigen fragments, pp150-d1 and pp150-d2, revealed geometric mean antibody titers in the first cohort that were 100–1000 fold higher in the CMV positive sera compared to the CMV negative samples (p < 0.0001) and infection status exactly matched the ELISA results for the 46 samples of the first cohort (100% sensitivity and 100% specificity). Two additional antigen fragments, pp65-d1 and pp65-d2 also showed robust antibody titers in some CMV-infected sera and yielded 50% and 96% sensitivity, respectively. Analysis of a second cohort of 70 samples using a mixture of the 4 antigens, which simplifies data collection and analysis, yielded values which correlated well with the sum of the values from the 4 separate tests (r_s = 0.93, p < 0.00001). While comparison of the LIPS results from this second cohort with ELISA showed 100% sensitivity, LIPS detected six additional CMV positive samples that were not detected by ELISA. Heat map analysis revealed that several of the LIPS positive/ELISA negative samples had positive LIPS immunoreactivity with 3–4 of the CMV antigens.

Conclusion

These results suggest that LIPS provides a highly robust and quantitative method for studying anti-CMV antibodies and has the potential to more accurately document CMV infection than standard ELISA.

Cytomegalovirus infection and disease in the new era of immunosuppression following solid organ transplantation

As the most prevalent pathogen among transplant patients, cytomegalovirus (CMV) affects up to three-quarters of all solid organ transplant recipients. While we have made great strides in preventing CMV infection and disease in the early post-transplant period, late CMV infection and indirect effects due to viral immunomodulation remain problematic. Changing immunosuppression practices, including the increasing use of T-cell depleting induction antibodies, have the potential to affect the risk for CMV infection and disease, even in the face of good prophylactic and preemptive therapy. The purpose of this review article is to discuss the impact of CMV infection on long-term allograft outcomes and to re-evaluate the risks and management strategies for prevention of CMV in the framework of evolving modern immunosuppressive strategies.

Viruses and kidney disease: beyond HIV

SUMMARY

Human immunodeficiency virus (HIV)-infected patients may acquire new viral co-infections; they also may experience the reactivation or worsening of existing viral infections, including active, smoldering, or latent infections. HIV-infected patients may be predisposed to these viral infections owing to immunodeficiency or risk factors common to HIV and other viruses. A number of these affect the kidney, either by direct infection or by deposition of immune complexes. In this review we discuss the renal manifestations and treatment of hepatitis C virus, BK virus, adenovirus, cytomegalovirus, and parvovirus B19 in patients with HIV disease. We also discuss an approach to the identification of new viral renal pathogens, using a viral gene chip to identify viral DNA or RNA.

Detection of Cytomegalovirus in Atherosclerotic Plaques and Nonatherosclerotic Arteries

Several studies have reported an association between infectious agents and atherosclerosis. Cytomegalovirus (CMV) is the most commonly implicated viral pathogen. However, the role of CMV in atherosclerosis remains obscure. The present study evaluated the presence of CMV DNA in atherosclerotic plaques and normal vessel walls. A total of 40 arterial specimens from coronary plaques and 27 samples from normal vessels were obtained from 26 patients who underwent aortocoronary bypass surgery. The specimens were analyzed by polymerase chain reaction for the presence of the CMV immediate early genomic region. CMV DNA was detected in 9 out of 26 patients (34.6%). Viral DNA was detected in both nonatherosclerotic tissues and atherosclerotic plaques. No statistically significant differences were observed between normal and diseased vessels. Our findings, in accordance with previous studies, do not support a direct causative role of CMV in the development of atherosclerotic plaques.

Tegument proteins of human cytomegalovirus

SUMMARY

Human cytomegalovirus (HCMV) is a common, medically relevant human herpesvirus. The tegument layer of herpesvirus virions lies between the genome-containing capsids and the viral envelope. Proteins within the tegument layer of herpesviruses are released into the cell upon entry when the viral envelope fuses with the cell membrane. These proteins are fully formed and active and control viral entry, gene expression, and immune evasion. Most tegument proteins accumulate to high levels during later stages of infection, when they direct the assembly and egress of progeny virions. Thus, viral tegument proteins play critical roles at the very earliest and very last steps of the HCMV lytic replication cycle. This review summarizes HCMV tegument composition and structure as well as the known and speculated functions of viral tegument proteins. Important directions for future investigation and the challenges that lie ahead are identified and discussed.

Bench-to-bedside review: rare and common viral infections in the intensive care unit--linking pathophysiology to clinical presentation

Viral infections are common causes of respiratory tract disease in the outpatient setting but much less common in the intensive care unit. However, a finite number of viral agents cause respiratory tract disease in the intensive care unit. Some viruses, such as influenza, respiratory syncytial virus (RSV), cytomegalovirus (CMV), and varicella-zoster virus (VZV), are relatively common. Others, such as adenovirus, severe acute respiratory syndrome (SARS)-coronavirus, Hantavirus, and the viral hemorrhagic fevers (VHFs), are rare but have an immense public health impact. Recognizing these viral etiologies becomes paramount in treatment, infection control, and public health measures. Therefore, a basic understanding of the pathogenesis of viral entry, replication, and host response is important for clinical diagnosis and initiating therapeutic options. This review discusses the basic pathophysiology leading to clinical presentations in a few common and rare, but important, viruses found in the intensive care unit: influenza, RSV, SARS, VZV, adenovirus, CMV, VHF, and Hantavirus.

Combination of native and recombinant cytomegalovirus antigens in a new ELISA for detection of CMV-specific antibodies

BACKGROUND

Serological detection of cytomegalovirus (CMV)-specific antibodies varies greatly due to antigen composition and the lack of antigen standardization.

OBJECTIVES

To develop and evaluate a new ELISA with native and/or recombinant cytomegalovirus antigens for the detection of anti-CMV IgG and IgM antibodies.

RESULTS

The diagnostic performance of three anti-CMV ELISAs coated with different CMV antigen preparations, (i) native CMV antigen, (ii) a mixture of recombinant CMV peptides pp150, pp28, gB2 and pp52 and (iii) a combination of native CMV antigens and recombinant CMV IE1 antigen applied in the new Genzyme Virotech CMV ELISA, were compared. All tested sera were derived from patients or healthy blood donors and were predefined with the Dade Behring Enzygnost CMV ELISA as well as by CMV PCR analysis. Additionally, official well-characterized serum panels were also tested. The new Genzyme Virotech CMV ELISA IgG/IgM test applying a combination of native antigens and recombinant IE1 antigen was evaluated and the performance was compared to the Dade Behring Enzygnost CMV ELISA. The sensitivities were 98.9% (IgG) and 98.2% (IgM), the specificities were 98.8% (IgG) and 98.9% (IgM) for the Genzyme Virotech CMV ELISA. Furthermore all sera of the BBI mixed titer performance panel as well as the BBI seroconversion panel were identified 100% correctly with the new Genzyme Virotech ELISA.

CONCLUSIONS

These data suggest that the new Genzyme Virotech CMV ELISA has higher sensitivity and specificity than ELISAs based on native antigens or recombinant peptides only. Specific combinations of native and recombinant antigens increase the serological detection of CMV infections and may add to further standardization of CMV serology.

Is phage therapy acceptable in the immunocompromised host?

Over the last decade, bacteriophages (bacterial viruses) have emerged as the major alternative to antibiotics in the treatment of antibiotic-resistant infections. While a considerable body of evidence has accumulated for the efficacy and safety of phage therapy in immunocompetent patients, data remain relatively scarce regarding its use in the immunocompromised host. To our knowledge, the present article is the first to summarize all findings, of both experimental and clinical studies, that may be relevant to the employment of phage therapy in immunocompromised patients. The available data suggest that bacteriophages could also be an efficacious and safe therapeutic modality in such patients.