Ebola Research Articles

Modeling the Transmission Dynamics of the Ebola Virus: Effects of Quarantine and Vaccination

Quarantine and vaccination of individuals suspected of exposure to infectious agents are fundamental public health strategies that have historically been employed to mitigate the transmission of contagious diseases within human populations. This study introduced a modified SEIVQRD deterministic model to evaluate the population-level effects of quarantine and vaccination on individuals potentially exposed to the Ebola virus. The study showed that the Model exhibits backward bifurcation when . This implies that even when the reproductive number An unstable endemic and a stable disease-free equilibrium can coexist in less than one. This phenomenon arises from imperfect quarantine and indicates that while is necessary for adequate infection control; it is no longer sufficient and creates additional challenges for effectively controlling Ebola. Furthermore, the sensitivity analysis revealed that the quarantine effectiveness parameter and the parameter related to the isolation of vulnerable individuals had less influence on the incidence of new Ebola cases. However, vaccinating non-quarantined susceptible individuals significantly affects the infection burden and can lower the reproductive value to less than one. Overall, the Model emphasizes the critical role of vaccination in reducing Ebola virus transmission. Although quarantine measures alone may not be sufficient, their combination with vaccination can significantly reduce infection rates.

Susceptibility Inference and Response on Transmission Dynamics of Ebola Virus in Fuzzy Environment

Susceptibility Inference and Response on Transmission Dynamics of Ebola Virus in Fuzzy Environment

A CRISPR-Cas13b System Degrades SARS-CoV and SARS-CoV-2 RNA In Vitro

In a time of climate change, population growth, and globalization, the risk of viral spread has significantly increased. The 21st century has already witnessed outbreaks of Severe Acute Respiratory Syndrome virus (SARS-CoV), Severe Acute Respiratory Syndrome virus 2 (SARS-CoV-2), Ebola virus and Influenza virus, among others. Viruses rapidly adapt and evade human immune systems, complicating the development of effective antiviral countermeasures. Consequently, the need for novel antivirals resilient to viral mutations is urgent. In this study, we developed a CRISPR-Cas13b system to target SARS-CoV-2. Interestingly, this system was also efficient against SARS-CoV, demonstrating broad-spectrum potential. Our findings highlight CRISPR-Cas13b as a promising tool for antiviral therapeutics, underscoring its potential in RNA-virus-associated pandemic responses.

Ebola Virus Matrix Protein VP40 Single Mutations G198R and G201R Significantly Enhance Plasma Membrane Localization.

Viral proteins frequently undergo single or multiple amino acid mutations during replication, which can significantly alter their functionality. The Ebola virus matrix protein VP40 is multifunctional but primarily responsible for creating the viral envelope by binding to the inner leaflet of the host cell plasma membrane (PM). Changes to the VP40 surface cationic charge via mutations can influence PM interactions, resulting in altered viral assembly and budding. A recent mutagenesis study evaluated the effects of several mutations and found that mutations G198R and G201R enhanced VP40 assembly at the PM and virus-like particle budding. These two mutations lie in the loop region of the C-terminal domain (CTD), which directly interacts with the PM. To understand the role of these mutations in PM localization at the molecular level, we performed both all-atom and coarse-grained molecular dynamics simulations using a dimer-dimer configuration of VP40, which contains the CTD-CTD interface. Our studies indicate that the location of mutations on the outer surface of the CTD regions can lead to changes in membrane binding orientation and degree of membrane penetration. Direct PI(4,5)P2 interactions with the mutated residues seem to further stabilize and pull VP40 into the PM, thereby enhancing interactions with numerous amino acids that were otherwise infrequently or completely inaccessible. These multiscale computational studies provide new insights at the atomic and molecular level as to how VP40-PM interactions are altered through single amino acid mutations. Given the high case fatality rates associated with Ebola virus disease in humans, it is essential to explore the mechanisms of viral assembly in the presence of mutations to mitigate the severity of the disease and understand the potential of future outbreaks.

Ebola Virus Infection of Flt3-Dependent, Conventional Dendritic Cells and Antigen Cross-presentation Leads to High Levels of T-Cell Activation.

Previous studies have described that Ebola virus (EBOV) infection of human monocyte-derived dendritic cells (moDCs) inhibits dendritic cell (DC) maturation, resulting in poor T-cell activation. However, it is unknown how other DC subsets distinct from moDCs respond to EBOV infection. To better understand how DCs initiate T-cell activation during EBOV infection, we assessed the response of conventional mouse DCs (cDCs) to EBOV infection utilizing a recombinant EBOV expressing the model antigen ovalbumin. In contrast to moDCs, mouse cDC2s and cDC1s were poorly infected with EBOV but were highly activated. DCs were able to prime CD8 T cells via cross-presentation of antigens obtained from cell debris of EBOV-infected cells. EBOV infection further enhanced DC cross-presentation. Our findings indicate that EBOV infection of cDCs results in activation rather than inhibition, leading to high levels of T-cell activation. With that we propose a mechanistic explanation for the excess T-cell activation observed in human Ebola virus disease.

Modular Polymerase Synthesis and Internal Protein Domain Swapping via Dual Opposed Frameshifts in the Ebola Virus L Gene.

Sequence analysis of the Zaire ebolavirus (EBOV) polymerase (L gene) mRNA, using online tools, identified a highly ranked -1 programmed ribosomal frameshift (FS) signal including an ideal slippery sequence heptamer (UUUAAAA), with an overlapping coding region featuring two tandem UGA codons, immediately followed by an RNA region that is the inverse complement (antisense) to a region of the mRNA of the selenoprotein iodothyronine deiodinase II (DIO2). This antisense interaction was confirmed in vitro via electrophoretic gel shift assay, using cDNAs at the EBOV and DIO2 segments. The formation of a duplex between the two mRNAs could trigger the ribosomal frameshift, by mimicking the enhancing role of a pseudoknot structure, while providing access to the selenocysteine insertion sequence (SECIS) element contained in the DIO2 mRNA. This process would allow the -1 frame UGA codons to be recoded as selenocysteine, forming part of a C-terminal module in a low abundance truncated isoform of the viral polymerase, potentially functioning in a redox role. Remarkably, 90 bases downstream of the -1 FS site, an active +1 FS site can be demonstrated, which, via a return to the zero frame, would enable the attachment of the entire C-terminal of the polymerase protein. Using a construct with upstream and downstream reporter genes, spanning a wildtype or mutated viral insert, we show significant +1 ribosomal frameshifting at this site. Acting singly or together, frameshifting at these sites (both of which are highly conserved in EBOV strains) could enable the expression of several modified isoforms of the polymerase. The 3D modeling of the predicted EBOV polymerase FS variants using the AI tool, AlphaFold, reveals a peroxiredoxin-like active site with arginine and threonine residues adjacent to a putative UGA-encoded selenocysteine, located on the back of the polymerase "hand". This module could serve to protect the viral RNA from peroxidative damage.

Biomechanics Model to Characterize Atomic Force Microscopy-Based Virus-Host Cell Adhesion Measurements.

We present a model for virus-cell adhesion that can be used for quantitative extraction of adhesive properties from atomic force microscopy (AFM)-based force spectroscopy measurements. We extend a previously reported continuum model of viral cell interactions based on a single parameter representing adhesive energy density by using a cohesive zone model in which adhesion is represented by two parameters, a pull-off stress and associated characteristic displacement. This approach accounts for the deformability of the adhesive receptors, such as the Spike protein and transmembrane immunoglobulin and mucin domain (TIM) family that mediate adhesion of SARS-CoV-2 and Ebola viruses, and the omnipresent glycocalyx. Our model represents receptors as a Winkler foundation and aims to predict the pull-off force needed to break the adhesion between the virus and the cell. By comparing the force-separation curves simulated by the model and experimental data, we found that the model can effectively explain the AFM pull-off force trace, thus allowing quantification of the adhesion parameters. Our model provides a more refined understanding of viral cell adhesion and also establishes a framework for interpreting and predicting AFM force spectroscopy measurements.

Knowledge, attitudes and practices on prevention and control of high-consequence infectious diseases and critical care among intensive care personnel in Rwanda: a cross-sectional survey

Intensive care personnel in countries prone to outbreaks of high-consequence infectious diseases (HCIDs), such as Ebola virus disease, stand at the forefront of caring for affected patients. This study describes the knowledge, attitudes and practices (KAP) of intensive care personnel in Rwanda on the management and infection prevention and control (IPC) of HCIDs. A cross-sectional survey was carried out among staff working in the 4 operational intensive care units in September 2022. The self-administered questionnaire collected information on participants' background and their KAP on critical care (CC), HCIDs and IPC. Of the 107 participants, 67 (62.6%) had less than 4 years' work experience in CC. 41 (38.3%) of them had attended trainings on IPC since 2020. In univariate analyses, a higher knowledge score was associated with being a physician, years of working in CC and differed by hospital. A large proportion perceived their knowledge on CC as good or very good (58.0%) and their everyday risk of acquiring an infection as at least high (48.6%). Overall, 72.9% reported compliance with hand hygiene measures. However, around a quarter of participants reported rarely or never avoiding recapping of needles or never or rarely taking additional precautions during aerosol-generating procedures. Staff had a moderate knowledge base and might benefit from continuous learning on CC and HCIDs. The perception of high risk of infection at work stands in contrast with lack of compliance with basic IPC practices which should be reinforced to avoid preventable and potentially fatal infections.

Intracellular Ebola virus nucleocapsid assembly revealed by in situ cryo-electron tomography

Filoviruses, including the Ebola and Marburg viruses, cause hemorrhagic fevers with up to 90% lethality. The viral nucleocapsid is assembled by polymerization of the nucleoprotein (NP) along the viral genome, together with the viral proteins VP24 and VP35. We employed cryo-electron tomography of cells transfected with viral proteins and infected with model Ebola virus to illuminate assembly intermediates, as well as a 9Å map of the complete intracellular assembly. This structure reveals a previously unresolved third and outer layer of NP complexed with VP35. The intrinsically disordered region, together with the C-terminal domain of this outer layer of NP, provides the constant width between intracellular nucleocapsid bundles and likely functions as a flexible tether to the viral matrix protein in the virion. A comparison of intracellular nucleocapsids with prior in-virion nucleocapsid structures reveals that the nucleocapsid further condenses vertically in the virion. The interfaces responsible for nucleocapsid assembly are highly conserved and offer targets for broadly effective antivirals.

Machine Learning Analysis of Radio Data to Uncover Community Perceptions on the Ebola Outbreak in Uganda

Radio is vital for people, especially in rural areas, to share their concerns through interactive talk shows. Understanding public perceptions of pandemics is crucial because they influence people’s attitudes and health-seeking behaviors. This study used machine learning to analyze English and Luganda radio broadcast data to understand public perceptions and perspectives on the Ebola outbreak in Uganda. Our findings revealed three main speaker categories: media personalities, community guests and listeners, and government officials. The government made the most significant effort to educate the public about the Ebola outbreak. The analysis showed that the community was hesitant to use Ebola vaccines, believing that they had not been tested on other populations where the Ebola virus had originated. The community was also concerned about the effects of the lockdown measures imposed during the COVID-19 pandemic. The analysis of the radio broadcast data revealed differences in the timing and content of the conversations between male and female speakers. These experiences can inform population-specific policies for handling ongoing and future pandemics.

Lipid Selectivity of Membrane Action of the Fragments of Fusion Peptides of Marburg and Ebola Viruses.

The life cycle of Ebola and Marburg viruses includes a step of the virion envelope fusion with the cell membrane. Here, we analyzed whether the fusion of liposome membranes under the action of fragments of fusion peptides of Ebola and Marburg viruses depends on the composition of lipid vesicles. A fluorescence assay and electron microscopy were used to quantify the fusogenic activity of the virus fusion peptides and to identify the lipid determinants affecting membrane merging. Differential scanning calorimetry of lipid phase transitions revealed alterations in the physical properties of the lipid matrix produced by virus fusion peptides. Additionally, we found that plant polyphenols, quercetin, and myricetin inhibited vesicle fusion induced by the Marburg virus fusion peptide.

Fc-FcγR interactions during infections: From neutralizing antibodies to antibody-dependent enhancement.

Advances in antibody technologies have resulted in the development of potent antibody-based therapeutics with proven clinical efficacy against infectious diseases. Several monoclonal antibodies (mAbs), mainly against viruses such as SARS-CoV-2, HIV-1, Ebola virus, influenza virus, and hepatitis B virus, are currently undergoing clinical testing or are already in use. Although these mAbs exhibit potent neutralizing activity that effectively blocks host cell infection, their antiviral activity results not only from Fab-mediated virus neutralization, but also from the protective effector functions mediated through the interaction of their Fc domains with Fcγ receptors (FcγRs) on effector leukocytes. Fc-FcγR interactions confer pleiotropic protective activities, including the clearance of opsonized virions and infected cells, as well as the induction of antiviral T-cell responses. However, excessive or inappropriate activation of specific FcγR pathways can lead to disease enhancement and exacerbated pathology, as seen in the context of dengue virus infections. A comprehensive understanding of the diversity of Fc effector functions during infection has guided the development of engineered antiviral antibodies optimized for maximal effector activity, as well as the design of targeted therapeutic approaches to prevent antibody-dependent enhancement of disease.

Discovery of Thiophene Derivatives as Potent, Orally Bioavailable, and Blood-Brain Barrier-Permeable Ebola Virus Entry Inhibitors.

The endemic nature of the Ebola virus disease in Africa underscores the need for prophylactic and therapeutic drugs that are affordable and easy to administer. Through a phenotypic screening employing viral pseudotypes and our in-house chemical library, we identified a promising hit featuring a thiophene scaffold, exhibiting antiviral activity in the micromolar range. Following up on this thiophene hit, a new series of compounds that retain the five-membered heterocyclic scaffold while modifying several substituents was synthesized. Initial screening using a pseudotype viral system and validation assays employing authentic Ebola virus demonstrated the potential of this new chemical class as viral entry inhibitors. Subsequent investigations elucidated the mechanism of action through site-directed mutagenesis. Furthermore, we conducted studies to assess the pharmacokinetic profile of selected compounds to confirm its pharmacological and therapeutic potential.

Long-term cellular immunity of vaccines for Zaire Ebola Virus Diseases

Recent Ebola outbreaks underscore the importance of continuous prevention and disease control efforts. Authorized vaccines include Merck’s Ervebo (rVSV-ZEBOV) and Johnson & Johnson’s two-dose combination (Ad26.ZEBOV/MVA-BN-Filo). Here, in a five-year follow-up of the PREVAC randomized trial (NCT02876328), we report the results of the immunology ancillary study of the trial. The primary endpoint is to evaluate long-term memory T-cell responses induced by three vaccine regimens: Ad26–MVA, rVSV, and rVSV–booster. Polyfunctional EBOV-specific CD4+ T-cell responses increase after Ad26 priming and are further boosted by MVA, whereas minimal responses are observed in the rVSV groups, declining after one year. In-vitro expansion for eight days show sustained EBOV-specific T-cell responses for up to 60 months post-prime vaccination with both Ad26-MVA and rVSV, with no decline. Cytokine production analysis identify shared biomarkers between the Ad26-MVA and rVSV groups. In secondary endpoint, we observed an elevation of pro-inflammatory cytokines at Day 7 in the rVSV group. Finally, we establish a correlation between EBOV-specific T-cell responses and anti-EBOV IgG responses. Our findings can guide booster vaccination recommendations and help identify populations likely to benefit from revaccination.

Transport of Patients With High-Consequence Infectious Diseases: Development of European Capacity in Norway.

Infection of Western aid workers with Ebola virus disease during the 2014-2016 West African outbreak demonstrated the need for medical evacuation to high-level isolation units in Europe and the United States. In Norway, an ad hoc preparedness team was established for aeromedical evacuation in case of need. In October 2014, this team transported an infected aid worker from the military section of Oslo Airport to Oslo University Hospital. To maintain and strengthen the capacity for domestic ambulance transport on the ground and in the air, the Norwegian Medical Emergency Response Team for High Consequence Infectious Diseases (in Norway known as "Nasjonalt medisinsk utrykningsteam for høyrisikosmitte"), or NORTH, was established as a permanent service in 2017. Recognizing the expertise of this domestic team, Norway was subsequently entrusted with the task of enhancing the European aeromedical transport capacity for high-consequence infectious diseases and establishing the Norwegian rescEU Jet Air Ambulance for Transport of Highly Infectious Patients, or NOJAHIP, in 2022. In this case study, we present experiences and lessons learned from these 2 services and discuss how they can be further developed.

Clinical Management of Hospitalized Patients With High-Consequence Infectious Diseases in England.

Infectious disease physicians in England have been diagnosing and managing occasional cases of viral hemorrhagic fever since 1971, including the United Kingdom's first case of Ebola virus disease in 1976. Specialist isolation facilities to provide safe and effective care have been present since that time. Following the emergence of Middle East respiratory syndrome (MERS) in 2012, and the avian influenza A (H7N9) outbreak in 2013, and the 2014-2016 Ebola virus disease outbreak in West Africa, clinical and public health preparedness and response pathways in England have been strengthened for these types of diseases, now called high-consequence infectious diseases (HCIDs). The HCID program, led by NHS England and Public Health England between 2016 and 2018, helped to deliver these enhancements, which have since been used on multiple occasions for new UK cases and outbreaks of MERS, mpox, avian influenza, and Lassa fever. Additionally, HCID pathways were activated for COVID-19 during the first 3 months of 2020, before the pandemic had been declared and little was known about COVID-19 but HCID status had been assigned temporarily to COVID-19 as a precaution. The HCID program also led to the commissioning of a network of new airborne HCID treatment centers in England, to supplement the existing network of contact HCID treatment centers, which includes the United Kingdom's only 2 high-level isolation units. In this case study, the authors describe the airborne and contact HCID treatment center networks in England, including their formation and structures, their approach to safe and effective clinical management of patients with HCIDs in the United Kingdom, and challenges they may face going forward.

Enabling laboratory readiness and preparedness for the evaluation of suspected viral hemorrhagic fevers: development of a laboratory toolkit.

Viral hemorrhagic fevers (VHFs), such as Ebola virus disease, Marburg virus disease, and Lassa fever, are associated with significant morbidity and mortality and the potential for person-to-person transmission. While most individuals in whom VHF is suspected will ultimately be diagnosed with a non-VHF illness, such patients may present to any United States healthcare facility (HCF) for initial evaluation; therefore, all HCFs must be prepared to evaluate and initiate care for suspect VHF patients, especially if they are acutely ill. Included within this evaluation is the ability to perform basic routine laboratory testing before VHF-specific diagnostic test results are available, as well as rapid malaria testing to assess for a common, dangerous "VHF mimic." To improve laboratory preparedness and readiness in the initial care of suspect VHF patients who may present to acute care hospitals. Plan-Do-Study-Act quality improvement model. Frontline healthcare facilities and their clinical laboratories. We describe the development of a laboratory testing toolkit for a suspect VHF patient that can assist frontline HCFs in providing basic laboratory testing required for the care of these patients. The toolkit provides guidance on infection prevention and control, waste management, occupational health, laboratory test collection, processing, and resulting, in the context of suspect VHF patient evaluation. The toolkit is designed to be readily adapted by any frontline HCF in the US. With the guidance provided, facilities will be able to support safer initial evaluation of VHF suspects and ensure high-quality patient care.

Gene expression analysis identifies hub genes and pathways distinguishing fatal from survivor outcomes of Ebola virus disease.

The Ebola virus poses a severe public health threat, yet understanding factors influencing disease outcomes remains incomplete. Our study aimed to identify critical pathways and hub genes associated with fatal and survivor Ebola disease outcomes. We analyzed differentially expressed hub genes (DEGs) between groups with fatal and survival outcomes, as well as a healthy control group. We conducted additional analysis to determine the functions and pathways associated with these DEGs. We found 13,198 DEGs in the fatal and 12,039 DEGs in the survival group compared to healthy controls, and 1873 DEGs in the acute fatal and survivor groups comparison. Upregulated DEGs in the comparison between the acute fatal and survivor groups were linked to ECM receptor interaction, complement and coagulation cascades, and PI3K-Akt signaling. Upregulated hub genes identified from the acute fatal and survivor comparison (FGB, C1QA, SERPINF2, PLAT, C9, SERPINE1, F3, VWF) were enriched in complement and coagulation cascades; the downregulated hub genes (IL1B, 1L17RE, XCL1, CXCL6, CCL4, CD8A, CD8B, CD3D) were associated with immune cell processes. Hub genes CCL2 and F2 were unique to fatal outcomes, while CXCL1, HIST1H4F, and IL1A were upregulated hub genes unique to survival outcomes compared to healthy controls. Our results demonstrate for the first time the association of EVD outcomes to specific hub genes and their associated pathways and biological processes. The identified hub genes and pathways could help better elucidate Ebola disease pathogenesis and contribute to the development of targeted interventions and personalized treatment for distinct EVD outcomes.

ANTIVIRAL TEXTILES AND ANTIVIRAL ACTIVITY TESTING - THE USE OF BACTERIOPHAGE SURROGATE FOR ANTIVIRAL ACTIVITY TESTING

The risk of dissemination of highly contagious viral diseases (as COVID-19, Ebola) led in the increasing need to develop functional textiles and surfaces with antiviral effect. Antiviral textiles are designed to reduce the viability and infectivity of viruses on their surfaces and by this way to reduce the cases of infection (including re-infection or cross-infection with contaminated textiles). Different antiviral agents and diverse techniques of their application are used for functionalized textiles manufacturing. The most often used antivirals are metallic and ionic silver and copper, iron oxide, quaternary ammonium salts. The aim of the process is to prepare textiles with long-term durable finishing effective in viral activity inhibition. The basic step of functionalized antiviral textiles development is antiviral effectivity testing. The safe method of testing with the use of Phi6 bacteriophage, SARS-CoV-2 and Ebola virus surrogate, was modified for antiviral textiles testing. The samples of textiles with antiviral finishing were tested by the bacteriophage-based method and excellent antiviral activity was detected for all tested materials. The woven cotton was used as reference untreated material, the different textile cotton structures with similar square weight were compared and no statistically significant difference was found between the resulting antiviral efficacy values. A simple and quickly feasible screening method for determining the antiviral properties of textiles, especially with leaching-type of treatment, was also designed and tested.

Feasibility Assessment of a Novel Isolation Care Tent in Uganda During the 2022 Sudan ebolavirus Outbreak.

This case study describes a feasibility assessment of a novel isolation care tent used in health facilities in Uganda during the 2022 Sudan ebolavirus outbreak. The Isolation System for Treatment and Agile Response to High-Risk Infections Model 1B (ISTARI 1B) is a single-occupancy, portable, negative-pressure isolation tent designed for the safe delivery of standard care to patients with a communicable disease, including Ebola disease (Sudan). At the request of the Uganda Ministry of Health, the Makerere University Infectious Diseases Institute and University of Nebraska Medical Center partnered to evaluate 7 health facilities across 4 districts in Uganda for infrastructure, case management, and infection prevention and control (IPC) capacity relevant to isolation care and ISTARI 1B use. A 3-day workshop was held with IPC leaders to provide familiarization and hands-on experience with the ISTARI 1B, delineate appropriate use scenarios in Ugandan healthcare settings, contextualize ISTARI 1B use in case management and IPC workflows, develop a framework for site assessment and implementation readiness, and consider ongoing monitoring, assessment, and intervention tools. Workshop participants performed a comprehensive site assessment and mock deployment of the ISTARI 1B. In this case study, we describe lessons learned from health facility assessments and workshop outcomes and offer recommendations to support successful ISTARI 1B implementation. Use scenarios and implementation strategies were identified across facility levels, including tools for site assessment, training, risk communication, and ongoing quality and safety monitoring.