Molecular Study of Varicella zoster virus in Cerebrospinal Fluid from Stroke Patients of Thi-Qar province.

INTRODUCTION: Varicella zoster virus (VZV) is a type of alpha-herpesvirus that specifically targets the nervous system. The initial infection, typically occurring during childhood, results in varicella (commonly known as chickenpox), after which the virus enters a dormant state in cranial nerve ganglia, dorsal root ganglia, and autonomic ganglia throughout the entire neuroaxis. AIM OF THE STUDY: Molecular and genetic studies of viruses are an important tool for virus development and identifying viral treatments to combat the diseases. The aim of the study was to determine the whole ORF4 sequence of the local VZV strains for phylogenetic analysis to determine the variability in the viral sequence. MATERIAL AND METHODS: Ten samples of VZV DNA were subjected to the sequencing of the whole ORF4 region following identification using the PCR method. RESULTS: Sequences from five samples have been successfully analyzed. All clinical strains were discovered to possess a genome with a length of 124,884 base pairs. The sequences exhibited the occurrence of two distinct mutations, one being a transversion and the other a transition, with the latter resulting in an alteration of the amino acid. A phylogenetic tree was constructed using the maximum likelihood method based on the sequences of five nucleotide sequences from clinical samples and nine reference VZV strains. The tree displayed the evolutionary distances between these sequences. The analysis of the phylogenetic tree revealed the presence of five primary clades, with four of them originating from India (isolates S1, S2, S4, S5), while S3 exhibited similarity to a strain from the United Kingdom.

Preliminary investigation and analysis of nucleotide site variability of nine glycoproteins on varicella-zoster virus envelope, Jilin Province, China, 2010-March 2024.

Varicella is endemic worldwide. In China, varicella has not yet been included in the list of legal infectious diseases, nor has a unified national surveillance program been established. And the live attenuated varicella vaccine has not been included in routine immunization. In this study, we analyzed for the first time the varicella epidemiology in Jilin Province in the past 20 years, and the nucleotide site, amino acid site and N-glycosylation site variation of glycoprotein in varicella-zoster virus (VZV) surface 9 in the past 15 years. The results showed that the reported incidence of varicella in Jilin Province in the last 20 years was fluctuating above and below 20/100,000, especially after the epidemic of the COVID-19, and fatal cases appeared in individual years. The genotypic branching of VZV was monitored as Clade 2 in the last 15 years. 9 glycogen nucleotide sites of VZV had different degrees of variability, and the variability had specificity. Therefore, it gives us the idea that in order to reduce the incidence of varicella and herpes zoster, a provincial or even national surveillance program should be introduced as early as possible, and the dynamic monitoring of the variability of the nucleotide sites of VZV should be strengthened at the same time as the vaccine immunization strategy is introduced.

Genotype of Varicella-zoster virus isolated in Jiangsu, China.

OBJECTIVE: To analyze the genotypes of VZV in Jiangsu province to identify vaccine strains and wild strains, providing a molecular biological background for the effective prevention and control of varicella. METHOD: Stratified sampling was used to collect herpes fluid or throat swab from patients diagnosed with varicella. ORF22 was carried out, and the restriction enzyme site of ORF38, ORF54 and ORF62 were detected. RESULTS: All 207 virus strains were Clade 2 type by sequencing the PCR products of ORF22. The sequencing results showed that five SNP sites changed compared to the Dumas reference strain(Clade 1). From A to G at 37,902, from T to c at 38,055, from A to C at 38,081, and from G to A at 38,177, from G to A at 39,394. The prevalent VZV genotypes in Jiangsu is consistent with the P-Oka. The restriction enzyme site analysis of PCR amplification products from ORF38 (PstI), ORF54 (BglI), ORF62 (SmaI) showed that all 207 virus strains were wild-type. There were two different types of the wild strains, and 183 strains (88.4%) were PstI (+), BglI (+), SmaI (-). The wild strains between different regions showed no significant differences (χ2 = 0.05, P = 0.982). CONCLUSIONS: The prevalent VZV genotypes are Clade 2 and the prevalent virus strains are wild strains in Jiangsu Province, the primary wild strain observed is mainly PstI (+), BglI (+), SmaI (-).

An adult with hemorrhagic varicella co-infects with cytomegalovirus: a case report.

BACKGROUND: Hemorrhagic varicella (HV) is a particular form of chicken pox.,with high mortality in adults. This form of the disease is rare, to date, approximately 4 cases have been reported. Occasional cases of HV have been documented in adults with hematologic disorders or other diseases. While there is one reported case of simultaneous reactivation of cytomegalovirus in an adult with chickenpox, there is a lack of information regarding changes in liver function indicators for such patients. This is unfortunate, as CMV reactivation can further exacerbate liver failure and increase mortality. In this report, we present a case of hemorrhagic varicella reactivation with cytomegalovirus and provide some relevant discussions. CASE PRESENTATION: We present the case of a 25-year-old male with HV, who had a history of nephrotic syndrome generally controlled with orally administered prednisone at a dosage of 50 mg per day for two months. The patient arrived at the emergency room with complaints of abdominal pain and the presence of hemorrhagic vesicles on his body for the past 3 days. Despite medical evaluation, a clear diagnosis was not immediately determined. Upon admission, the leukocyte count was recorded as 20.96 × 109/L on the first day, leading to the initiation of broad-spectrum antibiotic treatment. Despite the general interpretation that a positive IgG and a negative IgM indicate a previous infection, the patient's extraordinarily elevated IgG levels, coupled with a markedly increased CMV DNA quantification, prompted us to suspect a reactivation of the CMV virus. In light of these findings, we opted for the intravenous administration of ganciclovir as part of the treatment strategy. Unfortunately,,the patient succumbed to rapidly worsening symptoms and passed away. Within one week of the patient's demise, chickenpox gradually developed in the medical staff who had been in contact with him. In such instances, we speculate that the patient's diagnosis should be classified as a rare case of hemorrhagic varicella. CONCLUSION: Swift identification and timely administration of suitable treatment for adult HV are imperative to enhance prognosis.

Diagnostic value of anti-VZV IgG in neurological diseases among varicella unvaccinated individuals.

Varicella zoster virus (VZV) is a neurotropic alphaherpesvirus that causes neurological manifestations either as a complication of primary infection or reactivation. VZV induced neurological diseases have a good prognosis when confirmed early and treated with anti-viral therapy. Myelitis, encephalitis, ventriculitis or meningitis can occur without a telltale rash in immunocompetent and immunocompromised individuals making the diagnosis difficult. We analyzed CSF and serum samples from 30 unvaccinated study participants (17 male and 13 female) to determine the presence of VZV DNA by PCR in CSF and to estimate serum and CSF anti-VZV IgG and albumin levels in participants with neurological manifestations with/without rash. Anti-VZV IgG was detected in CSF (n = 22, [73%]) and serum (n = 29, [97%]) of pediatric and adult participants. Anti-VZV IgG were detected in CSF of participants with varied clinical presentation altered sensorium (n = 8, [36%]), meningitis (n = 4, [18%]), acute febrile illness (n = 3, [14%], encephalopathy/meningoencephalitis (n = 2, [9%]), irritability (n = 2, [9%]) and each patient from cerebrovascular stroke, demyelinating disorder and febrile seizure (n = 1, [4.5%]). VZV DNA was detected from one participant and CSF serum albumin levels were elevated in 53% of study participants. VZV DNA is present up to 1-2 weeks post onset of disease, after which anti-VZV antibody may be the only indicator of disease and therefore both VZV DNA and anti-VZV IgG need to be tested for in CSF. As VZV DNA and VZV IgG antibody are both good indicators of VZV reactivation, routine testing would result in reduced morbidity and mortality by early detection of disease and antiviral treatment.

Varicella-zoster virus-related neurological complications: From infection to immunomodulatory therapies.

The Varicella-zoster virus (VZV), classified as a neurotropic member of the Herpesviridae family, exhibits a characteristic pathogenicity, predominantly inducing varicella, commonly known as chickenpox, during the initial infectious phase, and triggering the reactivation of herpes zoster, more commonly recognized as shingles, following its emergence from a latent state. The pathogenesis of VZV-associated neuroinflammation involves a complex interplay between viral replication within sensory ganglia and immune-mediated responses that contribute to tissue damage and dysfunction. Upon primary infection, VZV gains access to sensory ganglia, establishing latent infection within neurons. During reactivation, the virus can spread along sensory nerves, triggering a cascade of inflammatory mediators, chemokines, and immune cell infiltration in the affected neural tissues. The role of both adaptive and innate immune reactions, including the contributions of T and B cells, macrophages, and dendritic cells, in orchestrating the immune-mediated damage in the central nervous system is elucidated. Furthermore, the aberrant activation of the natural defence mechanism, characterised by the dysregulated production of immunomodulatory proteins and chemokines, has been implicated in the pathogenesis of VZV-induced neurological disorders, such as encephalitis, myelitis, and vasculopathy. The intricate balance between protective and detrimental immune responses in the context of VZV infection emphasises the necessity for an exhaustive comprehension of the immunopathogenic mechanisms propelling neuroinflammatory processes. Despite the availability of vaccines and antiviral therapies, VZV-related neurological complications remain a significant concern, particularly in immunocompromised individuals and the elderly. Elucidating these mechanisms might facilitate the emergence of innovative immunomodulatory strategies and targeted therapies aimed at mitigating VZV-induced neuroinflammatory damage and improving clinical outcomes. This comprehensive understanding enhances our grasp of viral pathogenesis and holds promise for pioneering therapeutic strategies designed to mitigate the neurological ramifications of VZV infections.

Serious neurological adverse events in immunocompetent children and adolescents caused by viral reactivation in the years following varicella vaccination.

Serious adverse events following vaccination include medical complications that require hospitalisation. The live varicella vaccine that was approved by the Food and Drug Administration in the United States in 1995 has an excellent safety record. Since the vaccine is a live virus, adverse events are more common in immunocompromised children who are vaccinated inadvertently. This review includes only serious adverse events in children considered to be immunocompetent. The serious adverse event called varicella vaccine meningitis was first reported in a hospitalised immunocompetent child in 2008. When we carried out a literature search, we found 15 cases of immunocompetent children and adolescents with varicella vaccine meningitis; the median age was 11 years. Eight of the children had received two varicella vaccinations. Most of the children also had a concomitant herpes zoster rash, although three did not. The children lived in the United States, Greece, Germany, Switzerland, and Japan. During our literature search, we found five additional cases of serious neurological events in immunocompetent children; these included 4 cases of progressive herpes zoster and one case of acute retinitis. Pulses of enteral corticosteroids as well as a lack of herpes simplex virus antibody may be risk factors for reactivation in immunocompetent children. All 20 children with adverse events were treated with acyclovir and recovered; 19 were hospitalised and one child was managed as an outpatient. Even though the number of neurological adverse events remains exceedingly low following varicella vaccination, we recommend documentation of those caused by the vaccine virus.

Spatiotemporal distribution of varicella in the Republic of Korea.

Varicella is a highly contagious disease caused by the varicella-zoster virus (VZV). Given its tendency to cluster geographically, spatial analyses may provide a better understanding of the pattern of varicella transmission. We investigated the spatial characteristics of varicella in Korea and the risk factors for varicella at a national level. Using national surveillance and demographic data, we examined the spatial distribution of incidence rates and their spatial autocorrelation and calculated Moran's index. Spatial regression analysis was used to identify sociodemographic predictors of varicella incidence at the district level. An increasing tendency in the annual incidence of varicella was observed over a 12-year period (2006-2018), with a surge in 2017. There was a clear positive spatial autocorrelation of the varicella incidence rate during the surveillance period. During 2006-2014, High-High (HH) clusters were mostly confined to the northeast region and neighboring districts. The spatial error model showed that population density had a negative coefficient and childhood percentage, percentage of children under 12 years of age among the total population, had positive coefficient, whereas vaccine coverage was insignificant. The varicella incidence according to geographic region varied with population density, childhood percentage, suggesting the importance of community-level surveillance and monitoring strategies.

Recent Issues in Varicella-Zoster Virus Latency.

Varicella-zoster virus (VZV) is a human herpes virus which causes varicella (chicken pox) as a primary infection, and, following a variable period of latency in neurons in the peripheral ganglia, may reactivate to cause herpes zoster (shingles) as well as a variety of neurological syndromes. In this overview we consider some recent issues in alphaherpesvirus latency with special focus on VZV ganglionic latency. A key question is the nature and extent of viral gene transcription during viral latency. While it is known that this is highly restricted, it is only recently that the very high degree of that restriction has been clarified, with both VZV gene 63-encoded transcripts and discovery of a novel VZV transcript (VLT) that maps antisense to the viral transactivator gene 61. It has also emerged in recent years that there is significant epigenetic regulation of VZV gene transcription, and the mechanisms underlying this are complex and being unraveled. The last few years has also seen an increased interest in the immunological aspects of VZV latency and reactivation, in particular from the perspective of inborn errors of host immunity that predispose to different VZV reactivation syndromes.

A case of reactivation of varicella-zoster virus after BNT162b2 vaccine second dose?

We report a case of itchy papulovesicular rash consistent with varicella-zoster virus reactivation after Pfizer-BioNTech vaccine second dose administration. While there have been cases of varicella-zoster virus reactivation due to COVID-19 or COVID-19 vaccine inoculation in older individuals with pre-existing conditions, this case report describes the first case of varicella-zoster virus reactivation on a healthy, young male in the absence of pre-existing conditions. The mechanisms underlying varicella-zoster virus reactivation in patients with COVID-19 are unknown and should be further characterized.

Long -term persistence of antibodies against varicella in fully immunized healthcare workers: an Italian retrospective cohort study.

BACKGROUND: Chickenpox is a highly contagious disease caused by the varicella zoster virus (VZV), and in infants, adolescents, adults, pregnant women, and the immunocompromised it can be serious. The best way to prevent chickenpox is immunization with the varicella vaccine. Protective levels of antibodies induced by the varicella vaccine decline over time, but there is currently no formal recommendation for testing anti-varicella zoster virus (VZV) IgG levels in immunized healthcare workers (HCWs). METHODS: The aims of this study were to evaluate the seroprevalence of circulating anti-VZV IgG in a sample a sample of students and residents of the medical school of the University of Bari, the long-term immunogenicity of the varicella vaccine, and the effectiveness of a strategy consisting of a third vaccine booster dose. The study population was screened as part of a biological risk assessment conducted between April 2014 and October 2020. A strategy for the management of non-responders was also examined. RESULTS: The 182 students and residents included in the study had a documented history of immunization (two doses of varicella vaccine). The absence of anti-VZV IgG was determined in 34% (62/182; 95%CI = 27.2-41.4%), with serosusceptibility more common among males than females (p < 0.05). After a third varicella dose, seroconversion was achieved in 100% of this previously seronegative group. No serious adverse events were recorded. CONCLUSIONS: One-third of the study population immunized against VZV lacked a protective antibody titer, but a third dose of vaccine restored protection. Since it is highly unlikely that VZV will be eliminated in the immediate future, the loss of immunity in a substantial portion of the population implies a risk of varicella outbreaks in the coming years. Screening for varicella immunity in routine assessments of the biological risk of medical students and HCWs may help to prevent nosocomial VZV infections.

Varicella-Zoster Virus Infection of Neurons Derived from Neural Stem Cells.

Varicella-Zoster virus (VZV) is a human herpesvirus that causes varicella (chickenpox) as a primary infection, and, following a variable period of ganglionic latency in neurons, it reactivates to cause herpes zoster (shingles). An analysis of VZV infection in cultures of neural cells, in particular when these have been obtained from induced pluripotent stem cells (iPSCs) or neural stem cells consisting of highly purified neuronal cultures, has revealed much data that may be of neurobiological significance. Early studies of VZV infection of mature cultured neural cells were mainly descriptive, but more recent studies in homogeneous neural stem cell cultures have used both neuronal cell markers and advanced molecular technology. Two general findings from such studies have been that (a) VZV infection of neurons is less severe, based on several criteria, than that observed in human fibroblasts, and (b) VZV infection of neurons does not lead to apoptosis in these cells in contrast to apoptosis observed in fibroblastic cells. Insights gained from such studies in human neural stem cells suggest that a less severe initial lytic infection in neurons, which are resistant to apoptosis, is likely to facilitate a pathological pathway to a latent state of the virus in human ganglia.

Ischemic Cerebellar Stroke in a 4-Year-Old Boy After Chickenpox: An Atypical Vascular Involvement.

Cerebrovascular events in pediatric population are very rare. Up to 30% may result from varicella zoster (VZV) arteriopathy, usually as a delayed complication of varicella primary infection. The most typical pattern includes involvement of anterior brain circulation arteries, probably by VZV migration from the trigeminal ganglia. Strokes related with VZV usually have a good prognosis, but risk of recurrence is greater when compared to other stroke etiologies in this age group. We report the case of a 4-year-old boy, immunocompetent, who presented a basilar artery stenosis and a cerebellar stroke, an extremely rare presentation of VZV arteriopathy. The investigation workup and treatment are detailed, as the clinical and imaging follow-up after one year.

Acceptance of universal varicella vaccination among Swiss pediatricians and general practitioners who treat pediatric patients.

BACKGROUND: Over the last two decades, several countries have initiated universal varicella vaccination (UVV) programs in infants. In 2019, the Swiss National Immunization Technical Advisory Group (NITAG) decided to start evaluating the introduction of universal varicella vaccination. There is a theoretical concern that suboptimal vaccination coverage could lead to a shift in the varicella incidence to older age groups, thereby potentially increasing complication rates. To achieve a high vaccination coverage rate, it is important that practicing physicians comply with a potential recommendation for UVV. We studied the perception of varicella and the current vaccination behavior among Swiss pediatricians and general practitioners (GPs) who treat children. We also assessed their intention to advise parents to vaccinate their children against varicella in the event the Swiss NITAG will recommend UVV. METHODS: Primary data was collected through a structured, 20-min online survey with Swiss pediatricians and GPs who treat children. RESULTS: 150 physicians participated in the study: 40 GPs in the German-speaking part, 20 GPs in the French-speaking part, 67 pediatricians in the German-speaking part, and 23 pediatricians in the French-speaking part. The majority (64%) of all participants reported that they currently recommend varicella vaccination for risk groups according to the national immunization plan. About one third of physicians (35%) - predominantly pediatricians - currently already recommend it for all infants. In these situations, a measles, mumps, rubella, varicella combination vaccine is currently used by 58% for the first dose and by 59% for the second dose. 86% of participants stated that they would advise parents to have their children vaccinated against varicella in case of a recommendation for UVV by the Swiss NITAG. 68% responded that they expect many questions from parents and 65% agreed that they have good arguments to convey the importance of varicella vaccination. CONCLUSIONS: The survey study results show that most participating pediatricians and GPs indicated a favorable attitude towards childhood vaccination against varicella in the setting of a Swiss NITAG recommendation for UVV. This data shows the importance of NITAG recommendations in influencing vaccine education and supporting achievement of high coverage of varicella vaccination.

Calcineurin phosphatase activity regulates Varicella-Zoster Virus induced cell-cell fusion.

Cell-cell fusion (abbreviated as cell fusion) is a characteristic pathology of medically important viruses, including varicella-zoster virus (VZV), the causative agent of chickenpox and shingles. Cell fusion is mediated by a complex of VZV glycoproteins, gB and gH-gL, and must be tightly regulated to enable skin pathogenesis based on studies with gB and gH hyperfusogenic VZV mutants. Although the function of gB and gH-gL in the regulation of cell fusion has been explored, whether host factors are directly involved in this regulation process is unknown. Here, we discovered host factors that modulated VZV gB/gH-gL mediated cell fusion via high-throughput screening of bioactive compounds with known cellular targets. Two structurally related non-antibiotic macrolides, tacrolimus and pimecrolimus, both significantly increased VZV gB/gH-gL mediated cell fusion. These compounds form a drug-protein complex with FKBP1A, which binds to calcineurin and specifically inhibits calcineurin phosphatase activity. Inhibition of calcineurin phosphatase activity also enhanced both herpes simplex virus-1 fusion complex and syncytin-1 mediated cell fusion, indicating a broad role of calcineurin in modulating this process. To characterize the role of calcineurin phosphatase activity in VZV gB/gH-gL mediated fusion, a series of biochemical, biological and infectivity assays was performed. Pimecrolimus-induced, enhanced cell fusion was significantly reduced by shRNA knockdown of FKBP1A, further supporting the role of calcineurin phosphatase activity in fusion regulation. Importantly, inhibition of calcineurin phosphatase activity during VZV infection caused exaggerated syncytia formation and suppressed virus propagation, which was consistent with the previously reported phenotypes of gB and gH hyperfusogenic VZV mutants. Seven host cell proteins that remained uniquely phosphorylated when calcineurin phosphatase activity was inhibited were identified as potential downstream factors involved in fusion regulation. These findings demonstrate that calcineurin is a critical host cell factor pivotal in the regulation of VZV induced cell fusion, which is essential for VZV pathogenesis.

A Novel Human Skin Tissue Model To Study Varicella-Zoster Virus and Human Cytomegalovirus.

The herpesviruses varicella-zoster virus (VZV) and human cytomegalovirus (HCMV) are endemic to humans. VZV causes varicella (chicken pox) and herpes zoster (shingles), while HCMV causes serious disease in immunocompromised patients and neonates. More effective, less toxic antivirals are needed, necessitating better models to study these viruses and evaluate antivirals. Previously, VZV and HCMV models used fetal tissue; here, we developed an adult human skin model to study VZV and HCMV in culture and in vivo While VZV is known to grow in skin, it was unknown whether skin could support an HCMV infection. We used TB40/E HCMV and POka VZV strains to evaluate virus tropism in skin organ culture (SOC) and skin xenograft mouse models. Adult human skin from reduction mammoplasties was prepared for culture on NetWells or mouse implantation. In SOC, VZV infected the epidermis and HCMV infected the dermis. Specifically, HCMV infected fibroblasts, endothelial cells, and hematopoietic cells, with some infected cells able to transfer infection. VZV and HCMV mouse models were developed by subcutaneous transplantation of skin into SCID/beige or athymic nude mice at 2 independent sites. Viruses were inoculated directly into one xenograft, and widespread infection was observed for VZV and HCMV. Notably, we detected VZV- and HCMV-infected cells in the contralateral, uninoculated xenografts, suggesting dissemination from infected xenografts occurred. For the first time, we showed HCMV successfully grows in adult human skin, as does VZV. Thus, this novel system may provide a much-needed preclinical small-animal model for HCMV and VZV and, potentially, other human-restricted viruses.IMPORTANCE Varicella-zoster virus and human cytomegalovirus infect a majority of the global population. While they often cause mild disease, serious illness and complications can arise. Unfortunately, there are few effective drugs to treat these viruses, and many are toxic. To complicate this, these viruses are restricted to replication in human cells and tissues, making them difficult to study in traditional animal models. Current models rely heavily on fetal tissues, can be prohibitively expensive, and are often complicated to generate. While fetal tissue models provide helpful insights, it is necessary to study human viruses in human tissue systems to fully understand these viruses and adequately evaluate novel antivirals. Adult human skin is an appropriate model for these viruses because many target cells are present, including basal keratinocytes, fibroblasts, dendritic cells, and lymphocytes. Skin models, in culture and xenografts in immunodeficient mice, have potential for research on viral pathogenesis, tissue tropism, dissemination, and therapy.

An adult co-presented with varicella and herpes zoster caused by varicella zoster virus genotype J, China: a case report.

BACKGROUND: Varicella zoster virus (VZV) causes varicella primarily in childhood, and some rare adults also report varicella. Herpes zoster mainly occurs in adults by endogenous reactivation of latent VZV. Until now, varicella and herpes zoster have seldom been reported simultaneously in one patient. Here, we report a rare case co-presenting with varicella and herpes zoster in a Chinese adult. CASE PRESENTATION: A 44-year-old Chinese man suffered papules and vesicles with pain on the left ear. Five days after onset, he was admitted to the Department of Dermatology of The Third Hospital of Xiamen. Physical examination revealed that small vesicles surrounded by erythema had developed on his trunk, back and neck, and unilateral papules and vesicles in ribbons had also developed on the left ear. This patient was excluded from human immunodeficiency virus and Treponema pallidum infections by ELISA antibody tests. Laboratory tests revealed that the ratio of eosinophils (0.1%) and eosinophil count (0.0 × 109/L) were significantly downregulated. Treatment with valacyclovir, ebastine, mecobalamine, pregabalin and calamine lotion for 5 days was effective therapy for varicella and herpes zoster. Polymerase chain reaction for vesicular fluids from varicella and herpes zoster was positive for VZV, and further phylogenetic analysis and single nucleotide polymorphism variations confirmed that the VZV genotype was type J (clade 2). CONCLUSIONS: This rare case highlights awareness of varicella and herpes zoster caused by VZV infection in adults. Our report provides novel insight into the rare clinical presentation of VZV genotype J.

Exocytosis of Progeny Infectious Varicella-Zoster Virus Particles via a Mannose-6-Phosphate Receptor Pathway without Xenophagy following Secondary Envelopment.

The literature on the egress of different herpesviruses after secondary envelopment is contradictory. In this report, we investigated varicella-zoster virus (VZV) egress in a cell line from a child with Pompe disease, a glycogen storage disease caused by a defect in the enzyme required for glycogen digestion. In Pompe cells, both the late autophagy pathway and the mannose-6-phosphate receptor (M6PR) pathway are interrupted. We have postulated that intact autophagic flux is required for higher recoveries of VZV infectivity. To test that hypothesis, we infected Pompe cells and then assessed the VZV infectious cycle. We discovered that the infectious cycle in Pompe cells was remarkably different from that of either fibroblasts or melanoma cells. No large late endosomes filled with VZV particles were observed in Pompe cells; only individual viral particles in small vacuoles were seen. The distribution of the M6PR pathway (trans-Golgi network to late endosomes) was constrained in infected Pompe cells. When cells were analyzed with two different anti-M6PR antibodies, extensive colocalization of the major VZV glycoprotein gE (known to contain M6P residues) and the M6P receptor (M6PR) was documented in the viral highways at the surfaces of non-Pompe cells after maximum-intensity projection of confocal z-stacks, but neither gE nor the M6PR was seen in abundance at the surfaces of infected Pompe cells. Taken together, our results suggested that (i) Pompe cells lack a VZV trafficking pathway within M6PR-positive large endosomes and (ii) most infectious VZV particles in conventional cell substrates are transported via large M6PR-positive vacuoles without degradative xenophagy to the plasma membrane.IMPORTANCE The long-term goal of this research has been to determine why VZV, when grown in cultured cells, invariably is more cell associated and has a lower titer than other alphaherpesviruses, such as herpes simplex virus 1 (HSV1) or pseudorabies virus (PRV). Data from both HSV1 and PRV laboratories have identified a Rab6 secretory pathway for the transport of single enveloped viral particles from the trans-Golgi network within small vacuoles to the plasma membrane. In contrast, after secondary envelopment in fibroblasts or melanoma cells, multiple infectious VZV particles accumulated within large M6PR-positive late endosomes that were not degraded en route to the plasma membrane. We propose that this M6PR pathway is most utilized in VZV infection and least utilized in HSV1 infection, with PRV's usage being closer to HSV1's usage. Supportive data from other VZV, PRV, and HSV1 laboratories about evidence for two egress pathways are included.