Characterization of viremia at different stages of varicella-zoster virus infection

Metabolomics profiling in predicting of post-herpetic neuralgia induced by varicella zoster

To explore potential metabolomics biomarkers in predicting post-herpetic neuralgia (PHN) induced by herpes zoster (HZ). A total of 90 eligible patients were prospectively enrolled and assigned into an acute pain (ACP) group and a PHN group. Serum samples were collected before clinical intervention to perform metabolomics profiling analyses using gas chromatography mass spectrometry (GC-MS). Key metabolites were identified using partial least squares discriminant analysis (PLS-DA). A binary logistic regression was used to build a combined biomarker model to predict PHN from ACP. The discriminating efficiency of the combined biomarker model was investigated and validated by internal validation. Six metabolites were identified as the key metabolites related to PHN. All these metabolites (N-Acetyl-5-hydroxytryptaMine, glucose, dehydroascorbic acid, isopropyl-beta-D-thiogalactopyranoside, 1,5-anhydro-D-sorbitol, and glutamic acid) were found elevated in the PHN group. Pathway analyses showed that glucose-alanine cycle, tryptophan metabolism, tyrosine metabolism, lactose degradation, malate-aspartate shuttle were top five metabolic pathways evolved in PHN. The AUC was 0.85 (95% CI 0.76-0.93) for the combined biomarker model, and was 0.91 (95% CI 0.84-1.00) for the internal validation data set to predict PHN. Metabolomics analyses of key metabolites could be used to predict PHN induced by HZ.

A Guide to Preclinical Models of Zoster-Associated Pain and Postherpetic Neuralgia

Reactivation of latent varicella-zoster virus (VZV) causes herpes zoster (HZ), which is commonly accompanied by acute pain and pruritus over the time course of a zosteriform rash. Although the rash and associated pain are self-limiting, a considerable fraction of HZ cases will subsequently develop debilitating chronic pain states termed postherpetic neuralgia (PHN). How VZV causes acute pain and the mechanisms underlying the transition to PHN are far from clear. The human-specific nature of VZV has made in vivo modeling of pain following reactivation difficult to study because no single animal can reproduce reactivated VZV disease as observed in the clinic. Investigations of VZV pathogenesis following primary infection have benefited greatly from human tissues harbored in immune-deficient mice, but modeling of acute and chronic pain requires an intact nervous system with the capability of transmitting ascending and descending sensory signals. Several groups have found that subcutaneous VZV inoculation of the rat induces prolonged and measurable changes in nociceptive behavior, indicating sensitivity that partially mimics the development of mechanical allodynia and thermal hyperalgesia seen in HZ and PHN patients. Although it is not a model of reactivation, the rat is beginning to inform how VZV infection can evoke a pain response and induce long-lasting alterations to nociception. In this review, we will summarize the rat pain models from a practical perspective and discuss avenues that have opened for testing of novel treatments for both zoster-associated pain and chronic PHN conditions, which remain in critical need of effective therapies.

Varicella-Zoster virus ORF9 is an antagonist of the DNA sensor cGAS

Varicella-Zoster virus (VZV) causes chickenpox and shingles. Although the infection is associated with severe morbidity in some individuals, molecular mechanisms that determine innate immune responses remain poorly defined. We found that the cGAS/STING DNA sensing pathway was required for type I interferon (IFN) induction during VZV infection and that recognition of VZV by cGAS restricted its replication. Screening of a VZV ORF expression library identified the essential VZV tegument protein ORF9 as a cGAS antagonist. Ectopically or virally expressed ORF9 bound to endogenous cGAS leading to reduced type I IFN responses to transfected DNA. Confocal microscopy revealed co-localisation of cGAS and ORF9. ORF9 and cGAS also interacted directly in a cell-free system and phase-separated together with DNA. Furthermore, ORF9 inhibited cGAMP production by cGAS. Taken together, these results reveal the importance of the cGAS/STING DNA sensing pathway for VZV recognition and identify a VZV immune antagonist that partially but directly interferes with DNA sensing via cGAS.

Live virus vaccination of pediatric solid organ transplant candidates within 1 month prior to transplantation: A multicenter experience

BACKGROUND

Solid organ transplant (SOT) recipients are at increased risk of vaccine-preventable illness due to the high degree of immunosuppression required following transplantation. The current recommendation is to vaccinate with live attenuated vaccines, including Measles, Mumps, and Rubella (MMR) and Varicella (VAR) vaccines, at least 4 weeks prior to transplant. However, data to support the time interval between vaccine and transplant are limited.

METHODS

We conduct a literature review of the natural history of the viruses and length of viremia following live-attenuated viral vaccines, and we describe a series of 5 cases from 2 pediatric transplant centers in which live attenuated viral vaccines were administered within 21 days prior to SOT.

RESULTS

None of the 5 children who received MMR or VAR 8-21 days prior to liver (2) and heart (3) transplant suffered from vaccine-related viral illness after transplant, even in the presence of significant immunosuppression with T-cell-depleting agents.

CONCLUSION

These cases support that shorter intervals of live vaccine administration prior to transplant may be safe, allowing the vaccination of a larger cohort of SOT candidates. Increasing pretransplant vaccinations is crucial since, in most cases, live viral vaccines are contraindicated posttransplantation, and the most effective vaccine approaches utilize prime-boost strategies, priming before and boosting after transplant.

Corticosteroids Contribute to Serious Adverse Events Following Live Attenuated Varicella Vaccination and Live Attenuated Zoster Vaccination

Corticosteroids, when given in high dosages, have long been recognized as a risk factor for severe infection with wild-type varicella-zoster virus in both children and adults. The goal of this review is to assess the degree to which both low-dosage and high-dosage corticosteroids contribute to serious adverse events (SAEs) following live varicella vaccination and live zoster vaccination. To this end, we examined multiple published reports of SAEs following varicella vaccination (Varivax^TM) and zoster vaccination (Zostavax^TM). We observed that five of eight viral SAEs following varicella vaccination, including two deaths, occurred in children receiving corticosteroids, while one of three fatal viral SAEs following live zoster vaccination occurred in an adult being treated with low-dosage prednisone. The latter death after live zoster vaccination occurred in a 70 year-old man with rheumatoid arthritis, being treated with prednisone 10 mg daily. Thus, corticosteroids contributed to more severe infectious complications in subjects immunized with each of the two live virus vaccines. Further, when we surveyed the rheumatology literature as well as individual case reports, we documented examples where daily dosages of 7.5–20 mg prednisone were associated with increased rates of severe wild-type varicella-zoster virus infections in children and adults.

Equine Herpesvirus Type 1 Modulates Cytokine and Chemokine Profiles of Mononuclear Cells for Efficient Dissemination to Target Organs

Equine herpesvirus type 1 (EHV-1) causes encephalomyelopathy and abortion, for which cell-associated viremia and subsequent virus transfer to and replication in endothelial cells (EC) are responsible and prerequisites. Viral and cellular molecules responsible for efficient cell-to-cell spread of EHV-1 between peripheral blood mononuclear cells (PBMC) and EC remain unclear. We have generated EHV-1 mutants lacking ORF1, ORF2, and ORF17 genes, either individually or in combination. Mutant viruses were analyzed for their replication properties in cultured equine dermal cells, PBMC infection efficiency, virus-induced changes in the PBMC proteome, and cytokine and chemokine expression profiles. ORF1, ORF2, and ORF17 are not essential for virus replication, but ORF17 deletion resulted in a significant reduction in plaque size. Deletion of ORF2 and ORF17 gene significantly reduced cell-to-cell virus transfer from virus-infected PBMC to EC. EHV-1 infection of PBMC resulted in upregulation of several pathways such as Ras signaling, oxidative phosphorylation, platelet activation and leukocyte transendothelial migration. In contrast, chemokine signaling, RNA degradation and apoptotic pathways were downregulated. Deletion of ORF1, ORF2 and ORF17 modulated chemokine signaling and MAPK pathways in infected PBMC, which may explain the impairment of virus spread between PBMC and EC. The proteomic results were further confirmed by chemokine assays, which showed that virus infection dramatically reduced the cytokine/chemokine release in infected PBMC. This study uncovers cellular proteins and pathways influenced by EHV-1 after PBMC infection and provide an important resource for EHV-1 pathogenesis. EHV-1-immunomodulatory genes could be potential targets for the development of live attenuated vaccines or therapeutics against virus infection.

Manipulation of the Innate Immune Response by Varicella Zoster Virus

Varicella zoster virus (VZV) is the causative agent of chickenpox (varicella) and shingles (herpes zoster). VZV and other members of the herpesvirus family are distinguished by their ability to establish a latent infection, with the potential to reactivate and spread virus to other susceptible individuals. This lifelong relationship continually subjects VZV to the host immune system and as such VZV has evolved a plethora of strategies to evade and manipulate the immune response. This review will focus on our current understanding of the innate anti-viral control mechanisms faced by VZV. We will also discuss the diverse array of strategies employed by VZV to regulate these innate immune responses and highlight new knowledge on the interactions between VZV and human innate immune cells.

Frequency of subclinical herpes zoster in pediatric hematology-oncology patients receiving chemotherapy: A retrospective cohort analysis

Varicella-zoster virus (VZV) reactivation from the enteric nervous system can cause ileus (Ogilvie's syndrome) in adult patients. Since no pediatric cases have been described, we sought to retrospectively analyze VZV reactivation in pediatric hematology-oncology patients to determine whether VZV infection including subclinical VZV reactivation can induce gastrointestinal complications such as Ogilvie's syndrome. Thirty-five patients who received chemotherapy at our institution between September 2013 and June 2018 were included. Serum samples were collected weekly during hospitalization and every 3 months during outpatient maintenance chemotherapy. A real-time polymerase chain reaction assay was used to measure VZV DNA load in serum. The clinical features of patients with VZV infection were retrospectively analyzed. Of 1165 serum samples, 7 (0.6%) were positive for VZV DNA. VZV DNA was detected in 3 of 35 patients. In patient A, VZV DNA was detected during two episodes. The first episode involved varicella-like eruptions caused by the Oka VZV vaccine strain. The second episode involved herpes zoster (HZ) caused by the same strain. Patients B and C had a clinical course that was typical for HZ caused by wild-type VZV. No gastrointestinal symptoms were observed at the time of VZV infection in these three patients. VZV DNA was not detected in any other samples. No pediatric cases with Ogilvie's syndrome caused by VZV reactivation were demonstrated in this cohort. Additionally, no subclinical VZV reactivation was found in this cohort. Further study is needed to elucidate the precise incidence of pediatric Ogilvie's syndrome caused by VZV reactivation.

Varicella zoster virus productively infects human peripheral blood mononuclear cells to modulate expression of immunoinhibitory proteins and blocking PD-L1 enhances virus-specific CD8+ T cell effector function

Varicella zoster virus (VZV) is a lymphotropic alpha-herpesvirinae subfamily member that produces varicella on primary infection and causes zoster, vascular disease and vision loss upon reactivation from latency. VZV-infected peripheral blood mononuclear cells (PBMCs) disseminate virus to distal organs to produce clinical disease. To assess immune evasion strategies elicited by VZV that may contribute to dissemination of infection, human PBMCs and VZV-specific CD8+ T cells (V-CD8+) were mock- or VZV-infected and analyzed for immunoinhibitory protein PD-1, PD-L1, PD-L2, CTLA-4, LAG-3 and TIM-3 expression using flow cytometry. All VZV-infected PBMCs (monocytes, NK, NKT, B cells, CD4+ and CD8+ T cells) and V-CD8+ showed significant elevations in PD-L1 expression compared to uninfected cells. VZV induced PD-L2 expression in B cells and V-CD8+. Only VZV-infected CD8+ T cells, NKT cells and V-CD8+ upregulated PD-1 expression, the immunoinhibitory receptor for PD-L1/PD-L2. VZV induced CTLA-4 expression only in V-CD8+ and no significant changes in LAG-3 or TIM-3 expression were observed in V-CD8+ or PBMC T cells. To test whether PD-L1, PD-L2 or CTLA-4 regulates V-CD8+ effector function, autologous PBMCs were VZV-infected and co-cultured with V-CD8+ cells in the presence of blocking antibodies against PD-L1, PD-L2 or CTLA-4; ELISAs revealed significant elevations in IFNγ only upon blocking of PD-L1. Together, these results identified additional immune cells that are permissive to VZV infection (monocytes, B cells and NKT cells); along with a novel mechanism for inhibiting CD8+ T cell effector function through induction of PD-L1 expression.

Infection and Functional Modulation of Human Monocytes and Macrophages by Varicella-Zoster Virus

Varicella-zoster virus (VZV) is associated with viremia during primary infection that is presumed to stem from infection of circulating immune cells. While VZV has been shown to be capable of infecting a number of different subsets of circulating immune cells, such as T cells, dendritic cells, and NK cells, less is known about the interaction between VZV and monocytes. Here, we demonstrate that blood-derived human monocytes are permissive to VZV replication in vitro VZV-infected monocytes exhibited each temporal class of VZV gene expression, as evidenced by immunofluorescent staining. VZV virions were observed on the cell surface and viral nucleocapsids were observed in the nucleus of VZV-infected monocytes by scanning electron microscopy. In addition, VZV-infected monocytes were able to transfer infectious virus to human fibroblasts. Infected monocytes displayed impaired dextran-mediated endocytosis, and cell surface immunophenotyping revealed the downregulation of CD14, HLA-DR, CD11b, and the macrophage colony-stimulating factor (M-CSF) receptor. Analysis of the impact of VZV infection on M-CSF-stimulated monocyte-to-macrophage differentiation demonstrated the loss of cell viability, indicating that VZV-infected monocytes were unable to differentiate into viable macrophages. In contrast, macrophages differentiated from monocytes prior to exposure to VZV were highly permissive to infection. This study defines the permissiveness of these myeloid cell types to productive VZV infection and identifies the functional impairment of VZV-infected monocytes.IMPORTANCE Primary VZV infection results in the widespread dissemination of the virus throughout the host. Viral transportation is known to be directly influenced by susceptible immune cells in the circulation. Moreover, infection of immune cells by VZV results in attenuation of the antiviral mechanisms used to control infection and limit spread. Here, we provide evidence that human monocytes, which are highly abundant in the circulation, are permissive to productive VZV infection. Furthermore, monocyte-derived macrophages were also highly permissive to VZV infection, although VZV-infected monocytes were unable to differentiate into macrophages. Exploring the relationships between VZV and permissive immune cells, such as human monocytes and macrophages, elucidates novel immune evasion strategies and provides further insight into the control that VZV has over the immune system.

Varicella zoster virus productively infects human natural killer cells and manipulates phenotype

Varicella zoster virus (VZV) is a ubiquitous human alphaherpesvirus, responsible for varicella upon primary infection and herpes zoster following reactivation from latency. To establish lifelong infection, VZV employs strategies to evade and manipulate the immune system to its advantage in disseminating virus. As innate lymphocytes, natural killer (NK) cells are part of the early immune response to infection, and have been implicated in controlling VZV infection in patients. Understanding of how VZV directly interacts with NK cells, however, has not been investigated in detail. In this study, we provide the first evidence that VZV is capable of infecting human NK cells from peripheral blood in vitro. VZV infection of NK cells is productive, supporting the full kinetic cascade of viral gene expression and producing new infectious virus which was transmitted to epithelial cells in culture. We determined by flow cytometry that NK cell infection with VZV was not only preferential for the mature CD56^dim NK cell subset, but also drove acquisition of the terminally-differentiated maturity marker CD57. Interpretation of high dimensional flow cytometry data with tSNE analysis revealed that culture of NK cells with VZV also induced a potent loss of expression of the low-affinity IgG Fc receptor CD16 on the cell surface. Notably, VZV infection of NK cells upregulated surface expression of chemokine receptors associated with trafficking to the skin –a crucial site in VZV disease where highly infectious lesions develop. We demonstrate that VZV actively manipulates the NK cell phenotype through productive infection, and propose a potential role for NK cells in VZV pathogenesis.

Varicella zoster virus (VZV) is a pervasive pathogen, causing chickenpox during primary infection and shingles when the virus reactivates from latency. VZV is therefore a lifelong infection for humans, warranting investigation of how this virus interacts with the immune system. One of the first immune cells to respond to viral infection are natural killer (NK) cells, yet little is known about how VZV interacts with NK cells. We demonstrate for the first time that VZV infects human blood NK cells and can use them to pass on infection to other cells in culture. Furthermore, VZV displays a predilection for infecting mature NK cells, and amplifies expression of receptors that would promote trafficking to the skin– the site of highly infectious lesions during chickenpox and shingles. Our findings suggest a role for NK cells in VZV disease and enhances our understanding of how lifelong infections interact with the human immune system.

Simian Varicella Virus Is Present in Macrophages, Dendritic Cells, and T Cells in Lymph Nodes of Rhesus Macaques after Experimental Reactivation

Like varicella-zoster virus (VZV), simian varicella virus (SVV) reactivates to produce zoster. In the present study, 5 rhesus macaques were inoculated intrabronchially with SVV, and 5 months later, 4 monkeys were immunosuppressed; 1 monkey was not immunosuppressed but was subjected to the stress of transportation. In 4 monkeys, a zoster rash developed 7 to 12 weeks after immunosuppression, and a rash also developed in the monkey that was not immunosuppressed. Analysis at 24 to 48 h after zoster revealed SVV antigen in the lung alveolar wall, in ganglionic neurons and nonneuronal cells, and in skin and in lymph nodes. In skin, SVV was found primarily in sweat glands. In lymph nodes, the SVV antigen colocalized mostly with macrophages, dendritic cells, and, to a lesser extent, T cells. The presence of SVV in lymph nodes, as verified by quantitative PCR detection of SVV DNA, might reflect the sequestration of virus by macrophages and dendritic cells in lymph nodes or the presentation of viral antigens to T cells to initiate an immune response against SVV, or both.

IMPORTANCE

VZV causes varicella (chickenpox), becomes latent in ganglia, and reactivates to produce zoster and multiple other serious neurological disorders. SVV in nonhuman primates has proved to be a useful model in which the pathogenesis of the virus parallels the pathogenesis of VZV in humans. Here, we show that SVV antigens are present in sweat glands in skin and in macrophages and dendritic cells in lymph nodes after SVV reactivation in monkeys, raising the possibility that macrophages and dendritic cells in lymph nodes serve as antigen-presenting cells to activate T cell responses against SVV after reactivation.

Pathogenesis of varicelloviruses in primates

Varicelloviruses in primates comprise the prototypic human varicella-zoster virus (VZV) and its non-human primate homologue, simian varicella virus (SVV). Both viruses cause varicella as a primary infection, establish latency in ganglionic neurons and reactivate later in life to cause herpes zoster in their respective hosts. VZV is endemic worldwide and, although varicella is usually a benign disease in childhood, VZV reactivation is a significant cause of neurological disease in the elderly and in immunocompromised individuals. The pathogenesis of VZV infection remains ill-defined, mostly due to the species restriction of VZV that impedes studies in experimental animal models. SVV infection of non-human primates parallels virological, clinical, pathological and immunological features of human VZV infection, thereby providing an excellent model to study the pathogenesis of varicella and herpes zoster in its natural host. In this review, we discuss recent studies that provided novel insight in both the virus and host factors involved in the three elementary stages of Varicellovirus infection in primates: primary infection, latency and reactivation.

Absence of varicella zoster virus reactivation after infliximab administration for plaque psoriasis

BACKGROUND

Herpes zoster (HZ) in patients receiving tumor necrosis factor (TNF) antagonists may be more severe and the incidence seems increased. The influence of TNF antagonists on varicella zoster virus (VZV) reactivation is unknown.

OBJECTIVE

To prospectively search in a pilot study for VZV DNA in sequential blood samples before and after infliximab administration.

SETTING

University medical center.

SUBJECTS AND METHODS

Blood samples of six patients with longstanding and severe plaque psoriasis were taken on day 1 (before infliximab administration) and on days 2, 7, 21 and 42 for the determination of VZV viremia by ORF21 real-time polymerase chain reaction. Patients with varicella, HZ and normal subjects were included as controls.

RESULTS

None of the six patients presented VZV viremia at any of the time points. High-load viremia was present during varicella, low-load viremia in some HZ patients and no viremia in the control patients.

LIMITATIONS

Small number of patients.

CONCLUSIONS

In this pilot study, infliximab did not reactivate VZV and did not induce subclinical VZV viremia.

Current and emerging Legionella diagnostics for laboratory and outbreak investigations

Legionnaires' disease (LD) is an often severe and potentially fatal form of bacterial pneumonia caused by an extensive list of Legionella species. These ubiquitous freshwater and soil inhabitants cause human respiratory disease when amplified in man-made water or cooling systems and their aerosols expose a susceptible population. Treatment of sporadic cases and rapid control of LD outbreaks benefit from swift diagnosis in concert with discriminatory bacterial typing for immediate epidemiological responses. Traditional culture and serology were instrumental in describing disease incidence early in its history; currently, diagnosis of LD relies almost solely on the urinary antigen test, which captures only the dominant species and serogroup, Legionella pneumophila serogroup 1 (Lp1). This has created a diagnostic "blind spot" for LD caused by non-Lp1 strains. This review focuses on historic, current, and emerging technologies that hold promise for increasing LD diagnostic efficiency and detection rates as part of a coherent testing regimen. The importance of cooperation between epidemiologists and laboratorians for a rapid outbreak response is also illustrated in field investigations conducted by the CDC with state and local authorities. Finally, challenges facing health care professionals, building managers, and the public health community in combating LD are highlighted, and potential solutions are discussed.

One-year follow-up of patients with long-lasting post-herpetic neuralgia

BACKGROUND

Recent information on epidemiology and management of post-herpetic neuralgia (PHN), a painful complication of zoster, is scarce.

METHODS

This study was conducted at the Pain Clinic of the Policlinico Tor Vergata, Rome, Italy, on eighty-five immunocompetent patients with a clinical diagnosis of PHN. At enrollment (time 0, T0), the patients were interviewed by physicians to obtain demographic data and information about their zoster clinical history and underwent a blood test for VZV-DNA research. DN4 and SF-12 questionnaires were used to assess the neuropathic nature of pain and the overall health status, respectively. A one-year follow-up was planned for enrolled cases, who were visited at regular intervals of at least 3 months.

RESULTS

At T0 all the patients were at least 6 months from the episode of acute zoster and still presented with intense pain (mean VAS =6.7; mean DN4 = 5.7). Using antivirals within 72 hours from the rash onset was associated to a significant reduction of pain at T0 (p = 0.006 vs untreated patients). Only 2.6% of patients treated with antivirals during acute zoster but 18.6% of the untreated ones presented with neuropathic pain at T12 (p =0.007), even though the two groups were similar at T0. VZV-DNA was found in 5 out of the 50 available blood samples. At the last follow-up visit, PCS and MCS scores of the PHN patients were found to be recovered over those of the historical age-matched healthy controls. Undesirable side effects of analgesic therapies were observed in 15.3 to 28.8% of the patients.

CONCLUSIONS

Patients who six months after acute zoster still have significant neuropathic pain, have a high probability of suffering from chronic pain in the subsequent months/years. The initial antiviral treatment has a significant impact on the pain. Current strategies of analgesic therapy are effective to achieve relief of pain in PHN patients, but they are burdened with heavy and undesirable side effects.

Varicella-zoster virus and virus DNA in the blood and oropharynx of people with latent or active varicella-zoster virus infections

Varicella-zoster virus (VZV) can be detected in the blood from approximately 5 days before to 4 days after varicella. VZV DNA, primarily in T-lymphocytes, is detected as early as 8-10 days prior to rash and can persist for a week. The duration and magnitude of VZV DNAemia correlates with immune status and the efficacy of antiviral therapy. VZV DNA is also readily detected in the oropharynx just prior to rash and for 1-2 weeks thereafter. Detection of VZV DNA in blood and saliva has been useful for diagnosis and prognosis in atypical cases of varicella. Herpes zoster (HZ) is also characterized by VZV DNAemia at onset and for many weeks thereafter, and VZV DNA is present in the oropharynx shortly after HZ onset. Detection of VZV DNA in blood and saliva facilitates the diagnosis of zoster sine herpete and other atypical manifestations of VZV reactivation, such as neurologic syndromes when cerebrospinal fluid is not available, Bell's palsy, and atypical pain syndromes. VZV DNA is sometimes present in the blood and saliva of asymptomatic individuals. In total these observations extend understanding of the pathophysiology and epidemiology of VZV, and increasingly contribute to the clinical management of VZV infections.

Sampling of herpes zoster skin lesion types and the impact on viral DNA detection

This was a multicenter, non-therapeutic study to determine the optimal type of lesion sample for quantitative PCR detection of varicella zoster virus (VZV) DNA in herpes zoster patients. Up to three crusts, three crust swabs, three vesicle swabs, and three papule swabs were collected from 41 adults with clinically diagnosed herpes zoster. 83% of subjects had at least one valid crust swab (detectable VZV or β-actin DNA), 78% had at least one valid crust, 78% had at least one valid vesicle swab, and 32% had at least one valid papule swab. Of valid samples, 97% of crusts, 94% of vesicle swabs, 90% of crust swabs, and 84% of papule swabs were VZV-DNA-positive (≥10 DNA copies/sample). 37 (90%) subjects had at least one VZV DNA-positive sample. VZV DNA copy numbers were highest for vesicle swabs and crusts. The probability of a false-negative result was 5% for crusts, 6% for vesicle swabs, 14% for papule swabs, and 24% for crust swabs. Overall, vesicle swabs and crusts were the most specific and sensitive samples for detecting VZV.

The long and evolving relationship between viruses and multiple sclerosis

Multiple sclerosis (MS) is a demyelinating disorder of unknown etiology, possibly caused by a virus or is virus-triggered. Several viruses, including herpesviruses, were suggested as etiologic agents or risk factors for exacerbation in the course of illness but none have been shown to be irrefutably linked. Recently the interest of researchers and clinicians in the association between viruses and MS was reawakened by the development of progressive multifocal leukoencephalopathy, a demyelinating and fatal disease caused by JC polyomavirus replication, in natalizumab-treated MS patients. In this review, we will illustrate the evidence underlying the viral hypothesis for MS pathogenesis and will review the main features of the potential viral candidates. We will also describe the risks associated with newer MS therapies and with viral/bacterial vaccinations.

Experimental infection of Cynomolgus Macaques (Macaca fascicularis) with human varicella-zoster virus

Varicella-zoster virus (VZV) is a member of the alphaherpesvirus family and the causative agent of chickenpox and shingles. To determine the utility of cynomolgus macaques (Macaca fascicularis) as a nonhuman primate model to evaluate VZV-based simian immunodeficiency virus/human immunodeficiency virus (SIV/HIV) vaccines, we experimentally inoculated 10 animals with the parental Oka (Oka-P) strain of VZV derived from MeWo or Telo-RF cells. VZV DNA could be detected in the lungs as late as 4 days postinfection, with replicating virus detected by shell vial culture assay in one case. Infection did not result in any overt clinical symptoms but was characterized by humoral and cell-mediated immunity in a time frame and at a magnitude similar to those observed following VZV vaccination in humans. The cell line source of VZV inoculum influenced both the magnitude and polyfunctionality of cell-mediated immunity. Animals mounted a vigorous anamnestic antibody response following a second inoculation 12 weeks later. Inoculations resulted in transient increases in CD4(+) T-cell activation and proliferation, as well as a sustained increase in CD4(+) T cells coexpressing CCR5 and α4β7 integrin. In contrast to previous failed attempts to successfully utilize attenuated VZV-Oka as an SIV vaccine vector in rhesus macaques due to suboptimal infectivity and cellular immunogenicity, the ability to infect cynomolgus macaques with Oka-P VZV should provide a valuable tool for evaluating VZV-vectored SIV/HIV vaccines.

Molecular studies of the Oka varicella vaccine

Varicella zoster virus (VZV) is one of eight members of the Herpesviridae family for which humans are the primary host; it causes two distinct diseases, varicella (chickenpox) and zoster (shingles). Varicella results from primary infection, during which the virus establishes latency in sensory neurons, a characteristic of all members of the Alphaherpesvirinae subfamily. Zoster is caused by reactivation of latent virus, which typically occurs when cellular immunity is impaired. VZV is the first human herpesvirus for which a vaccine has been licensed. The vaccine preparation, v-Oka, is a live-attenuated virus stock produced by the classic method of tissue culture passage in animal and human cell lines. Over 90 million doses of the vaccine have been administered in countries worldwide, including the USA, where varicella morbidity and mortality has declined dramatically. Over the last decade, several laboratories have been committed to investigating the mechanism by which the Oka vaccine is attenuated. Mutations have accumulated across the genome of the vaccine during the attenuation process; however, studies of the contribution of these changes to vaccine attenuation have been hampered by the lack of a suitable animal model of VZV disease and by the heterogeneity that exists among the viral population within the vaccine preparation. Notwithstanding, a wealth of data has been generated using various laboratory methodologies. Studies of the vaccine virus in human xenografts implanted in severe combined immunodeficiency-hu mice, have enabled analyses of the replication dynamics of the vaccine in dorsal root ganglia, T lymphocytes and skin. In vitro assays have been used to investigate the effect of vaccine mutations on viral gene expression and sequence analysis of vaccine rash viruses has permitted investigations into spread of the vaccine virus in a human host. We present here a review of what has been learned thus far about the molecular and phenotypic characteristics of the Oka vaccine.

Review: The neurobiology of varicella zoster virus infection

Varicella zoster virus (VZV) is a neurotropic herpesvirus that infects nearly all humans. Primary infection usually causes chickenpox (varicella), after which virus becomes latent in cranial nerve ganglia, dorsal root ganglia and autonomic ganglia along the entire neuraxis. Although VZV cannot be isolated from human ganglia, nucleic acid hybridization and, later, polymerase chain reaction proved that VZV is latent in ganglia. Declining VZV-specific host immunity decades after primary infection allows virus to reactivate spontaneously, resulting in shingles (zoster) characterized by pain and rash restricted to one to three dermatomes. Multiple other serious neurological and ocular disorders also result from VZV reactivation. This review summarizes the current state of knowledge of the clinical and pathological complications of neurological and ocular disease produced by VZV reactivation, molecular aspects of VZV latency, VZV virology and VZV-specific immunity, the role of apoptosis in VZV-induced cell death and the development of an animal model provided by simian varicella virus infection of monkeys.

Varicella zoster virus and relapsing remitting multiple sclerosis

Multiple sclerosis (MS) is an immune-mediated disorder; however, little is known about the triggering factors of the abnormal immune response. Different viruses from the herpes family have been mentioned as potential participants. Here, we review the evidences that support the association of varicella zoster virus (VZV) with MS. Epidemiological studies from geographical areas, where incidence of MS has increased in recent decades, pointed out a high frequency of varicella and zoster in the clinical antecedents of MS patients, and also laboratory investigations have found large quantities of DNA from VZV in leucocytes and cerebrospinal fluid of MS patients restricted to the ephemeral period of MS relapse, followed by disappearance of the virus during remission. The above observations and the peculiar features of VZV, mainly characterized by its neurotropism and long periods of latency followed by viral reactivation, support the idea on the participation of VZV in the etiology of MS. However, as with reports from studies with other viruses, particularly Epstein Barr virus, conflicting results on confirmatory studies about the presence of viral gene products in brain tissue indicate the need for further research on the potential participation of VZV in the etiology of MS.

Persistence of varicella-zoster virus viraemia in patients with herpes zoster

BACKGROUND

Herpes zoster is caused by the reactivation of varicella-zoster virus from sensory neurons. The commonest complication following zoster is chronic pain termed post herpetic neuralgia.

OBJECTIVES

To investigate the dynamics of VZV viraemia and viral load following the resolution of zoster and its relationship to PHN development.

STUDY DESIGN

Blood samples were collected at baseline, 1 month, 3 months and 6 month from a prospective study of 63 patients with active zoster. Quantification of VZV DNA in whole blood was performed using a real-time PCR assay.

RESULTS

During acute zoster, all patients had detectable VZV DNA in their blood. VZV DNA remained detectable in the blood of 91% of patients at 6 months although levels declined significantly (p<0.0001). A history of prodromal symptoms (p=0.005) and severity of pain at baseline (p=0.038) as well as taking antivirals (p=0.046) and being immunocompromised (p=0.043) were associated, with longer time to recovery from PHN. Viral DNA loads were consistently higher in patients with risk factors for PHN and higher viral DNA loads over time were associated with longer time to recovery (p=0.058 overall and 0.038 in immunocompetent).

CONCLUSIONS

Based on these observations we hypothesise that VZV replication persists following acute shingles and that higher viral DNA loads contribute to the risk factors for PHN.

Occult varicella

BACKGROUND

Localized varicella has been associated with UV-exposure and skin trauma. Varicella restricted to a pre-existent dermatitis is exceptional.

OBJECTIVES

The clinical features, cytohistologic and immunohistochemical results, as well as serologic data of 6 patients with a sudden eruption of vesicular and eroded lesions restricted to a pre-existent dermatitis are presented.

RESULTS

All patients (mean age: 8,3 years, range: 3-22) showed crops of a few to numerous vesicular lesions clustered on the restricted sites of posttraumatic wound, perianal streptococcal dermatitis, dermatomycosis, allergic contact dermatitis, lichen sclerosus, and atopic foot dermatitis. All the Tzanck smears and 1 biopsy revealed multinucleated giant cells, consistent with herpes simplex virus (HSV) or varicella zoster virus (VZV) infection. Immunohistochemistry using specific anti-VZV antibodies (IE63 and gE) was positive on all the smears and the biopsy, whereas HSV-I and HSV-II immunolabeling was negative. VZV specific IgM+, IgG- EIA-based serology, and positive VZV-specific IgM complement fixation test suggested primary VZV infection. None had received varicella vaccine. None of the patients presented a history of varicella nor experienced breakthrough varicella. It was decided not to administer antiviral treatment, as the varicella lesions remained localized without any further skin extension and systemic signs. About 2 months later, EIA-serology revealed positive VZV-IgG and negative IgM levels in 5/5 patients.

CONCLUSION

Some patients have varicella infection that remains hidden in a pre-existent infectious and/or inflammatory dermatitis without ever presenting full-blown chickenpox. The sudden occurrence of vesicular and/or ulcerated lesions on a pre-existent dermatitis should prompt searching for a viral infection.

Simian varicella virus infection of rhesus macaques recapitulates essential features of varicella zoster virus infection in humans

Simian varicella virus (SVV), the etiologic agent of naturally occurring varicella in primates, is genetically and antigenically closely related to human varicella zoster virus (VZV). Early attempts to develop a model of VZV pathogenesis and latency in nonhuman primates (NHP) resulted in persistent infection. More recent models successfully produced latency; however, only a minority of monkeys became viremic and seroconverted. Thus, previous NHP models were not ideally suited to analyze the immune response to SVV during acute infection and the transition to latency. Here, we show for the first time that intrabronchial inoculation of rhesus macaques with SVV closely mimics naturally occurring varicella (chickenpox) in humans. Infected monkeys developed varicella and viremia that resolved 21 days after infection. Months later, viral DNA was detected only in ganglia and not in non-ganglionic tissues. Like VZV latency in human ganglia, transcripts corresponding to SVV ORFs 21, 62, 63 and 66, but not ORF 40, were detected by RT-PCR. In addition, as described for VZV, SVV ORF 63 protein was detected in the cytoplasm of neurons in latently infected monkey ganglia by immunohistochemistry. We also present the first in depth analysis of the immune response to SVV. Infected animals produced a strong humoral and cell-mediated immune response to SVV, as assessed by immunohistology, serology and flow cytometry. Intrabronchial inoculation of rhesus macaques with SVV provides a novel model to analyze viral and immunological mechanisms of VZV latency and reactivation.

Prolonged varicella viraemia and streptococcal toxic shock syndrome following varicella vaccination of a health care worker

A 49-year-old health care worker received varicella vaccine in accordance with current Australian guidelines. She developed streptococcal toxic shock syndrome, complicated by acute atraumatic dislocation of the right wrist secondary to poststreptococcal reactive arthritis - to our knowledge, the first report of spontaneous wrist dislocation as a complication in this condition. Vaccination was accompanied by prolonged viraemia with the varicella vaccine strain - also, we believe, the first report of this in an immunocompetent patient.

Herpes zoster and postherpetic neuralgia: past, present and future

OBJECTIVES

The history behind the current understanding of the varicella-zoster virus and its relationship to the pain conditions caused by shingles and postherpetic neuralgia are reviewed. The framework for the current conceptualization is Hope-Simpson's latency hypothesis. Data from recent work in virology, neuroanatomy and epidemiology are reviewed, as is work using varicella-zoster virus-infected animals. The recent data largely confirm Hope-Simpson's hypothesis and extend it significantly.

Viral load, clinical disease severity and cellular immune responses in primary varicella zoster virus infection in Sri Lanka

BACKGROUND

In Sri Lanka, varicella zoster virus (VZV) is typically acquired during adulthood with significant associated disease morbidity and mortality. T cells are believed to be important in the control of VZV replication and in the prevention of reactivation. The relationship between viral load, disease severity and cellular immune responses in primary VZV infection has not been well studied.

METHODOLOGY

We used IFNgamma ELISpot assays and MHC class II tetramers based on VZV gE and IE63 epitopes, together with quantitative real time PCR assays to compare the frequency and phenotype of specific T cells with virological and clinical outcomes in 34 adult Sri Lankan individuals with primary VZV infection.

PRINCIPAL FINDINGS

Viral loads were found to be significantly higher in patients with moderate to severe infection compared to those with mild infection (p<0.001) and were significantly higher in those over 25 years of age (P<0.01). A significant inverse correlation was seen between the viral loads and the ex vivo IFNgamma ELISpot responses of patients (P<0.001, r = -0.85). VZV-specific CD4+ T cells expressed markers of intermediate differentiation and activation.

CONCLUSIONS

Overall, these data show that increased clinical severity in Sri Lankan adults with primary VZV infection associates with higher viral load and reduced viral specific T cell responses.

Varicella zoster virus infection: clinical features, molecular pathogenesis of disease, and latency

Varicella zoster virus (VZV) is an exclusively human neurotropic alphaherpesvirus. Primary infection causes varicella (chickenpox), after which virus becomes latent in cranial nerve ganglia, dorsal root ganglia, and autonomic ganglia along the entire neuraxis. Years later, in association with a decline in cell-mediated immunity in elderly and immunocompromised individuals, VZV reactivates and causes a wide range of neurologic disease. This article discusses the clinical manifestations, treatment, and prevention of VZV infection and reactivation; pathogenesis of VZV infection; and current research focusing on VZV latency, reactivation, and animal models.

Varicella-zoster virus in the saliva of patients with herpes zoster

Fifty-four patients with herpes zoster were treated with valacyclovir. On treatment days 1, 8, and 15, pain was scored and saliva examined for varicella-zoster virus (VZV) DNA. VZV DNA was found in every patient the day treatment was started and later disappeared in 82%. There was a positive correlation between the presence of VZV DNA and pain and between VZV DNA copy number and pain (P <.0005). VZV DNA was present in 1 patient before rash and in 4 after pain resolved and was not present in any of 6 subjects with chronic pain or in 14 healthy subjects. Analysis of human saliva has potential usefulness in the diagnosis of neurological disease produced by VZV without rash.

Varicella-zoster virus in cerebrospinal fluid at relapses of multiple sclerosis

OBJECTIVE

Recent studies in peripheral blood mononuclear cells (PBMCs) have indicated that exacerbations of multiple sclerosis (MS) could be associated with the reactivation of latent varicella-zoster virus (VZV).

METHODS

Ultrastructural observations for viral particles were made by electron microscopy in cerebrospinal fluid (CSF) from 15 MS patients during relapse, 19 MS patients during remission, and 28 control subjects. Initial findings were reproduced in a confirmation cohort. In addition, DNA from VZV was quantified by real-time polymerase chain reaction in PBMCs and CSF from a large number of MS patients (n = 78).

RESULTS

We found by electron microscopy the presence of abundant viral particles identical to VZV in CSF obtained from MS patients within the first few days of an acute relapse. In contrast, viral particles were not seen in CSF samples from MS patients in remission or from neurological control subjects. Also, DNA from VZV was present in CSF and in PBMCs during relapse, disappearing in most patients during remission. The mean viral load was 542 times greater in CSF at relapse than in CSF at remission and 328 times greater in CSF at relapse than in PBMCs at relapse.

INTERPRETATION

The ultrastructural finding of viral particles identical to VZV, together with the simultaneous presence of large quantities of DNA from VZV in the subarachnoid space, almost restricted to the periods of exacerbation, as well as its steady diminution and eventual disappearance from clinical relapse to clinical remission are surprising and constitute the strongest evidence to support the participation of VZV in the pathogenesis of MS.

On the viral hypothesis of multiple sclerosis: Participation of varicella-zoster virus

Recent studies, including our own, have accumulated evidence suggesting the etiological participation of varicella-zoster virus in multiple sclerosis. If confirmed, complex issues of individual susceptibility and immunopathogenesis would have to be unveiled.

Effect of viral load on the outcome of herpes zoster

Varicella-zoster virus (VZV) is a member of the Herpesviridae family, primary infection with which causes varicella, more commonly known as chicken pox. Characteristic of members of the alphaherpesvirus subfamily, VZV is neurotropic and establishes latency in sensory neurons. Reactivation of VZV causes herpes zoster, also known as shingles. The most frequent complication following zoster is chronic and often debilitating pain called postherpetic neuralgia (PHN), which can last for months after the disappearance of a rash. During episodes of acute zoster, VZV viremia occurs in some, but not all, patients; however, the effect of the viral load on the disease outcome is not known. Here we describe the development of a highly specific, sensitive, and reproducible real-time PCR assay to investigate the factors that may contribute to the presence and levels of baseline viremia in patients with zoster and to determine the relationship between viremia and the development and persistence of PHN. VZV DNA was detected in the peripheral blood mononuclear cells (PBMCs) of 78% of patients with acute zoster and in 9% of healthy asymptomatic blood donors. The presence of VZV in the PBMCs of patients with acute zoster was independently associated with age and being on antivirals but not with gender, immune status, extent of rash, the age of the rash at the time of blood sampling, having a history of prodromal pain, or the extent of acute pain. Prodromal pain was significantly associated with higher baseline viral loads. Viral load levels were not associated with the development or persistence of PHN at 6, 12, or 26 weeks.

Downregulation of class I major histocompatibility complex surface expression by varicella-zoster virus involves open reading frame 66 protein kinase-dependent and -independent mechanisms

We show here that the varicella-zoster virus (VZV) open reading frame 66 (ORF66) protein kinase is one mechanism employed to reduce class I major histocompatibility complex (MHC-I) surface expression in VZV-infected cells. Cells expressing enhanced green fluorescent protein-tagged functional and inactivated ORF66 (GFP-66 and GFP-66kd) from replication-defective adenovirus vectors revealed that ORF66 reduced MHC-I surface levels in a manner dependent on kinase activity. Cells infected with recombinant VZV expressing GFP-66 exhibited a significantly greater reduction in MHC-I surface expression than that observed in cells infected with VZV disrupted in GFP-66 expression. MHC-I maturation was delayed in its transport from the endoplasmic reticulum through the Golgi in both adenovirus-transduced cells expressing only GFP-66 and in VZV-infected cells expressing high levels of GFP-66, and this was predominantly kinase dependent. MHC-I levels were reduced in VZV-infected cells, and analyses of intracellular MHC-I revealed accumulation of folded MHC-I in the Golgi region, irrespective of ORF66 expression. Thus, the ORF66 kinase is important for VZV-mediated MHC-I downregulation, but additional mechanisms also may be involved. Analyses of the VZV ORF9a protein, the ortholog of the bovine herpesvirus 1 transporter associated with antigen processing inhibitor UL49.5 revealed no effects on MHC-I. These results establish a new role for viral protein kinases in immune evasion and suggest that VZV utilizes unique mechanisms to inhibit antigen presentation.

Herpes simplex and varicella zoster viruses: forgotten but not gone

Herpesvirus infections are common complications of organ transplantation. The most frequent herpesvirus infections are caused by cytomegalovirus (CMV), herpes simplex (HSV) and varicella zoster (VZV). Despite expansion of the therapeutic armamentarium, HSV and VZV continue to cause morbidity and occasional mortality in transplant recipients. Here we review the incidence and risk factors for HSV and VZV disease, their clinical presentation, effects of newer immunosuppressive regimens and prophylaxis for HSV and VZV in solid organ transplant recipients.

Varicella-zoster virus at relapses of multiple sclerosis

The possible participation of different herpes viruses was studied during exacerbations of multiple sclerosis (MS). We searched for the presence of DNA from the following herpes viruses: varicella zoster virus (VZV), herpes-simplex viruses 1 and 2; Epstein-Barr virus (EBV) and human herpes-virus-6 (HHV6) in mononuclear cells from patients with MS during relapse (n = 40), MS during remission (n = 131) and controls (n = 125). Additionally, immune cells containing viral antigens were quantified by flow cytometry, and VZV load was determined by real time PCR in 2 MS patients at various times during relapse and remission. DNA from VZV was found in 95% of MS patients during relapse and in 17% during remission; all controls were negative; by contrast, DNA from HHV6 was found in 24% of MS patients during relapse and in 2% during remission; DNA from herpes simplex viruses was not found in any subject; and DNA from EBV was found in a similar percentage of subjects from all groups. Sequential quantification of VZV-load showed a curve that increased during relapse and disappeared at remission. Also, VZV antigens were found inside a large number of immune cells from MS patients during relapse as compared with MS patients on remission and controls. In the typical forms of VZV infection, varicella and herpes-zoster, DNA from VZV is found in mononuclear cells exclusively during brief periods at the beginning of the active infection, but not during latency; thus, the conspicuous presence of VZV during relapses of MS may indicate a period of active infection and suggests the participation of VZV in the pathogenesis of MS.

Molecular studies of Varicella zoster virus

VZV is a highly cell-associated member of the Herpesviridae family and one of the eight herpesviruses to infect humans. The virus is ubiquitous in most populations worldwide, primary infection with which causes varicella, more commonly known as chickenpox. Characteristic of members of the alphaherpesvirus sub-family, VZV is neurotropic and establishes latency in sensory neurones. Reactivation from latency, usually during periods of impaired cellular immunity, causes herpes zoster (shingles). Despite being one of the most genetically stable human herpesviruses, nucleotide alterations in the virus genome have been used to classify VZV strains from different geographical regions into distinct clades. Such studies have also provided evidence that, despite pre-existing immunity to VZV, subclinical reinfection and reactivation of reinfecting strains to cause zoster is also occurring. During both primary infection and reactivation, VZV infects several PBMC and skin cell lineages. Difficulties in studying the pathogenesis of VZV because of its high cell association and narrow host range have been overcome through the development of the VZV severe combined immunodeficient mouse model carrying human tissue implants. This model has provided a valuable tool for studying the importance of individual viral proteins during both the complex intracellular replication and assembly of new virions and for understanding the underlying mechanism of attenuation of the live varicella vaccine. In addition, a rat model has been developed and successfully used to uncover which viral proteins are important for both the establishment and maintenance of latent VZV infection.

Varicella-zoster virus activates inflammatory cytokines in human monocytes and macrophages via Toll-like receptor 2

The pattern recognition receptor Toll-like receptor 2 (TLR2) has been implicated in the response to several human viruses, including herpes simplex viruses (types 1 and 2) and cytomegalovirus. We demonstrated that varicella-zoster virus (VZV) activates inflammatory cytokine responses via TLR2. VZV specifically induced interleukin-6 (IL-6) in human monocytes via TLR2-dependent activation of NF-kappaB, and small interfering RNA designed to suppress TLR2 mRNA reduced the IL-6 response to VZV in human monocyte-derived macrophages. Unlike other herpesviruses, the cytokine response to VZV was species specific. VZV did not induce cytokines in murine embryonic fibroblasts or in a mouse cell line, although VZV did activate NF-kappaB in a human cell line expressing a murine TLR2 construct. Together, these results suggest that TLR2 may play a role in the inflammatory response to VZV infection.

Retrospective analysis of varicella zoster virus (VZV) copy DNA numbers in plasma of immunocompetent patients with herpes zoster, of immunocompromised patients with disseminated VZV disease, and of asymptomatic solid organ transplant recipients

BACKGROUND

Varicella zoster virus (VZV) causes significant morbidity and mortality in immunocompromised patients. Subclinical reactivation has been described in solid organ recipients and has been associated with graft versus host disease in bone marrow transplantation. Newer studies assessing the prevalence and impact of subclinical VZV reactivation in solid organ transplant (SOT) recipients are lacking.

METHODS AND RESULTS

In a first step we developed a highly sensitive quantitative polymerase chain reaction (qPCR) assay for VZV DNA with a detection limit of < or = 20 copies/mL. Using this assay, we retrospectively analyzed plasma samples of different patient groups for VZV DNA. VZV DNA was found in 10/10 plasma samples of immunocompetent patients with herpes zoster (VZV copy numbers/mL: mean+/-SEM 1710+/-1018), in 1/1 sample of a human immunodeficiency virus-infected patient with primary VZV disease (15,192 copies/mL) and in 4/4 plasma samples of immunocompromised patients with visceral VZV disease (mean of first value 214,214+/-178,572). All 108 plasma samples of asymptomatic SOT recipients off any antiviral therapy, randomly sampled over 1 year, were negative for VZV DNA.

CONCLUSION

Our qPCR assay proved to be highly sensitive (100%) in symptomatic VZV disease. We did not detect subclinical reactivation in asymptomatic SOT recipients during the first post-transplant year. Thus, subclinical VZV reactivation is either a rare event or does not exist. These data need to be confirmed in larger prospective trials.