Persistence of Ebola Virus in Ocular Fluid during Convalescence

Fatal meningoencephalitis associated with Ebola virus persistence in two survivors of Ebola virus disease in the Democratic Republic of the Congo: a case report study

BACKGROUND

During the 2018-20 Ebola virus disease outbreak in the Democratic Republic of the Congo, thousands of patients received unprecedented vaccination, monoclonal antibody (mAb) therapy, or both, leading to a large number of survivors. We aimed to report the clinical, virological, viral genomic, and immunological features of two previously vaccinated and mAb-treated survivors of Ebola virus disease in the Democratic Republic of the Congo who developed second episodes of disease months after initial discharge, ultimately complicated by fatal meningoencephalitis associated with viral persistence.

METHODS

In this case report study, we describe the presentation, management, and subsequent investigations of two patients who developed recrudescent Ebola virus disease and subsequent fatal meningoencephalitis. We obtained data from epidemiological databases, Ebola treatment units, survivor programme databases, laboratory datasets, and hospital records. Following national protocols established during the 2018-20 outbreak in the Democratic Republic of the Congo, blood, plasma, and cerebrospinal fluid (CSF) samples were collected during the first and second episodes of Ebola virus disease from both individuals and were analysed by molecular (quantitative RT-PCR and next-generation sequencing) and serological (IgG and IgM ELISA and Luminex assays) techniques.

FINDINGS

The total time between the end of the first Ebola virus episode and the onset of the second episode was 342 days for patient 1 and 137 days for patient 2. In both patients, Ebola virus RNA was detected in blood and CSF samples during the second episode of disease. Complete genomes from CSF samples from this relapse episode showed phylogenetic relatedness to the genome sequenced from blood samples collected from the initial infection, confirming in-host persistence of Ebola virus. Serological analysis showed an antigen-specific humoral response with typical IgM and IgG kinetics in patient 1, but an absence of an endogenous adaptive immune response in patient 2.

INTERPRETATION

We report the first two cases of fatal meningoencephalitis associated with Ebola virus persistence in two survivors of Ebola virus disease who had received vaccination and mAb-based treatment in the Democratic Republic of the Congo. Our findings highlight the importance of long-term monitoring of survivors, including continued clinical, virological, and immunological profiling, as well as the urgent need for novel therapeutic strategies to prevent and mitigate the individual and public health consequences of Ebola virus persistence.

FUNDING

Ministry of Health of the Democratic Republic of the Congo, Institut National de Recherche Biomédicale, Infectious Disease Rapid Response Reserve Fund, US Centers for Disease Control and Prevention, French National Research Institute for Development, and WHO.

Clinical characteristics and aetiology of uveitis in a viral haemorrhagic fever zone

BACKGROUND/OBJECTIVES

Studies on uveitis in Sierra Leone were conducted prior to the Ebola Virus Disease epidemic of 2013-16, which was associated with uveitis in 20% of survivors. They did not include imaging or investigation of tuberculosis and used laboratory services outside the country. We performed a cross-sectional study on patients presenting with uveitis to establish their clinical characteristics and identify the impact of in-country laboratory diagnoses.

METHODS

We invited uveitis cases presenting to Eye Clinics in Sierra Leone from March to September 2022 to participate in the study. They underwent a diagnostic work-up, including fundus and ocular coherence tomography imaging. Active uveitis cases underwent further investigations including serology and immunological tests for syphilis, tuberculosis, herpetic viruses and HIV and chest radiographs.

RESULTS

We recruited 128 patients. The median age was 34 (IQR 19) years and there was an equal gender split. Panuveitis was the predominant anatomical uveitis type (n = 51, 40%), followed by posterior uveitis (n = 36, 28%). Bilateral disease affected 40 patients (31%). Active uveitis was identified in 75 (59%) cases. ICD 11 definition of blindness with VA < 3/60 occurred in 55 (33%) uveitis eyes. Aetiology of uveitis from clinical and laboratory assessment demonstrated that most cases were of undifferentiated aetiology (n = 66, 52%), followed by toxoplasmosis (n = 46, 36%). Trauma contributed to eight (6%) cases, syphilis to 5 (4%) cases and Ebola to 2 (2%).

CONCLUSIONS

Uveitis was associated with high levels of visual impairment. Posterior and panuveitis contributed to the highest proportion of uveitis cases. Laboratory studies helped differentiate syphilis as a significant aetiology of uveitis.

Ebola virus-induced eye sequelae: a murine model for evaluating glycoprotein-targeting therapeutics

BACKGROUND

Ebola virus disease (EVD) survivors experience ocular sequelae including retinal lesions, cataracts, and vision loss. While monoclonal antibodies targeting the Ebola virus glycoprotein (EBOV-GP) have shown promise in improving prognosis, their effectiveness in mitigating ocular sequelae remains uncertain.

METHODS

We developed and characterized a BSL-2-compatible immunocompetent mouse model to evaluate therapeutics targeting EBOV-GP by inoculating neonatal mice with vesicular stomatitis virus expressing EBOV-GP (VSV-EBOV). To examine the impact of anti-EBOV-GP antibody treatment on acute retinitis and ocular sequelae, VSV-EBOV-infected mice were treated with polyclonal antibodies or monoclonal antibody preparations with antibody-dependent cellular cytotoxicity (ADCC-mAb) or neutralizing activity (NEUT-mAb).

FINDINGS

Treatment with all anti-EBOV-GP antibodies tested dramatically reduced viremia and improved survival. Further, all treatments reduced the incidence of cataracts. However, NEUT-mAb alone or in combination with ADCC-mAb reduced viral load in the eyes, downregulated the ocular immune and inflammatory responses, and minimized retinal damage more effectively.

INTERPRETATION

Anti-EBOV-GP antibodies can improve survival among EVD patients, but improved therapeutics are needed to reduce life altering sequelae. This animal model offers a new platform to examine the acute and long-term effect of the virus in the eye and the relative impact of therapeutic candidates targeting EBOV-GP. Results indicate that even antibodies that improve systemic viral clearance and survival can differ in their capacity to reduce acute ocular inflammation, and long-term retinal pathology and corneal degeneration.

FUNDING

This study was partly supported by Postgraduate Research Fellowship Awards from ORISE through an interagency agreement between the US DOE and the US FDA.

Causes of infectious pediatric uveitis: A review

Infectious pediatric uveitis is a rare disease that can cause severe ocular damage if not detected rapidly and treated properly. Additionally, early identification of an infection can protect the child from life-threatening systemic infection. Infectious uveitis can be congenital or acquired and may manifest as a primary ocular infection or as a reactivation. Nevertheless, publications on infectious paediatric uveitis are usually limited to a small number of patients or a case report. So far, most studies on uveitis in children have focused primarily on noninfectious uveitis, and a systematic study on infectious uveitis is lacking. In this review, we summarize the literature on infectious uveitis in pediatric populations and report on the epidemiology, pathophysiology, clinical signs, diagnostic tests, and treatment. We will describe the different possible pathogens causing uveitis in childhood by microbiological group (i.e. parasites, viruses, bacteria, and fungi). We aim to contribute to early diagnosis and management of infectious pediatric uveitis, which in turn might improve not only visual outcome, but also the general health outcome.

SARS-CoV-2 infects cells lining the blood-retinal barrier and induces a hyperinflammatory immune response in the retina via systemic exposure

SARS-CoV-2 has been shown to cause wide-ranging ocular abnormalities and vision impairment in COVID-19 patients. However, there is limited understanding of SARS-CoV-2 in ocular transmission, tropism, and associated pathologies. The presence of viral RNA in corneal/conjunctival tissue and tears, along with the evidence of viral entry receptors on the ocular surface, has led to speculation that the eye may serve as a potential route of SARS-CoV-2 transmission. Here, we investigated the interaction of SARS-CoV-2 with cells lining the blood-retinal barrier (BRB) and the role of the eye in its transmission and tropism. The results from our study suggest that SARS-CoV-2 ocular exposure does not cause lung infection and moribund illness in K18-hACE2 mice despite the extended presence of viral remnants in various ocular tissues. In contrast, intranasal exposure not only resulted in SARS-CoV-2 spike (S) protein presence in different ocular tissues but also induces a hyperinflammatory immune response in the retina. Additionally, the long-term exposure to viral S-protein caused microaneurysm, retinal pigmented epithelium (RPE) mottling, retinal atrophy, and vein occlusion in mouse eyes. Notably, cells lining the BRB, the outer barrier, RPE, and the inner barrier, retinal vascular endothelium, were highly permissive to SARS-CoV-2 replication. Unexpectedly, primary human corneal epithelial cells were comparatively resistant to SARS-CoV-2 infection. The cells lining the BRB showed induced expression of viral entry receptors and increased susceptibility towards SARS-CoV-2-induced cell death. Furthermore, hyperglycemic conditions enhanced the viral entry receptor expression, infectivity, and susceptibility of SARS-CoV-2-induced cell death in the BRB cells, confirming the reported heightened pathological manifestations in comorbid populations. Collectively, our study provides the first evidence of SARS-CoV-2 ocular tropism via cells lining the BRB and that the virus can infect the retina via systemic permeation and induce retinal inflammation.

Effect of anti-Ebola virus monoclonal antibodies on endogenous antibody production in survivors of Ebola virus disease in the Democratic Republic of the Congo: an observational cohort study

BACKGROUND

The use of specific anti-Ebola virus therapy, especially monoclonal antibodies, has improved survival in patients with Ebola virus disease. We aimed to assess the effect of monoclonal antibodies on anti-Ebola virus antibody responses in survivors of the 2018-20 Ebola outbreak in the Democratic Republic of the Congo.

METHODS

In this observational prospective cohort study, participants were enrolled at three Ebola survivor clinics in Beni, Mangina, and Butembo (Democratic Republic of the Congo). Eligible children and adults notified as survivors of Ebola virus disease (ie, who had confirmed Ebola virus disease [RT-PCR positive in blood sample] and were subsequently declared recovered from the virus [RT-PCR negative in blood sample] with a certificate of recovery from Ebola virus disease issued by an Ebola treatment centre) during the 2018-20 Ebola virus disease outbreak were invited to participate in the study. Participants were recruited on discharge from Ebola treatment centres and followed up for 12-18 months depending on recruitment date. Routine follow-up assessments were done at 1, 3, 6, and 12-18 months after inclusion. We collected sociodemographic (age, sex, visit site), clinical (anti-Ebola virus drugs), and laboratory data (RT-PCR and Ct values). The primary outcome was the antibody concentrations against Ebola virus glycoprotein, nucleoprotein, and 40-kDa viral protein antigens over time assessed in all participants. Antibody concentrations were measured by the multiplex immunoassay, and the association between anti-Ebola virus antibody levels and the relevant exposures, such as anti-Ebola virus disease drugs (ansuvimab, REGN-EB3, ZMapp, or remdesivir), was assessed using both linear and logistic mixed regression models. This study is registered at ClinicalTrials.gov, NCT04409405.

FINDINGS

Between April 16, 2020, and Oct 18, 2021, 1168 survivors were invited to participate in the Les Vainqueurs d'Ebola cohort study. 787 survivors were included in the study, of whom 358 had data available for antibody responses. 85 (24%) of 358 were seronegative for at least two Ebola virus antigens on discharge from the Ebola treatment centre. The antibody response over time fluctuated but a continuous decrease in an overall linear evolution was observed. Quantitative modelling showed a decrease in nucleoprotein, glycoprotein, and VP-40 antibody concentrations over time (p<0·0001) with the fastest decrease observed for glycoprotein. The probability of being seropositive for at least two antigens after 36 months was 53·6% (95% CI 51·6-55·6) for participants who received ansuvimab, 73·5% (71·5-75·5) for participants who received REGN-EB3, 76·8% (74·8-78·8) for participants who received remdesivir, and 78·5% (76·5-80·5) for participants who received ZMapp.

INTERPRETATION

Almost a quarter of survivors were seronegative on discharge from the Ebola treatment centre and antibody concentrations decreased rapidly over time. These results indicate that monoclonal antibodies might negatively affect the production of anti-Ebola virus antibodies in survivors of Ebola virus disease which could increase the risk of reinfection or reactivation.

FUNDING

The French National Agency for AIDS Research-Emergent Infectious Diseases-The French National Institute of Health and Medical Research, the French National Research Institute for Development, and the European and Developing Countries Clinical Trials Partnership.

TRANSLATION

For the French translation of the abstract see Supplementary Materials section.

2020 Ebola virus disease outbreak in Équateur Province, Democratic Republic of the Congo: a retrospective genomic characterisation

BACKGROUND

The Democratic Republic of the Congo has had 15 Ebola virus disease (EVD) outbreaks, from 1976 to 2023. On June 1, 2020, the Democratic Republic of the Congo declared an outbreak of EVD in the western Équateur Province (11th outbreak), proximal to the 2018 Tumba and Bikoro outbreak and concurrent with an outbreak in the eastern Nord Kivu Province. In this Article, we assessed whether the 11th outbreak was genetically related to previous or concurrent EVD outbreaks and connected available epidemiological and genetic data to identify sources of possible zoonotic spillover, uncover additional unreported cases of nosocomial transmission, and provide a deeper investigation into the 11th outbreak.

METHODS

We analysed epidemiological factors from the 11th EVD outbreak to identify patient characteristics, epidemiological links, and transmission modes to explore virus spread through space, time, and age groups in the Équateur Province, Democratic Republic of the Congo. Trained field investigators and health professionals recorded data on suspected, probable, and confirmed cases, including demographic characteristics, possible exposures, symptom onset and signs and symptoms, and potentially exposed contacts. We used blood samples from individuals who were live suspected cases and oral swabs from individuals who were deceased to diagnose EVD. We applied whole-genome sequencing of 87 available Ebola virus genomes (from 130 individuals with EVD between May 19 and Sept 16, 2020), phylogenetic divergence versus time, and Bayesian reconstruction of phylogenetic trees to calculate viral substitution rates and study viral evolution. We linked the available epidemiological and genetic datasets to conduct a genomic and epidemiological study of the 11th EVD outbreak.

FINDINGS

Between May 19 and Sept 16, 2020, 130 EVD (119 confirmed and 11 probable) cases were reported across 13 Équateur Province health zones. The individual identified as the index case reported frequent consumption of bat meat, suggesting the outbreak started due to zoonotic spillover. Sequencing revealed two circulating Ebola virus variants associated with this outbreak-a Mbandaka variant associated with the majority (97%) of cases and a Tumba-like variant with similarity to the ninth EVD outbreak in 2018. The Tumba-like variant exhibited a reduced substitution rate, suggesting transmission from a previous survivor of EVD.

INTERPRETATION

Integrating genetic and epidemiological data allowed for investigative fact-checking and verified patient-reported sources of possible zoonotic spillover. These results demonstrate that rapid genetic sequencing combined with epidemiological data can inform responders of the mechanisms of viral spread, uncover novel transmission modes, and provide a deeper understanding of the outbreak, which is ultimately needed for infection prevention and control during outbreaks.

FUNDING

WHO and US Centers for Disease Control and Prevention.

Ophthalmic implications of biological threat agents according to the chemical, biological, radiological, nuclear, and explosives framework

As technology continues to evolve, the possibility for a wide range of dangers to people, organizations, and countries escalate globally. The United States federal government classifies types of threats with the capability of inflicting mass casualties and societal disruption as Chemical, Biological, Radiological, Nuclear, and Energetics/Explosives (CBRNE). Such incidents encompass accidental and intentional events ranging from weapons of mass destruction and bioterrorism to fires or spills involving hazardous or radiologic material. All of these have the capacity to inflict death or severe physical, neurological, and/or sensorial disabilities if injuries are not diagnosed and treated in a timely manner. Ophthalmic injury can provide important insight into understanding and treating patients impacted by CBRNE agents; however, improper ophthalmic management can result in suboptimal patient outcomes. This review specifically addresses the biological agents the Center for Disease Control and Prevention (CDC) deems to have the greatest capacity for bioterrorism. CBRNE biological agents, encompassing pathogens and organic toxins, are further subdivided into categories A, B, and C according to their national security threat level. In our compendium of these biological agents, we address their respective CDC category, systemic and ophthalmic manifestations, route of transmission and personal protective equipment considerations as well as pertinent vaccination and treatment guidelines.

Select Agent Regulatory Challenges in a Patient Care Setting: Review and Recommendations

The Federal Select Agent Program ensures the safe and secure possession, use, and transfer of biological select agents and toxins through the select agent regulations (42 CFR §73, 7 CFR §331, and 9 CFR §121). These regulations are primarily written for interpretation by diagnostic and research laboratories, with limited text pertaining to the care of individuals infected with a select agent. The regulations applicable to patient care settings are ambiguous, resulting in challenges with regulatory compliance. The COVID-19 pandemic called attention to these shortcomings and the need to clarify and modify the select agent regulations. In this article, we discuss 3 select agent regulation phrases regarding patient care that need clarification-specifically, the window of time to transfer, patient care setting, and conclusion of patient care-and provide recommendations for improvement. These recommendations include implementing minimum security standards to safeguard patient specimens against theft, loss, or release prior to the appropriate transfer or destruction of the material and increasing the time allowed for the transfer or destruction of specimens before entities are subject to the select agent regulations. We encourage the Federal Select Agent Program to release a policy statement clarifying the select agent regulations regarding patient care discussed herein and to lengthen the designated time to destroy or transfer agents to a registered entity. Addressing these challenges will aid in compliance with the select agent regulations in patient care settings.

Ebola virus disease in children: epidemiology, pathogenesis, management, and prevention

Ebola disease is a severe disease with extremely high case-fatality rates ranging from 28-100%. Observations made during the 2013-2016 West African epidemic improved our understanding of the clinical course of Ebola disease and accelerated the study of therapeutic and preventative strategies. The epidemic also highlighted the unique challenges associated with providing optimal care for children during Ebola disease outbreaks. In this review, we outline current understanding of Ebola disease epidemiology, pathogenesis, management, and prevention, highlighting data pertinent to the care of children. IMPACT: In this review, we summarize recent advancements in our understanding of Ebola disease epidemiology, clinical presentation, and therapeutic and preventative strategies. We highlight recent data pertinent to the care of children and pregnant women and identify research gaps for this important emerging viral infection in children.

The economic burden of Ebola virus disease: a review and recommendations for analysis

BACKGROUND

Ebola virus disease (EVD) continues to be a major public health threat globally, particularly in the low-and-middle-income countries (LMICs) of Africa. The social and economic burdens of EVD are substantial and have triggered extensive research into prevention and control. We aim to highlight the impact and economic implications, identify research gaps, and offer recommendations for future economic studies pertaining to EVD.

METHOD

We conducted a comprehensive librarian-led search in PubMed/Medline, Embase, Google Scholar, EconLit and Scopus for economic evaluations of EVD. After study selection and data extraction, findings on the impact and economics of EVD were synthesized using a narrative approach, while identifying gaps, and recommending critical areas for future EVD economic studies.

RESULTS

The economic evaluations focused on the burden of illness, vaccine cost-effectiveness, willingness-to-pay for a vaccine, EVD funding, and preparedness costs. The estimated economic impact of the 2014 EVD outbreak in Guinea, Liberia, and Sierra Leone across studies ranged from $30 billion to $50 billion. Facility construction and modification emerged as significant cost drivers for preparedness. The EVD vaccine demonstrated cost-effectiveness in a dynamic transmission model; resulting in an incremental cost-effectiveness ratio of about $96 per additional disability adjusted life year averted. Individuals exhibited greater willingness to be vaccinated if it incurred no personal cost, with a minority willing to pay about $1 for the vaccine.

CONCLUSIONS

The severe impact of EVD puts pressure on governments and the international community for better resource utilization and re-allocation. Several technical and methodological issues related to economic evaluation of EVD remain to be addressed, especially for LMICs. We recommend conducting cost-of-sequelae and cost-of-distribution analyses in addition to adapting existing economic analytical methods to EVD. Characteristics of the affected regions should be considered to provide evidence-based economic plans and economic-evaluation of mitigations that enhance resource allocation for prevention and treatment.

Viral infections and pathogenesis of glaucoma: a comprehensive review

Glaucoma is a leading cause of irreversible blindness worldwide, caused by the gradual degeneration of retinal ganglion cells and their axons. While glaucoma is primarily considered a genetic and age-related disease, some inflammatory conditions, such as uveitis and viral-induced anterior segment inflammation, cause secondary or uveitic glaucoma. Viruses are predominant ocular pathogens and can impose both acute and chronic pathological insults to the human eye. Many viruses, including herpes simplex virus, varicella-zoster virus, cytomegalovirus, rubella virus, dengue virus, chikungunya virus, Ebola virus, and, more recently, Zika virus (ZIKV) and severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), have been associated with sequela of either primary or secondary glaucoma. Epidemiological and clinical studies suggest the association between these viruses and subsequent glaucoma development. Despite this, the ocular manifestation and sequela of viral infections are not well understood. In fact, the association of viruses with glaucoma is considered relatively uncommon in part due to underreporting and/or lack of long-term follow-up studies. In recent years, literature on the pathological spectrum of emerging viral infections, such as ZIKV and SARS-CoV-2, has strengthened this proposition and renewed research activity in this area. Clinical studies from endemic regions as well as laboratory and preclinical investigations demonstrate a strong link between an infectious trigger and development of glaucomatous pathology. In this article, we review the current understanding of the field with a particular focus on viruses and their association with the pathogenesis of glaucoma.

Natural history of Ebola virus disease in rhesus monkeys shows viral variant emergence dynamics and tissue-specific host responses

Ebola virus (EBOV) causes Ebola virus disease (EVD), marked by severe hemorrhagic fever; however, the mechanisms underlying the disease remain unclear. To assess the molecular basis of EVD across time, we performed RNA sequencing on 17 tissues from a natural history study of 21 rhesus monkeys, developing new methods to characterize host-pathogen dynamics. We identified alterations in host gene expression with previously unknown tissue-specific changes, including downregulation of genes related to tissue connectivity. EBOV was widely disseminated throughout the body; using a new, broadly applicable deconvolution method, we found that viral load correlated with increased monocyte presence. Patterns of viral variation between tissues differentiated primary infections from compartmentalized infections, and several variants impacted viral fitness in a EBOV/Kikwit minigenome system, suggesting that functionally significant variants can emerge during early infection. This comprehensive portrait of host-pathogen dynamics in EVD illuminates new features of pathogenesis and establishes resources to study other emerging pathogens.

The evolution and determinants of neutralization of potent head-binding antibodies against Ebola virus

Monoclonal antibodies against the Ebola virus (EBOV) surface glycoprotein are effective treatments for EBOV disease. Antibodies targeting the EBOV glycoprotein (GP) head epitope have potent neutralization and Fc effector function activity and thus are of high interest as therapeutics and for vaccine design. Here we focus on the head-binding antibodies 1A2 and 1D5, which have been identified previously in a longitudinal study of survivors of EBOV infection. 1A2 and 1D5 have the same heavy- and light-chain germlines despite being isolated from different individuals and at different time points after recovery from infection. Cryoelectron microscopy analysis of each antibody in complex with the EBOV surface GP reveals key amino acid substitutions in 1A2 that contribute to greater affinity, improved neutralization potency, and enhanced breadth as well as two strategies for antibody evolution from a common site.

Atypical Ebola Virus Disease in a Rhesus Macaque

Ebola virus (EBOV)-Makona infected more than 30 000 people from 2013 to 2016 in West Africa, among them many health care workers including foreign nationals. Most of the infected foreign nationals were evacuated and treated in their respective home countries, resulting in detailed reports of the acute disease following EBOV infection as well as descriptions of symptoms now known as post-Ebola syndrome, which occurred months after the infection. Symptoms associated with this syndrome include uveitis and neurological manifestations. In 1 of our EBOV-Makona nonhuman primate (NHP) studies, 1 NHP was euthanized on day 28 after infection having completely recovered from the acute disease. During convalescence, this NHP developed neurological signs and acute respiratory distress requiring euthanasia. The organ tropism had changed with high virus titers in lungs, brain, eye, and reproductive organs but no virus in the typical target organs for acute EBOV infection. This in part reflects sequelae described for EBOV survivors albeit developing quicker after recovery from acute disease.

Ebola Virus Tropism in Ex Vivo Cynomolgus Macaque Ocular Tissues

Ocular complications of Ebola virus disease are well-documented and long-term sequelae in survivors are common and lead to considerable morbidity. However, little is currently known regarding EBOV's tropism and replication kinetics within the eye. To date, limited studies have utilized in vitro infections of ocular cell lines and analyses of archived pathology samples to investigate these issues. Here, we employed ex vivo cultures of cynomolgus macaque eyes to determine the tropism of EBOV in 7 different ocular tissues: cornea, anterior sclera with bulbar conjunctiva, ciliary body, iris, lens, neural retina, and retina pigment epithelium. We report that, except for neural retina, all tissues supported EBOV replication. Retina pigment epithelium produced the fastest growth and highest viral RNA loads, although the differences were not statistically significant. Immunohistochemical staining confirmed and further characterized infection. This study demonstrates that EBOV has a broad tropism within the eye.

The Multiple Origins of Ebola Disease Outbreaks

BACKGROUND

The origins of Ebola disease outbreaks remain enigmatic. Historically outbreaks have been attributed to spillover events from wildlife. However, recent data suggest that some outbreaks may originate from human-to-human transmission of prior outbreak strains instead of spillover. Clarifying the origins of Ebola disease outbreaks could improve detection and mitigation of future outbreaks.

METHODS

We reviewed the origins of all Ebola disease outbreaks from 1976 to 2022 to analyze the earliest cases and characteristics of each outbreak. The epidemiology and phylogenetic relationships of outbreak strains were used to further identify the likely source of each outbreak.

RESULTS

From 1976 to 2022 there were 35 Ebola disease outbreaks with 48 primary/index cases. While the majority of outbreaks were associated with wildlife spillover, resurgence of human-to-human transmission could account for roughly a quarter of outbreaks caused by Ebola virus. Larger outbreaks were more likely to lead to possible resurgence, and nosocomial transmission was associated with the majority of outbreaks.

CONCLUSIONS

While spillover from wildlife has been a source for many Ebola disease outbreaks, multiple outbreaks may have originated from flare-ups of prior outbreak strains. Improving access to diagnostics as well as identifying groups at risk for resurgence of ebolaviruses will be crucial to preventing future outbreaks.

Ebola Virus Uses Tunneling Nanotubes as an Alternate Route of Dissemination

Ebola virus (EBOV) disease is marked by rapid virus replication and spread. EBOV enters the cell by macropinocytosis and replicates in the cytoplasm, and nascent virions egress from the cell surface to infect neighboring cells. Here, we show that EBOV uses an alternate route to disseminate: tunneling nanotubes (TNTs). TNTs, an actin-based long-range intercellular communication system, allows for direct exchange of cytosolic constituents between cells. Using live, scanning electron, and high-resolution quantitative 3-dimensional microscopy, we show that EBOV infection of primary human cells results in the enhanced formation of TNTs containing viral nucleocapsids. TNTs promote the intercellular transfer of nucleocapsids in the absence of live virus, and virus could replicate in cells devoid of entry factors after initial stall. Our studies suggest an alternate model of EBOV dissemination within the host, laying the groundwork for further investigations into the pathogenesis of filoviruses and, importantly, stimulating new areas of antiviral design.

SARS-CoV-2 reservoir in post-acute sequelae of COVID-19 (PASC)

Millions of people are suffering from Long COVID or post-acute sequelae of COVID-19 (PASC). Several biological factors have emerged as potential drivers of PASC pathology. Some individuals with PASC may not fully clear the coronavirus SARS-CoV-2 after acute infection. Instead, replicating virus and/or viral RNA-potentially capable of being translated to produce viral proteins-persist in tissue as a 'reservoir'. This reservoir could modulate host immune responses or release viral proteins into the circulation. Here we review studies that have identified SARS-CoV-2 RNA/protein or immune responses indicative of a SARS-CoV-2 reservoir in PASC samples. Mechanisms by which a SARS-CoV-2 reservoir may contribute to PASC pathology, including coagulation, microbiome and neuroimmune abnormalities, are delineated. We identify research priorities to guide the further study of a SARS-CoV-2 reservoir in PASC, with the goal that clinical trials of antivirals or other therapeutics with potential to clear a SARS-CoV-2 reservoir are accelerated.

Long-Term Decrease in Intraocular Pressure in Survivors of Ebola Virus Disease in the Partnership for Research on Vaccines and Infectious Diseases in Liberia (PREVAIL) III Study

Objective

Survivors of Ebola virus disease (EVD) experience decreased intraocular pressure (IOP) relative to unaffected close contacts during the first year of convalescence. Whether this effect persists over time and its relationship to intraocular pathology are unclear. We sought to determine whether IOP remained lower in survivors of EVD over 4 years of follow-up and to identify associated risk factors.

Design

Partnership for Research on Vaccines and Infectious Diseases in Liberia (PREVAIL) III is a 5-year, longitudinal cohort study of survivors of EVD and their close contacts and is a collaboration between the Liberian Ministry of Health and the United States National Institutes of Health.

Participants

Participants who enrolled in PREVAIL III at John F. Kennedy Medical Center in Liberia, West Africa from June 2015 to March 2016 who underwent comprehensive ophthalmic evaluation annually for 5 consecutive visits.

Methods

Intraocular pressure was measured at each visit by a handheld rebound tonometer using sterile tips. Comparisons are made between antibody-positive survivors and antibody-negative close contacts.

Main Outcome Measures

Intraocular pressure, measured in mmHg, at each study visit.

Results

Of 565 antibody-positive survivors and 644 antibody-negative close contacts enrolled in the study at baseline, the majority of participants returned annually, with 383 (67.8%) and 407 (63.2%) participants, respectively, presenting for the final study visit at a median of 60 months after symptom onset. A sustained, relative decrease in IOP was observed in survivors relative to close contacts, with mean difference of -0.72 mmHg (95% confidence interval [CI] -1.18 to -0.27) at the final study visit. This difference remained constant throughout the study period (P = 0.4 for interaction over time). Among survivors, physical examination findings of vitreous cell and OCT findings of vitreous opacities both demonstrated a significant association with decreased IOP at baseline (P < 0.05 for both). After adjusting for such factors, the difference throughout the follow-up (-0.93 mmHg, 95% CI, -1.23 to -0.63) remained significant.

Conclusions

Survivors of EVD experienced a sustained decrease in IOP relative to close contacts over a 5-year period after EVD. The results highlight the importance of considering long-term sequelae of emerging infectious diseases within a population.

Financial Disclosures

Proprietary or commercial disclosure may be found after the references.

Visual acuity and vision-related quality of life outcomes following cataract surgery in Ebola virus disease survivors

Objectives

The objectives of this study were to assess relationships between vision-related quality of life (QoL) and visual acuity (VA) in Ebola virus disease (EVD) survivors after cataract surgery in the Ebola Viral Persistence in Ocular Tissues and Fluids (EVICT) Study.

Materials and Methods

EVD survivors with undetectable Ebola virus (EBOV) ribonucleic acid in their aqueous humour were eligible to receive manual small-incision cataract surgery (MSICS). Among those that received surgery, assessments of VA and vision-related QoL were assessed pre-and post-cataract surgery. VA was converted from units on a tumbling 'E' chart to the logarithm of the minimal angle of resolution VA (logMAR VA). Vision-related QoL was assessed using the 25-item National Eye Institute Visual Function Questionnaire (NEI VFQ-25). Linear regression was used to evaluate the associations between VA and vision-related QoL. P = 0.05 was considered statistically significant for all analyses.

Results

Thirty-four EVD survivors underwent cataract surgery in the EVICT study. Before MSICS, the mean logMAR VA was 2.24 (standard deviation [SD]: 0.98), and the mean NEI-VFQ-25 composite score was 54 (SD: 15); however, there was no significant association between the pre-surgery measurements (average difference in VA/10 unit increase in NEI-VFQ-25: -0.04, 95% confidence interval (CI): -0.33-0.26, P = 0.80). There was a significant improvement in logMAR VA after MSICS (mean: 1.6, P < 0.001), but there was no significant change in the NEI-VFQ-25 composite (-0.87, 95% (CI): -10.32-8.59, P = 0.85). None of the subscales showed significant improvements (P > 0.12 for all); however, the magnitude of the mean change for distance activities (6.65), near activities (6.76), general vision (-7.69), social functioning (-9.13) and colour vision (13.33) met the criteria for a clinically meaningful difference (4-6). In the subset with paired measurements (n = 16), there were no significant association changes in logMAR VA and NEI VFQ-25 composite scores (P > 0.12 for all).

Conclusion

Following cataract surgery, VA in EVD survivors improved, but these improvements were not reflected in NEI VFQ-25 composite scores or specific subscales; however, the small sample size limits generalizability absent more research. Differences in sociocultural context and activities that affect the QoL in resource-limited areas may contribute to the limitations seen with NEI VFQ-25. In addition, better eye dominance could contribute to any lack of association as NEI VFQ-25 evaluates vision as a whole. Further, assessment of factors contributing to improved QoL may help to define the impact of vision health in varied environments.

Ebola virus disease: A review for the emergency medicine clinician

INTRODUCTION

Ebolavirus, the causative agent of Ebola virus disease (EVD) has been responsible for sporadic outbreaks mainly in sub-Saharan Africa since 1976. EVD is associated with high risk of transmission, especially to healthcare workers during patient care.

OBJECTIVE

The purpose of this review is to provide a concise review of EVD presentation, diagnosis, and management for emergency clinicians.

DISCUSSION

EVD is spread through direct contact, including blood, bodily fluids or contact with a contaminated object. Patients may present with non-specific symptoms such as fevers, myalgias, vomiting, or diarrhea that overlap with other viral illnesses, but rash, bruising, and bleeding may also occur. Laboratory analysis may reveal transaminitis, coagulopathy, and disseminated intravascular coagulation. The average clinical course is approximately 8-10 days with an average case fatality rate of 50%. The mainstay of treatment is supportive care, with two U.S. Food and Drug Administration-approved monoclonal antibody treatments (Ebanga and Inmazeb). Survivors of the disease may have a complicated recovery, marked by long-term symptoms.

CONCLUSION

EVD is a potentially deadly condition that can present with a wide range of signs and symptoms. Emergency clinicians must be aware of the presentation, evaluation, and management to optimize the care of these patients.

Linked Mutations in the Ebola Virus Polymerase Are Associated with Organ Specific Phenotypes

Ebola virus (EBOV) causes a severe infection called Ebola virus disease (EVD). The pathogenesis of EBOV infection is complex, and outcome has been associated with a variety of immunological and cellular factors. Disease can result from several mechanisms, including direct organ and endothelial cell damage as a result of viral replication. During the2013 to 2016 Western Africa EBOV outbreak, several mutants emerged, with changes in the genes of nucleoprotein (NP), glycoprotein (GP), and the large (L) protein. Reverse genetic analysis has been used to investigate whether these mutations played any role in pathogenesis with mixed results depending on the experimental system used. Previous studies investigated the impact of three single nonsynonymous mutations (GP-A82V, NP-R111C, and L-D759G) on the fatality rate of mouse and ferret models and suggested that the L-D759G mutation decreased the virulence of EBOV. In this study, the effect of these three mutations was further evaluated by deep sequencing to determine viral population genetics and the host response in longitudinal samples of blood, liver, kidney, spleen, and lung tissues taken from the previous ferret model. The data indicated that the mutations were maintained in the different tissues, but the frequency of minor genomic mutations were different. In addition, compared to wild-type virus, the recombinant mutants had different within host effects, where the D759G (and accompanying Q986H) substitution in the L protein resulted in an upregulation of the immune response in the kidney, liver, spleen, and lungs. Together these studies provide insights into the biology of EBOV mutants both between and within hosts. IMPORTANCE Ebola virus infection can have dramatic effects on the human body which manifest in Ebola virus disease. The outcome of infection is either survival or death and in the former group with the potential of longer-term health consequences and persistent infection. Disease severity is undoubtedly associated with the host response, often with overt inflammatory responses correlated with poorer outcomes. The scale of the2013 to 2016 Western African Ebola virus outbreak revealed new aspects of viral biology. This included the emergence of mutants with potentially altered virulence. Biobanked tissue from ferret models of EBOV infected with different mutants that emerged in the Western Africa outbreak was used to investigate the effect of EBOV genomic variation in different tissues. Overall, the work provided insights into the population genetics of EBOV and showed that different organs in an animal model can respond differently to variants of EBOV.

An update on immunological and molecular tests and their impact in infectious uveitis

Early diagnosis of infectious uveitis can lead to prompt initiation of treatment to minimize vision-threatening sequelae. As various infectious etiologies of uveitis share similar clinical features, advancements in polymerase chain reaction (PCR) and metagenomic next-generation sequencing (MDS) have shown significant promise in improving diagnostic capabilities. Various techniques of PCR, including real-time, multiplex, comprehensive, and broad-range, have increased the armamentarium for infectious uveitis diagnosis. Additionally, metagenomic deep sequencing technology has provided a methodology to identify causative pathogens as well as novel etiologies of uveitis. This review discusses the diagnostic tools available for infectious uveitis and highlights the advantages and disadvantages of the techniques.

Ophthalmic consequences of viral hemorrhagic fevers: Insights from the clinic and laboratory

Viral hemorrhagic fevers (VHFs) are a diverse group of RNA virus-mediated systemic diseases with significant morbidity and mortality and represent a significant public health concern. Given the high systemic morbidity and mortality in a number of these entities, delays in diagnosis can lead to downstream public health consequences. Many viral hemorrhagic fevers have ophthalmic manifestations and ophthalmologists thus play a key role in disease recognition and the management of ocular complications associated with specific hemorrhagic fevers. This review summarizes the key ophthalmic consequences of viral hemorrhagic fevers, viral disease pathogenesis, disease findings, and areas of unmet research need.

Characterization of an air-liquid interface primary human vaginal epithelium to study Ebola virus infection and testing of antivirals

Ebola virus (EBOV) is the causative agent of the often-fatal Ebola virus disease (EVD) characterized by hemorrhagic fever in humans and non-human primates. Sexual transmission from male survivors has been at the origin of multiple outbreak flare-ups between 2015 and 2021. However, this route is still poorly understood and the resulting EVD from it is also understudied. To support epidemiological studies documenting sexual transmission to women, and as a transition from previously using monolayer vaginal epithelial cells (VK2/E6E7), we first determined the biological relevance of two similar air-liquid interface models of the human vaginal epithelium (VEC and VLC Epivaginal™) and then characterized their susceptibility to EBOV and virus-induced inflammation. Finally, we evaluated toxicity of Polyphenylene Carboxymethylene (PPCM) microbicide in VLC and reassessed its antiviral effect. As expected, the VEC, but also VLC model showed stratified layers including a lamina propria under an epithelial structure similar to the full thickness of the human vaginal epithelium. However, we could not detect the immune cells featured in the most relevant model (VLC) of the vaginal epithelium using the dendritic cell CD1a and CD11c markers. Consistent with our previous work using the VK2/E6E7 cell line, infectious virus was detected from the apical side of both primary human cell systems, but only when using a high infective dose, with titers remaining at a constant level of 103-4 pfu/ml over 7 days suggesting lasting infectious virus shedding. In addition, infection caused disruption of the epithelium of both models and virus antigen was found from the apical superficial layers down to the lamina propria suggesting full virus penetration and overall confirming the susceptibility of the human vaginal tissue for EBOV. Just like previously seen in VK2/E6E7 cells, VLC infection also caused significant increase in inflammatory markers including IL-6, IL-8, and IP-10 suggesting vaginitis which is again consistent with tissue lesions seen in non-human primates. Finally, both virus infection and virus-induced inflammatory response in VLC could be prevented by a single 5-min PPCM microbicide treatment prior infection.

Risk Factors for Ebola Virus Persistence in Semen of Survivors in Liberia

BACKGROUND

Long-term persistence of Ebola virus (EBOV) in immunologically privileged sites has been implicated in recent outbreaks of Ebola virus disease (EVD) in Guinea and the Democratic Republic of Congo. This study was designed to understand how the acute course of EVD, convalescence, and host immune and genetic factors may play a role in prolonged viral persistence in semen.

METHODS

A cohort of 131 male EVD survivors in Liberia were enrolled in a case-case study. "Early clearers" were defined as those with 2 consecutive negative EBOV semen test results by real-time reverse-transcription polymerase chain reaction (rRT-PCR) ≥2 weeks apart within 1 year after discharge from the Ebola treatment unit or acute EVD. "Late clearers" had detectable EBOV RNA by rRT-PCR >1 year after discharge from the Ebola treatment unit or acute EVD. Retrospective histories of their EVD clinical course were collected by questionnaire, followed by complete physical examinations and blood work.

RESULTS

Compared with early clearers, late clearers were older (median, 42.5 years; P < .001) and experienced fewer severe clinical symptoms (median 2, P = .006). Late clearers had more lens opacifications (odds ratio, 3.9 [95% confidence interval, 1.1-13.3]; P = .03), after accounting for age, higher total serum immunoglobulin G3 (IgG3) titers (P = .005), and increased expression of the HLA-C*03:04 allele (0.14 [.02-.70]; P = .007).

CONCLUSIONS

Older age, decreased illness severity, elevated total serum IgG3 and HLA-C*03:04 allele expression may be risk factors for the persistence of EBOV in the semen of EVD survivors. EBOV persistence in semen may also be associated with its persistence in other immunologically protected sites, such as the eye.

Post-Ebola Symptoms 7 Years After Infection: The Natural History of Long Ebola

BACKGROUND

Lingering symptoms have been reported by survivors of Ebola virus disease (EVD). There are few data describing the persistence and severity of these symptoms over time.

METHODS

Symptoms of headache, fatigue, joint pain, muscle pain, hearing loss, visual loss, numbness of hands or feet were longitudinally assessed among participants in the Liberian Ebola Survivors Cohort study. Generalized linear mixed effects models, adjusted for sex and age, were used to calculate the odds of reporting a symptom and it being rated as highly interfering with life.

RESULTS

From June 2015 to June 2016, 326 survivors were enrolled a median of 389 days (range 51-614) from acute EVD. At baseline 75.2% reported at least 1 symptom; 85.8% were highly interfering with life. Over a median follow-up of 5.9 years, reporting of any symptom declined (odds ratio for each 90 days of follow-up = 0.96, 95% confidence interval [CI]: .95, .97; P < .0001) with all symptoms declining except for numbness of hands or feet. Rating of any symptom as highly interfering decreased over time. Among 311 with 5 years of follow-up, 52% (n = 161) reported a symptom and 29% (n = 47) of these as highly interfering with their lives.

CONCLUSIONS

Major post-EVD symptoms are common early during convalescence and decline over time along with severity. However, even 5 years after acute infection, a majority continue to have symptoms and, for many, these continue to greatly impact their lives. These findings call for investigations to identify the mechanisms of post-EVD sequelae and therapeutic interventions to benefit the thousands of effected EVD survivors.

High-depth sequencing characterization of viral dynamics across tissues in fatal COVID-19 reveals compartmentalized infection

SARS-CoV-2 distribution and circulation dynamics are not well understood due to challenges in assessing genomic data from tissue samples. We develop experimental and computational workflows for high-depth viral sequencing and high-resolution genomic analyses from formalin-fixed, paraffin-embedded tissues and apply them to 120 specimens from six subjects with fatal COVID-19. To varying degrees, viral RNA is present in extrapulmonary tissues from all subjects. The majority of the 180 viral variants identified within subjects are unique to individual tissue samples. We find more high-frequency (>10%) minor variants in subjects with a longer disease course, with one subject harboring ten such variants, exclusively in extrapulmonary tissues. One tissue-specific high-frequency variant was a nonsynonymous mutation in the furin-cleavage site of the spike protein. Our findings suggest adaptation and/or compartmentalized infection, illuminating the basis of extrapulmonary COVID-19 symptoms and potential for viral reservoirs, and have broad utility for investigating human pathogens.

Ebola virus disrupts the inner blood-retinal barrier by induction of vascular endothelial growth factor in pericytes

Ebola virus (EBOV) causes severe hemorrhagic fever in humans with high mortality. In Ebola virus disease (EVD) survivors, EBOV persistence in the eyes may break through the inner blood-retinal barrier (iBRB), leading to ocular complications and EVD recurrence. However, the mechanism by which EBOV affects the iBRB remains unclear. Here, we used the in vitro iBRB model to simulate EBOV in retinal tissue and found that Ebola virus-like particles (EBO-VLPs) could disrupt the iBRB. Cytokine screening revealed that EBO-VLPs stimulate pericytes to secrete vascular endothelial growth factor (VEGF) to cause iBRB breakdown. VEGF downregulates claudin-1 to disrupt the iBRB. Ebola glycoprotein is crucial for VEGF stimulation and iBRB breakdown. Furthermore, EBO-VLPs caused iBRB breakdown by stimulating VEGF in rats. This study provides a mechanistic insight into that EBOV disrupts the iBRB, which will assist in developing new strategies to treat EBOV persistence in EVD survivors.

Persistent intraocular Ebola virus RNA is associated with severe uveitis in a convalescent rhesus monkey

Despite increasing evidence that uveitis is common and consequential in survivors of Ebola virus disease (EVD), the host-pathogen determinants of the clinical phenotype are undefined, including the pathogenetic role of persistent viral antigen, ocular tissue-specific immune responses, and histopathologic characterization. Absent sampling of human intraocular fluids and tissues, these questions might be investigated in animal models of disease; however, challenges intrinsic to the nonhuman primate model and the animal biosafety level 4 setting have historically limited inquiry. In a rhesus monkey survivor of experimental Ebola virus (EBOV) infection, we observed and documented the clinical, virologic, immunologic, and histopathologic features of severe uveitis. Here we show the clinical natural history, resultant ocular pathology, intraocular antigen-specific antibody detection, and persistent intraocular EBOV RNA detected long after clinical resolution. The association of persistent EBOV RNA as a potential driver of severe immunopathology has pathophysiologic implications for understanding, preventing, and mitigating vision-threatening uveitis in EVD survivors.

Systemic prime exacerbates the ocular immune response to heat-killed Mycobacterium tuberculosis

Post-infectious uveitis describes the condition of chronic immune mediated ocular inflammation associated with pathogens such as Mycobacterium tuberculosis (Mtb). Mtb associated post-infectious uveitis can be modeled in mice by intravitreal injection of heat-killed Mtb (HKMtb). To better understand how prior systemic exposure to the pathogen alters the local immune response to Mtb, we used flow cytometry and multiplex ELISAs to compare ocular responses to intravitreal HKMtb in the presence or absence of a systemic "prime" of HKMtb. Priming resulted in exacerbation of local inflammation with significantly increased clinical and histologic inflammation scores and increased vitreous cytokines concentrations one day after intravitreal injection of HKMtb. Seven days after injection, uveitis in unprimed animals had largely resolved. In contrast in primed animals, clinical signs of chronic inflammation were associated with a significant increase in the number of ocular T cells, NK cells, and Ly6Chi macrophages and increasing vitreous concentrations of IL-17, VEGF, MIG(CXCL9), IP-10(CXCL10), IL-12p40 and MIP-1α(CCL3). In mice lacking mature T and B cells (RAG2 deficient), the impact of priming on the ocular immune response was ameliorated with significantly lower vitreous cytokine concentrations and spontaneous resolution of uveitis. Altogether these results suggest that the ocular response to Mtb is exacerbated by prior systemic Mtb infection and chronic post-infectious uveitis is mediated by local production of cytokines and chemokines that amplify Th17 and Th1 responses. This mouse model of chronic Mtb associated uveitis will help elucidate mechanisms of disease in patients with post-infectious uveitis.

Ocular manifestations of recent viral pandemics: A literature review

Viral pandemics often take the world by storm, urging the medical community to prioritize the most evident systemic manifestations, often causing ocular manifestations to go unnoticed. This literature review highlights the ocular complications of the Monkeypox, SARS-CoV-2, MERS, Ebola, H1N1, and Zika viruses as the most recent viral pandemics. Research into the effects of these pandemics began immediately. Moreover, it also discusses the ocular complications of the vaccines and treatments that were used in the scope of the viral pandemics. Additionally, this review discusses the role of the eye as an important route of viral transmission, and thereafter, the International recommendations to reduce the incidence of viral transmission were mentioned. Lastly, this paper wants to lay out a platform for researchers who want to learn more about how viruses show up in the eye.

Breaking new frontiers: Assessment and re-evaluation of clinical trial design for nutraceuticals

Despite sophisticated study designs and measurement tools, we have yet to create an innovative space for diet and dietary supplements in the health care system. The path is challenging due to current hierarchies of scientific evidence and regulatory affairs. The role of the randomized, double-blind, placebo-controlled clinical trial (RCT) as a research approach functions well to characterize the benefits and risks of drugs but lacks the sensitivity to capture the efficacy and safety of nutraceuticals. While some facets of RCTs can be relevant and useful when applied to nutraceuticals, other aspects are limiting and potentially misleading when taken in their entirety. A differentiation between guidelines for evidence-based medicine and the evidence required for nutrition spotlight the need to reconceptualize constituents of the RCT and their applicability with relevance to health promotion. This perspective identifies the limitations of the traditional RCT to capture the complexities of nutraceuticals and proposes the N-of-1 as Level 1 evidence better suited for the proof of efficacy of nutraceuticals.

Molecular, ecological, and behavioral drivers of the bat-virus relationship

Bats perform important ecological roles in our ecosystem. However, recent studies have demonstrated that bats are reservoirs of emerging viruses that have spilled over into humans and agricultural animals to cause severe diseases. These viruses include Hendra and Nipah paramyxoviruses, Ebola and Marburg filoviruses, and coronaviruses that are closely related to severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV), and the recently emerged SARS-CoV-2. Intriguingly, bats that are naturally or experimentally infected with these viruses do not show clinical signs of disease. Here we have reviewed ecological, behavioral, and molecular factors that may influence the ability of bats to harbor viruses. We have summarized known zoonotic potential of bat-borne viruses and stress on the need for further studies to better understand the evolutionary relationship between bats and their viruses, along with discovering the intrinsic and external factors that facilitate the successful spillover of viruses from bats.

The Evolution of Medical Countermeasures for Ebola Virus Disease: Lessons Learned and Next Steps

The Ebola virus disease outbreak that occurred in Western Africa from 2013-2016, and subsequent smaller but increasingly frequent outbreaks of Ebola virus disease in recent years, spurred an unprecedented effort to develop and deploy effective vaccines, therapeutics, and diagnostics. This effort led to the U.S. regulatory approval of a diagnostic test, two vaccines, and two therapeutics for Ebola virus disease indications. Moreover, the establishment of fieldable diagnostic tests improved the speed with which patients can be diagnosed and public health resources mobilized. The United States government has played and continues to play a key role in funding and coordinating these medical countermeasure efforts. Here, we describe the coordinated U.S. government response to develop medical countermeasures for Ebola virus disease and we identify lessons learned that may improve future efforts to develop and deploy effective countermeasures against other filoviruses, such as Sudan virus and Marburg virus.

Rapid RNA detection through intra-enzyme chain replacement-promoted Cas13a cascade cyclic reaction without amplification

The clinical methods to detect RNA viruses and disease-related RNAs suffer from time-consuming processes, high false-positive rates, or limited sensitivity. Here, we propose a strategy for rapid RNA detection through intra-enzyme chain replacement-mediated Cas13a cascade cyclic reaction without target amplification. A hairpin RNA mediator (a cleavage substrate for target-activated Cas13a) and a guiding RNA recognized by the cleavage product through intra-enzyme chain replacement were designed and optimized. Upon the recognition and binding of the target RNA to the Cas13a/CrRNA complex, Cas13a is initially activated to cleave the mediator, and the cleavage products recognize the corresponding Cas13a/CrRNA complex by intra-enzyme chain replacement and initiate the circular cascade of Cas13a cleavage and activation. The accumulated active Cas13a cleaves fluorescent reporter probe for achieving target RNA detection. This "mix & read" RNA detection at room temperature was performed in total 30 min. Using miRNA-21 as the target, the changes in fluorescence intensity were linearly correlated to the concentrations from 10 fM to 50 pM with the detection limit of 75 aM, while no significant changes in fluorescence intensity were detected for non-targets. This method applied to the clinical sputum respiratory syncytial virus-positive samples gave results consistent with those from the clinical fluorescence immunoassay. Thus, intra-enzyme chain replacement-promoted Cas13a cascade cyclic reaction for detection of RNA viruses in the "mix & read" mode at room temperature is rapid, simple, convenient, and efficient for RNA detection and can be adapted to point-of-care testing for high throughput screening of RNA virus infections.

The prevalence of Post-Ebola Syndrome hearing loss, Sierra Leone

BACKGROUND

Globally, hearing loss is the second leading cause of disability, affecting approximately 18.7% of the world's population. However, the burden of hearing loss is unequally distributed, with the majority of affected individuals located in Asia or Sub-Saharan Africa. Following the 2014 West African Ebola Outbreak, disease survivors began to describe hearing loss as part of the constellation of symptoms known as Post-Ebola Syndrome. The goal of this study was to more fully characterize hearing loss among Ebola Virus Disease (EVD) survivors.

METHODOLOGY AND PRINCIPAL FINDINGS

EVD survivors and their household contacts were recruited (n = 1,12) from Eastern Sierra Leone. Each individual completed a symptom questionnaire, physical exam, and a two-step audiometry process measuring both air and bone conduction thresholds. In comparison to contacts, EVD survivors were more likely to have complaints or abnormal findings affecting every organ system. A significantly greater percentage of EVD survivors were found to have hearing loss in comparison to contacts (23% vs. 9%, p < 0.001). Additionally, survivors were more likely to have bilateral hearing loss of a mixed etiology. Logistic regression revealed that the presence of any symptoms of middle or inner ear (p < 0.001), eye (p = 0.005), psychiatric (p = 0.019), and nervous system (p = 0.037) increased the odds of developing hearing loss.

CONCLUSIONS AND SIGNIFICANCE

This study is the first to use an objective and standardized measurement to report hearing loss among EVD survivors in a clinically meaningful manner. In this study it was found that greater than 1/5th of EVD survivors develop hearing loss. The association between hearing impairment and symptoms affecting the eye and nervous system may indicate a similar mechanism of pathogenesis, which should be investigated further. Due to the quality of life and socioeconomic detriments associated with untreated hearing loss, a greater emphasis must be placed on understanding and mitigating hearing loss following survival to aid in economic recovery following infectious disease epidemics.

RNA Viruses, Pregnancy and Vaccination: Emerging Lessons from COVID-19 and Ebola Virus Disease

Pathogenic viruses with an RNA genome represent a challenge for global human health since they have the tremendous potential to develop into devastating pandemics/epidemics. The management of the recent COVID-19 pandemic was possible to a certain extent only because of the strong foundations laid by the research on previous viral outbreaks, especially Ebola Virus Disease (EVD). A clear understanding of the mechanisms of the host immune response generated upon viral infections is a prime requisite for the development of new therapeutic strategies. Hence, we present here a comparative study of alterations in immune response upon SARS-CoV-2 and Ebola virus infections that illustrate many common features. Vaccination and pregnancy are two important aspects that need to be studied from an immunological perspective. So, we summarize the outcomes and immune responses in vaccinated and pregnant individuals in the context of COVID-19 and EVD. Considering the significance of immunomodulatory approaches in combating both these diseases, we have also presented the state of the art of such therapeutics and prophylactics. Currently, several vaccines against these viruses have been approved or are under clinical trials in various parts of the world. Therefore, we also recapitulate the latest developments in these which would inspire researchers to look for possibilities of developing vaccines against many other RNA viruses. We hope that the similar aspects in COVID-19 and EVD open up new avenues for the development of pan-viral therapies.

Ophthalmic sequelae and psychosocial impact in pediatric ebola survivors

Background

Ebola virus disease (EVD) outbreaks in West Africa (2013-2016) and the Democratic Republic of Congo (2018-2020) have resulted in thousands of EVD survivors who remain at-risk for survivor sequelae. While EVD survivorship has been broadly reported in adult populations, pediatric EVD survivors are under-represented. In this cross-sectional study, we investigated the prevalence of eye disease, health-related quality-of-life, vision-related quality-of-life, and the burden of mental illness among pediatric EVD survivors in Sierra Leone.

Methods

Twenty-three pediatric EVD survivors and 58 EVD close contacts were enrolled. Participants underwent a comprehensive ophthalmic examination and completed the following surveys: Pediatric Quality of Life Inventory Version 4.0, Effect of Youngsters Eyesight on Quality-of-Life, and the Revised Child Anxiety and Depression Scale.

Findings

A higher prevalence of uveitis was observed in EVD survivor eyes (10·8%) cohort compared to close contacts eyes (1·7%, p=0·03). Overall, 47·8% of EVD survivor eyes and 31·9% of close contact eyes presented with an eye disease at the time of our study (p=0·25). Individuals diagnosed with an ocular complication had poorer vision-related quality-of-life (p=0·02).

Interpretation

Both health related quality-of-life and vision-related quality-of-life were poor among EVD survivors and close contacts. The high prevalence of eye disease associated with reduced vision health, suggests that cross-disciplinary approaches are needed to address the unmet needs of EVD survivors.

Funding

National Institutes of Health R01 EY029594, K23 EY030158; National Eye Institute; Research to Prevent Blindness (Emory Eye Center); Marcus Foundation Combating Childhood Illness; Emory Global Health Institute; Stanley M. Truhlsen Family Foundation.

Why does viral RNA sometimes persist after recovery from acute infections?

DNA viruses often persist in the body of their host, becoming latent and recurring many months or years later. By contrast, most RNA viruses cause acute infections that are cleared from the host as they lack the mechanisms to persist. However, it is becoming clear that viral RNA can persist after clinical recovery and elimination of detectable infectious virus. This persistence can either be asymptomatic or associated with late progressive disease or nonspecific lingering symptoms, such as may be the case following infection with Ebola or Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Why does viral RNA sometimes persist after recovery from an acute infection? Where does the RNA come from? And what are the consequences?

Combination therapy with remdesivir and monoclonal antibodies protects nonhuman primates against advanced Sudan virus disease

A major challenge in managing acute viral infections is ameliorating disease when treatment is delayed. Previously, we reported the success of a 2-pronged mAb and antiviral remdesivir therapeutic approach to treat advanced illness in rhesus monkeys infected with Marburg virus (MARV). Here, we explored the benefit of a similar combination therapy for Sudan ebolavirus (Sudan virus; SUDV) infection. Importantly, no licensed anti-SUDV therapeutics currently exist, and infection of rhesus macaques with SUDV results in a rapid disease course similar to MARV with a mean time to death of 8.3 days. When initiation of therapy with either remdesivir or a pan-ebolavirus mAb cocktail (MBP431) was delayed until 6 days after inoculation, only 20% of macaques survived. In contrast, when remdesivir and MBP431 treatment were combined beginning 6 days after inoculation, significant protection (80%) was achieved. Our results suggest that combination therapy may be a viable treatment for patients with advanced filovirus disease that warrants further clinical testing in future outbreaks.

Complement-Mediated Neutralisation Identified in Ebola Virus Disease Survivor Plasma: Implications for Protection and Pathogenesis

The 2013-2016 Ebola virus (EBOV) epidemic in West Africa was unprecedented in case numbers and fatalities, and sporadic outbreaks continue to arise. Antibodies to the EBOV glycoprotein (GP) are strongly associated with survival and their use in immunotherapy is often initially based on their performance in neutralisation assays. Other immune effector functions also contribute to EBOV protection but are more complex to measure. Their interactions with the complement system in particular are comparatively under-researched and commonly excluded from cellular immunoassays. Using EBOV convalescent plasma samples from the 2013-2016 epidemic, we investigated antibody and complement-mediated neutralisation and how these interactions can influence immunity in response to EBOV-GP and its secreted form (EBOV-sGP). We defined two cohorts: one with low-neutralising titres in relation to EBOV-GP IgG titres (LN cohort) and the other with a direct linear relationship between neutralisation and EBOV-GP IgG titres (N cohort). Using flow cytometry antibody-dependent complement deposition (ADCD) assays, we found that the LN cohort was equally efficient at mediating ADCD in response to the EBOV-GP but was significantly lower in response to the EBOV-sGP, compared to the N cohort. Using wild-type EBOV neutralisation assays with a cohort of the LN plasma, we observed a significant increase in neutralisation associated with the addition of pooled human plasma as a source of complement. Flow cytometry ADCD was also applied using the GP of the highly virulent Sudan virus (SUDV) of the Sudan ebolavirus species. There are no licensed vaccines or therapeutics against SUDV and it overlaps in endemicity with EBOV. We found that the LN plasma was significantly less efficient at cross-reacting and mediating ADCD. Overall, we found a differential response in ADCD between LN and N plasma in response to various Ebolavirus glycoproteins, and that these interactions could significantly improve EBOV neutralisation for selected LN plasma samples. Preservation of the complement system in immunoassays could augment our understanding of neutralisation and thus protection against infection.

Mathematical analysis of a model of Ebola disease with control measures

The re-emergence of the Ebola virus disease has pushed researchers to investigate more on this highly deadly disease in order to better understand and control the outbreak and recurrence of epidemics. It is in this perspective that we formulate a realistic mathematical model for the dynamic transmission of Ebola virus disease, incorporating relevant control measures and factors such as ban on eating bush-meat, social distancing, observance of hygiene rules and containment, waning of the vaccine-induced, imperfect contact tracing and vaccine efficacy, quarantine, hospitalization and screening to fight against the spread of the disease. First, by considering the constant control parameters case, we thoroughly compute the control reproduction number [Formula: see text] from which the dynamics of the model is analyzed. The existence and stability of steady states are established under appropriate assumptions on [Formula: see text]. Also, the effect of all the control measures is investigated and the global sensitivity analysis of the control reproduction number is performed in order to determine the impact of parameters and their relative importance to disease transmission and prevalence. Second, in the time-dependent control parameters case, an optimal control problem is formulated to design optimal control strategies for eradicating the disease transmission. Using Pontryagin’s Maximum Principle, we derive necessary conditions for optimal control of the disease. The cost-effectiveness analysis of all combinations of the control measures is made by calculating the infection averted ratio and the incremental cost-effectiveness ratio. This reveals that combining the four restrictive measures conveyed through educational campaigns, screening, safe burial and the care of patients in health centers for better isolation is the most cost-effective among the strategies considered. Numerical simulations are performed to illustrate the theoretical results obtained.

Plasma Proteomic Analysis Distinguishes Severity Outcomes of Human Ebola Virus Disease

Ebola virus (EBV) disease (EVD) is a highly virulent systemic disease characterized by an aggressive systemic inflammatory response and impaired vascular and coagulation systems, often leading to uncontrolled hemorrhaging and death. In this study, the proteomes of 38 sequential plasma samples from 12 confirmed EVD patients were analyzed. Of these 12 cases, 9 patients received treatment with interferon beta 1a (IFN-β-1a), 8 survived EVD, and 4 died; 2 of these 4 fatalities had received IFN-β-1a. Our analytical strategy combined three platforms targeting different plasma subproteomes: a liquid chromatography-mass spectrometry (LC-MS)-based analysis of the classical plasma proteome, a protocol that combines the depletion of abundant plasma proteins and LC-MS to detect less abundant plasma proteins, and an antibody-based cytokine/chemokine multiplex assay. These complementary platforms provided comprehensive data on 1,000 host and viral proteins. Examination of the early plasma proteomes revealed protein signatures that differentiated between fatalities and survivors. Moreover, IFN-β-1a treatment was associated with a distinct protein signature. Next, we examined those proteins whose abundances reflected viral load measurements and the disease course: resolution or progression. Our data identified a prognostic 4-protein biomarker panel (histone H1-5, moesin, kininogen 1, and ribosomal protein L35 [RPL35]) that predicted EVD outcomes more accurately than the onset viral load. IMPORTANCE As evidenced by the 2013-2016 outbreak in West Africa, Ebola virus (EBV) disease (EVD) poses a major global health threat. In this study, we characterized the plasma proteomes of 12 individuals infected with EBV, using two different LC-MS-based proteomics platforms and an antibody-based multiplexed cytokine/chemokine assay. Clear differences were observed in the host proteome between individuals who survived and those who died, at both early and late stages of the disease. From our analysis, we derived a 4-protein prognostic biomarker panel that may help direct care. Given the ease of implementation, a panel of these 4 proteins or subsets thereof has the potential to be widely applied in an emergency setting in resource-limited regions.

Ebola virus persistence and disease recrudescence in the brains of antibody-treated nonhuman primate survivors

Effective therapeutics have been developed against acute Ebola virus disease (EVD) in both humans and experimentally infected nonhuman primates. However, the risk of viral persistence and associated disease recrudescence in survivors receiving these therapeutics remains unclear. In contrast to rhesus macaques that survived Ebola virus (EBOV) exposure in the absence of treatment, we discovered that EBOV, despite being cleared from all other organs, persisted in the brain ventricular system of rhesus macaque survivors that had received monoclonal antibody (mAb) treatment. In mAb-treated macaque survivors, EBOV persisted in macrophages infiltrating the brain ventricular system, including the choroid plexuses. This macrophage infiltration was accompanied by severe tissue damage, including ventriculitis, choroid plexitis, and meningoencephalitis. Specifically, choroid plexus endothelium-derived EBOV infection led to viral persistence in the macaque brain ventricular system. This resulted in apoptosis of ependymal cells, which constitute the blood-cerebrospinal fluid barrier of the choroid plexuses. Fatal brain-confined recrudescence of EBOV infection manifested as severe inflammation, local pathology, and widespread infection of the ventricular system and adjacent neuropil in some of the mAb-treated macaque survivors. This study highlights organ-specific EBOV persistence and fatal recrudescent disease in rhesus macaque survivors after therapeutic treatment and has implications for the long-term follow-up of human survivors of EVD.

An Ophthalmologist's Insight Into The Viral Pandemics

In recent past, major pandemics and epidemics have occurred due to the emergence and resurgence of the novel strains of viruses like Influenza [HINI-A "Spanish Flu", H1N1-Novel A "Swine flu"], Corona [Middle East Respiratory Syndrome (MERS), Severe acute respiratory syndrome (SARS-CoV-1, SARS-CoV-2)] and Ebola virus [Ebola virus disease]. These infectious diseases may have several ocular manifestations and rarely might be the presenting symptom of the underlying disease. The eyes can act as a portal of entry and/or route of viral transmission for these pathogens. Therefore, an ophthalmologist/optometrist needs to act with ample preparedness and responsibility. Establishing a standard of care in ophthalmic practice by modifying the conventional examination techniques and adopting tele-ophthalmology model to triage the patients can control the community spread of the disease. This article aims to elucidate the ocular manifestations in these pandemics and measures that should be adopted in ophthalmic practice to prevent the disease transmission.

Characterization of the therapeutic effect of antibodies targeting the Ebola glycoprotein using a novel BSL2-compliant rVSVΔG-EBOV-GP infection model

Ebola virus (EBOV) infections cause haemorrhagic fever, multi-organ failure and death, and survivors can experience neurological sequelae. Licensing of monoclonal antibodies targeting EBOV glycoprotein (EBOV-GP) improved its prognosis, however, this treatment is primarily effective during early stages of disease and its effectiveness in reducing neurological sequela remains unknown. Currently, the need for BSL4 containment hinders research and therapeutic development; development of an accessible BSL-2 in vivo mouse model would facilitate preclinical studies to screen and select therapeutics. Previously, we have shown that a subcutaneous inoculation with replicating EBOV-GP pseudotyped vesicular stomatitis virus (rVSVΔG-EBOV-GP or VSV-EBOV) in neonatal mice causes transient viremia and infection of the mid and posterior brain resulting in overt neurological symptoms and death. Here, we demonstrate that the model can be used to test therapeutics that target the EBOV-GP, by using an anti-EBOV-GP therapeutic (SAB-139) previously shown to block EBOV infection in mice and primates. We show that SAB-139 treatment decreases the severity of neurological symptoms and improves survival when administered before (1 day prior to infection) or up to 3 dpi, by which time animals have high virus titres in their brains. Improved survival was associated with reduced viral titres, microglia loss, cellular infiltration/activation, and inflammatory responses in the brain. Interestingly, SAB-139 treatment significantly reduced the severe VSV-EBOV-induced long-term neurological sequalae although convalescent mice showed modest evidence of abnormal fear responses. Together, these data suggest that the neonatal VSV-EBOV infection system can be used to facilitate assessment of therapeutics targeting EBOV-GP in the preclinical setting.