Neuroinvasive potential of human coronavirus OC43: case report of fatal encephalitis in an immunocompromised host

Remdesivir for the Treatment of Human Coronavirus OC43 Encephalitis

Human coronavirus OC43 (HCoV-OC43) is predominantly associated with mild respiratory infections. HCoV-OC43 also has neuroinvasive properties, and severe encephalitis has been described in immunocompromised patients, with fatal outcomes due to the lack of specific antiviral treatment. We report a case of severe febrile encephalitis attributed to HCoV-OC43 that progressively worsened over 3 months in a 65-year-old immunocompromised man. Clinical symptoms improved remarkably after treatment with remdesivir, with an increase of the Glasgow Coma Score from 8 to 14 within 7 days.

Transcriptome dynamics of the BHK21 cell line in response to human coronavirus OC43 infection

The progress of viral infection involves numerous transcriptional regulatory events. The identification of the newly synthesized transcripts helps us to understand the replication mechanisms and pathogenesis of the virus. Here, we utilized a time-resolved technique called metabolic RNA labeling approach called thiol(SH)-linked alkylation for the metabolic sequencing of RNA (SLAM-seq) to differentially elucidate the levels of steady-state and newly synthesized RNAs of BHK21 cell line in response to human coronavirus OC43 (HCoV-OC43) infection. Our results showed that the Wnt/β-catenin signaling pathway was significantly enriched with the newly synthesized transcripts of BHK21 cell line in response to HCoV-OC43 infection. Moreover, inhibition of the Wnt pathway promoted viral replication in the early stage of infection, but inhibited it in the later stage of infection. Furthermore, remdesivir inhibits the upregulation of the Wnt/β-catenin signaling pathway induced by early infection with HCoV-OC43. Collectively, our study showed the diverse roles of Wnt/β-catenin pathway at different stages of HCoV-OC43 infection, suggesting a potential target for the antiviral treatment. In addition, although infection with HCoV-OC43 induces cytopathic effects in BHK21 cells, inhibiting apoptosis does not affect the intracellular replication of the virus. Monitoring newly synthesized RNA based on such time-resolved approach is a highly promising method for studying the mechanism of viral infections.

Persistence and free chlorine disinfection of human coronaviruses and their surrogates in water

The coronavirus disease 2019 pandemic illustrates the importance of understanding the behavior and control of human pathogenic viruses in the environment. Exposure via water (drinking, bathing, and recreation) is a known route of transmission of viruses to humans, but the literature is relatively void of studies on the persistence of many viruses, especially coronaviruses, in water and their susceptibility to chlorine disinfection. To fill that knowledge gap, we evaluated the persistence and free chlorine disinfection of human coronavirus OC43 (HCoV-OC43) and its surrogates, murine hepatitis virus (MHV) and porcine transmissible gastroenteritis virus (TGEV), in drinking water and laboratory buffer using cell culture methods. The decay rate constants of human coronavirus and its surrogates in water varied, depending on virus and water matrix. In drinking water without disinfectant addition, MHV showed the largest decay rate constant (estimate ± standard error, 2.25 ± 0.09 day-1) followed by HCoV-OC43 (0.99 ± 0.12 day-1) and TGEV (0.65 ± 0.06 day-1), while in phosphate buffer without disinfectant addition, HCoV-OC43 (0.51 ± 0.10 day-1) had a larger decay rate constant than MHV (0.28 ± 0.03 day-1) and TGEV (0.24 ± 0.02 day-1). Upon free chlorine disinfection, the inactivation rates of coronaviruses were independent of free chlorine concentration and were not affected by water matrix, though they still varied between viruses. TGEV showed the highest susceptibility to free chlorine disinfection with the inactivation rate constant of 113.50 ± 7.50 mg-1 min-1 L, followed by MHV (81.33 ± 4.90 mg-1 min-1 L) and HCoV-OC43 (59.42 ± 4.41 mg-1 min-1 L).

IMPORTANCE

This study addresses an important knowledge gap on enveloped virus persistence and disinfection in water. Results have immediate practical applications for shaping evidence-based water policies, particularly in the development of disinfection strategies for pathogenic virus control.

Complications of the Central Nervous System in Pediatric Patients With Common Cold Coronavirus Infection During 2014-2019

BACKGROUND

In pediatric patients, the common cold coronavirus (ccCoV) usually causes mild respiratory illness. There are reports of coronavirus causing central nervous system (CNS) infection in experimental animal models. Some immunocompromised patients have also been reported to have fatal CNS infections with ccCoV. The aim of this study was to investigate the clinical characteristics of CNS complications related to ccCoV infection.

METHODS

From January 2014 to December 2019, a retrospective analysis was performed of medical records from hospitalized patients under 19 years of age whose ccCoV was detected through polymerase chain reaction in respiratory specimens. The CNS complications were defined as clinically diagnosed seizure, meningitis, encephalopathy, and encephalitis.

RESULTS

A total of 436 samples from 420 patients were detected as ccCoV. Among the 420 patients, 269 patients were immunocompetent and 151 patients were immunocompromised. The most common type of ccCoV was OC43 (52% in immunocompetent, 37% in immunocompromised). CNS complications were observed in 9.4% (41/436). The most common type of CNS complication was the fever-provoked seizure under pre-existing neurologic disease (42% in immunocompetent and 60% in immunocompromised patients). Among patients with CNS complications, two immunocompetent patients required intensive care unit admission due to encephalitis. Three patients without underlying neurological disease started anti-seizure medications for the first time at this admission. There was no death related to ccCoV infection.

CONCLUSION

ccCoV infection may cause severe clinical manifestations such as CNS complications or neurologic sequelae, even in previously healthy children.

Neurological Manifestations of Coronavirus Disease 2019 and Mpox in Pediatric Patients and Their Management: A State-of-the-Art Systematic Review

BACKGROUND

There is an increasing number of cases being reported of neurological manifestations of Coronavirus disease 2019 (COVID-19) infection and Monkeypox (Mpox), both during the course of the infection and as a presenting symptom. We aim to review the neurological manifestations of COVID-19 and monkeypox in pediatric patients and their management.

METHODS

We conducted a systematic review that included cohort studies and case series or reports involving a pediatric population of patients with a confirmed COVID-19 or Mpox infection and their neurological manifestations. We searched the following electronic databases: PubMed, EMBASE, and Scopus.

RESULTS

From 1136 articles identified, 127 studies were included. Headache, stroke, Guillain-Barré syndrome, seizure, nerve palsies, and multisystem inflammatory syndrome in children were the most common neurological symptoms caused by COVID-19, whereas encephalitis was commonly seen in patients with Mpox. Rare neurological manifestations of COVID-19 included cerebral venous sinus thrombosis, plexopathies, demyelinating disorders, encephalitis, etc., and rare neurological manifestations of Mpox included headache.

CONCLUSIONS

Our review highlights the importance of investigating possible neurological manifestations and closely monitoring these patients to develop a better understanding of the treatment strategies that can be adopted.

Human Coronavirus OC43 as a Low-Risk Model to Study COVID-19

The coronavirus disease 2019 (COVID-19) pandemic has had irreversible and devastating impacts on every aspect of human life. To better prepare for the next similar pandemic, a clear understanding of coronavirus biology is a prerequisite. Nevertheless, the high-risk nature of the causative agent of COVID-19, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), requires the use of a cumbersome biosafety level-3 (BSL-3) confinement facility. To facilitate the development of preventive and therapeutic measures against SARS-CoV-2, one of the endemic strains of low-risk coronaviruses has gained attention as a useful research alternative: human coronavirus OC43 (HCoV-OC43). In this review, its history, classification, and clinical manifestations are first summarized. The characteristics of its viral genomes, genes, and evolution process are then further explained. In addition, the host factors necessary to support the life cycle of HCoV-OC43 and the innate, as well as adaptive, immunological responses to HCoV-OC43 infection are discussed. Finally, the development of in vitro and in vivo systems to study HCoV-OC43 and its application to the discovery of potential antivirals for COVID-19 by using HCoV-OC43 models are also presented. This review should serve as a concise guide for those who wish to use HCoV-OC43 to study coronaviruses in a low-risk research setting.

Coronaviruses: Troubling Crown of the Animal Kingdom

The existence of coronaviruses has been known for many years. These viruses cause significant disease that primarily seems to affect agricultural species. Human coronavirus disease due to the 2002 outbreak of Severe Acute Respiratory Syndrome and the 2012 outbreak of Middle East Respiratory Syndrome made headlines; however, these outbreaks were controlled, and public concern quickly faded. This complacency ended in late 2019 when alarms were raised about a mysterious virus responsible for numerous illnesses and deaths in China. As we now know, this novel disease called Coronavirus Disease 2019 (COVID-19) was caused by Severe acute respiratory syndrome-related-coronavirus-2 (SARS-CoV-2) and rapidly became a worldwide pandemic. Luckily, decades of research into animal coronaviruses hastened our understanding of the genetics, structure, transmission, and pathogenesis of these viruses. Coronaviruses infect a wide range of wild and domestic animals, with significant economic impact in several agricultural species. Their large genome, low dependency on host cellular proteins, and frequent recombination allow coronaviruses to successfully cross species barriers and adapt to different hosts including humans. The study of the animal diseases provides an understanding of the virus biology and pathogenesis and has assisted in the rapid development of the SARS-CoV-2 vaccines. Here, we briefly review the classification, origin, etiology, transmission mechanisms, pathogenesis, clinical signs, diagnosis, treatment, and prevention strategies, including available vaccines, for coronaviruses that affect domestic, farm, laboratory, and wild animal species. We also briefly describe the coronaviruses that affect humans. Expanding our knowledge of this complex group of viruses will better prepare us to design strategies to prevent and/or minimize the impact of future coronavirus outbreaks.

Comparison of the Antiviral Activity of Remdesivir, Chloroquine, and Interferon-β as Single or Dual Agents Against the Human Beta-Coronavirus OC43

The human beta-coronavirus strain, OC43, provides a useful model for testing the antiviral activity of various agents. We compared the activity of several antiviral drugs against OC43, including remdesivir, chloroquine, interferon (IFN)-β, IFN-λ1, and IFN-λ4, in two distinct cell types: human colorectal carcinoma cell line (HCT-8 cells) and normal human bronchial epithelial (NHBE) cells. We also tested whether these agents mediate additive, synergistic, or antagonistic activity against OC43 infection when used in combination. When used as single agents, remdesivir exhibited stronger antiviral activity than chloroquine, and IFN-β exhibited stronger activity than IFN-λ1 or IFN-λ4 against OC43 in both HCT-8 and NHBE cells. Anakinra (IL-1 inhibitor) and tocilizumab (IL-6 inhibitor) did not mediate any antiviral activity. The combination of IFN-β plus chloroquine or remdesivir resulted in higher synergy scores and higher expression of IFN-stimulated genes than did IFN-β alone. In contrast, the combination of remdesivir plus chloroquine resulted in an antagonistic interaction in NHBE cells. Our findings indicate that the combined use of IFN-β plus remdesivir or chloroquine induces maximal antiviral activity against human coronavirus strain OC43 in primary human respiratory epithelial cells. Furthermore, our experimental OC43 virus infection model provides an excellent method for evaluating the biological activity of antiviral drugs.

Multi-target mechanisms against coronaviruses of constituents from Chinese Dagang Tea revealed by experimental and docking studies

ETHNOPHARMACOLOGICAL RELEVANCE

The leaves of Eurya chinensis（Chinese Dagang Tea）have been consumed as herbal tea for centuries in Guangdong, China, and have also been used to prevent influenza and treat colds and fevers in traditional Chinese medicine. However, there are no reports on the chemical profile and efficacy of its leaves for the treatment of fever and viral infections.

MATERIALS AND METHODS

The chemical constituents of Eurya chinensis leaves were isolated and identified by phytochemical study and spectroscopic data, E. chinensis extracts and compounds were evaluated for their antiviral activities by cytopathic effect (CPE) reduction and antibody-based EC₅₀ assay. The antiviral effect of the main component was confirmed by immunofluorescence and transmission electron microscopy. Virtual screening and docking enzyme inhibition experiments were performed to analyze the anti-coronavirus mechanisms of the compounds from E. chinensis leaves.

RESULTS

In this study, we found for the first time that E. chinensis leaf extract exhibited inhibitory effects against coronaviruses HCoV-OC43 in vitro. Among 23 monomer compounds isolated from E. chinensis leaf extract, the triterpenoids (betulinic acid, α-amyrin) and the flavonoids (naringenin, eriodictyol and quercetin) showed marked antiviral activity. Microscopic optical analyses further demonstrated that betulinic acid can remove virus particles from HCoV-OC43 infected cells. Virtual screening and docking analysis towards the coronavirus in vogue revealed that betulinic acid was able to bind well to PLpro and Nsp14N7-MTase, and that the flavonoids prefer to bind with PLpro, Nsp3MES, NspP14N7-MTase, Nsp16GTA, and Nsp16SAM. The enzyme inhibition experiments demonstrated that betulinic acid (1) exhibited significant inhibition of PLpro and N7-MTase activity of SARS-CoV-2.

CONCLUSION

This study proposes E. chinensis and its triterpenoids and flavonoids as promising potential treatments for coronaviruses.

Alveolar macrophages protect mice from MERS-CoV-induced pneumonia and severe disease

Emerging and re-emerging human coronaviruses (hCoVs) cause severe respiratory illness in humans, but the basis for lethal pneumonia in these diseases is not well understood. Alveolar macrophages (AMs) are key orchestrators of host antiviral defense and tissue tolerance during a variety of respiratory infections, and AM dysfunction is associated with severe COVID-19. In this study, using a mouse model of Middle East respiratory syndrome coronavirus (MERS-CoV) infection, we examined the role of AMs in MERS pathogenesis. Our results show that depletion of AMs using clodronate (CL) liposomes significantly increased morbidity and mortality in human dipeptidyl peptidase 4 knock-in (hDPP4-KI) mice. Detailed examination of control and AM-depleted lungs at different days postinfection revealed increased neutrophil activity but a significantly reduced MERS-CoV-specific CD4 T-cell response in AM-deficient lungs during later stages of infection. Furthermore, enhanced MERS severity in AM-depleted mice correlated with lung inflammation and lesions. Collectively, these data demonstrate that AMs are critical for the development of an optimal virus-specific T-cell response and controlling excessive inflammation during MERS-CoV infection.

cGAS and DDX41-STING mediated intrinsic immunity spreads intercellularly to promote neuroinflammation in SOD1 ALS model

Neuroinflammation exacerbates the progression of SOD1-driven amyotrophic lateral sclerosis (ALS), although the underlying mechanisms remain largely unknown. Herein, we demonstrate that misfolded SOD1 (SOD1^Mut)-causing ALS results in mitochondrial damage, thus triggering the release of mtDNA and an RNA:DNA hybrid into the cytosol in an mPTP-independent manner to activate IRF3- and IFNAR-dependent type I interferon (IFN-I) and interferon-stimulating genes. The neuronal hyper-IFN-I and pro-inflammatory responses triggered in ALS-SOD1^Mut were sufficiently robust to cause a strong physiological outcome in vitro and in vivo. cGAS/DDX41-STING-signaling is amplified in bystander cells through inter-neuronal gap junctions. Our results highlight the importance of a common DNA-sensing pathway between SOD1 and TDP-43 in influencing the progression of ALS.

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Constitutive basal activation of IFN-I was found in the SOD1-ALS animal model

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SOD1-ALS damaged mitochondria to release mtDNA and RNA:DNA to activate the STING-pathway

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Blocking cGAS and STING diminishes neurodegeneration in vivo in the SOD1-ALS model

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Connexin and pannexin channels are required to propagate neuroinflammation in SOD1-ALS

Mechanisms of Entry Into the Central Nervous System by Neuroinvasive Pathogens

BACKGROUND

The literature on neurological manifestations, cerebrospinal fluid analyses, and autopsies in patients with COVID-19 continues to grow. The proposed mechanisms for neurological disease in patients with COVID-19 include indirect processes such as inflammation, microvascular injury, and hypoxic-ischemic damage. An alternate hypothesis suggests direct viral entry of SARS-CoV-2 into the brain and cerebrospinal fluid, given varying reports regarding isolation of viral components from these anatomical sites.

EVIDENCE ACQUISITION

PubMed, Google Scholar databases, and neuroanatomical textbooks were manually searched and reviewed.

RESULTS

We provide clinical concepts regarding the mechanisms of viral pathogen invasion in the central nervous system (CNS); advances in our mechanistic understanding of CNS invasion in well-known neurotropic pathogens can aid in understanding how viruses evolve strategies to enter brain parenchyma. We also present the structural components of CNS compartments that influence viral entry, focusing on hematogenous and transneuronal spread, and discuss this evidence as it relates to our understanding of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2).

CONCLUSIONS

Although there is a paucity of data supporting direct viral entry of SARS-CoV-2 in humans, increasing our knowledge of the structural components of CNS compartments that block viral entry and pathways exploited by pathogens is fundamental to preparing clinicians and researchers for what to expect when a novel emerging virus with neurological symptoms establishes infection in the CNS, and how to design therapeutics to mitigate such an infection.

Stem Cell-based therapies for COVID-19-related acute respiratory distress syndrome

As the number of confirmed cases and resulting death toll of the COVID-19 pandemic continue to increase around the globe - especially with the emergence of new mutations of the SARS-CoV-2 virus in addition to the known alpha, beta, gamma, delta and omicron variants - tremendous efforts continue to be dedicated to the development of interventive therapeutics to mitigate infective symptoms or post-viral sequelae in individuals for which vaccines are not accessible, viable or effective in the prevention of illness. Many of these investigations aim to target the associated acute respiratory distress syndrome, or ARDS, which induces damage to lung epithelia and other physiologic systems and is associated with progression in severe cases. Recently, stem cell-based therapies have demonstrated preliminary efficacy against ARDS based on a number of preclinical and preliminary human safety studies, and based on promising outcomes are now being evaluated in phase II clinical trials for ARDS. A number of candidate stem cell therapies have been found to exhibit low immunogenicity, coupled with inherent tropism to injury sites. In recent studies, these have demonstrated the ability to modulate suppression of pro-inflammatory cytokine signals such as those characterizing COVID-19-associated ARDS. Present translational studies are aiming to optimize the safety, efficacy and delivery to fully validate stem cell-based strategies targeting COVID-19 associated ARDS for viable clinical application.

Montelukast Inhibits HCoV-OC43 Infection as a Viral Inactivator

Coronaviruses (CoVs) consist of a large group of RNA viruses causing various diseases in humans and in lots of animals. Human coronavirus (HCoV) OC43, the prototype of beta-coronavirus discovered in the 1960s, has been circulating in humans for long time, and infection with other emerging strains of beta-coronavirus (SARS-CoV, SARS-CoV-2, and MERS-CoV) can lead to severe illness and death. In this study, we found that montelukast, a leukotriene receptor antagonist, potently inhibited the infection of HCoV-OC43 in distinct cells in a dose- and time- dependent manner. Additionally, the results showed that montelukast induced release of HCoV-OC43 genomic RNA by disrupting the integrity of the viral lipid membrane, and irreversibly inhibited viral infection. Considering the similarity among HCoV-OC43, MERS-CoV, and SARS-CoV-2, it suggests that montelukast may be a potential candidate for the treatment of human beta-coronavirus infection.

The Causes and Long-Term Consequences of Viral Encephalitis

Reports regarding brain inflammation, known as encephalitis, have shown an increasing frequency during the past years. Encephalitis is a relevant concern to public health due to its high morbidity and mortality. Infectious or autoimmune diseases are the most common cause of encephalitis. The clinical symptoms of this pathology can vary depending on the brain zone affected, with mild ones such as fever, headache, confusion, and stiff neck, or severe ones, such as seizures, weakness, hallucinations, and coma, among others. Encephalitis can affect individuals of all ages, but it is frequently observed in pediatric and elderly populations, and the most common causes are viral infections. Several viral agents have been described to induce encephalitis, such as arboviruses, rhabdoviruses, enteroviruses, herpesviruses, retroviruses, orthomyxoviruses, orthopneumovirus, and coronaviruses, among others. Once a neurotropic virus reaches the brain parenchyma, the resident cells such as neurons, astrocytes, and microglia, can be infected, promoting the secretion of pro-inflammatory molecules and the subsequent immune cell infiltration that leads to brain damage. After resolving the viral infection, the local immune response can remain active, contributing to long-term neuropsychiatric disorders, neurocognitive impairment, and degenerative diseases. In this article, we will discuss how viruses can reach the brain, the impact of viral encephalitis on brain function, and we will focus especially on the neurocognitive sequelae reported even after viral clearance.