Infected peripheral blood mononuclear cells transmit latent varicella zoster virus infection to the guinea pig enteric nervous system

The mechanisms of nerve injury caused by viral infection in the occurrence of gastrointestinal motility disorder-related diseases

Gastrointestinal motility refers to the peristalsis and contractility of gastrointestinal muscles, including the force and frequency of gastrointestinal muscle contraction. Gastrointestinal motility maintains the normal digestive function of the human body and is a critical component of the physiological function of the digestive tract. At present, gastrointestinal motility disorder-related diseases are gradually affecting human production and life. In recent years, it has been consistently reported that the enteric nervous system has a coordinating and controlling role in gastrointestinal motility. Motility disorders are closely related to functional or anatomical changes in the gastrointestinal nervous system. At the same time, some viral infections, such as herpes simplex virus and varicella-zoster virus infections, can cause damage to the gastrointestinal nervous system. Therefore, this paper describes the mechanisms of viral infection in the gastrointestinal nervous system and the associated clinical manifestations. Studies have indicated that the means by which viruses can cause the infection of the enteric nervous system are various, including retrograde transport, hematogenous transmission and centrifugal transmission from the central nervous system. When viruses infect the enteric nervous system, they can cause clinical symptoms, such as abdominal pain, abdominal distension, early satiation, belching, diarrhea, and constipation, by recruiting macrophages, lymphocytes and neutrophils and regulating intestinal microbes. The findings of several case‒control studies suggest that viruses are the cause of some gastrointestinal motility disorders. It is concluded that one of the causes of gastrointestinal motility disorders is viral infection of the enteric nervous system. In such disorders, the relationships between viruses and nerves remain to be studied more deeply. Further studies are necessary to evaluate whether prophylactic antiviral therapy is feasible in gastrointestinal motility disorders.

Varicella-zoster virus infection and autonomic dysfunction

BACKGROUND AND PURPOSE

Autonomic dysfunction has been occasionally described in varicella-zoster virus (VZV) infection, while few systematic reviews are available. We systematically review autonomic dysfunction due to VZV infection.

METHODS

This study followed the PRISMA guideline, and three databases were researched and included cross-sectional studies in full-length publications in the English language using appropriate search keywords.

RESULTS

A total of 102 articles were identified initially; finally 45 studies were used for review, comprising pupillomotor dysfunction in 4, sudomotor dysfunction in 2, cardiovascular dysfunction in 2, gastrointestinal dysfunction in 14, and urogenital dysfunction in 23. They can be summarized as (1) VZV infection rarely produces orthostatic hypotension, which involves diffuse sympathetic dysfunction by polyneuropathy. (2) In contrast, VZV infection produces dysfunction of the bladder and the bowel, which involves segmental parasympathetic or sympathetic dysfunction by dorsal root ganglionopathy.

CONCLUSIONS

Awareness of VZV-related autonomic dysfunction is important, because such patients may first visit a gastroenterology or urology clinic. Close collaboration among neurologists, dermatologists, gastroenterologists, and urologists is important to start early antiviral agents and maximize bowel and bladder care in such patients.

Research Trends and Hotspots on Herpes Zoster: A 10-Year Bibliometric Analysis (2012-2021)

Purpose

Herpes zoster infection, with its considerable burden to individuals and society, remains a challenge around the world. However, to the knowledge of the authors, little bibliometric quantitative or qualitative analysis has been carried out to evaluate herpes zoster research. This study aimed to use a bibliometric analysis to evaluate current publication trends and hotspots on herpes zoster research worldwide, in order to advance research in this field.

Methods

Relevant publications from January 2012 to December 2021 were collected from the Web of Science Core Collection database. Citespace (V5.8.R3) was used to analyze the research points, including publication countries, institutions and authors, cited author, cited reference and their clustering, and keyword co-occurrence, and burst keyword to acquire research trends and hotspots.

Results

A total of 9,259 publications were obtained, with a steady increase in the number of annual publications during the decade. Articles were the main type of publication. The United States is the leading country in this research, and the University of Colorado has the highest influence in this field. Oxman is the most representative author, with a main research interest in herpes zoster vaccines. The top five cited authors' publications focused on herpes zoster vaccines, molecular mechanisms, and postherpetic neuralgia. A co-citation map resulted 19 main clusters, and revealed that vaccines, postherpetic neuralgia, treatments, varicella zoster virus and its mechanisms, and epidemiology of herpes zoster were the current research focus after clustering co-cited publications. Human herpesviruses, antiviral prophylaxis, rheumatoid arthritis, recombinant zoster vaccine, varicella vaccination and postherpetic neuralgia were the top clusters after co-occurrence keywords analysis. Moreover, burst keywords detection showed that the subunit vaccine was the new hotspot in the field of herpes zoster.

Conclusion

This bibliometric study defined the overall prospects in the field of herpes zoster and provided valuable instruction for the ongoing research. The keyword "subunit vaccine" indicated that a vaccine for herpes zoster prevention was the hotspot. Efforts to prevent varicella zoster virus infection will be essential to improve herpes zoster outcomes.

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.

Modeling Varicella Zoster Virus Persistence and Reactivation - Closer to Resolving a Perplexing Persistent State

The latent state of the human herpesvirus varicella zoster virus (VZV) has remained enigmatic and controversial. While it is well substantiated that VZV persistence is established in neurons after the primary infection (varicella or chickenpox), we know little of the types of neurons harboring latent virus genomes, if all can potentially reactivate, what exactly drives the reactivation process, and the role of immunity in the control of latency. Viral gene expression during latency has been particularly difficult to resolve, although very recent advances indicate that it is more restrictive than was once thought. We do not yet understand how genes expressed in latency function in the maintenance and reactivation processes. Model systems of latency are needed to pursue these questions. This has been especially challenging for VZV because the development of in vivo models of VZV infection has proven difficult. Given that up to one third of the population will clinically reactivate VZV to develop herpes zoster (shingles) and suffer from its common long term problematic sequelae, there is still a need for both in vivo and in vitro model systems. This review will summarize the evolution of models of VZV persistence and address insights that have arisen from the establishment of new in vitro human neuron culture systems that not only harbor a latent state, but permit experimental reactivation and renewed virus production. These models will be discussed in light of the recent data gleaned from the study of VZV latency in human cadaver ganglia.

Current In Vivo Models of Varicella-Zoster Virus Neurotropism

Varicella-zoster virus (VZV), an exclusively human herpesvirus, causes chickenpox and establishes a latent infection in ganglia, reactivating decades later to produce zoster and associated neurological complications. An understanding of VZV neurotropism in humans has long been hampered by the lack of an adequate animal model. For example, experimental inoculation of VZV in small animals including guinea pigs and cotton rats results in the infection of ganglia but not a rash. The severe combined immune deficient human (SCID-hu) model allows the study of VZV neurotropism for human neural sub-populations. Simian varicella virus (SVV) infection of rhesus macaques (RM) closely resembles both human primary VZV infection and reactivation, with analyses at early times after infection providing valuable information about the extent of viral replication and the host immune responses. Indeed, a critical role for CD4 T-cell immunity during acute SVV infection as well as reactivation has emerged based on studies using RM. Herein we discuss the results of efforts from different groups to establish an animal model of VZV neurotropism.

Varicella Virus-Host Interactions During Latency and Reactivation: Lessons From Simian Varicella Virus

Varicella zoster virus (VZV) is a neurotropic alphaherpesvirus and the causative agent of varicella (chickenpox) in humans. Following primary infection, VZV establishes latency in the sensory ganglia and can reactivate to cause herpes zoster, more commonly known as shingles, which causes significant morbidity, and on rare occasions mortality, in the elderly. Because VZV infection is highly restricted to humans, the development of a reliable animal model has been challenging, and our understanding of VZV pathogenesis remains incomplete. As an alternative, infection of rhesus macaques with the homologous simian varicella virus (SVV) recapitulates the hallmarks of VZV infection and thus constitutes a robust animal model to provide critical insights into VZV pathogenesis and the host antiviral response. In this model, SVV infection results in the development of varicella during primary infection, generation of an adaptive immune response, establishment of latency in the sensory ganglia, and viral reactivation upon immune suppression. In this review, we discuss our current knowledge about host and viral factors involved in the establishment of SVV latency and reactivation as well as the important role played by T cells in SVV pathogenesis and antiviral immunity.

Varicella-Zoster Virus and the Enteric Nervous System

Varicella zoster virus (VZV) infects and becomes latent in sensory, enteric, and other autonomic neurons during the viremia of varicella. Reactivation of VZV in neurons that project to the skin causes the rash of zoster; however, reactivation of VZV in enteric neurons can cause a painful gastrointestinal disorder ("enteric zoster") without cutaneous manifestations. Detection of VZV DNA in saliva of patients with gastrointestinal symptoms may suggest enteric zoster. This diagnosis is reinforced by observing a response to antiviral therapy and can be confirmed by detecting VZV gene products in intestinal mucosal biopsies. We developed an in vivo guinea pig model that may be useful in studies of VZV latency and reactivation. VZV-infected lymphocytes are used to induce latent infection in sensory and enteric neurons; evidence suggests that exosomes and stimulator of interferon genes (STING) may, by preventing proliferation play roles in the establishment of neuronal latency.

An alternative pathway of enteric PEDV dissemination from nasal cavity to intestinal mucosa in swine

Porcine epidemic diarrhea virus (PEDV) has catastrophic impacts on the global pig industry. Although the fecal–oral route is generally accepted, an increased number of reports indicate that airborne transmission may contribute to PEDV outbreak. Here, we show that PEDV could cause typical diarrhea in piglets through a nasal spray. Firstly, PEDV can develop a transient nasal epithelium infection. Subsequently, PEDV-carrying dendritic cells (DCs) allow the virus to be transferred to CD3⁺ T cells via the virological synapse. Finally, virus-loaded CD3⁺ T cells reach the intestine through the blood circulation, leading to intestinal infection via cell-to-cell contact. Our study provides evidence for airborne transmission of a gastrointestinal infected coronavirus and illustrates the mechanism of its transport from the entry site to the pathogenic site.

Outbreaks of porcine epidemic diarrhea virus (PEDV) have seriously affected pig farms around the world. Here, Li et al. show that PEDV can cause disease in piglets when inoculated by nasal spray, and provide insights into the cellular mechanisms underlying PEDV dissemination within the host.

Latent versus productive infection: the alpha herpesvirus switch

Alpha herpesviruses are common pathogens of mammals. They establish a productive infection in many cell types, but a life-long latent infection occurs in PNS neurons. A vast majority of the human population has latent HSV-1 infections. Currently, there is no cure to clear latent infections. Even though HSV-1 is among the best studied viral pathogens, regulation of latency and reactivation is not well understood due to several challenges including a lack of animal models that precisely recapitulate latency/reactivation episodes; a difficulty in modeling in vitro latency; and a limited understanding of neuronal biology. In this review, we discuss insights gained from in vitro latency models with a focus on the neuronal and viral factors that determine the mode of infection.

Simian Varicella Virus Infects Enteric Neurons and α4β7 Integrin-Expressing Gut-Tropic T-Cells in Nonhuman Primates

The pathogenesis of enteric zoster, a rare debilitating complication of reactivation of latent varicella-zoster virus (VZV) in the enteric nervous system (ENS), is largely unknown. Infection of monkeys with the closely related Varicellovirus simian varicella virus (SVV) mimics VZV disease in humans. In this study, we determined the applicability of the SVV nonhuman primate model to study Varicellovirus infection of the ENS. We confirmed VZV infection of the gut in latently infected adults and demonstrated that SVV DNA was similarly present in gut of monkeys latently infected with SVV using quantitative real-time PCR. In situ analyses showed that enteric neurons expressed SVV open reading frame (ORF) 63 RNA, but not viral nucleocapsid proteins, suggestive of latent ENS infection. During primary infection, SVV-infected T-cells were detected in gut-draining mesenteric lymph nodes and located in close vicinity to enteric nerves in the gut. Furthermore, flow cytometric analysis of blood from acutely SVV-infected monkeys demonstrated that virus-infected T-cells expressed the gut-homing receptor α4β7 integrin. Collectively, the data demonstrate that SVV infects ENS neurons during primary infection and supports the role of T-cells in virus dissemination to the gut. Because SVV reactivation can be experimentally induced, the SVV nonhuman primate model holds great potential to study the pathogenesis of enteric zoster.

Varicella zoster virus glycoprotein C increases chemokine-mediated leukocyte migration

Varicella zoster virus (VZV) is a highly prevalent human pathogen that establishes latency in neurons of the peripheral nervous system. Primary infection causes varicella whereas reactivation results in zoster, which is often followed by chronic pain in adults. Following infection of epithelial cells in the respiratory tract, VZV spreads within the host by hijacking leukocytes, including T cells, in the tonsils and other regional lymph nodes, and modifying their activity. In spite of its importance in pathogenesis, the mechanism of dissemination remains poorly understood. Here we addressed the influence of VZV on leukocyte migration and found that the purified recombinant soluble ectodomain of VZV glycoprotein C (rSgC) binds chemokines with high affinity. Functional experiments show that VZV rSgC potentiates chemokine activity, enhancing the migration of monocyte and T cell lines and, most importantly, human tonsillar leukocytes at low chemokine concentrations. Binding and potentiation of chemokine activity occurs through the C-terminal part of gC ectodomain, containing predicted immunoglobulin-like domains. The mechanism of action of VZV rSgC requires interaction with the chemokine and signalling through the chemokine receptor. Finally, we show that VZV viral particles enhance chemokine-dependent T cell migration and that gC is partially required for this activity. We propose that VZV gC activity facilitates the recruitment and subsequent infection of leukocytes and thereby enhances VZV systemic dissemination in humans.

Varicella zoster virus (VZV) causes two main pathologies in humans, chickenpox during primary infection, and shingles following reactivation. The latter is a painful condition that is often followed by chronic pain in a large numbers of shingles patients. Despite the existence of a vaccine, shingles-related complications cause expenses of more than $1 billion per year in the USA alone. Following primary infection, the virus infects leukocytes including T cells, spreading to the skin causing chickenpox. Direct infection of neurons from leukocytes has also been postulated. Given the relevance of leukocytes in VZV biology and the importance of chemokines in directing their migration, we investigated whether VZV modulates the function of chemokines. Our results show that VZV glycoprotein C potentiates the activity of chemokines, inducing higher migration of human leukocytes at low chemokine concentration. This may attract additional susceptible leukocytes to the site of infection enhancing virus spread and pathogenesis.

Safety and Immunogenicity of the Recombinant BCG Vaccine AERAS-422 in Healthy BCG-naïve Adults: A Randomized, Active-controlled, First-in-human Phase 1 Trial

BACKGROUND

We report a first-in-human trial evaluating safety and immunogenicity of a recombinant BCG, AERAS-422, over-expressing TB antigens Ag85A, Ag85B, and Rv3407 and expressing mutant perfringolysin.

METHODS

This was a randomized, double-blind, dose-escalation trial in HIV-negative, healthy adult, BCG-naïve volunteers, negative for prior exposure to Mtb, at one US clinical site. Volunteers were randomized 2:1 at each dose level to receive a single intradermal dose of AERAS-422 (>10(5)-<10(6)CFU=low dose, ≥10(6)-<10(7)CFU=high dose) or non-recombinant Tice BCG (1-8×10(5)CFU). Randomization used an independently prepared randomly generated sequence of treatment assignments. The primary and secondary outcomes were safety and immunogenicity, respectively, assessed in all participants through 182days post-vaccination. ClinicalTrials.gov registration number: NCT01340820.

FINDINGS

Between Nov 2010 and Aug 2011, 24 volunteers were enrolled (AERAS-422 high dose, n=8; AERAS-422 low dose, n=8; Tice BCG, n=8); all were included in the safety and immunogenicity analyses. All 24 subjects had at least one adverse event, primarily expected local reactions. High dose AERAS-422 vaccination induced Ag85A- and Ag85B-specific lymphoproliferative responses and marked anti-mycobacterial activity in a whole blood bactericidal activity culture assay (WBA), but was associated with varicella zoster virus (VZV) reactivation in two vaccinees. These volunteers displayed high BCG-specific IFN-γ responses pre- and post-vaccination possibly predisposing them to autocrine/paracrine negative regulation of immune control of latent VZV. A systems biology transcriptomal approach identified positive correlations between post-vaccination T cell expression modules and WBA, and negative correlations between post-vaccination monocyte expression modules and WBA. The expression of one key macrophage marker (F4/80) was constitutively elevated in the two volunteers with zoster.

INTERPRETATION

The unexpected development of VZV in two of eight healthy adult vaccine recipients resulted in discontinuation of AERAS-422 vaccine development. Immunological and transcriptomal data identified correlations with the development of TB immunity and VZV that require further investigation.

FUNDING

Aeras, FDA, Bill and Melinda Gates Foundation.

THE JEREMIAH METZGER LECTURE VARICELLA ZOSTER VIRUS: FROM OUTSIDE TO INSIDE

Varicella zoster virus (VZV) gives rise to two diseases, a primary infection, varicella, and a secondary infection, zoster. Morbidity and mortality from VZV in the United States has decreased by 80% to 90% due to the effective use of attenuated live viral vaccines. Because latent VZV continues to reactivate, however, serious VZV-induced disease persists. Newly developed molecular analyses have revealed that zoster is more common than previously realized; moreover, the establishment of VZV latency in neurons, such as those of the enteric nervous system, which do not project to the skin, leads to unexpected, serious, and clandestine manifestations of disease, including perforating gastrointestinal ulcers and intestinal pseudo-obstruction. The development of the first animal model of zoster, in guinea pigs, now enables the pathophysiology of latency and reactivation to be analyzed.

Bioengineering functional human sphincteric and non-sphincteric gastrointestinal smooth muscle constructs

Digestion and motility of luminal content through the gastrointestinal (GI) tract are achieved by cooperation between distinct cell types. Much of the 3 dimensional (3D) in vitro modeling used to study the GI physiology and disease focus solely on epithelial cells and not smooth muscle cells (SMCs). SMCs of the gut function either to propel and mix luminal contents (phasic; non-sphincteric) or to act as barriers to prevent the movement of luminal materials (tonic; sphincteric). Motility disorders including pyloric stenosis and chronic intestinal pseudoobstruction (CIPO) affect sphincteric and non-sphincteric SMCs, respectively. Bioengineering offers a useful tool to develop functional GI tissue mimics that possess similar characteristics to native tissue. The objective of this study was to bioengineer 3D human pyloric sphincter and small intestinal (SI) constructs in vitro that recapitulate the contractile phenotypes of sphincteric and non-sphincteric human GI SMCs. Bioengineered 3D human pylorus and circular SI SMC constructs were developed and displayed a contractile phenotype. Constructs composed of human pylorus SMCs displayed tonic SMC characteristics, including generation of basal tone, at higher levels than SI SMC constructs which is similar to what is seen in native tissue. Both constructs contracted in response to potassium chloride (KCl) and acetylcholine (ACh) and relaxed in response to vasoactive intestinal peptide (VIP). These studies provide the first bioengineered human pylorus constructs that maintain a sphincteric phenotype. These bioengineered constructs provide appropriate models to study motility disorders of the gut or replacement tissues for various GI organs.

Varicella zoster virus infection

Infection with varicella zoster virus (VZV) causes varicella (chickenpox), which can be severe in immunocompromised individuals, infants and adults. Primary infection is followed by latency in ganglionic neurons. During this period, no virus particles are produced and no obvious neuronal damage occurs. Reactivation of the virus leads to virus replication, which causes zoster (shingles) in tissues innervated by the involved neurons, inflammation and cell death - a process that can lead to persistent radicular pain (postherpetic neuralgia). The pathogenesis of postherpetic neuralgia is unknown and it is difficult to treat. Furthermore, other zoster complications can develop, including myelitis, cranial nerve palsies, meningitis, stroke (vasculopathy), retinitis, and gastroenterological infections such as ulcers, pancreatitis and hepatitis. VZV is the only human herpesvirus for which highly effective vaccines are available. After varicella or vaccination, both wild-type and vaccine-type VZV establish latency, and long-term immunity to varicella develops. However, immunity does not protect against reactivation. Thus, two vaccines are used: one to prevent varicella and one to prevent zoster. In this Primer we discuss the pathogenesis, diagnosis, treatment, and prevention of VZV infections, with an emphasis on the molecular events that regulate these diseases. For an illustrated summary of this Primer, visit: http://go.nature.com/14xVI1.

An in vitro model of latency and reactivation of varicella zoster virus in human stem cell-derived neurons

Varicella zoster virus (VZV) latency in sensory and autonomic neurons has remained enigmatic and difficult to study, and experimental reactivation has not yet been achieved. We have previously shown that human embryonic stem cell (hESC)-derived neurons are permissive to a productive and spreading VZV infection. We now demonstrate that hESC-derived neurons can also host a persistent non-productive infection lasting for weeks which can subsequently be reactivated by multiple experimental stimuli. Quiescent infections were established by exposing neurons to low titer cell-free VZV either by using acyclovir or by infection of axons in compartmented microfluidic chambers without acyclovir. VZV DNA and low levels of viral transcription were detectable by qPCR for up to seven weeks. Quiescently-infected human neuronal cultures were induced to undergo renewed viral gene and protein expression by growth factor removal or by inhibition of PI3-Kinase activity. Strikingly, incubation of cultures induced to reactivate at a lower temperature (34°C) resulted in enhanced VZV reactivation, resulting in spreading, productive infections. Comparison of VZV genome transcription in quiescently-infected to productively-infected neurons using RNASeq revealed preferential transcription from specific genome regions, especially the duplicated regions. These experiments establish a powerful new system for modeling the VZV latent state, and reveal a potential role for temperature in VZV reactivation and disease.

Most adults worldwide harbor latent VZV in their ganglia, and reactivation from it causes herpes zoster. This painful disease is frequently complicated by long-term pain, neurological sequelae, or vision loss that require improved prevention and treatment strategies. Study of VZV latency and reactivation has been severely hampered by the inability to reproduce a persistent state in vitro or in vivo that can be experimentally reactivated. Our study establishes a system using human neurons derived from embryonic stem cells where multiple stimuli can induce reactivation from long term experimental latency. A potential role for temperature in VZV reactivation has been revealed with this system, which can now be used to study the latent/lytic switch of VZV for the first time.

Enteric neural differentiation in innervated, physiologically functional, smooth muscle constructs is modulated by bone morphogenic protein 2 secreted by sphincteric smooth muscle cells

The enteric nervous system (ENS) controls gastrointestinal (GI) functions, including motility and digestion, which are impaired in ENS disorders. Differentiation of enteric neurons is mediated by factors released by the gut mesenchyme, including smooth muscle cells (SMCs). SMC-derived factors involved in adult enteric neural progenitor cells (NPCs) differentiation remain elusive. Furthermore, physiologically relevant in vitro models to investigate the innervations of various regions of the gut, such as the pylorus and lower oesophageal sphincter (LES), are not available. Here, neural differentiation in bioengineered innervated circular constructs composed of SMCs isolated from the internal anal sphincter (IAS), pylorus, LES and colon of rabbits was investigated. Additionally, SMC-derived factors that induce neural differentiation were identified to optimize bioengineered construct innervations. Sphincteric and non-sphincteric bioengineered constructs aligned circumferentially and SMCs maintained contractile phenotypes. Sphincteric constructs generated spontaneous basal tones. Higher levels of excitatory and inhibitory motor neuron differentiation and secretion of bone morphogenic protein 2 (BMP2) were observed in bioengineered, innervated, sphincteric constructs compared to non-sphincteric constructs. The addition of BMP2 to non-sphincteric colonic SMC constructs increased nitrergic innervations, and inhibition of BMP2 with noggin in sphincteric constructs decreased functional relaxation. These studies provide: (a) the first bioengineered innervated pylorus and LES constructs; (b) physiologically relevant models to investigate SMCs and adult NPCs interactions; and (c) evidence of the region-specific effects of SMCs on neural differentiation mediated by BMP2. Furthermore, this study paves the way for the development of innervated bioengineered GI tissue constructs tailored to specific disorders and locations within the gut. Copyright © 2015 John Wiley & Sons, Ltd.

A comparison of herpes simplex virus type 1 and varicella-zoster virus latency and reactivation

Herpes simplex virus type 1 (HSV-1; human herpesvirus 1) and varicella-zoster virus (VZV; human herpesvirus 3) are human neurotropic alphaherpesviruses that cause lifelong infections in ganglia. Following primary infection and establishment of latency, HSV-1 reactivation typically results in herpes labialis (cold sores), but can occur frequently elsewhere on the body at the site of primary infection (e.g. whitlow), particularly at the genitals. Rarely, HSV-1 reactivation can cause encephalitis; however, a third of the cases of HSV-1 encephalitis are associated with HSV-1 primary infection. Primary VZV infection causes varicella (chickenpox) following which latent virus may reactivate decades later to produce herpes zoster (shingles), as well as an increasingly recognized number of subacute, acute and chronic neurological conditions. Following primary infection, both viruses establish a latent infection in neuronal cells in human peripheral ganglia. However, the detailed mechanisms of viral latency and reactivation have yet to be unravelled. In both cases latent viral DNA exists in an 'end-less' state where the ends of the virus genome are joined to form structures consistent with unit length episomes and concatemers, from which viral gene transcription is restricted. In latently infected ganglia, the most abundantly detected HSV-1 RNAs are the spliced products originating from the primary latency associated transcript (LAT). This primary LAT is an 8.3 kb unstable transcript from which two stable (1.5 and 2.0 kb) introns are spliced. Transcripts mapping to 12 VZV genes have been detected in human ganglia removed at autopsy; however, it is difficult to ascribe these as transcripts present during latent infection as early-stage virus reactivation may have transpired in the post-mortem time period in the ganglia. Nonetheless, low-level transcription of VZV ORF63 has been repeatedly detected in multiple ganglia removed as close to death as possible. There is increasing evidence that HSV-1 and VZV latency is epigenetically regulated. In vitro models that permit pathway analysis and identification of both epigenetic modulations and global transcriptional mechanisms of HSV-1 and VZV latency hold much promise for our future understanding in this complex area. This review summarizes the molecular biology of HSV-1 and VZV latency and reactivation, and also presents future directions for study.

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.

Disseminated, persistent, and fatal infection due to the vaccine strain of varicella-zoster virus in an adult following stem cell transplantation

Live attenuated varicella vaccine is recommended for healthy individuals who are susceptible to varicella. Although the vaccine is safe, effective, and used worldwide, serious adverse events have been reported, mainly in immunocompromised patients who subsequently recovered. Here, we describe the fatality of an immunocompromised patient who received the varicella vaccine. His medical history provides a cautionary lens through which to view the decision of when vaccination is appropriate. A middle-aged man with non-Hodgkin lymphoma received chemotherapy and a stem cell transplant. He was vaccinated 4 years post-transplantation, despite diagnosis of a new low-grade lymphoma confined to the lymph nodes. Within 3 months of vaccination, he developed recurrent rashes with fever, malaise, weakness, hepatitis, weight loss, and renal failure. The syndrome was eventually determined to be associated with persistent disseminated zoster caused by the vaccine virus. This case illustrates a circumstance when a live viral vaccine should not be used.