Algorithm for optimized mRNA design improves stability and immunogenicity.

Messenger RNA (mRNA) vaccines are being used to combat the spread of COVID-19 (refs. 1-3), but they still exhibit critical limitations caused by mRNA instability and degradation, which are major obstacles for the storage, distribution and efficacy of the vaccine products4. Increasing secondary structure lengthens mRNA half-life, which, together with optimal codons, improves protein expression5. Therefore, a principled mRNA design algorithm must optimize both structural stability and codon usage. However, owing to synonymous codons, the mRNA design space is prohibitively large-for example, there are around 2.4 × 10632 candidate mRNA sequences for the SARS-CoV-2 spike protein. This poses insurmountable computational challenges. Here we provide a simple and unexpected solution using the classical concept of lattice parsing in computational linguistics, where finding the optimal mRNA sequence is analogous to identifying the most likely sentence among similar-sounding alternatives6. Our algorithm LinearDesign finds an optimal mRNA design for the spike protein in just 11 minutes, and can concurrently optimize stability and codon usage. LinearDesign substantially improves mRNA half-life and protein expression, and profoundly increases antibody titre by up to 128 times in mice compared to the codon-optimization benchmark on mRNA vaccines for COVID-19 and varicella-zoster virus. This result reveals the great potential of principled mRNA design and enables the exploration of previously unreachable but highly stable and efficient designs. Our work is a timely tool for vaccines and other mRNA-based medicines encoding therapeutic proteins such as monoclonal antibodies and anti-cancer drugs7,8.

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.

Varicella Zoster Virus disrupts MAIT cell polyfunctional effector responses.

Mucosal-associated invariant T (MAIT) cells are unconventional T cells that respond to riboflavin biosynthesis and cytokines through TCR-dependent and -independent pathways, respectively. MAIT cell activation plays an immunoprotective role against several pathogens, however the functional capacity of MAIT cells following direct infection or exposure to infectious agents remains poorly defined. We investigated the impact of Varicella Zoster Virus (VZV) on blood-derived MAIT cells and report virus-mediated impairment of activation, cytokine production, and altered transcription factor expression by VZV infected (antigen+) and VZV exposed (antigen-) MAIT cells in response to TCR-dependent and -independent stimulation. Furthermore, we reveal that suppression of VZV exposed (antigen-) MAIT cells is not mediated by a soluble factor from neighbouring VZV infected (antigen+) MAIT cells. Finally, we demonstrate that VZV impairs the cytolytic potential of MAIT cells in response to riboflavin synthesising bacteria. In summary, we report a virus-mediated immune-evasion strategy that disarms MAIT cell responses.

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.

HLA Associations of Intrathecal IgG Production against Specific Viruses in Multiple Sclerosis.

OBJECTIVE: Specific human leucocyte antigen (HLA) alleles are not only associated with higher risk to develop multiple sclerosis (MS) and other autoimmune diseases, but also with the severity of various viral and bacterial infections. Here, we analyzed the most specific biomarker for MS, that is, the polyspecific intrathecal IgG antibody production against measles, rubella, and varicella zoster virus (MRZ reaction), for possible HLA associations in MS. METHODS: We assessed MRZ reaction from 184 Swiss patients with MS and clinically isolated syndrome (CIS) and 89 Swiss non-MS/non-CIS control patients, and performed HLA sequence-based typing, to check for associations of positive MRZ reaction with the most prevalent HLA alleles. We used a cohort of 176 Swedish MS/CIS patients to replicate significant findings. RESULTS: Whereas positive MRZ reaction showed a prevalence of 38.0% in MS/CIS patients, it was highly specific (97.7%) for MS/CIS. We identified HLA-DRB1*15:01 and other tightly linked alleles of the HLA-DR15 haplotype as the strongest HLA-encoded risk factors for a positive MRZ reaction in Swiss MS/CIS (odds ratio [OR], 3.90, 95% confidence interval [CI] 2.05-7.46, padjusted = 0.0004) and replicated these findings in Swedish MS/CIS patients (OR 2.18, 95%-CI 1.16-4.02, padjusted = 0.028). In addition, female MS/CIS patients had a significantly higher probability for a positive MRZ reaction than male patients in both cohorts combined (padjusted <0.005). INTERPRETATION: HLA-DRB1*15:01, the strongest genetic risk factor for MS, and female sex, 1 of the most prominent demographic risk factors for developing MS, predispose in MS/CIS patients for a positive MRZ reaction, the most specific CSF biomarker for MS. ANN NEUROL 2024;95:1112-1126.

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.

Unraveling the Immune Signature of Herpes Zoster: Insights Into the Pathophysiology and Human Leukocyte Antigen Risk Profile.

The varicella-zoster virus (VZV) infects >95% of the population. VZV reactivation causes herpes zoster (HZ), known as shingles, primarily affecting the elderly and individuals who are immunocompromised. However, HZ can occur in otherwise healthy individuals. We analyzed the immune signature and risk profile in patients with HZ using a genome-wide association study across different UK Biobank HZ cohorts. Additionally, we conducted one of the largest HZ human leukocyte antigen association studies to date, coupled with transcriptomic analysis of pathways underlying HZ susceptibility. Our findings highlight the significance of the major histocompatibility complex locus for HZ development, identifying 5 protective and 4 risk human leukocyte antigen alleles. This demonstrates that HZ susceptibility is largely governed by variations in the major histocompatibility complex. Furthermore, functional analyses revealed the upregulation of type I interferon and adaptive immune responses. These findings provide fresh molecular insights into the pathophysiology and activation of innate and adaptive immune responses triggered by symptomatic VZV reactivation.

Assessing herpes zoster vaccine efficacy in patients with diabetes: A community-based cohort study.

The effectiveness of herpes zoster (HZ) vaccines in patients with diabetes over the age of 50 remains an active area of research. Utilizing a real-world database from the US community, this study spanning from 2006 to 2023, aimed to evaluate the impact of HZ vaccination on newly diagnosed diabetes patients who received an HZ vaccination within 1 year of diagnosis. Exclusion criteria were established to omit patients with immune deficiencies. The cohort consisted of 53 885 patients, with an average age of 63.5 years, including 43% females and 58% whites. After implementing 1:1 propensity score matching for age, sex, race, comorbidities, diabetes medication, and hemoglobin A1c to ensure comparability, the study population was further stratified into four groups: N1 comparing any HZ vaccination to non-HZ vaccination (53 882 matched pairs), N2 for Shingrix versus non-HZ vaccination (16 665 matched pairs), N3 for Zostavax versus non-HZ vaccination (12 058 matched pairs), and N4 for Shingrix versus Zostavax (11 721 matched pairs). Cox proportional hazards regression analysis revealed a hazard ratio (HR) for HZ incidence post any HZ vaccination of 0.92 (95% confidence interval [CI]: 0.83-1.01). Additional analyses yielded HRs of 1.12 (95% CI: 0.93-1.34) for Shingrix versus non-HZ vaccine, 1.02 (95% CI: 0.86-1.20) for Zostavax versus non-HZ vaccine, and 1.06 (95% CI: 0.87-1.29) for Shingrix versus Zostavax. Subgroup analyses across age, sex, and follow-up duration also showed no significant differences. These findings underscore the lack of a significant benefit from HZ vaccination in newly diagnosed diabetes patients aged over 50, highlighting the necessity for further prospective research.

Elevated cerebrospinal fluid IgG index in herpes simplex encephalitis post-HSV-1 clearance: A preliminary study.

Herpes simplex encephalitis (HSE) is an acute form of encephalitis that can lead to poor neurological outcomes. Although the exact pathogenesis of HSE remains elusive, recent reports suggest a significant role for postinfectious immune-inflammatory processes in the central nervous system (CNS). This study aimed to clarify the association between CNS autoimmune responses and clinical presentation in patients with HSE, focusing on cerebrospinal fluid (CSF) characteristics, particularly the IgG index. We retrospectively analyzed 176 consecutive patients suspected of having aseptic meningitis /encephalitis for chronological changes in CSF findings and clinical presentations. These patients underwent PCR screening for herpesviruses (HV) in their CSF. We identified seven patients positive for herpes simplex virus type 1 (HSV-1), 20 patients positive for varicella-zoster virus, and 17 patients who met the criteria for aseptic meningitis but were PCR-negative for HV. Patients in the HSV-1-positive group exhibited a significant increase in the IgG index at the time of PCR-negative conversion compared with on admission (p = 0.0156), while such a change was not observed in the other two groups. Additionally, all patients in the HSV-1-positive group tested negative for anti-neural autoantibodies in CSF and serum samples collected approximately 3 weeks after onset. This study, therefore, highlights that CSF IgG index elevation occurs even after PCR-confirmed HSV-1 clearance, which might indicate immunopathogenesis that is independent of antibody-mediated mechanisms.

A systematic review and meta-analysis of herpes zoster occurrence/recurrence after COVID-19 infection and vaccination.

To inform surveillance, prevention, and management strategies for the varicella zoster virus (VZV) during the COVID-19 pandemic, this study aimed to evaluate the risk of herpes zoster (HZ) occurrence/recurrence following COVID-19 infection and vaccination. A comprehensive search across seven databases was conducted up to January 31, 2024, to identify studies relevant to the occurrence of HZ following COVID-19 infection and vaccination. The meta-analysis included five studies on postinfection HZ and 13 studies on postvaccination HZ. Patients infected with COVID-19 had a 2.16-fold increased risk of HZ (95% confidence interval [CI]: 1.24-3.76) than uninfected individuals. However, there was no significant association between COVID-19 vaccination and the risk of HZ compared to controls, with a relative risk (RR) of 1.08 (95% CI: 0.84-1.39). Furthermore, a descriptive analysis of 74 postinfection and 153 postvaccination HZ studies found no significant differences on gender or age (<50 and ≥50 years) following COVID-19 infection. Notably, 44.0% of the HZ cases postinfection appeared within the first week, with 69.5% resolving within 10 days, predominantly presenting as skin lesions. In the postvaccination group, the majority (60.1%) developed HZ after the first dose and 66.7% occurred within 1 week. Moreover, 44.6% resolved within 10 days and 50.0% within a month, primarily exhibiting skin lesions and postherpetic neuralgia. The study found that COVID-19 infection increases the risk of HZ, but the COVID-19 vaccine does not. Further study is needed to explore the association between COVID-19 and HZ.

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.

Simian varicella virus infection and reactivation in rhesus macaques trigger cytokine and Aß40/42 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 Aß42/Aß40 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 Aß42/Aß40 levels compared to pre-inoculation levels. Overall, peripheral infection appears to affect CNS cytokine and Aß42/Aß40 levels independent of serum responses, suggesting that peripheral disease may contribute to CNS disease.

Detection of intrathecal IgG antibody for varicella and measles diagnosis by evaluation and comparison of a commercial IgG chemiluminescent immunoassay with two ELISAs.

OBJECTIVES: Analyse alternative methods of intrathecal antibody detection by comparing chemiluminescent immunoassay (CLIA) and enzyme-linked immunosorbent assay (ELISA) techniques to determine if CLIA can replace ELISA in the diagnosis of CNS infections. METHODS: A panel of 280 paired samples-cerebrospinal fluid (CSF) and serum-with known antibody reactivities (Varicella, n = 60; Measles, n = 120) and negative samples (n = 100) were used to evaluate the performance of six serological test kits (Enzygnost, VirClia®, and Serion ELISA (Measles and Variella). RESULTS: For Measles virus IgG, the VirClia® IgG monotest revealed 97% and 94% positive and negative agreement to the Enzygnost as reference test, respectively. In contrast, Serion ELISA kits yielded values of 18% and 90%. For the Varicella Zoster virus (VZV) IgG, the VirClia® IgG monotest showed 97% and 90% positive and negative agreement compared to Enzygnost. The Serion ELISA kits showed values of 55% and 86%, respectively. ROC analysis revealed that the areas under the curve for Measles and VZV IgGs were 0.7 and 0.852, respectively, using the Serion kit, and 0.963 and 0.955, for Vircell S.L CLIA technique. VirClia® monotest values were calculated using an antibody index cut-off of 1.3. CONCLUSION: The findings indicate that CLIA testing can improve antibody detection in CSF samples, aiding the diagnosis of infectious neurological impairments.

Varicella-Zoster Virus Pretransplant Vaccination and Posttransplant Infections Among Pediatric Solid Organ Recipients in the Two-Dose Varicella Era: A Single-Center, Multi-Organ Retrospective Study.

BACKGROUND: Varicella-zoster virus (VZV) pretransplant immunization rates, exposures, and posttransplant disease are poorly characterized among pediatric solid organ transplant (SOT) recipients in the two-dose varicella vaccine era. METHODS: A retrospective analysis of the electronic health records among children <18 years old who received SOT from January 1, 2011 through December 31, 2021, was performed at a single center to assess for missed pretransplant varicella vaccination opportunities, characterize VZV exposures, and describe posttransplant disease. RESULTS: Among 525 children, 444 were ≥6 months old (m.o.) at SOT with a documented VZV vaccine status. Eighty-five (19%) did not receive VZV Dose One; 30 out of 85 (35%) could have been immunized. Infants 6-11 m.o. accounted for 14 out of 30 (47%) missed opportunities. Among children ≥12 m.o. with documented Dose Two status (n = 383), 72 had missed vaccination opportunities; 57 out of 72 (79%) were children 1-4 years old. Most children had unclassifiable pre-SOT serostatus as varicella serology was either not obtained/documented (n = 171) or the possibility of passive antibodies was not excluded (n = 137). Of those with classified serology (n = 188), 69 were seroimmune. Forty-seven of 525 (9%) children had recorded VZV exposures; two developed varicella-neither had documented pre-SOT seroimmunity nor had received post-exposure prophylaxis. Nine additional children had medically attended disease: four primary varicella and five zoster. Of the 11 cases, 10 had cutaneous lesions without invasive disease; one had multi-dermatomal zoster with transaminitis. Seven (64%) received treatment exclusively outpatient. CONCLUSIONS: VZV exposure and disease still occur. Optimizing immunization among eligible candidates and ensuring patients have a defined VZV serostatus pretransplantation remain goals of care.

Varicella-Zoster Virus Reactivation After Pediatric Allogeneic Hematopoietic Stem Cell Transplantation, Single-Center Experience of Acyclovir Prophylaxis.

BACKGROUND: Varicella-zoster virus (VZV) reactivation is the most common infectious complication in the late posthematopoietic stem cell transplantation (HSCT) period and is reported as 16%-41%. Acyclovir prophylaxis is recommended for at least 1 year after HSCT to prevent VZV infections. However, studies on the most appropriate prophylaxis are ongoing in pediatric patients. METHODS: Patients who underwent allogeneic HSCT between January 1, 1996 and January 1, 2020 were retrospectively analyzed to outline the characteristics of VZV reactivation after allogeneic HSCT in pediatric patients using 6 months acyclovir prophylaxis. RESULTS: There were 260 patients and 273 HSCTs. Median age was 10.43 (0.47-18.38), and 56% was male. Median follow-up was 2325 days (18-7579 days). VZV reactivation occurred in 21.2% (n = 58) at a median of 354 (55-3433) days post-HSCT. The peak incidence was 6-12 months post-HSCT (43.1%). Older age at HSCT, female gender, history of varicella infection, lack of varicella vaccination, low lymphocyte, CD4 count, and CD4/CD8 ratio at 9 and 12 months post-HSCT was found as a significant risk for herpes zoster (HZ) in univariate analysis, whereas history of varicella infection and low CD4/CD8 ratio at 12 months post-HSCT was an independent risk factor in multivariate analysis. CONCLUSIONS: Tailoring acyclovir prophylaxis according to pre-HCT varicella history, posttransplant CD4 T lymphocyte counts and functions, and ongoing immunosuppression may help to reduce HZ-related morbidity and mortality.

Management of a major varicella zoster exposure in a pediatric oncology population.

Management of the exposure of pediatric oncology patients to varicella zoster virus (VZV) is controversial. We report the exposure of 56 patients to a single child with chicken pox at a pediatric cancer housing facility and describe our strategic approach for their management. We reviewed the immune and clinical status of 56 children with cancer receiving ongoing treatment at Memorial Sloan Kettering Cancer Center (MSK) who, while living at a pediatric cancer housing facility, were exposed to the index patient. The management of patients exposed included: (1) determination of immune status, (2) availability of vaccination history or VZV disease prophylaxis, (3) exposure status and subsequent isolation during the period of incubation, and (4) VZV disease prophylaxis. In addition to the 56 patients exposed to the index case, eight children with cancer treated at other facilities and 11 healthy siblings living in the facility were exposed. Of the 56 MSK patients, 21 were classified as immunosuppressed and received varicella zoster immune globulin (human), intravenous standard immune globulin, or acyclovir based on serostatus and immune function. The cohort was followed for 4 weeks after the exposure and no secondary infections were diagnosed. We performed a risk assessment and created a management plan to control and prevent further exposure and development of disease. No secondary cases developed. This strategic approach could serve as a model for the management of VZV exposure for other pediatric oncology centers.

Glycoprotein E-Displaying Nanoparticles Induce Robust Neutralizing Antibodies and T-Cell Response against Varicella Zoster Virus.

The Varicella zoster virus (VZV), responsible for both varicella (chickenpox) and herpes zoster (shingles), presents significant global health challenges. While primary VZV infection primarily affects children, leading to chickenpox, reactivation in later life can result in herpes zoster and associated post-herpetic neuralgia, among other complications. Vaccination remains the most effective strategy for VZV prevention, with current vaccines largely based on the attenuated vOka strains. Although these vaccines are generally effective, they can induce varicella-like rashes and have sparked concerns regarding cell virulence. As a safer alternative, subunit vaccines circumvent these issues. In this study, we developed a nanoparticle-based vaccine displaying the glycoprotein E (gE) on ferritin particles using the SpyCatcher/SpyTag system, termed FR-gE. This FR-gE nanoparticle antigen elicited substantial gE-specific binding and VZV-neutralizing antibody responses in BALB/c and C57BL/6 mice-responses that were up to 3.2-fold greater than those elicited by the subunit gE while formulated with FH002C, aluminum hydroxide, or a liposome-based XUA01 adjuvant. Antibody subclass analysis revealed that FR-gE produced comparable levels of IgG1 and significantly higher levels of IgG2a compared to subunit gE, indicating a Th1-biased immune response. Notably, XUA01-adjuvanted FR-gE induced a significant increase in neutralizing antibody response compared to the live attenuated varicella vaccine and recombinant vaccine, Shingrix. Furthermore, ELISPOT assays demonstrated that immunization with FR-gE/XUA01 generated IFN-γ and IL-2 levels comparable to those induced by Shingrix. These findings underscore the potential of FR-gE as a promising immunogen for the development of varicella and herpes zoster vaccines.

Bone Marrow-Suppressive Treatment in Children Is Associated with Diminished IFN-γ Response from T Cells upon Polyclonal and Varicella Zoster Virus Peptide Stimulation.

Severe haematological diseases and lymphoid malignancies require bone marrow (BM)-suppressive treatments. Knowledge regarding the impact of BM-suppressive treatments on children's memory T cells is very limited. Memory T cells play a crucial role in defending against herpesviruses, which is particularly relevant in paediatric cancer care. We studied 53 children in total; 34 with cancer and 2 with severe haematological disorders, with some receiving BM-suppressive treatment with or without allogeneic-haematopoietic stem cell transplantation (allo-HSCT), alongside 17 healthy controls. We focused on peripheral blood proportions of memory T-cell subsets using flow cytometry and analysed cytokine-secreting T cells with a four-parameter FluoroSpot assay in response to T-cell mitogen and varicella zoster virus (VZV) peptides. Patients on BM-suppressive treatment showed increased clusters of differentiation (CD)4+ and CD8+ effector memory (TEM)/terminally differentiated effector (TEFF) T cells compared to the healthy controls. They also exhibited, amongst other things, when compared to the healthy controls, a reduced total number of cytokine-secreting cells, by means of interferon (IFN)-γ, interleukin (IL)-17A, IL-10, and IL-22, following mitogen activation. A diminished IFN-γ response among the children with BM-suppressive treatment was observed upon VZV-peptide stimulation, compared to the healthy children. Collectively, the findings herein indicate that the children who are undergoing or have finished BM-suppressive treatment display qualitative differences in their T-cell memory compartment, potentially increasing their susceptibility to severe viral infections and impacting their immunotherapy, which relies on the functional ability of autologous T cells.

Nectin-1 Is an Entry Mediator for Varicella-Zoster Virus Infection of Human Neurons.

Varicella-zoster virus (VZV) maintains lifelong latency in neurons following initial infection and can subsequently be reactivated to result in herpes zoster or severe neurological manifestations such as encephalitis. Mechanisms of VZV neuropathogenesis have been challenging to study due to the strict human tropism of the virus. Although neuronal entry mediators of other herpesviruses, including herpes simplex virus, have been identified, little is known regarding how VZV enters neurons. Here, we utilize a human stem cell-based neuronal model to characterize cellular factors that mediate entry. Through transcriptional profiling of infected cells, we identify the cell adhesion molecule nectin-1 as a candidate mediator of VZV entry. Nectin-1 is highly expressed in the cell bodies and axons of neurons. Either knockdown of endogenous nectin-1 or incubation with soluble forms of nectin-1 produced in mammalian cells results in a marked decrease in infectivity of neurons. Notably, while addition of soluble nectin-1 during viral infection inhibits infectivity, addition after infection has no effect on infectivity. Ectopic expression of human nectin-1 in a cell line resistant to productive VZV infection confers susceptibility to infection. In summary, we have identified nectin-1 as a neuronal entry mediator of VZV. IMPORTANCE Varicella-zoster virus (VZV) causes chickenpox, gains access to neurons during primary infection where it resides lifelong, and can later be reactivated. Reactivation is associated with shingles and postherpetic neuralgia, as well as with severe neurologic complications, including vasculitis and encephalitis. Although the varicella vaccine substantially decreases morbidity and mortality associated with primary infection, the vaccine cannot prevent the development of neuronal latency, and vaccinated populations are still at risk for reactivation. Furthermore, immunocompromised individuals are at higher risk for VZV reactivation and associated complications. Little is known regarding how VZV enters neurons. Here, we identify nectin-1 as an entry mediator of VZV in human neurons. Identification of nectin-1 as a neuronal VZV entry mediator could lead to improved treatments and preventative measures to reduce VZV related morbidity and mortality.