Zika virus-induced neuro-ocular pathology in immunocompetent mice correlates with anti-ganglioside autoantibodies

Adjusting susceptibilities of C57BL/6 mice to orthoflaviviruses for evaluation of antiviral drugs by altering the levels of interferon alpha/beta receptor function

The purpose of this study was to optimize the infectivity of four different orthoflaviviruses in mice for evaluating antiviral drugs by using wild-type mice with intact interferon responses, type 1 interferon alpha/beta receptor knockout mice, or by injecting wild type C57BL/6 mice with varying doses of anti-type 1 interferon receptor antibody (MAR1-5A3) to optimize the infectivity and lethality. West Nile virus productively infected wild-type C57BL/6 mice to cause lethality, whereas Usutu virus required a complete absence of type 1 interferon receptor function. Deer tick virus (lineage 2 Powassan virus) and Japanese encephalitis viruses required a dampening of type 1 interferon responses by adjusting the doses of MAR1-5A3 antibody injections. Challenge dose-responsive mortality, weight loss, and viral titers of these two viruses were observed if the type 1 interferon responses were dampened with MAR1-5A3. Conversely, without MAR1-5A3 injections, these disease phenotypes were not viral challenge dose-responsive. From these different interferon-responsive models, the appropriate lethality was identified to determine that 7-deaza-2'-C-methyladenosine has high efficacy for West Nile and Usutu viruses, and low efficacy for deer tick and Japanese encephalitis viruses.

Flaviviruses-Induced Neurological Sequelae

Flaviviruses, a group of single-stranded RNA viruses spread by mosquitoes or ticks, include several significant neurotropic viruses, such as West Nile virus (WNV), Japanese encephalitis virus (JEV), tick-borne encephalitis virus (TBEV), and Zika virus (ZIKV). These viruses can cause a range of neurological diseases during acute infection, from mild, flu-like symptoms to severe and fatal encephalitis. A total of 20-50% of patients who recovered from acute flavivirus infections experienced long-term cognitive issues. Here, we discuss these major neurotropic flaviviruses-induced clinical diseases in humans and the recent findings in animal models and provide insights into the underlying disease mechanisms.

Exploring Zika Virus Impact on Endothelial Permeability: Insights into Transcytosis Mechanisms and Vascular Leakage

Treating brain disease is challenging, and the Zika virus (ZIKV) presents a unique obstacle due to its neuroinvasive nature. In this review, we discuss the immunopathogenesis of ZIKV and explore how the virus interacts with the body's immune responses and the role of the protein Mfsd2a in maintaining the integrity of the blood-brain barrier (BBB) during ZIKV neuroinvasion. ZIKV has emerged as a significant public health concern due to its association with severe neurological problems, including microcephaly and Gillain-Barré Syndrome (GBS). Understanding its journey through the brain-particularly its interaction with the placenta and BBB-is crucial. The placenta, which is designed to protect the fetus, becomes a pathway for ZIKV when infected. The BBB is composed of brain endothelial cells, acts as a second barrier, and protects the fetal brain. However, ZIKV finds ways to disrupt these barriers, leading to potential damage. This study explores the mechanisms by which ZIKV enters the CNS and highlights the role of transcytosis, which allows the virus to move through the cells without significantly disrupting the BBB. Although the exact mechanisms of transcytosis are unclear, research suggests that ZIKV may utilize this pathway.

Guillain-barré syndrome (GBS) with antecedent chikungunya infection: a case report and literature review

Guillain-Barré Syndrome (GBS) is an autoimmune neuropathy. Antecedent infections have been seen to be significant triggering factors for developing GBS. Among them, arboviral infections are rapidly gaining importance as significant triggers, especially in the areas where they are endemic. Chikungunya, an arboviral infection that usually causes a self-limiting acute febrile illness can lead to GBS as one its severe complications. Herein, we describe a case of a 21-year-old female who presented with weakness in all four limbs and paresthesia. Nerve conduction study and cerebrospinal fluid (CSF) analysis showed axonal, demyelinating motor and sensory neuropathy with albuminocytological dissociation indicating Acute Motor and Sensory Axonal Neuropathy (AMSAN) variant of GBS. Serum IgM antibodies against ganglioside GM1 were detected. Anti-Chikungunya IgM antibodies were found in both serum and CSF samples. The patient was initiated with Intravenous Immunoglobulin (IVIG) therapy. In view of hypoxia, she was intubated and was on mechanical ventilation. After 2 weeks of being comatose, the patient gradually improved and was discharged with no sequelae.A literature review on antecedent infections in GBS is presented alongside the case report to better understand the association of GBS with antecedent infections, especially the endemic arboviral infections like Chikungunya, Dengue and Zika. This will help in reinforcing the significance of having robust surveillance and public health control measures for infectious diseases.

Pathogenesis and Manifestations of Zika Virus-Associated Ocular Diseases

Zika virus (ZIKV) is mosquito-borne flavivirus that caused a significant public health concern in French Polynesia and South America. The two major complications that gained the most media attention during the ZIKV outbreak were Guillain-Barré syndrome (GBS) and microcephaly in newborn infants. The two modes of ZIKV transmission are the vector-borne and non-vector borne modes of transmission. Aedes aegypti and Aedes albopictus are the most important vectors of ZIKV. ZIKV binds to surface receptors on permissive cells that support infection and replication, such as neural progenitor cells, dendritic cells, dermal fibroblasts, retinal pigment epithelial cells, endothelial cells, macrophages, epidermal keratinocytes, and trophoblasts to cause infection. The innate immune response to ZIKV infection is mediated by interferons and natural killer cells, whereas the adaptive immune response is mediated by CD8⁺T cells, Th1 cells, and neutralizing antibodies. The non-structural proteins of ZIKV, such as non-structural protein 5, are involved in the evasion of the host's immune defense mechanisms. Ocular manifestations of ZIKV arise from the virus' ability to cross both the blood-brain barrier and blood-retinal barrier, as well as the blood-aqueous barrier. Most notably, this results in the development of GBS, a rare neurological complication in acute ZIKV infection. This can yield ocular symptoms and signs. Additionally, infants to whom ZIKV is transmitted congenitally develop congenital Zika syndrome (CZS). The ocular manifestations are widely variable, and include nonpurulent conjunctivitis, anterior uveitis, keratitis, trabeculitis, congenital glaucoma, microphthalmia, hypoplastic optic disc, and optic nerve pallor. There are currently no FDA approved therapeutic agents for treating ZIKV infections and, as such, a meticulous ocular examination is an important aspect of the diagnosis. This review utilized several published articles regarding the ocular findings of ZIKV, antiviral immune responses to ZIKV infection, and the pathogenesis of ocular manifestations in individuals with ZIKV infection. This review summarizes the current knowledge on the viral immunology of ZIKV, interactions between ZIKV and the host's immune defense mechanism, pathological mechanisms, as well as anterior and posterior segment findings associated with ZIKV infection.

Emerging Infection, Vaccination, and Guillain-Barré Syndrome: A Review

Guillain-Barré syndrome (GBS) is an autoimmune disorder of the peripheral nervous system that typically develops within 4 weeks after infection. In addition to conventional infectious diseases with which we are familiar, emerging infectious diseases, such as Zika virus infection and coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), have also been suggested to be associated with GBS. GBS is mainly categorized into a demyelinating subtype known as acute inflammatory demyelinating polyneuropathy (AIDP) and an axonal subtype known as acute motor axonal neuropathy (AMAN). Most patients who develop GBS after Zika virus infection or COVID-19 have AIDP. The concept of molecular mimicry between pathogens and human peripheral nerve components was established through studies of AMAN with anti-ganglioside GM1 antibodies occurring after Campylobacter jejuni infection. Although such mimicry between specific pathogens and myelin or Schwann cell components has not been clearly demonstrated in AIDP, a similarity of Zika virus and SARS-CoV-2 proteins to human proteins has been suggested. With the development of global commerce and travel, emerging infectious diseases will continue to threaten public health. From this viewpoint, the development of vaccines and antiviral drugs is important to prepare for and control emerging infectious diseases. Although a decrease in the number of patients after the 2015-2016 Zika epidemic increased the difficulty in conducting phase 3 trials for Zika virus vaccines, the efficacy and safety of new vaccines have recently been demonstrated for COVID-19. In general, vaccines can decrease the risk of infectious disease by stimulating the immune system, and discussions regarding an increased risk of autoimmune disorders, such as GBS, have been ongoing for many years. However, the risk of GBS is not considered a legitimate reason to limit the administration of currently available vaccines, as only a trivial association or no association with GBS has been demonstrated.

Bioinformatic analyses hinted at augmented T helper 17 cell differentiation and cytokine response as the central mechanism of COVID-19-associated Guillain-Barré syndrome

Objectives

Guillain‐Barré syndrome (GBS) results from autoimmune attack on the peripheral nerves, causing sensory, motor and autonomic abnormalities. Emerging evidence suggests that there might be an association between COVID‐19 and GBS. Nevertheless, the underlying pathophysiological mechanism remains unclear.

Materials and Methods

We performed bioinformatic analyses to delineate the potential genetic crosstalk between COVID‐19 and GBS.

Results

COVID‐19 and GBS were associated with a similar subset of immune/inflammation regulatory genes, including TNF, CSF2, IL2RA, IL1B, IL4, IL6 and IL10. Protein‐protein interaction network analysis revealed that the combined gene set showed an increased connectivity as compared to COVID‐19 or GBS alone, particularly the potentiated interactions with CD86, IL23A, IL27, ISG20, PTGS2, HLA‐DRB1, HLA‐DQB1 and ITGAM, and these genes are related to Th17 cell differentiation. Transcriptome analysis of peripheral blood mononuclear cells from patients with COVID‐19 and GBS further demonstrated the activation of interleukin‐17 signalling in both conditions.

Conclusions

Augmented Th17 cell differentiation and cytokine response was identified in both COVID‐19 and GBS. PBMC transcriptome analysis also suggested the pivotal involvement of Th17 signalling pathway. In conclusion, our data suggested aberrant Th17 cell differentiation as a possible mechanism by which COVID‐19 can increase the risk of GBS.