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

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

Mutagenesis and functional analysis of the varicella-zoster virus portal protein.

Herpesviruses replicate by cleaving concatemeric dsDNA into single genomic units that are packaged through an oligomeric portal present in preformed procapsids. In contrast to what is known about phage portal proteins, details concerning herpesvirus portal structure and function are not as well understood. A panel of 65 Varicella-Zoster virus (VZV) recombinant portal proteins with five amino acid in-frame insertions were generated by random transposon mutagenesis of the VZV portal gene, ORF54. Subsequently, 65 VZVLUC recombinant viruses (TNs) were generated via recombineering. Insertions were mapped to predicted portal domains (clip, wing, stem, wall, crown, and ß-hairpin tunnel-loop) and recombinant viruses were characterized for plaque morphology, replication kinetics, pORF54 expression, and classified based on replication in non-complementing (ARPE19) or complementing (ARPE54C50) cell lines. The N- and C-termini were tolerant to insertion mutagenesis, as were certain clip sub-domains. The majority of mutants mapping to the wing, wall, ß-hairpin tunnel loop, and stem domains were lethal. Elimination of the predicted ORF54 start codon revealed that the first 40 amino acids of the N-terminus were not required for viral replication. Stop codon insertions in the C-terminus showed that the last 100 amino acids were not required for viral replication. Lastly, a putative protease cleavage site was identified in the C-terminus of pORF54. Cleavage was likely orchestrated by a viral protease; however, processing was not required for DNA encapsidation and viral replication. The panel of recombinants should prove valuable in future studies to dissect mammalian portal structure and function.IMPORTANCEThough nucleoside analogs and a live-attenuated vaccine are currently available to treat some human herpesvirus family members, alternate methods of combating herpesvirus infection could include blocking viral replication at the DNA encapsidation stage. The approval of Letermovir provided proof of concept regarding the use of encapsidation inhibitors to treat herpesvirus infections in the clinic. We propose that small-molecule compounds could be employed to interrupt portal oligomerization, assembly into the capsid vertex, or affect portal function/dynamics. Targeting portal at any of these steps would result in disruption of viral DNA packaging and a decrease or absence of mature infectious herpesvirus particles. The oligomeric portals of herpesviruses are structurally conserved, and therefore, it may be possible to find a single compound capable of targeting portals from one or more of the herpesvirus subfamilies. Drug candidates from such a series would be effective against viruses resistant to the currently available antivirals.

Suppression of the host antiviral response by non-infectious varicella zoster virus extracellular vesicles.

Varicella zoster virus (VZV) reactivates from ganglionic sensory neurons to produce herpes zoster (shingles) in a unilateral dermatomal distribution, typically in the thoracic region. Reactivation not only heightens the risk of stroke and other neurological complications but also increases susceptibility to co-infections with various viral and bacterial pathogens at sites distant from the original infection. The mechanism by which VZV results in complications remote from the initial foci remains unclear. Small extracellular vesicles (sEVs) are membranous signaling structures that can deliver proteins and nucleic acids to modify the function of distal cells and tissues during normal physiological conditions. Although viruses have been documented to exploit the sEV machinery to propagate infection, the role of non-infectious sEVs released from VZV-infected neurons in viral spread and disease has not been studied. Using multi-omic approaches, we characterized the content of sEVs released from VZV-infected human sensory neurons (VZV sEVs). One viral protein was detected (immediate-early 62), as well as numerous immunosuppressive and vascular disease-associated host proteins and miRNAs that were absent in sEVs from uninfected neurons. Notably, VZV sEVs are non-infectious yet transcriptionally altered primary human cells, suppressing the antiviral type 1 interferon response and promoting neuroinvasion of a secondary pathogen in vivo. These results challenge our understanding of VZV infection, proposing that the virus may contribute to distant pathologies through non-infectious sEVs beyond the primary infection site. Furthermore, this study provides a previously undescribed immune-evasion mechanism induced by VZV that highlights the significance of non-infectious sEVs in early VZV pathogenesis. IMPORTANCE: Varicella zoster virus (VZV) is a ubiquitous human virus that predominantly spreads by direct cell-cell contact and requires efficient and immediate host immune evasion strategies to spread. The mechanisms of immune evasion prior to virion entry have not been fully elucidated and represent a critical gap in our complete understanding of VZV pathogenesis. This study describes a previously unreported antiviral evasion strategy employed by VZV through the exploitation of the infected host cell's small extracellular vesicle (sEV) machinery. These findings suggest that non-infectious VZV sEVs could travel throughout the body, affecting cells remote from the site of infection and challenging the current understanding of VZV clinical disease, which has focused on local effects and direct infection. The significance of these sEVs in early VZV pathogenesis highlights the importance of further investigating their role in viral spread and secondary disease development to reduce systemic complications following VZV infections.

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.

A comprehensive, updated systematic review and meta-analysis of epidemiologic evidence on the connection between herpes zoster infection and the risk of stroke.

Stroke is a common worldwide cause of death and disability, resulting from an obstruction or reduction in blood flow to the brain. Research has demonstrated that systemic infection such as herpes zoster (HZ) / ophthalmicus herpes zoster (HZO) can potentially trigger stroke. This study includes an updated systematic review and meta-analysis of the epidemiologic data on the connection between HZ/HZO infection and the risk of stroke. A meticulous search of different database yielded 905 studies. Furthermore, an additional 14 studies from a previous meta-analysis were incorporated. Eligible studies underwent rigorous screening, resulting in 18 papers. Statistical analyses, including random/fixed effects models and subgroup analyses, were conducted to assess pooled relative risk (RR) and heterogeneity. The meta-analysis consisted of 5,505,885 participants and found a statistically significant association between HZ infection and the risk of stroke (pooled RR = 1.22, 95% confidence interval [CI] 1.12-1.34). The HZO infection showed a significantly higher overall pooled RR of 1.71 (95% CI 1.06-2.75), indicating a strong connection with the risk of stroke. Subgroup analysis revealed that the odds ratio might play a significant role in causing heterogeneity. Time since infection emerged as a crucial factor, with heightened stroke risk in the initial year post-HZ/HZO exposure, followed by a decline after the first year. Asian/Non-Asian studies demonstrated varied results in HZ/HZO patients. Meta-analysis reveals a significant HZ/HZO-stroke link. Subgroups highlight varied risks and warrant extended Asian/non-Asian patient investigation.

Prior Herpes Simplex Virus Infection and the Risk of Herpes Zoster.

BACKGROUND: The incidence of herpes zoster (HZ) has increased in the United States concurrent with decrease in herpes simplex virus (HSV) prevalence. We hypothesized that lack of HSV-elicited cross-reactive immunity to varicella-zoster virus (VZV) results in an increased risk of HZ. Using specimens from the placebo arm of the Shingles Prevention Study, we investigated whether persons who develop HZ are less likely to have prior HSV infection than persons who do not develop HZ, and whether HZ is less severe in persons with HSV than in HSV seronegative persons. METHODS: We conducted a nested case-control (1:2) study comparing the seroprevalence of HSV-1 and HSV-2 in cases (persons with polymerase chain reaction-confirmed HZ) to age-, sex-, and health-matched controls (persons without HZ). RESULTS: Sera from 639 study participants (213 cases and 426 controls) yielded definitive HSV antibody results and were analyzed. Overall, HSV seropositivity rate was 75%. HSV seronegativity was significantly higher in HZ cases than controls (30.5% vs 22.3%; P = .024), with a 55% higher risk of HZ in HSV seronegative than HSV seropositive participants. HSV seropositivity was associated with more severe HZ (P = .021). CONCLUSIONS: Our study demonstrated that prior infection with HSV partly protects against HZ.

Mpox Epidemiology and Risk Factors, Nigeria, 2022.

To investigate epidemiology of and risk factors for laboratory-confirmed mpox during the 2022 outbreak in Nigeria, we enrolled 265 persons with suspected mpox. A total of 163 (61.5%) were confirmed to have mpox; 137 (84.0%) were adults, 112 (68.7%) male, 143 (87.7%) urban/semi-urban dwellers, 12 (7.4%) self-reported gay men, and 3 (1.8%) female sex workers. Significant risk factors for adults were sexual and nonsexual contact with persons who had mpox, as well as risky sexual behavior. For children, risk factors were close contact with an mpox-positive person and prior animal exposure. Odds of being mpox positive were higher for adults with HIV and lower for those co-infected with varicella zoster virus (VZV). No children were HIV-seropositive; odds of being mpox positive were higher for children with VZV infection. Our findings indicate mpox affects primarily adults in Nigeria, partially driven by sexual activity; childhood cases were driven by close contact, animal exposure, and VZV co-infection.

Differential diagnosis of exanthematous viruses during the 2022 Mpox outbreak in Minas Gerais, Brazil.

The monkeypox virus (MPXV) outbreak, primarily endemic to Africa, has spread globally, with Brazil reporting the second-highest number of cases. The emergence of MPXV in non-endemic areas has raised concerns, particularly due to the co-circulation of other exanthematous viruses such as varicella-zoster virus (VZV) and molluscum contagiosum virus (MOCV). To perform an accurate differential diagnosis of MPXV during the ongoing outbreak in Minas Gerais, Brazil, a 5PLEX qPCR assay targeting orthopoxviruses (OPV), VZV, and MOCV was used to retrospectively analyze all clinical samples that tested negative for MPXV in the initial screening conducted at Funed. In summary, our study analyzed 1,175 clinical samples received from patients suspected of MPXV infection and found a positivity rate of 33.8% (397 samples) for MPXV using the non-variola qPCR assay. Testing the 778 MPXV-negative clinical samples using the 5PLEX qPCR assay revealed that 174 clinical samples (22.36%) tested positive for VZV. MOCV DNA was detected in 13 and other OPV in 3 clinical samples. The sequencing of randomly selected amplified clinical samples confirmed the initial molecular diagnosis. Analysis of patient profiles revealed a significant difference in the median age between groups testing positive for MPXV and VZV and a male predominance in MPXV cases. The geographic distribution of positive cases was concentrated in the most populous mesoregions of Minas Gerais state. This study highlights the challenges posed by emerging infectious diseases. It emphasizes the importance of epidemiological surveillance and accurate diagnosis in enabling timely responses for public health policies and appropriate medical care. IMPORTANCE: Brazil ranks second in the number of cases during the global monkeypox epidemic. The study, conducted in Minas Gerais, the second most populous state in Brazil with over 20 million inhabitants, utilized differential diagnostics, revealing a significant number of positive cases for other exanthematous viruses and emphasizing the need for accurate diagnoses. During the study, we were able to assess the co-circulation of other viruses alongside monkeypox, including varicella-zoster virus, molluscum contagiosum virus, and other orthopoxviruses. The significance of the research is underscored by the concentration of positive cases in populous areas, highlighting the challenges posed by emerging infectious diseases. This demographic context further amplifies the importance of the research in guiding public health policies and medical interventions, given the substantial population at risk. The study not only addresses a global concern but also holds critical implications for a state with such a large population and geographic expanse within Brazil. Overall, the study emphasizes the pivotal role of surveillance and precise diagnosis in guiding effective public health responses and ensuring appropriate medical interventions.

Construction of a pathological model of skin lesions in acute herpes zoster virus infection and its molecular mechanism.

Varicella-zoster virus (VZV), a common pathogen with humans as the sole host, causes primary infection and undergoes a latent period in sensory ganglia. The recurrence of VZV is often accompanied by severe neuralgia in skin tissue, which has a serious impact on the life of patients. During the acute infection of VZV, there are few related studies on the pathophysiological mechanism of skin tissue. In this study, transcriptome sequencing data from the acute response period within 2 days of VZV antigen stimulation of the skin were used to explore a model of the trajectory of skin tissue changes during VZV infection. It was found that early VZV antigen stimulation caused activation of mainly natural immune-related signaling pathways, while in the late phase activation of mainly active immune-related signaling pathways. JAK-STAT, NFκB, and TNFα signaling pathways are gradually activated with the progression of infection, while Hypoxia is progressively inhibited. In addition, we found that dendritic cell-mediated immune responses play a dominant role in the lesion damage caused by VZV antigen stimulation of the skin. This study provides a theoretical basis for the study of the molecular mechanisms of skin lesions during acute VZV infection.