The Spectrum of Neurological Manifestations of Varicella-Zoster Virus Reactivation

Expanded spectrum of varicella disease and the need for vaccination in India

Varicella vaccine was first licensed in Japan and South Korea in 1989 for use in healthy children and was introduced in US in 1995. So far, 29 countries have adopted varicella vaccine in their universal immunization program (UIP). No Asian country, India included, has adopted the varicella vaccine as part of their UIP. The extra-cutaneous sites for VZV diseases are central nervous system and gastrointestinal tract, the expanded disease spectrum includes vasculopathy, myelitis, inflammatory bowel disease, perforated ulcers, and gastritis. The actual disease burden of varicella is not known as most of the infected individuals may not visit the physician. The amplifiable VZV DNA will not always be detectable in cerebrospinal fluid (CSF) samples in protracted illnesses such as vasculopathies, but demonstrable anti-VZV IgG in CSF has diagnostic value. The World Health Organization (WHO) position paper 2014 recommends two doses of varicella and zoster vaccines in targeted population. In India, varicella vaccine is not included in the UIP due to the cost and the belief that lifelong immunity occurs following primary infection. The expanded spectrum of VZV disease and the mounting body of evidence, however, suggest the need for both varicella and zoster vaccines in routine immunization schedule.

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.

[Clinical presentation and treatment of herpes zoster and postherpetic neuralgia]

Herpes zoster (HZ) is a common disease caused by reactivation of varicella zoster virus. Diagnosis is usually based on the typical clinical presentation. Standard treatment includes antiviral, topical and analgesic therapies. As a complication, postherpetic neuralgia (PHN) can result from acute HZ infection, particularly in older and/or immunocompromised people. This can seriously impair the quality of life of those affected and requires adequate analgesia. In addition to the genesis, clinical presentation and treatment recommendations for HZ and PHN, this article also deals in particular with the vaccination prophylaxis recommended by the standing vaccination commission of the Robert Koch Institute (STIKO).

Genetics of causal relationships between circulating inflammatory proteins and postherpetic neuralgia: a bidirectional Mendelian randomization study

Objective

According to data from several observational studies, there is a strong association between circulating inflammatory cytokines and postherpetic neuralgia (PHN), but it is not clear whether this association is causal or confounding; therefore, the main aim of the present study was to analyze whether circulating inflammatory proteins have a bidirectional relationship with PHN at the genetic inheritance level using a Mendelian randomization (MR) study.

Methods

The Genome-Wide Association Study (GWAS) database was used for our analysis. We gathered data on inflammation-related genetic variation from three GWASs of human cytokines. These proteins included 91 circulating inflammatory proteins, tumor necrosis factor-alpha (TNF-α), macrophage inflammatory protein 1b (MIP-1b), and CXC chemokine 13 (CXCL13). The PHN dataset was obtained from the FinnGen biobank analysis round 5, and consisted of 1,413 cases and 275,212 controls. We conducted a two-sample bidirectional MR study using the TwoSampleMR and MRPRESSO R packages (version R.4.3.1). Our main analytical method was inverse variance weighting (IVW), and we performed sensitivity analyses to assess heterogeneity and pleiotropy, as well as the potential influence of individual SNPs, to validate our findings.

Results

According to our forward analysis, five circulating inflammatory proteins were causally associated with the development of PHN: interleukin (IL)-18 was positively associated with PHN, and IL-13, fibroblast growth factor 19 (FGF-19), MIP-1b, and stem cell growth factor (SCF) showed reverse causality with PHN. Conversely, we found that PHN was closely associated with 12 inflammatory cytokines, but no significant correlation was found among the other inflammatory factors. Among them, only IL-18 had a bidirectional causal relationship with PHN.

Conclusion

Our research advances the current understanding of the role of certain inflammatory biomarker pathways in the development of PHN. Additional verification is required to evaluate the viability of these proteins as targeted inflammatory factors for PHN-based treatments.

Associations of infections and vaccines with Alzheimer's disease point to a role of compromised immunity rather than specific pathogen in AD

INTRODUCTION

Diverse pathogens (viral, bacterial, fungal) have been associated with Alzheimer's disease (AD) and related traits in various studies. This suggests that compromised immunity, rather than specific microbes, may play a role in AD by increasing an individual's vulnerability to various infections, which could contribute to neurodegeneration. If true, then vaccines that have heterologous effects on immunity, extending beyond protection against the targeted disease, may hold a potential for AD prevention.

METHODS

We evaluated the associations of common adult infections (herpes simplex, zoster (shingles), pneumonia, and recurrent mycoses), and vaccinations against shingles and pneumonia, with the risks of AD and other dementias in a pseudorandomized sample of the Health and Retirement Study (HRS).

RESULTS

Shingles, pneumonia and mycoses, diagnosed between ages 65 and 75, were all associated with significantly increased risk of AD later in life, by 16 %-42 %. Pneumococcal and shingles vaccines administered between ages 65-75 were both associated with a significantly lower risk of AD, by 15 %-21 %. These effects became less pronounced when AD was combined with other dementias.

DISCUSSION

Our findings suggest that both the pneumococcal polysaccharide vaccine and the live attenuated zoster vaccine can offer significant protection against AD. It remains to be determined if non-live shingles vaccine has a similar beneficial effect on AD. This study also found significant associations of various infections with the risk of AD, but not with the risks of other dementias. This indicates that vulnerability to infections may play a more significant role in AD than in other types of dementia, which warrants further investigation.

Varicella zoster virus-induced autophagy in human neuronal and hematopoietic cells exerts antiviral activity

Autophagy is a degradational pathway with pivotal roles in cellular homeostasis and survival, including protection of neurons in the central nervous system (CNS). The significance of autophagy as antiviral defense mechanism is recognized and some viruses hijack and modulate this process to their advantage in certain cell types. Here, we present data demonstrating that the human neurotropic herpesvirus varicella zoster virus (VZV) induces autophagy in human SH-SY5Y neuronal cells, in which the pathway exerts antiviral activity. Productively VZV-infected SH-SY5Y cells showed increased LC3-I-LC3-II conversion as well as co-localization of the viral glycoprotein E and the autophagy receptor p62. The activation of autophagy was dependent on a functional viral genome. Interestingly, inducers of autophagy reduced viral transcription, whereas inhibition of autophagy increased viral transcript expression. Finally, the genotype of patients with severe ocular and brain VZV infection were analyzed to identify potential autophagy-associated inborn errors of immunity. Two patients expressing genetic variants in the autophagy genes ULK1 and MAP1LC3B2, respectively, were identified. Notably, cells of both patients showed reduced autophagy, alongside enhanced viral replication and death of VZV-infected cells. In conclusion, these results demonstrate a neuro-protective role for autophagy in the context of VZV infection and suggest that failure to mount an autophagy response is a potential predisposing factor for development of severe VZV disease.

Guillain-Barre syndrome of acute motor axonal neuropathy (AMAN) type associated with herpes zoster: a case report

Guillain Barre syndrome (GBS) following Varicella zoster is a rare presentation and has only been reported in a few cases around the world. Of the reported cases, the type of GBS is not specified in the majority, and where specified is of the acute inflammatory demyelinating polyradiculoneuropathy (AIDP) type. We report a case of acute motor axonal neuropathy (AMAN) type GBS following herpes zoster in a 27-year-old male who presented with bilateral lower limb weakness and left sided lower motor neuron type facial nerve palsy a week after herpes zoster infection.

Don't rash it! The clinical significance of positive Varicella zoster virus PCR in cerebrospinal fluid of patients with neurological symptoms

BACKGROUND

Varicella zoster virus (VZV) is among the leading pathogens causing meningitis and encephalitis. While VZV-PCR-positive CSF is considered a gold-standard for diagnosis, it is not-uncommon to detect VZV-DNA in CSF of patients with other acute or chronic illness. Our goal was to determine the clinical relevance of VZV-PCR-positive CSF when investigating patients with neurological symptoms.

METHODS

In this retrospective cohort from the largest hospital in Israel, we collected demographic, clinical and laboratory data of patients with VZV-PCR-positive CSF, analyzing the significance of various parameters.

RESULTS

During a 5-years study, 125 patient-unique VZV-PCR-positive CSFs were recorded, in which only 9 alternative diagnoses were noted. The commonest symptoms were headache (N = 104, 83 %) and rash (N = 96, 76 %). PCR-cycle-threshold (Ct), a surrogate of viral burden, did not significantly vary across the clinical manifestations; however, patients with rash and Ct<35 were prone to develop stroke in the following year (N = 6, 7 %). Empiric nucleoside-analogue treatment was not associated with a better outcome compared to treatment administered upon a positive-PCR result.

DISCUSSION

Our findings suggest that in patients with neurological symptoms, detection of VZV-DNA in CSF renders VZV the probable culprit. Nevertheless, a systematic evaluation of treatment and follow-up algorithms of patients with suspected or proved VZV meningitis and encephalitis is needed. The benefits of a prompt treatment should be weighed against the potential complications of nucleoside-analogue. Conversely, the propensity for stroke in patients with higher viral-burden, necessitates further studies assessing VZV causal role, directing additional workup, treatment and monitoring policy.