Simian varicella virus infection and reactivation in rhesus macaques trigger cytokine and Aβ40/42 alterations in serum and cerebrospinal fluid

Simian varicella virus (SVV) produces peripheral inflammatory responses during varicella (primary infection) and zoster (reactivation) in rhesus macaques (RM). However, it is unclear if peripheral measures are accurate proxies for central nervous system (CNS) responses. Thus, we analyzed cytokine and Aβ42/Aβ40 changes in paired serum and cerebrospinal fluid (CSF) during the course of infection. During varicella and zoster, every RM had variable changes in serum and CSF cytokine and Aβ42/Aβ40 levels compared to pre-inoculation levels. Overall, peripheral infection appears to affect CNS cytokine and Aβ42/Aβ40 levels independent of serum responses, suggesting that peripheral disease may contribute to CNS disease.

Simian Varicella Virus Infection and Reactivation in Rhesus Macaques Trigger Cytokine and Aβ40/42 Alterations in Serum and Cerebrospinal Fluid

Simian varicella virus (SVV) produces peripheral inflammatory responses during varicella (primary infection) and zoster (reactivation) in rhesus macaques (RM). However, it is unclear if peripheral measures are accurate proxies for central nervous system (CNS) responses. Thus, we analyzed cytokine and Aβ42/Aβ40 changes in paired serum and cerebrospinal fluid (CSF) during the course of infection. During varicella and zoster, every RM had variable changes in serum and CSF cytokine and Aβ42/Aβ40 levels compared to pre-inoculation levels. Overall, peripheral infection appears to affect CNS cytokine and Aβ42/Aβ40 levels independent of serum responses, suggesting that peripheral disease may contribute to CNS disease.

Zoster-Associated Prothrombotic Plasma Exosomes and Increased Stroke Risk

Herpes zoster (HZ; shingles) caused by varicella zoster virus reactivation increases stroke risk for up to 1 year after HZ. The underlying mechanisms are unclear, however, the development of stroke distant from the site of zoster (eg, thoracic, lumbar, sacral) that can occur months after resolution of rash points to a long-lasting, virus-induced soluble factor (or factors) that can trigger thrombosis and/or vasculitis. Herein, we investigated the content and contributions of circulating plasma exosomes from HZ and non-HZ patient samples. Compared with non-HZ exosomes, HZ exosomes (1) contained proteins conferring a prothrombotic state to recipient cells and (2) activated platelets leading to the formation of platelet-leukocyte aggregates. Exosomes 3 months after HZ yielded similar results and also triggered cerebrovascular cells to secrete the proinflammatory cytokines, interleukin 6 and 8. These results can potentially change clinical practice through addition of antiplatelet agents for HZ and initiatives to increase HZ vaccine uptake to decrease stroke risk.

The Enduring Legacy of Randall Cohrs: A Meeting of the Minds in the Rocky Mountains

Randall Cohrs established the Colorado Alphaherpesvirus Latency Society (CALS) in 2011 [...]

Azadirachta indica A. Juss bark extract and its Nimbin isomers restrict β-coronaviral infection and replication

Emerging mutations in the SARS-CoV-2 genome pose a challenge for vaccine development and antiviral therapy. The antiviral efficacy of Azadirachta indica bark extract (NBE) was assessed against SARS-CoV-2 and m-CoV-RSA59 infection. Effects of in vivo intranasal or oral NBE administration on viral load, inflammatory response, and histopathological changes were assessed in m-CoV-RSA59-infection. NBE administered inhibits SARS-CoV-2 and m-CoV-RSA59 infection and replication in vitro, reducing Envelope and Nucleocapsid gene expression. NBE ameliorates neuroinflammation and hepatitis in vivo by restricting viral replication and spread. Isolated fractions of NBE enriched in Nimbin isomers shows potent inhibition of m-CoV-RSA59 infection in vitro. In silico studies revealed that NBE could target Spike and RdRp of m-CoV and SARS-CoV-2 with high affinity. NBE has a triterpenoids origin that may allow them to competitively target panoply of viral proteins to inhibit mouse and different strains of human coronavirus infections, suggesting its potential as an antiviral against pan-β-Coronaviruses.

Targeted RNA Sequencing of Formalin-Fixed, Paraffin-Embedded Temporal Arteries From Giant Cell Arteritis Cases Reveals Viral Signatures

BACKGROUND AND OBJECTIVES

Varicella zoster virus (VZV) antigen has been detected in temporal arteries (TAs) of individuals with giant cell arteritis (GCA), the most common systemic vasculitis in older adults. Thus, we explored the contribution of VZV to GCA pathogenesis.

METHODS

Formalin-fixed, paraffin-embedded TA sections from biopsy-positive GCA participants with VZV antigen (GCA/VZV-positive; n = 20) and without (GCA/VZV-negative, n = 20) and from normal participants with VZV antigen (control/VZV-positive, n = 11) and without (control/VZV-negative, n = 20) were analyzed by targeted RNA sequencing of the whole human transcriptome (BioSpyder TempO-Seq). Ingenuity pathway analysis and R-computational program were used to identify differentially expressed genes and pathways between groups.

RESULTS

Compared with control/VZV-negative TAs, GCA/VZV-negative and GCA/VZV-positive TAs were significantly enriched for human transcripts specific for pathways involved in viral infections, including viral entry, nuclear factor kappa B activation by viruses, and other pathogen-related immune activation pathways. Similarly, human gene sets supporting viral infection were found in control/VZV-positive TAs that showed no morphological signs of inflammation, suggesting that the enriched pathways were not nonspecific signatures of infiltrating immune cells. All GCA TAs and control/VZV-positive TAs showed enrichment of transcripts involved in vascular remodeling, including smooth muscle cell migration.

DISCUSSION

The detection of viral and immune activation pathways in GCA TAs supports a role for virus infection in GCA pathogenesis. In addition, the detection of viral pathways in control/VZV-positive TAs, along with vascular remodeling pathways, suggests that these samples may represent early infection with progression to clinical disease, depending on host and other environmental factors.

Design and preparation of nanostructures based on Krafft point of nonionic amphiphiles for delivery of poorly water-soluble compounds

Micellar solubilization can effectively dissolve low water-soluble compounds in aqueous environment, however, the micellar systems are not able to withstand dilution and maintain solubilization of poorly water-soluble drugs below critical micelle concentration. To overcome the drawbacks of conventional micellar solubilization, nonionic polyoxyethylated surfactants with Krafft points at or higher than body temperature were chosen to create novel micelle-based nanostructures as a delivery vehicle for poorly water-soluble compounds. A technique "thermo-spray process" was developed for the preparation of the nanostructures-containing formulation, in which the drug-containing micelle solution was first prepared and maintained at the elevated temperature above the Krafft point of the surfactant, then spray dried to solidify the obtained micelle-like nanostructure at room temperature. Lactose was used as an excipient to embed the nanostructures in the thermo-spray products. Water insoluble spherical nanoparticles with size range from 80 to 250 nm were obtained after reconstitution of the product at the temperature lower than Krafft point. When paclitaxel was used as model drug, the micelle-like nanostructures exhibited similar drug entrapment efficiency, solubility enhancement and drug release facilitation as conventional micelles, but provided lower critical micellar concentration at body temperature, and good encapsulation stability upon storage and dilution. These findings indicated that the developed thermo-spray product can serve as a promising delivery platform for drugs with low aqueous solubility.

Amylin, Aβ42, and Amyloid in Varicella Zoster Virus Vasculopathy Cerebrospinal Fluid and Infected Vascular Cells

BACKGROUND

Varicella zoster virus (VZV) vasculopathy is characterized by persistent arterial inflammation leading to stroke. Studies show that VZV induces amyloid formation that may aggravate vasculitis. Thus, we determined if VZV central nervous system infection produces amyloid.

METHODS

Aβ peptides, amylin, and amyloid were measured in cerebrospinal fluid (CSF) from 16 VZV vasculopathy subjects and 36 stroke controls. To determine if infection induced amyloid deposition, mock- and VZV-infected quiescent primary human perineurial cells (qHPNCs), present in vasculature, were analyzed for intracellular amyloidogenic transcripts/proteins and amyloid. Supernatants were assayed for amyloidogenic peptides and ability to induce amyloid formation. To determine amylin's function during infection, amylin was knocked down with small interfering RNA and viral complementary DNA (cDNA) was quantitated.

RESULTS

Compared to controls, VZV vasculopathy CSF had increased amyloid that positively correlated with amylin and anti-VZV antibody levels; Aβ40 was reduced and Aβ42 unchanged. Intracellular amylin, Aβ42, and amyloid were seen only in VZV-infected qHPNCs. VZV-infected supernatant formed amyloid fibrils following addition of amyloidogenic peptides. Amylin knockdown decreased viral cDNA.

CONCLUSIONS

VZV infection increased levels of amyloidogenic peptides and amyloid in CSF and qHPNCs, indicating that VZV-induced amyloid deposition may contribute to persistent arterial inflammation in VZV vasculopathy. In addition, we identified a novel proviral function of amylin.

Varicella-Zoster Virus Infection of Primary Human Spinal Astrocytes Produces Intracellular Amylin, Amyloid-β, and an Amyloidogenic Extracellular Environment

BACKGROUND

Herpes zoster is linked to amyloid-associated diseases, including dementia, macular degeneration, and diabetes mellitus, in epidemiological studies. Thus, we examined whether varicella-zoster virus (VZV)-infected cells produce amyloid.

METHODS

Production of intracellular amyloidogenic proteins (amylin, amyloid precursor protein [APP], and amyloid-β [Aβ]) and amyloid, as well as extracellular amylin, Aβ, and amyloid, was compared between mock- and VZV-infected quiescent primary human spinal astrocytes (qHA-sps). The ability of supernatant from infected cells to induce amylin or Aβ42 aggregation was quantitated. Finally, the amyloidogenic activity of viral peptides was examined.

RESULTS

VZV-infected qHA-sps, but not mock-infected qHA-sps, contained intracellular amylin, APP, and/or Aβ, and amyloid. No differences in extracellular amylin, Aβ40, or Aβ42 were detected, yet only supernatant from VZV-infected cells induced amylin aggregation and, to a lesser extent, Aβ42 aggregation into amyloid fibrils. VZV glycoprotein B (gB) peptides assembled into fibrils and catalyzed amylin and Aβ42 aggregation.

CONCLUSIONS

VZV-infected qHA-sps produced intracellular amyloid and their extracellular environment promoted aggregation of cellular peptides into amyloid fibrils that may be due, in part, to VZV gB peptides. These findings suggest that together with host and other environmental factors, VZV infection may increase the toxic amyloid burden and contribute to amyloid-associated disease progression.

Simian Varicella Virus DNA in Saliva and Buccal Cells After Experimental Acute Infection in Rhesus Macaques

Simian varicella virus (SVV) infection of non-human primates is the counterpart of varicella zoster virus (VZV) infection in humans. To develop non-invasive methods of assessing SVV infection, we tested for the presence of SVV DNA in saliva, as has been documented in human VZV infection, and in buccal cells to determine whether epithelial cells might provide a more reliable source of material for analysis. Five rhesus macaques intratracheally inoculated with SVV all developed varicella with viremia and macular-papular skin rash in 1-2 weeks, which resolved followed by establishment of latency. DNA extracted from longitudinal blood peripheral blood mononuclear cells (PBMCs), saliva and buccal samples collected during acute infection and establishment of latency were analyzed by real-time qPCR. After intratracheal inoculation, viremia was observed, with peak levels of 10¹-10² copies of SVV DNA in 100 ng of PBMC DNA at 4 and 7 days post inoculation (dpi), which then decreased at 9-56 dpi. In saliva and buccal cells at 7 dpi, 10¹-10⁴ copies and 10¹-10⁵ copies of SVV DNA in 100 ng of cellular DNA, respectively, were detected in all the five monkeys. At 9 dpi, saliva samples from only two of the five monkeys contained SVV DNA at 10²-10³ copies/100 ng of saliva DNA, while buccal cells from all five monkeys showed 10⁰-10³ copies of SVV DNA/100 ng of buccal cell DNA. Similar to viremia, SVV DNA in saliva and buccal cells at 11-56 dpi was lower, suggesting clearance of viral shedding. SVV DNA levels were generally higher in buccal cells than in saliva. Our findings indicate that SVV shedding into the oral cavity parallels acute SVV infection and underscore the relevance of both saliva and buccal cell samples to monitor acute varicella virus 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.

Simian varicella virus inhibits the interferon gamma signalling pathway

The alphaherpesvirus simian varicella virus (SVV) causes varicella and zoster in nonhuman primates. Herpesviruses evolved elaborate mechanisms to escape host immunity, but the immune evasion strategies employed by SVV remain ill-defined. We analysed whether SVV impairs the cellular response to key antiviral cytokine interferon-γ (IFNγ). SVV infection inhibited the expression of IFNγ-induced genes like C-X-C motif chemokine 10 and interferon regulatory factor 1. Phosphorylation and nuclear translocation of the signal transducer and activator of transcription 1 (STAT1) was blocked in SVV-infected cells, which did not involve cellular and viral phosphatases. SVV infection did not downregulate IFNγ receptor α and β chain expression on the cell surface. Instead, STAT1, Janus tyrosine kinases 1 (JAK1) and JAK2 protein levels were significantly decreased in SVV-infected cells. Collectively, these results demonstrate that SVV targets three proteins in the IFNγ signal transduction pathway to escape the antiviral effects of IFNγ.

Interacting protein partners of Arabidopsis RNA-binding protein AtRBP45b

RNA binding proteins, important players in post-transcriptional gene regulation, usually exist in ribonuclear complexes. However, even in model systems like Arabidopsis characterisation of RBP associated proteins is limited. In this study, we investigated the interacting proteins of the Arabidopsis AtRBP45b, which is involved in stress signalling. In vivo localisation of AtRBP45b was conducted using 35S-GFP. FLAG-tagged AtRBP45b under control of the 35S promoter in the Atrbp45b-1 mutant background was used to pull down AtRBP45b interacting proteins. Yeast two-hybrid analysis, fluorescence energy resonance transfer assays were used to confirm the veracity of the AtRBP45b interacting proteins. In planta GFP-tagging indicated AtRBP45b is localised to the nucleus and the cytosol. AtRBP45b protein has a N-terminal proline-rich region and a C-terminal glutamine-rich domain that are usually involved in protein-protein interactions. Co-immunoprecipitation followed by mass spectrometry-based protein sequencing led to identification of 30 proteins that interacted with AtRBP45b. Using information from interactome databases (BIOGRID, INTACT and STRING), pull-down assays and localisation data, 12 putative interacting proteins were selected for yeast two-hybrid analysis. Cap-binding protein (CBP20, At5g44200) and polyA-binding protein (PAB8, At1g49760) were shown to interact with AtRBP45b. Based on its interacting partners we speculate that AtRBP45b may play an important role in RNA metabolism, especially in aspects related to mRNA stability and translation initiation during stress conditions in plants.

Characterization of the immune response in ganglia after primary simian varicella virus infection

Primary simian varicella virus (SVV) infection in non-human primates causes varicella, after which the virus becomes latent in ganglionic neurons and reactivates to cause zoster. The host response in ganglia during establishment of latency is ill-defined. Ganglia from five African green monkeys (AGMs) obtained at 9, 13, and 20 days post-intratracheal SVV inoculation (dpi) were analyzed by ex vivo flow cytometry, immunohistochemistry, and in situ hybridization. Ganglia at 13 and 20 dpi exhibited mild inflammation. Immune infiltrates consisted mostly of CD8(dim) and CD8(bright) memory T cells, some of which expressed granzyme B, and fewer CD11c(+) and CD68(+) cells. Chemoattractant CXCL10 transcripts were expressed in neurons and infiltrating inflammatory cells but did not co-localize with SVV open reading frame 63 (ORF63) RNA expression. Satellite glial cells expressed increased levels of activation markers CD68 and MHC class II at 13 and 20 dpi compared to those at 9 dpi. Overall, local immune responses emerged as viral DNA load in ganglia declined, suggesting that intra-ganglionic immunity contributes to restricting SVV replication.

Varicella Zoster Virus in the Nervous System

Varicella zoster virus (VZV) is a ubiquitous, exclusively human alphaherpesvirus. Primary infection usually results in varicella (chickenpox), after which VZV becomes latent in ganglionic neurons along the entire neuraxis. As VZV-specific cell-mediated immunity declines in elderly and immunocompromised individuals, VZV reactivates and causes herpes zoster (shingles), frequently complicated by postherpetic neuralgia. VZV reactivation also produces multiple serious neurological and ocular diseases, such as cranial nerve palsies, meningoencephalitis, myelopathy, and VZV vasculopathy, including giant cell arteritis, with or without associated rash. Herein, we review the clinical, laboratory, imaging, and pathological features of neurological complications of VZV reactivation as well as diagnostic tests to verify VZV infection of the nervous system. Updates on the physical state of VZV DNA and viral gene expression in latently infected ganglia, neuronal, and primate models to study varicella pathogenesis and immunity are presented along with innovations in the immunization of elderly individuals to prevent VZV reactivation.

Prevalence and distribution of VZV in temporal arteries of patients with giant cell arteritis

OBJECTIVE

Varicella-zoster virus (VZV) infection may trigger the inflammatory cascade that characterizes giant cell arteritis (GCA).

METHODS

Formalin-fixed, paraffin-embedded GCA-positive temporal artery (TA) biopsies (50 sections/TA) including adjacent skeletal muscle and normal TAs obtained postmortem from subjects >50 years of age were examined by immunohistochemistry for presence and distribution of VZV antigen and by ultrastructural examination for virions. Adjacent regions were examined by hematoxylin & eosin staining. VZV antigen-positive slides were analyzed by PCR for VZV DNA.

RESULTS

VZV antigen was found in 61/82 (74%) GCA-positive TAs compared with 1/13 (8%) normal TAs (p < 0.0001, relative risk 9.67, 95% confidence interval 1.46, 63.69). Most GCA-positive TAs contained viral antigen in skip areas. VZV antigen was present mostly in adventitia, followed by media and intima. VZV antigen was found in 12/32 (38%) skeletal muscles adjacent to VZV antigen-positive TAs. Despite formalin fixation, VZV DNA was detected in 18/45 (40%) GCA-positive VZV antigen-positive TAs, in 6/10 (60%) VZV antigen-positive skeletal muscles, and in one VZV antigen-positive normal TA. Varicella-zoster virions were found in a GCA-positive TA. In sections adjacent to those containing VZV, GCA pathology was seen in 89% of GCA-positive TAs but in none of 18 adjacent sections from normal TAs.

CONCLUSIONS

Most GCA-positive TAs contained VZV in skip areas that correlated with adjacent GCA pathology, supporting the hypothesis that VZV triggers GCA immunopathology. Antiviral treatment may confer additional benefit to patients with GCA treated with corticosteroids, although the optimal antiviral regimen remains to be determined.

Robust pro-inflammatory and lesser anti-inflammatory immune responses during primary simian varicella virus infection and reactivation in rhesus macaques

Simian varicella virus (SVV) infection of non-human primates models human varicella zoster virus (VZV) infection. Assessment of cell signaling immune responses in monkeys after primary SVV infection, after immunosuppression and during reactivation revealed strong pro-inflammatory responses and lesser anti-inflammatory components during varicella and reactivation. Pro-inflammatory mediators elevated during varicella included interferon-gamma (IFN-γ), interleukin (IL)-6, monocyte chemoattractant protein (MCP-1), interferon inducible T-cell α chemoattractant protein (I-TAC), interferon processing protein (IP-10), and anti-inflammatory interleukin-1 Receptor antagonist (IL-1Ra). After immunosuppression and at reactivation, levels of pro-inflammatory mediators MCP-1, eotaxin, IL-6, IL-8, MIF, RANTES (regulated-on-activation normal T-cell expressed and secreted), and HGF (hepatocyte growth factor) were elevated, as was the anti-inflammatory mediator IL-1Ra. Characterization of cytokine, chemokine and growth factor responses during different stages of varicella virus infection will facilitate immunotherapeutic and vaccine strategies.

Biopsy-negative, varicella zoster virus (VZV)-positive giant cell arteritis, zoster, VZV encephalitis and ischemic optic neuropathy, all in one

A 72-year-old man developed clinical features of giant cell arteritis (GCA) and ipsilateral ophthalmic-distribution zoster, followed within 2 weeks by VZV encephalitis and 2 months later by ischemic optic neuropathy. Temporal artery biopsy was histopathologically negative for GCA, but contained VZV antigen and VZV DNA in multiple non-contiguous (skip) areas. The collective clinical and laboratory findings revealed a remarkably close temporal association of zoster, multifocal VZV vasculopathy with temporal artery infection, biopsy-negative VZV-positive GCA and VZV encephalitis.

The variegate neurological manifestations of varicella zoster virus infection

Varicella zoster virus (VZV) is an exclusively human neurotropic alphaherpesvirus. Primary infection causes varicella (chickenpox), after which the virus becomes latent in ganglionic neurons along the entire neuraxis. With advancing age or immunosuppression, cell-mediated immunity to VZV declines, and the virus reactivates to cause zoster (shingles), dermatomal distribution, pain, and rash. Zoster is often followed by chronic pain (postherpetic neuralgia), cranial nerve palsies, zoster paresis, vasculopathy, meningoencephalitis, and multiple ocular disorders. This review covers clinical, laboratory, and pathological features of neurological complications of VZV reactivation, including diagnostic testing to verify active VZV infection in the nervous system. Additional perspectives are provided by discussions of VZV latency, animal models to study varicella pathogenesis and immunity, and of the value of vaccination of elderly individuals to boost cell-mediated immunity to VZV and prevent VZV reactivation.

GeXPS multiplex PCR analysis of the simian varicella virus transcriptome in productively infected cells in culture and acutely infected ganglia

Simian varicella zoster virus (SVV) infection of non-human primates serves as a model to study varicella zoster virus (VZV) infection and pathogenesis in humans. While macroarray analysis detected all 69 predicted unique open reading frames (ORFs) in SVV-infected cells in culture, it lacked the sensitivity to detect the low-abundance transcripts expressed in latently infected monkey ganglia. Recently, a multiplex RT-PCR assay using the GenomeLab Genetic Analysis System (GeXPS) identified 10 VZV transcripts in latently-infected human ganglia. GeXPS was used to analyze the SVV transcriptome in SVV-infected monkey cells in culture as well as in acutely infected ganglia from African green monkeys. Oligonucleotide primers containing both SVV ORF- and cell-specific sequences linked to universal DNA sequences were used in RT-PCR to produce products of predetermined sizes. Amplification products were resolved by capillary gel electrophoresis and detected by fluorescence spectrophotometry. Transcripts corresponding to all 69 predicted SVV ORFs, in addition to transcripts within the leftward end region and ORF 61 antisense transcripts were detected in virus-infected cells in culture. Except for two transcripts (ORFs 14 and 35), all transcripts found in infected tissue culture cells were also found in acutely infected monkey ganglia.

T-cell infiltration correlates with CXCL10 expression in ganglia of cynomolgus macaques with reactivated simian varicella virus

Ganglia of monkeys with reactivated simian varicella virus (SVV) contained more CD8 than CD4 T cells around neurons. The abundance of CD8 T cells was greater less than 2 months after reactivation than that at later times and correlated with that of CXCL10 RNA but not with those of SVV protein or open reading frame 61 (ORF61) antisense RNA. CXCL10 RNA colocalized with T-cell clusters. After SVV reactivation, transient T-cell infiltration, possibly mediated by CXCL10, parallels varicella zoster virus (VZV) reactivation in humans.

Cytological expression of early response to infection by Heterodera glycines Ichinohe in resistant PI 437654 soybean

The soybean PI 437654 is resistant to all known races of the soybean cyst nematode (SCN) in the U.S.A. and became a new source of resistance genes in cultivar development. Race 3, a wide-ranging nematode pathotype, was used to examine root cells of PI 437654 and susceptible 'Essex', 2, 3, and 5 days after inoculation (DAI). In initial response to SCN, both genotypes formed syncytia by cell wall dissolutions. Hypertrophy of syncytium component cells and hyperplasia of cells near syncytia were observed. At 2 DAI, incompatible response of PI 437654 to SCN was exhibited: limited cell hypertrophy, inhibition of syncytium growth, initiation of necrosis, and wall appositions. At 3 DAI, cellular events appeared to be a sum of the operative mechanisms for SCN resistance: irregular wall thickening, pronounced wall appositions, necrosis, and nuclear breakdown followed by cytoplasmic collapse. The cells surrounding the syncytia showed necrosis, wall apposition, and accumulation of electron-dense bodies. By 5 DAI, syncytia and neighboring cells were totally devoid of ground plasma and the degeneration process was completed. The normal route for early syncytium development in 'Essex' (increased number of organelles, intense vacuolization, accumulation of dense deposits in vacuoles, and wall ingrowths) suggests the involvement of portions of the developmental pathway of differentiating tissues in organogenesis. Early onset of SCN resistance 2 DAI in PI 437654 suggests rapid activation of genes in a cascade reaction leading to cell death. Key words : soybean, nematode, syncytium, cell death.

Does apoptosis play a role in varicella zoster virus latency and reactivation?

Varicella zoster virus (VZV) is an exclusively human highly neurotropic alphaherpesvirus. To date, VZV has been shown to induce apoptosis, primarily through the intrinsic pathway in different cell types, except for neurons in which the virus becomes latent. This review summarizes current studies of varicella-induced apoptosis in non‑neuronal cells. Future studies are proposed to determine whether apoptosis is terminated prematurely or even begins in neurons that are non-productively infected with VZV.

Varicella zoster virus vasculopathy: a treatable form of rapidly progressive multi-infarct dementia after 2 years' duration

We describe an extraordinarily protracted case of varicella zoster virus (VZV) multifocal vasculopathy in a man who presented initially with ischemic optic neuropathy and then suffered 4 episodes of stroke manifesting as multi-infarct dementia over a 2-year period. Brain magnetic resonance imaging (MRI) and angiography (MRA) revealed cortical and subcortical infarctions as well as vasculitic occlusion and stenosis. The patient was treated with corticosteroids and later with cyclophosphamide. More than 2 years after the onset of neurological disease, two cerebrospinal fluid (CSF) examinations revealed the presence of anti-VZV IgG antibody with reduced serum-to-CSF ratios of anti-VZV IgG compared with ratios for total IgG and albumin, indicative of intrathecal synthesis of anti-VZV IgG. After definitive diagnosis, immunosuppressive drugs were discontinued and he was treated with intravenous acyclovir; both mental status and gait improved and no further episodes of neurological dysfunction ensued. The favorable outcome in this patient indicates that VZV vasculopathy can be treated successfully even after 26 months. VZV must be considered as a possible cause of neurological disease in any patient with idiopathic multifocal vasculopathy.

Simian varicella virus infection of Chinese rhesus macaques produces ganglionic infection in the absence of rash

Varicella-zoster virus (VZV) causes varicella (chickenpox), becomes latent in ganglia along the entire neuraxis, and may reactivate to cause herpes zoster (shingles). VZV may infect ganglia via retrograde axonal transport from infected skin or through hematogenous spread. Simian varicella virus (SVV) infection of rhesus macaques provides a useful model system to study the pathogenesis of human VZV infection. To dissect the virus and host immune factors during acute SVV infection, we analyzed four SVV-seronegative Chinese rhesus macaques infected intratracheally with cell-associated 5 × 10³ plaque-forming units (pfu) of SVV-expressing green fluorescent protein (n = 2) or 5 × 10⁴ pfu of wild-type SVV (n = 2). All monkeys developed viremia and SVV-specific adaptive B- and T-cell immune responses, but none developed skin rash. At necropsy 21 days postinfection, SVV DNA was found in ganglia along the entire neuraxis and in viscera, and SVV RNA was found in ganglia, but not in viscera. The amount of SVV inoculum was associated with the extent of viremia and the immune response to virus. Our findings demonstrate that acute SVV infection of Chinese rhesus macaques leads to ganglionic infection by the hematogenous route and the induction of a virus-specific adaptive memory response in the absence of skin rash.

Reactivation of type 1 herpes simplex virus and varicella zoster virus in an immunosuppressed patient with acute peripheral facial weakness

We describe a 26-year-old man treated with azathioprine for myasthenia gravis who developed acute left-sided peripheral facial weakness. Brain magnetic resonance imaging (MRI) revealed enhancement in the left geniculate ganglion and in the intracanalicular and tympanic segments of the facial nerve. Analysis of cerebrospinal fluid (CSF) and serum revealed intrathecal synthesis of anti-varicella zoster virus (VZV) IgG antibody. Although previous analyses of saliva, blood mononuclear cells, serum antibodies, middle ear fluid, and auricular and geniculate zone skin scrapings have shown that a small but definite proportion of patients with idiopathic peripheral facial palsy ("Bell's palsy") have the Ramsay Hunt syndrome zoster sine herpete (RHS ZSH), this is the first confirmation of RHS ZSH by intrathecal synthesis of anti-VZV IgG antibody. In addition, herpes simplex virus (HSV)-1 DNA was found in saliva of the patient on 3 consecutive days. Simultaneous reactivation of two alphaherpesviruses (HSV-1 and VZV) in our immunosuppressed patient underscores the need to consider opportunistic infection as a cause of facial weakness.

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 vasculopathy: analysis of virus-infected arteries

OBJECTIVE

Varicella zoster virus (VZV) is an under-recognized yet treatable cause of stroke. No animal model exists for stroke caused by VZV infection of cerebral arteries. Thus, we analyzed cerebral and temporal arteries from 3 patients with VZV vasculopathy to identify features that will help in diagnosis and lead to a better understanding of VZV-induced vascular remodeling.

METHODS

Normal and VZV-infected cerebral and temporal arteries were examined histologically and by immunohistochemistry using antibodies directed against VZV, endothelium, and smooth muscle actin and myosin.

RESULTS

All VZV-infected arteries contained 1) a disrupted internal elastic lamina; 2) a hyperplastic intima composed of cells expressing α-smooth muscle actin (α-SMA) and smooth muscle myosin heavy chain (SM-myosin) but not endothelial cells expressing CD31; and 3) decreased medial smooth muscle cells. The location of VZV antigen, degree of neointimal thickening, and disruption of the media were related to the duration of disease.

CONCLUSIONS

The presence of VZV primarily in the adventitia early in infection and in the media and intima later supports the notion that after reactivation from ganglia, VZV spreads transaxonally to the arterial adventitia followed by transmural spread of virus. Disruption of the internal elastic lamina, progressive intimal thickening with cells expressing α-SMA and SM-MHC, and decreased smooth muscle cells in the media are characteristic features of VZV vasculopathy. Stroke in VZV vasculopathy may result from changes in arterial caliber and contractility produced in part by abnormal accumulation of smooth muscle cells and myofibroblasts in thickened neointima and disruption of the media.

Varicella zoster virus ischemic optic neuropathy and subclinical temporal artery involvement

OBJECTIVE

To demonstrate varicella zoster virus (VZV) infection in an asymptomatic extracranial (temporal) artery in a patient with ischemic optic neuropathy produced by VZV vasculopathy in whom the pathological changes were mistakenly identified as giant cell arteritis.

DESIGN

Case report.

SETTING

Teaching hospital, pathology and virology laboratory.

PATIENT

An 80-year-old man with left ophthalmic distribution zoster who developed left ischemic optic neuropathy.

INTERVENTION

An ipsilateral temporal artery biopsy revealed inflammation that was mistakenly identified as giant cell arteritis. The patient was initially treated with steroids but his condition did not improve. When the diagnosis of VZV vasculopathy was confirmed virologically and the patient was treated with intravenous acyclovir, his vision improved.

RESULTS

Pathological and virological studies provided proof of VZV vasculopathy in the asymptomatic temporal artery. Varicella zoster virus antigen was abundant in arterial adventitia and scattered throughout the media. With intravenous antiviral therapy, the patient's vision improved.

CONCLUSION

Although in previously studied patients who died of chronic VZV vasculopathy after 10 to 12 months, VZV antigen was present exclusively in the intima, collective analyses of chronic cases and the asymptomatic VZV-infected temporal artery suggest that virus enters arteries through the adventitia and spreads transmurally to the intima.

Latent simian varicella virus reactivates in monkeys treated with tacrolimus with or without exposure to irradiation

Simian varicella virus (SVV) infection of primates resembles human varicella-zoster virus (VZV) infection. After primary infection, SVV becomes latent in ganglia and reactivates after immunosuppression or social and environmental stress. Herein, natural SVV infection was established in 5 cynomolgus macaques (cynos) and 10 African green (AG) monkeys. Four cynos were treated with the immunosuppressant tacrolimus (80 to 300 &#x03BC;g/kg/day) for 4 months and 1 was untreated (group 1). Four AG monkeys were exposed to a single dose (200 cGy) of x-irradiation (group 2), and 4 other AG monkeys were irradiated and treated with tacrolimus for 4 months (group 3); the remaining 2 AG monkeys were untreated. Zoster rash developed 1 to 2 weeks after tacrolimus treatment in 3 of 4 monkeys in group 1, 6 weeks after irradiation in 1 of 4 monkeys in group 2, and 1 to 2 weeks after irradiation in all 4 monkeys in group 3. All monkeys were euthanized 1 to 4 months after immunosuppression. SVV antigens were detected immunohistochemically in skin biopsies as well as in lungs of most monkeys. Low copy number SVV DNA was detected in ganglia from all three groups of monkeys, including controls. RNA specific for SVV ORFs 61, 63, and 9 was detected in ganglia from one immunosuppressed monkey in group 1. SVV antigens were detected in multiple ganglia from all immunosuppressed monkeys in every group, but not in controls. These results indicate that tacrolimus treatment produced reactivation in more monkeys than irradiation and tacrolimus and irradiation increased the frequency of SVV reactivation as compared to either treatment alone.

Varicella-zoster virus-induced apoptosis in MeWo cells is accompanied by down-regulation of Bcl-2 expression

Varicella-zoster virus infects multiple human and monkey cells in culture. The mode of cell death appears to be autophagy or apoptosis. Analysis of VZV-infected human melanoma (MeWo) cells revealed that Bcl-2 mRNA and protein levels were decreased significantly 64 and 72 hpi (hours post infection), accompanied by the release of cytochrome c from mitochondria into the cytoplasm. Western blot analysis of virus-infected cells revealed activation of caspase-8, a marker for the extrinsic pathway of apoptosis, and caspase-9, a marker for the intrinsic pathway of apoptosis at 64 and 72 hpi. Significant increases in the levels of cleaved caspase-3 and cleaved poly (ADP) ribose polymerase (PARP) were also seen at the height of cytopathic effect. Thus VZV induces apoptosis in MeWo cells in which Bcl-2 is down-regulated. Future studies will determine differences in the cascade of apoptotic events in non-neuronal cells compared to neurons that allow VZV to become latent.

Virus vasculopathy and stroke: an under-recognized cause and treatment target

While arteriosclerotic disease and hypertension, with or without diabetes, are the most common causes of stroke, viruses may also produce transient ischemic attacks and stroke. The three most-well studied viruses in this respect are varicella zoster virus (VZV), cytomegalovirus (CMV) and human immunodeficiency virus (HIV), all of which are potentially treatable with antiviral agents. Productive VZV infection in cerebral arteries after reactivation (zoster) or primary infection (varicella) has been documented as a cause of ischemic and hemorrhagic stroke, aneurysms with subarachnoid and intracerebral hemorrhage, arterial ectasia and as a co-factor in cerebral arterial dissection. CMV has been suggested to play a role in the pathogenesis of arteriosclerotic plaques in cerebral arteries. HIV patients have a small but definite increased incidence of stroke which may be due to either HIV infection or opportunistic VZV infection in these immunocompromised individuals. Importantly, many described cases of vasculopathy in HIV-infected patients were not studied for the presence of anti-VZV IgG antibody in CSF, a sensitive indicator of VZV vasculopathy. Unlike the well-documented role of VZV in vasculopathy, evidence for a causal link between HIV or CMV and stroke remains indirect and awaits further studies demonstrating productive HIV and CMV infection of cerebral arteries in stroke patients. Nonetheless, all three viruses have been implicated in stroke and should be considered in clinical diagnoses.

Recurrent polymorphonuclear pleocytosis with increased red blood cells caused by varicella zoster virus infection of the central nervous system: Case report and review of the literature

We describe an immunocompetent 45-year-old woman who had four episodes of neurological disease (meningoencephalitis, multifocal vasculopathy, myelitis and inflammatory brain stem disease) produced by varicella zoster virus (VZV) over an 11-month period, all in the absence of rash. The cerebrospinal fluid (CSF) contained anti-VZV IgG antibody, but not VZV DNA throughout her illness, reaffirming the superiority of detection of anti-VZV IgG in CSF compared to VZV DNA in diagnosing VZV infection of the nervous system. Moreover, 3 of 7 CSF samples examined during the 11 months showed a VZV-induced pleocytosis consisting predominantly of polymorphonuclear cells (PMNs), and 4 of 7 samples also contained increased numbers of red blood cells (RBCs). Because increased PMNs and RBCs in CSF can also occur in patients with central and peripheral nervous system disease produced by cytomegalovirus (CMV), the differential diagnosis of chronic nervous system infection with increased PMNs and RBCs in CSF should include analyses for both VZV and CMV.

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.

Varicella zoster virus (VZV) is a ubiquitous herpesvirus that causes chickenpox (varicella) and establishes a life-long latent infection in humans. VZV can then reactivate causing herpes zoster, commonly known as shingles, a painful and debilitating disease that can be life-threatening in elderly and immunocompromised individuals. Our understanding of immunological factors that control VZV replication is limited due to the fact that VZV causes disease only in humans. Simian varicella virus (SVV) is a simian counterpart of VZV that infects nonhuman primates. Our study showed for the first time that infection of rhesus macaques with SVV recapitulates key aspects of VZV infection from chickenpox and the resolution of acute viremia to the establishment of latency in ganglia, and the development of B and T cell responses to virus. This model will allow us to improve our understanding of the immune response to varicella virus, and to develop and test vaccines and antiviral drugs that can reduce the incidence of shingles and its attendant neurological complications.

Varicella zoster virus vasculopathies: diverse clinical manifestations, laboratory features, pathogenesis, and treatment

Vasculopathies caused by varicella zoster virus (VZV) are indicative of a productive virus infection in cerebral arteries after either reactivation of VZV (shingles) or primary infection (chickenpox). VZV vasculopathy can cause ischaemic infarction of the brain and spinal cord, as well as aneurysm, subarachnoid and cerebral haemorrhage, carotid dissection, and, rarely, peripheral arterial disease. VZV vasculopathy in immunocompetent or immunocompromised individuals can be unifocal or multifocal with deep-seated and superficial infarctions. Lesions at the grey-white matter junction on brain imaging are a clue to diagnosis. Involvement of both large and small arteries is more common than that of either alone. Most patients have a mononuclear cerebrospinal fluid pleocytosis, often with red blood cells. Cerebrospinal fluid pleocytosis and rash are absent in about a third of cases. Anti-VZV IgG antibody in the cerebrospinal fluid is found more frequently than VZV DNA. In recent years, the number of recognised VZV vasculopathies has grown, and accurate diagnosis is important for the effective treatment of these disorders.

T cell senescence results in persistent simian varicella virus infection in aged rhesus macaques; a model for herpes zoster (44.4)

Herpes zoster (HZ, shingles) is caused by the reactivation of latent varicella zoster virus (VZV) and causes significant morbidity and sometimes mortality in the elderly. Several clinical studies suggest that the waning of T cell immunity with age is the underlying cause of VZV reactivation. However, the exact defects in T cell immunity remain poorly understood due to the fact that VZV infection of laboratory animals, including nonhuman primates, does not result in disease. We have developed a novel animal model wherein rhesus macaques are inoculated with the closely related simian varicella virus (SVV). SVV infection of rhesus macaques reproduces hallmarks of VZV infection in humans: 1) generalized varicella; 2) the development of cellular and humoral immunity; and 3) the establishment of latency with limited transcriptional activity in sensory ganglia. This is the only model where acute infection and latency can be studied in the same animal. Furthermore, whereas adult rhesus macaques can resolve acute SVV infection, aged animals remain persistently viremic. The SVV-specific antibody response generated by elderly animals was comparable to that of adult animals. On the other hand, the SVV-specific T cell response in aged animals was delayed and reduced in magnitude. These data suggest that, similar to clinical observations about VZV, the inability of aged animals to control SVV viremia is due to a reduced T cell response.

Clinical and molecular aspects of varicella zoster virus infection

A declining cell-mediated immunity to varicella zoster virus (VZV) with advancing age or immunosuppression results in virus reactivation from latently infected human ganglia anywhere along the neuraxis. Virus reactivation produces zoster, often followed by chronic pain (postherpetic neuralgia or PHN) as well as vasculopathy, myelopathy, retinal necrosis and cerebellitis. VZV reactivation also produces pain without rash (zoster sine herpete). Vaccination after age 60 reduces the incidence of shingles by 51%, PHN by 66% and the burden of illness by 61%. However, even if every healthy adult over age 60 years is vaccinated, there would still be about 500,000 zoster cases annually in the United States alone, about 200,000 of whom will experience PHN. Analyses of viral nucleic acid and gene expression in latently infected human ganglia and in an animal model of varicella latency in primates are serving to determine the mechanism(s) of VZV reactivation with the aim of preventing reactivation and the clinical sequelae.

Recurrent varicella zoster virus myelopathy

Myelopathy is an uncommon complication of VZV infection and may develop in the absence of rash. We report the rare recurrence of myelopathy in an immunocompetent adult who initially developed myelopathy after ophthalmic-distribution zoster. Recurrent myelopathy two years later caused by VZV was verified by the presence of new-onset clinical symptoms and signs consistent with myelopathy, new lesions in the spinal cord detected by MRI, and evidence of intrathecal synthesis of anti-VZV IgG antibody in CSF. After virological verification and antiviral therapy, myelopathy did not recur and anti-VZV IgG antibody could not be detected in CSF. In contrast to earlier cases of recurrent VZV myelopathy in immunocompetent adults that developed weeks to months after the first episode of myelopathy, this is the first instance of recurrence years later.

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.

The varicella zoster virus vasculopathies: clinical, CSF, imaging, and virologic features

BACKGROUND

Varicella zoster virus (VZV) vasculopathy produces stroke secondary to viral infection of cerebral arteries. Not all patients have rash before cerebral ischemia or stroke. Furthermore, other vasculitides produce similar clinical features and comparable imaging, angiographic, and CSF abnormalities.

METHODS

We review our 23 published cases and 7 unpublished cases of VZV vasculopathy. All CSFs were tested for VZV DNA by PCR and anti-VZV IgG antibody and were positive for either or both.

RESULTS

Among 30 patients, rash occurred in 19 (63%), CSF pleocytosis in 20 (67%), and imaging abnormalities in 29 (97%). Angiography in 23 patients revealed abnormalities in 16 (70%). Large and small arteries were involved in 15 (50%), small arteries in 11 (37%), and large arteries in only 4 (13%) of 30 patients. Average time from rash to neurologic symptoms and signs was 4.1 months, and from neurologic symptoms and signs to CSF virologic analysis was 4.2 months. CSF of 9 (30%) patients contained VZV DNA while 28 (93%) had anti-VZV IgG antibody in CSF; in each of these patients, reduced serum/CSF ratio of VZV IgG confirmed intrathecal synthesis.

CONCLUSIONS

Rash or CSF pleocytosis is not required to diagnose varicella zoster virus (VZV) vasculopathy, whereas MRI/CT abnormalities are seen in almost all patients. Most patients had mixed large and small artery involvement. Detection of anti-VZV IgG antibody in CSF was a more sensitive indicator of VZV vasculopathy than detection of VZV DNA (p < 0.001). Determination of optimal antiviral treatment and benefit of concurrent steroid therapy awaits studies with larger case numbers.

Prevention of shingles: safety and efficacy of live zoster vaccine

Primary infection with varicella zoster virus (VZV) causes chickenpox (varicella) after which virus becomes latent in cranial nerve, dorsal root and autonomic ganglia along the entire neuraxis. Virus may later reactivate, causing shingles (zoster), characterized by pain and rash restricted to 1-3 dermatomes. More than 40% of zoster patients over age 60 develop postherpetic neuralgia (PHN), pain that persists for months to years. The socioeconomic impact of primary varicella infection has been lessened by introduction of VZV vaccine for children. However, the effect of childhood vaccination on the incidence of zoster is unknown. Virus reactivation correlates with waning cell-mediated immunity (CMI) to VZV with normal aging. Adults exposed to children with varicella may have a boost in CMI to VZV. For at least several more decades, the incidence of zoster may increase as the elderly population grows. The anticipated increase in zoster burden of illness in future decades was a major impetus for the Shingles Prevention Study, a prospective, double-blind, placebo-controlled trial of attenuated VZV vaccine to prevent zoster in older adults. This review discusses clinical and virological aspects of zoster and its complications, current treatment options, and VZV vaccine development along with its future role in disease prevention.

Simian varicella virus reactivation in cynomolgus monkeys

SVV infection of primates closely resembles VZV infection of humans. Like VZV, SVV becomes latent in ganglionic neurons. We used this model to study the effect of immunosuppression on varicella reactivation. Cynomolgus monkeys latently infected with SVV were irradiated and treated with tacrolimus and prednisone. Of four latently infected monkeys that were immunosuppressed and subjected to the stress of transportation and isolation, one developed zoster, and three others developed features of subclinical reactivation. Another non-immunosuppressed latently infected monkey that was subjected to the same stress of travel and isolation showed features of subclinical reactivation. Virus reactivation was confirmed not only by the occurrence of zoster in one monkey, but also by the presence of late SVV RNA in ganglia, and the detection of SVV DNA in non-ganglionic tissue, and SVV antigens in skin, ganglia and lung.

The simian varicella virus genome contains an invertible 665 base pair terminal element that is absent in the varicella zoster virus genome

Simian varicella virus (SVV) causes chickenpox in monkeys, establishes latency and reactivates to produce zoster thus providing a model to study human varicella zoster virus (VZV) infection. Sequence analysis of a recombinant cosmid clone containing the left end of the SVV genome revealed a 665 base pair (bp) segment that is absent in VZV DNA. This segment inverts and contains 507 bp of unique sequences flanked on either side by 79 bp inverted repeats, making the SVV genome to be 124,785 bp in size. Part of the inverted repeat sequence (64 bp) is also present at the junction of the long and short segments of the SVV genome. The terminal DNA sequences are conserved among different SVV isolates and present in tissues from infected monkeys. The terminal region is transcriptionally active and is also present in the genomes of other animal varicelloviruses but absent in the VZV genome.

Herpesvirus infections of the nervous system

There are eight human herpesviruses (HHVs). Primary infection by any of the eight viruses, usually occurring in childhood, is either asymptomatic or produces fever and rash of skin or mucous membranes; other organs might be involved on rare occasions. After primary infection, the virus becomes latent in ganglia or lymphoid tissue. With the exception of HHV-8, which causes Kaposi's sarcoma in patients with AIDS, reactivation of HHVs can produce one or more of the following complications: meningitis, encephalitis, myelitis, vasculopathy, ganglioneuritis, retinal necrosis and optic neuritis. Disease can be monophasic, recurrent or chronic. Infection with each herpesvirus produces distinctive clinical features and imaging abnormalities. This Review highlights the patterns of neurological symptoms and signs, along with the typical imaging abnormalities, produced by each of the HHVs. Optimal virological studies of blood, cerebrospinal fluid and affected tissue for confirmation of diagnosis are discussed; this is particularly important because some HHV infections of the nervous system can be treated successfully with antiviral agents.

The value of detecting anti-VZV IgG antibody in CSF to diagnose VZV vasculopathy

BACKGROUND

Factors that may obscure the diagnosis of varicella zoster virus (VZV) vasculopathy include the absence of rash before TIAs or stroke as well as similar clinical features and imaging, angiographic, and CSF abnormalities to those of other vasculopathies. Diagnosis relies on virologic confirmation that detects VZV DNA, anti-VZV IgG antibody, or both in the CSF.

METHODS

We reviewed our current 14 cases of patients diagnosed with VZV vasculopathy based on combined clinical, imaging, angiographic, or CSF abnormalities. All CSFs must have been tested for VZV DNA by PCR and for anti-VZV IgG antibody by enzyme immunoassay and found to be positive for either or both. Of the 14 subjects, 8 had a history of recent zoster, whereas 6 had no history of zoster rash before developing vasculopathy.

RESULTS

All 14 subjects (100%) had anti-VZV IgG antibody in their CSF, whereas only 4 (28%) had VZV DNA. The detection of anti-VZV IgG antibody in CSF was a more sensitive indicator of VZV vasculopathy than detection of VZV DNA (p < 0.001).

CONCLUSIONS

In varicella zoster virus (VZV) vasculopathy, the diagnostic value of detecting anti-VZV IgG antibody in CSF is greater than that of detecting VZV DNA. Although a positive PCR for VZV DNA in CSF is helpful, a negative PCR does not exclude the diagnosis of VZV vasculopathy. Only when the CSF is negative for both VZV DNA and anti-VZV IgG antibody can the diagnosis of VZV vasculopathy be excluded.

Disseminated simian varicella virus infection in an irradiated rhesus macaque (Macaca mulatta)

We describe correlative clinicopathological/virological findings from a simian varicella virus (SVV)-seronegative monkey that developed disseminated varicella 105 days after gamma-irradiation. Twelve other monkeys in the colony were also irradiated, none of which developed varicella. Before irradiation, sera from the monkey that developed disseminated infection and one asymptomatic monkey were available. Analysis indicated that subclinical reactivation of latent SVV from an asymptomatic irradiated monkey likely led to disseminated varicella in the seronegative irradiated monkey. These findings parallel those from humans with disseminated varicella infection and support the usefulness of SVV infection as a model for human varicella-zoster virus infection, particularly virus reactivation after gamma-irradiation.

An animal model of varicella virus infection

Varicella-zoster virus (VZV) causes chickenpox in children; establishes latency in cranial nerve, dorsal root, and autonomic ganglia; and reactivates decades later to produce zoster. VZV produces disease only in humans. Although attempts to produce disease and study VZV latency in experimentally infected animals have resulted in virus in trigeminal or dorsal root ganglia, no clinical signs of infection or reactivation developed. In contrast, simian varicella virus (SVV) produces a naturally occurring exanthematous disease in non-human primates that mimics human varicella. Experimental inoculation of non-human primates causes similar, if not identical, clinical and pathological changes observed in monkeys naturally infected with SVV. Like VZV, SVV becomes latent in ganglia and reactivates, often with entire body rash. SVV and VZV encode antigenically related polypeptides. Both virus genomes have been sequenced and shown to be colinear, sharing up to 75% DNA homology. During latency, an SVV homolog of one of the five VZV genes transcribed in latently infected human ganglia has been detected in monkey ganglia. Preliminary studies in which monkeys were inoculated intratracheally with SVV revealed the presence of viral DNA and RNA in multiple tissues, including blood mononuclear cells, months after experimental infection. These findings differed from the expected restricted localization of the virus DNA to ganglia only and the expected limited viral gene expression, and probably reflect the high virus load delivered intratracheally compared to natural SVV infection in monkeys. Nevertheless, clinical, pathological, and molecular similarities between SVV and VZV indicate that SVV infection in non-human primates has considerable potential as an animal model for human varicella.