Progress of vaccine and drug development for Ebola preparedness

Why is repositioning public health innovation towards a social paradigm necessary? A reflection on the field of public health through the examples of Ebola and Covid-19

Health innovations are generally oriented on a techno-economic vision. In this perspective, technologies are seen as an end in themselves, and there is no arrangement between the technical and the social values of innovation. This vision prevails in sanitary crises, in which management is carried out based on the search for punctual, reactive, and technical solutions to remedy a specific problem without a systemic/holistic, sustainable, or proactive approach. This paper attempts to contribute to the literature on the epistemological orientation of innovations in the field of public health. Taking the Covid-19 and Ebola crises as examples, the primary objective is to show how innovation in health is oriented towards a techno-economic paradigm. Second, we propose a repositioning of public health innovation towards a social paradigm that will put more emphasis on the interaction between social and health dimensions in the perspective of social change. We will conclude by highlighting the roles that public health could play in allowing innovations to have more social value, especially during sanitary crises.

Exploiting the reverse vaccinology approach to design novel subunit vaccines against Ebola virus

Ebola virus is a highly pathogenic RNA virus that causes the Ebola haemorrhagic fever in human. This virus is considered as one of the dangerous viruses in the world with very high mortality rate. To date, no epitope-based subunit vaccine has yet been discovered to fight against Ebola although the outbreaks of this deadly virus took many lives in the past. In this study, approaches of reverse vaccinology were utilized in combination with different tools of immunoinformatics to design subunit vaccines against Ebola virus strain Mayinga-76. Three potential antigenic proteins of this virus i.e., matrix protein VP40, envelope glycoprotein and nucleoprotein were selected to construct the subunit vaccine. The MHC class-I, MHC class-II and B-cell epitopes were determined initially and after some robust analysis i.e., antigenicity, allergenicity, toxicity, conservancy and molecular docking study, EV-1, EV-2 and EV-3 were constructed as three potential vaccine constructs. These vaccine constructs are also expected to be effective on few other strains of Ebola virus since the highly conserved epitopes were used for vaccine construction. Thereafter, molecular docking study was conducted on these vaccines and EV-1 emerged as the best vaccine construct. Afterward, molecular dynamics simulation study revealed the good performances and stability of the intended vaccine protein. Finally, codon adaptation and in silico cloning were carried out to design a possible plasmid (pET-19b plasmid vector was used) for large scale production of the EV-1 vaccine. However, further in vitro and in vivo studies might be required on the predicted vaccines for final validation.

[Virus specific antibody - based remedies for the urgent prevention and treatment of Ebola virus disease]

The Ebola virus (member of Ebolavirus genus Filoviridae family) is the etiologic agent of extremely hazard human disease with high mortality rates (up to 90%). The most important components of spectrum of therapeutics for special prophylactic and current of disease, caused by Ebola virus, are prepares, based on virus specific antibodies (convalescent's plasma, geterologic immunoglobulins, monoclonal antibodies. The use of different class therapeutics, based on virus specific antibodies, the possible improvements of its composition and strategy of its application for special prophylactic and current of disease, caused by Ebola virus, are considered in this review.

[The use of monoclonal antibodies for the treatment of Ebola virus disease.]

Some drugs candidates for treatment of Ebola virus disease (EVD), have been studied, monoclonal antibody (mAb) cocktails have shown great potential as EVD therapeutics. The advantages of mAb therapy include low toxicity, high specifcity and versatility, with the range of biological effects being dependent upon the Fc region. Functions of mAbs include pathogen opsonisation, complement activation, antibody-dependent cell cytotoxicity and virus neutralization characteristics. The most known mAb cocktail, used as therapeutic, is ZMapр, manufactured by «Leaf Biopharmaceutical» from 2004. The elaborated mAb cocktails, structures and properties s of mAbs, the protective characteristics of mAbs and development of new pan-ebolavirus mAbs are reviewed in this article.

Immunogenicity of Recombinant Adenovirus Type 5 Vector-Based Ebola Vaccine Expressing Glycoprotein from the 2014 Epidemic Strain in Mice

The 2014 Ebola outbreak in West Africa highlighted the worldwide public health threat posed by this virus and the urgent need for an Ebola vaccine. A novel recombinant adenovirus type 5 vector-based Ebola vaccine (Ad5-EBOV), based on the 2014 Zaire Guinea epidemic strain, was developed in China. A good safety profile and robust immune response elicited by Ad5-EBOV were confirmed in phase 1 and phase 2 clinical trials. Nonetheless, clinical studies of this Ebola vaccine are still at an early stage and there are still no solid efficacy data for humans. For efficacy evaluation and quality control of Ad5-EBOV, the cellular and humoral immune responses in BALB/c mice vaccinated with Ad5-EBOV were examined at various time points. ELISpot and flow cytometric analysis showed that EBOV glycoprotein (GP)-specific T cell responses were detectable early in the first week after infection and by week 4 had increased to maximum levels, which lasted through week 6. During week 1, high titers of EBOV GP-specific antibodies were found (geometric mean [GM], 1783). These titers peaked at week 10 (GM, 26,214) and lasted to 6 months (GM, 1,351). The titer of neutralizing antibodies based on pseudovirus assays also increased over time to peak at 1:16 in one mouse and 1:8 in nine mice during week 6, before decreasing to zero by week 12. These results suggest that BALB/c mice can be used to evaluate the effectiveness of Ad5-EBOV, and that the cellular immune response and humoral immune response can be used as indicators to evaluate vaccine effectiveness. Rapid determination of such methods and indicators is critical for the evaluation of Ebola vaccine efficacy, and can provide effective quality control for Ad5-EBOV.

A review on the antagonist Ebola: A prophylactic approach

Ebola virus (EBOV), a member of Filoviridae virus family under the genus Ebolavirus, has emerged as a dangerous and potential threat to human health globally. It causes a severe and deadly hemorrhagic fever in humans and other mammals, called Ebola Virus Disease (EVD). In recent outbreaks of EVD, there has been loss of large numbers of individual’s life. Therefore, EBOV has attracted researchers and increased interests in developing new models for virus evolution, and therapies. The EBOV interacts with the immune system of the host which led to understand how the virus functions and effects immune system behaviour. This article presents an exhaustive review on Ebola research which includes EVD illness, symptoms, transmission patterns, patho-physiology conditions, development of antiviral agents and vaccines, resilient health system, dynamics and mathematical model of EBOV, challenges and prospects for future studies.

Ebola virus - epidemiology, diagnosis, and control: threat to humans, lessons learnt, and preparedness plans - an update on its 40 year's journey

Ebola virus (EBOV) is an extremely contagious pathogen and causes lethal hemorrhagic fever disease in man and animals. The recently occurred Ebola virus disease (EVD) outbreaks in the West African countries have categorized it as an international health concern. For the virus maintenance and transmission, the non-human primates and reservoir hosts like fruit bats have played a vital role. For curbing the disease timely, we need effective therapeutics/prophylactics, however, in the absence of any approved vaccine, timely diagnosis and monitoring of EBOV remains of utmost importance. The technologically advanced vaccines like a viral-vectored vaccine, DNA vaccine and virus-like particles are underway for testing against EBOV. In the absence of any effective control measure, the adaptation of high standards of biosecurity measures, strict sanitary and hygienic practices, strengthening of surveillance and monitoring systems, imposing appropriate quarantine checks and vigilance on trade, transport, and movement of visitors from EVD endemic countries remains the answer of choice for tackling the EBOV spread. Herein, we converse with the current scenario of EBOV giving due emphasis on animal and veterinary perspectives along with advances in diagnosis and control strategies to be adopted, lessons learned from the recent outbreaks and the global preparedness plans. To retrieve the evolutionary information, we have analyzed a total of 56 genome sequences of various EBOV species submitted between 1976 and 2016 in public databases.

Chemical Targeting of a G-Quadruplex RNA in the Ebola Virus L Gene

In the present study, our bioinformatics analysis first reveals the existence of a conserved guanine-rich sequence within the Zaire ebolavirus L gene. Using various methods, we show that this sequence tends to fold into G-quadruplex RNA. TMPyP4 treatment evidently inhibits L gene expression at the RNA level. Moreover, the mini-replicon assay demonstrates that TMPyP4 effectively inhibits the artificial Zaire ebolavirus mini-genome and is a more potent inhibitor than ribavirin. Although TMPyP4 treatment reduced the replication of the mutant mini-genome when G-quadruplex formation was abolished in the L gene, its inhibitory effect was significantly alleviated compared with wild-type. Our findings thus provide the first evidence that G-quadruplex RNA is present in a negative-sense RNA virus. Finally, G-quadruplex RNA stabilization may represent a new therapeutic strategy against Ebola virus disease.

Ebola virus disease: An update on current prevention and management strategies

Ebola virus disease (EVD) is characterised by systemic viral replication, immuno-suppression, abnormal inflammatory responses, large volume fluid and electrolyte losses, and high mortality in under-resourced settings. There are various therapeutic strategies targeting EVD including vaccines utilizing different antigen delivery methods, antibody-based therapies and antiviral drugs. These therapies remain experimental, but received attention following their use particularly in cases treated outside West Africa during the 2014-15 outbreak, in which 20 (80%) out of 25 patients survived. Emerging data from current trials look promising and are undergoing further study, however optimised supportive care remains the key to reducing mortality from EVD.

Updates in diagnosis and management of Ebola hemorrhagic fever

Ebola hemorrhagic fever is a lethal viral disease transmitted by contact with infected people and animals. Ebola infection represents a worldwide health threat causing enormous mortality rates and fatal epidemics. Major concern is pilgrimage seasons with possible transmission to Middle East populations. In this review, we aim to shed light on Ebola hemorrhagic fever as regard: virology, transmission, biology, pathogenesis, clinical picture, and complications to get the best results for prevention and management. We also aim to guide future research to new therapeutic perspectives to precise targets. Our methodology was to review the literature extensively to make an overall view of the biology of Ebola virus infection, its serious health effects and possible therapeutic benefits using currently available remedies and future perspectives. Key findings in Ebola patients are fever, hepatic impairment, hepatocellular necrosis, lymphopenia (for T-lymphocyte and natural killer cells) with lymphocyte apoptosis, hemorrhagic manifestations, and complications. Pathogenesis in Ebola infection includes oxidative stress, immune suppression of both cell-mediated and humoral immunities, hepatic and adrenal impairment and failure, hemorrhagic fever, activation of deleterious inflammatory pathways, for example, tumor necrosis factor-related apoptosis-inducing ligand, and factor of apoptotic signal death receptor pathways causing lymphocyte depletion. Several inflammatory mediators and cytokines are involved in pathogenesis, for example, interleukin-2, 6, 8, and 10 and others. In conclusion, Ebola hemorrhagic fever is a serious fatal viral infection that can be prevented using strict health measures and can be treated to some extent using some currently available remedies. Newer treatment lines, for example, prophetic medicine remedies as nigella sativa may be promising.

Model-Informed Risk Assessment and Decision Making for an Emerging Infectious Disease in the Asia-Pacific Region

BACKGROUND

Effective response to emerging infectious disease (EID) threats relies on health care systems that can detect and contain localised outbreaks before they reach a national or international scale. The Asia-Pacific region contains low and middle income countries in which the risk of EID outbreaks is elevated and whose health care systems may require international support to effectively detect and respond to such events. The absence of comprehensive data on populations, health care systems and disease characteristics in this region makes risk assessment and decisions about the provision of such support challenging.

METHODOLOGY/PRINCIPAL FINDINGS

We describe a mathematical modelling framework that can inform this process by integrating available data sources, systematically explore the effects of uncertainty, and provide estimates of outbreak risk under a range of intervention scenarios. We illustrate the use of this framework in the context of a potential importation of Ebola Virus Disease into the Asia-Pacific region. Results suggest that, across a wide range of plausible scenarios, preemptive interventions supporting the timely detection of early cases provide substantially greater reductions in the probability of large outbreaks than interventions that support health care system capacity after an outbreak has commenced.

CONCLUSIONS/SIGNIFICANCE

Our study demonstrates how, in the presence of substantial uncertainty about health care system infrastructure and other relevant aspects of disease control, mathematical models can be used to assess the constraints that limited resources place upon the ability of local health care systems to detect and respond to EID outbreaks in a timely and effective fashion. Our framework can help evaluate the relative impact of these constraints to identify resourcing priorities for health care system support, in order to inform principled and quantifiable decision making.

Analysis of Ebola virus polymerase domains to find strain-specific differences and to gain insight on their pathogenicity

Ebola virus, a member of the family Filoviridae has caused immense morbidity and mortality in recent times, especially in West Africa. The infection characterized by chills, fever, diarrhea, and myalgia can progress to hemorrhage and death. Hence, it is a high priority area to better understand its biology in order to expedite vaccine development pipelines. In this regard, this study analyzes the domains in RNA polymerase of fifteen publicly-available Ebola isolates belonging to three strains (Zaire, Sudan and Reston). The protein FASTA sequences of the isolates belonging Zaire, Sudan and Reston strains were extracted from UniProt database and submitted to the interactive web tool SMART for the polymerase domain profiles. Subsequent in silico investigation furnished interesting results that sure can contribute to the understanding of Ebola pathogenesis. The key findings and patterns have been presented, and based on them hypotheses have been formulated for further empirical validation.

Ebola virus disease: How can African pharmacists respond to future outbreaks?

In its forty years history (1976–2016), the West African region has recorded the most devastating form of the Ebola virus disease. The sparse knowledge of healthcare professionals and general public combined with lesser responses from international community are major factors for the dissemination of the disease. In the context of this outbreak, there is a need to highlight the roles and responsibilities of pharmacists, especially in the African healthcare setting. Moreover, the prerequisite of diagnostic kits for the timely detection of the infection as well as pharmacists' awareness of the current therapeutic regimen are recommended.

Lessons from the Ebola Outbreak: Action Items for Emerging Infectious Disease Preparedness and Response

As the Ebola outbreak in West Africa wanes, it is time for the international scientific community to reflect on how to improve the detection of and coordinated response to future epidemics. Our interdisciplinary team identified key lessons learned from the Ebola outbreak that can be clustered into three areas: environmental conditions related to early warning systems, host characteristics related to public health, and agent issues that can be addressed through the laboratory sciences. In particular, we need to increase zoonotic surveillance activities, implement more effective ecological health interventions, expand prediction modeling, support medical and public health systems in order to improve local and international responses to epidemics, improve risk communication, better understand the role of social media in outbreak awareness and response, produce better diagnostic tools, create better therapeutic medications, and design better vaccines. This list highlights research priorities and policy actions the global community can take now to be better prepared for future emerging infectious disease outbreaks that threaten global public health and security.

Induction of Cell-Cell Fusion by Ebola Virus Glycoprotein: Low pH Is Not a Trigger

Ebola virus (EBOV) is a highly pathogenic filovirus that causes hemorrhagic fever in humans and animals. Currently, how EBOV fuses its envelope membrane within an endosomal membrane to cause infection is poorly understood. We successfully measure cell-cell fusion mediated by the EBOV fusion protein, GP, assayed by the transfer of both cytoplasmic and membrane dyes. A small molecule fusion inhibitor, a neutralizing antibody, as well as mutations in EBOV GP known to reduce viral infection, all greatly reduce fusion. By monitoring redistribution of small aqueous dyes between cells and by electrical capacitance measurements, we discovered that EBOV GP-mediated fusion pores do not readily enlarge—a marked difference from the behavior of other viral fusion proteins. EBOV GP must be cleaved by late endosome-resident cathepsins B or L in order to become fusion-competent. Cleavage of cell surface-expressed GP appears to occur in endosomes, as evidenced by the fusion block imposed by cathepsin inhibitors, agents that raise endosomal pH, or an inhibitor of anterograde trafficking. Treating effector cells with a recombinant soluble cathepsin B or thermolysin, which cleaves GP into an active form, increases the extent of fusion, suggesting that a fraction of surface-expressed GP is not cleaved. Whereas the rate of fusion is increased by a brief exposure to acidic pH, fusion does occur at neutral pH. Importantly, the extent of fusion is independent of external pH in experiments in which cathepsin activity is blocked and EBOV GP is cleaved by thermolysin. These results imply that low pH promotes fusion through the well-known pH-dependent activity of cathepsins; fusion induced by cleaved EBOV GP is a process that is fundamentally independent of pH. The cell-cell fusion system has revealed some previously unappreciated features of EBOV entry, which could not be readily elucidated in the context of endosomal entry.

The devastation and transmissibility of Ebola virus (EBOV) are well known. However, the manner in which EBOV enters host cells through endosomal membrane remains elusive. Here, we have developed a convenient experimental system to mimic EBOV fusion in endosomes: cells expressing the fusion protein of EBOV, GP, on their surface are fused to target cells. This system exhibits the known key properties of EBOV fusion. We show that the pH-dependence of EBOV fusion is caused by the pH-dependence of cathepsins, proteases known to cleave EBOV GP into a fusion-competent form. We demonstrate that the fusion activity of this cleaved form is independent of pH. We further show that the enlargement of the fusion pore created by EBOV GP is unusually slow in reaching sizes necessary to pass EBOV’s genome—this is atypical of virally created fusion pores. This cell-cell fusion system should provide a useful platform for developing drugs against EBOV infection.

Human Polyclonal Antibodies Produced through DNA Vaccination of Transchromosomal Cattle Provide Mice with Post-Exposure Protection against Lethal Zaire and Sudan Ebolaviruses

DNA vaccination of transchromosomal bovines (TcBs) with DNA vaccines expressing the codon-optimized (co) glycoprotein (GP) genes of Ebola virus (EBOV) and Sudan virus (SUDV) produce fully human polyclonal antibodies (pAbs) that recognize both viruses and demonstrate robust neutralizing activity. Each TcB was vaccinated by intramuscular electroporation (IM-EP) a total of four times and at each administration received 10 mg of the EBOV-GP_co DNA vaccine and 10 mg of the SUDV-GP_co DNA vaccine at two sites on the left and right sides, respectively. After two vaccinations, robust antibody responses (titers > 1000) were detected by ELISA against whole irradiated EBOV or SUDV and recombinant EBOV-GP or SUDV-GP (rGP) antigens, with higher titers observed for the rGP antigens. Strong, virus neutralizing antibody responses (titers >1000) were detected after three vaccinations when measured by vesicular stomatitis virus-based pseudovirion neutralization assay (PsVNA). Maximal neutralizing antibody responses were identified by traditional plaque reduction neutralization tests (PRNT) after four vaccinations. Neutralizing activity of human immunoglobulins (IgG) purified from TcB plasma collected after three vaccinations and injected intraperitoneally (IP) into mice at a 100 mg/kg dose was detected in the serum by PsVNA up to 14 days after administration. Passive transfer by IP injection of the purified IgG (100 mg/kg) to groups of BALB/c mice one day after IP challenge with mouse adapted (ma) EBOV resulted in 80% protection while all mice treated with non-specific pAbs succumbed. Similarly, interferon receptor 1 knockout (IFNAR ^-/-) mice receiving the purified IgG (100 mg/kg) by IP injection one day after IP challenge with wild type SUDV resulted in 89% survival. These results are the first to demonstrate that filovirus GP DNA vaccines administered to TcBs by IM-EP can elicit neutralizing antibodies that provide post-exposure protection. Additionally, these data describe production of fully human IgG in a large animal system, a system which is capable of producing large quantities of a clinical grade therapeutic product.

Current and emerging strategies for the diagnosis, prevention and treatment of Lassa fever

ABSTRACT 

Lassa fever (LF) is a potentially fatal disease that affects an estimated 300,000–500,000 people in endemic areas of west Africa each year. Though past studies have identified fatality rates of 5–20% in patients suspected to have contracted Lassa virus (LASV), new studies using more precise clinical diagnoses and modern diagnostic assays show fatalities rates above 60% in acutely ill patients from endemic regions. Currently, there are no approved vaccines or therapeutics, and only one Comformité Européenne (CE) marked rapid immunodiagnostic for acute LASV infection. Therefore, preventing LASV transmission is the primary goal in endemic regions. Development of rapid immunodiagnostics and research into the efficacy of current treatment options continues toward saving lives in west Africa as well as creating a line of defense against the nefarious use of LASV in bioterrorism settings.