Exchange Protein Directly Activated by cAMP Modulates Ebola Virus Uptake into Vascular Endothelial Cells

Members of the family Filoviridae, including Ebola virus (EBOV) and Marburg virus (MARV), cause severe hemorrhagic fever in humans and nonhuman primates. Given their high lethality, a comprehensive understanding of filoviral pathogenesis is urgently needed. In the present studies, we revealed that the exchange protein directly activated by cAMP 1 (EPAC1) gene deletion protects vasculature in ex vivo explants from EBOV infection. Importantly, pharmacological inhibition of EPAC1 using EPAC-specific inhibitors (ESIs) mimicked the EPAC1 knockout phenotype in the ex vivo model. ESI treatment dramatically decreased EBOV infectivity in both ex vivo vasculature and in vitro vascular endothelial cells (ECs). Furthermore, postexposure protection of ECs against EBOV infection was conferred using ESIs. Protective efficacy of ESIs in ECs was observed also in MARV infection. Additional studies using a vesicular stomatitis virus pseudotype that expresses EBOV glycoprotein (EGP-VSV) confirmed that ESIs reduced infection in ECs. Ultrastructural studies suggested that ESIs blocked EGP-VSV internalization via inhibition of macropinocytosis. The inactivation of EPAC1 affects the early stage of viral entry after viral binding to the cell surface, but before early endosome formation, in a phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)-dependent manner. Our study delineated a new critical role of EPAC1 during EBOV uptake into ECs.

Ebola viral dynamics in nonhuman primates provides insights into virus immuno-pathogenesis and antiviral strategies

Despite several clinical trials implemented, no antiviral drug could demonstrate efficacy against Ebola virus. In non-human primates, early initiation of polymerase inhibitors favipiravir and remdesivir improves survival, but whether they could be effective in patients is unknown. Here we analyze the impact of antiviral therapy by using a mathematical model that integrates virological and immunological data of 44 cynomolgus macaques, left untreated or treated with favipiravir. We estimate that favipiravir has a ~50% efficacy in blocking viral production, which results in reducing virus growth and cytokine storm while IFNα reduces cell susceptibility to infection. Simulating the effect of delayed initiations of treatment, our model predicts survival rates of 60% for favipiravir and 100% for remdesivir when treatment is initiated within 3 and 4 days post infection, respectively. These results improve the understanding of Ebola immuno-pathogenesis and can help optimize antiviral evaluation in future outbreaks.

Antiviral Agents Against Ebola Virus Infection: Repositioning Old Drugs and Finding Novel Small Molecules

Ebola virus (EBOV) causes a deadly hemorrhagic syndrome in humans with mortality rate up to 90%. First reported in Zaire in 1976, EBOV outbreaks showed a fluctuating trend during time and fora long period it was considered a tragic disease confined to the isolated regions of the African continent where the EBOV fear was perpetuated among the poor communities. The extreme severity of the recent 2014-16 EBOV outbreak in terms of fatality rate and rapid spread out of Africa led to the understanding that EBOV is a global health risk and highlights the necessity to find countermeasures against it. In the recent years, several small molecules have been shown to display in vitro and in vivo efficacy against EBOV and some of them have advanced into clinical trials. In addition, also existing drugs have been tested for their anti-EBOV activity and were shown to be promising candidates. However, despite the constant effort addressed to identify anti-EBOV therapeutics, no approved drugs are available against EBOV yet. In this chapter, we describe the main EBOV life cycle steps, providing a detailed picture of the druggable viral and host targets that have been explored so far by different technologies. We then summarize the small molecules, nucleic acid oligomers, and antibody-based therapies reported to have an effect either in in silico, or in biochemical and cell-based assays or in animal models and clinical trials, listing them according to their demonstrated or putative mechanism of action.

Ebola: Lessons on Vaccine Development

The West African Ebola virus (EBOV) epidemic has fast-tracked countermeasures for this rare, emerging zoonotic pathogen. Until 2013-2014, most EBOV vaccine candidates were stalled between the preclinical and clinical milestones on the path to licensure, because of funding problems, lack of interest from pharmaceutical companies, and competing priorities in public health. The unprecedented and devastating epidemic propelled vaccine candidates toward clinical trials that were initiated near the end of the active response to the outbreak. Those trials did not have a major impact on the epidemic but provided invaluable data on vaccine safety, immunogenicity, and, to a limited degree, even efficacy in humans. There are plenty of lessons to learn from these trials, some of which are addressed in this review. Better preparation is essential to executing an effective response to EBOV in the future; yet, the first indications of waning interest are already noticeable.

Intensive care support and clinical outcomes of patients with Ebola virus disease (EVD) in West Africa

Purpose

We investigate the impact on outcome of different levels of supportive treatment in Ebola virus disease (EVD). The NGO EMERGENCY delivered care sequentially at two Ebola Treatment Centres (ETC) in Sierra Leone: first at Lakka (fluids, symptomatic, antibiotic, antimalaria treatment, and hospital level medical care), and thereafter in Goderich, adding organ support in the only African ETC with an equipped and staffed intensive care unit (ETC-ICU).

Methods

The primary outcome in this retrospective cohort study was in-ETC mortality. Secondarily, we used multivariable logistic regression to investigate the independent impact of the IC on mortality by comparing patients in two ETCs, adjusting for potential confounders, including the viral load (base-10 logarithm in copies/ml) (LVL), modelled as a piecewise linear function. Mortality was plotted versus LVL. Confidence bands were constructed by a bootstrap technique. The number of hospital-free days within 28 was computed to assess the burden of EVD.

Results

Data from 229 EVD patients were analysed (123 in Lakka, 106 in Goderich). Crude analysis showed a non-statistically significant difference in mortality (57.7% in Lakka vs 50.0% in Goderich; p = 0.19). Age and LVL were associated with mortality. Adjusted mortality was lower at the Goderich ICU-ETC (p = 0.055). This difference was observed with 80% confidence for patients with LVL between 7.5 and 8.5 copies/ml. Hospital-free days (of 28 days) were greater (7.7 vs 5.5; p = 0.03) for patients treated in the ICU-ETC.

Conclusions

Provision of critical care to patients with EVD is feasible in resource-limited settings and was associated with improved survival and less time in hospital.

Electronic supplementary material

The online version of this article (10.1007/s00134-018-5308-4) contains supplementary material, which is available to authorized users.

Small Animal Models for Evaluating Filovirus Countermeasures

The development of novel therapeutics and vaccines to treat or prevent disease caused by filoviruses, such as Ebola and Marburg viruses, depends on the availability of animal models that faithfully recapitulate clinical hallmarks of disease as it is observed in humans. In particular, small animal models (such as mice and guinea pigs) are historically and frequently used for the primary evaluation of antiviral countermeasures, prior to testing in nonhuman primates, which represent the gold-standard filovirus animal model. In the past several years, however, the filovirus field has witnessed the continued refinement of the mouse and guinea pig models of disease, as well as the introduction of the hamster and ferret models. We now have small animal models for most human-pathogenic filoviruses, many of which are susceptible to wild type virus and demonstrate key features of disease, including robust virus replication, coagulopathy, and immune system dysfunction. Although none of these small animal model systems perfectly recapitulates Ebola virus disease or Marburg virus disease on its own, collectively they offer a nearly complete set of tools in which to carry out the preclinical development of novel antiviral drugs.

Ebolaviruses: New roles for old proteins

In 2014, the world witnessed the largest Ebolavirus outbreak in recorded history. The subsequent humanitarian effort spurred extensive research, significantly enhancing our understanding of ebolavirus replication and pathogenicity. The main functions of each ebolavirus protein have been studied extensively since the discovery of the virus in 1976; however, the recent expansion of ebolavirus research has led to the discovery of new protein functions. These newly discovered roles are revealing new mechanisms of virus replication and pathogenicity, whilst enhancing our understanding of the broad functions of each ebolavirus viral protein (VP). Many of these new functions appear to be unrelated to the protein's primary function during virus replication. Such new functions range from bystander T-lymphocyte death caused by VP40-secreted exosomes to new roles for VP24 in viral particle formation. This review highlights the newly discovered roles of ebolavirus proteins in order to provide a more encompassing view of ebolavirus replication and pathogenicity.

Fundamental challenges to the development of a preventive HIV vaccine

There is consensus that only a preventive vaccine can contain the HIV/AIDS pandemic. After 30 years still there is no preventive HIV vaccine. This article examines fundamental challenges to the development of a preventive HIV vaccine. They include the initially erroneous but powerful perception of the natural history of HIV disease, as an acute rather than a chronic illness even in the absence of therapy, the lack of appreciation of the quasispecies biology of HIV and the abandonment of principles of immunology theory caused by the allure of technological prowess. In addition two other important aspects are discussed: vaccines directed against transmitted/founder viruses (T/F) and the reconsideration of HIV inactivation as a viable means to obtain a preventive HIV vaccine using novel safe methods of inactivation not available during the early years of the pandemic.

Viral Zoonoses

Zoonotic viral infections represent an important public health problem across the globe. Unlike infectious agents that are limited to humans, the presence of domestic and wild animal reservoirs and insect and arthropod vectors greatly complicate transmission dynamics and make control measures very difficult to implement. Some viral zoonoses are categorized as “emerging infectious diseases” because they are newly recognized or have shown significant changes in their geographic range and/or epidemiologic characteristics. This article provides updated information on the current status of the most important viral zoonotic diseases. The recent upsurge in Ebola virus infections in West Africa and the emergence of Zika virus in the Western Hemisphere are highlighted.

Management of Ebola Virus Disease in Children

The West African outbreak of 2013 to 2016 was the largest Ebola epidemic in history. With tens of thousands of patients treated during this outbreak, much was learned about how to optimize clinical care for children with Ebola. In anticipation of inevitable future outbreaks, a firsthand summary of the major aspects of pediatric Ebola case management in austere settings is presented. Emphasis is on early and aggressive critical care, including fluid resuscitation, electrolyte repletion, antimicrobial therapy, and nutritional supplementation.

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.

Development of vaccines against Crimean-Congo haemorrhagic fever virus

Crimean-Congo haemorrhagic fever virus (CCHFV) is a deadly human pathogen of the utmost seriousness being highly lethal causing devastating disease symptoms that result in intense and prolonged suffering to those infected. During the past 40years, this virus has repeatedly caused sporadic outbreaks responsible for relatively low numbers of human casualties, but with an alarming fatality rate of up to 80% in clinically infected patients. CCHFV is transmitted to humans by Hyalomma ticks and contact with the blood of viremic livestock, additionally cases of human-to-human transmission are not uncommon in nosocomial settings. The incidence of CCHF closely matches the geographical range of permissive ticks, which are widespread throughout Africa, Asia, the Middle East and Europe. As such, CCHFV is the most widespread tick-borne virus on earth. It is a concern that recent data shows the geographic distribution of Hyalomma ticks is expanding. Migratory birds are also disseminating Hyalomma ticks into more northerly parts of Europe thus potentially exposing naïve human populations to CCHFV. The virus has been imported into the UK on two occasions in the last five years with the first fatal case being confirmed in 2012. A licensed vaccine to CCHF is not available. In this review, we discuss the background and complications surrounding this limitation and examine the current status and recent advances in the development of vaccines against CCHFV.

High-Containment Pathogen Preparation in the Intensive Care Unit

The recent Ebola virus disease outbreak highlighted the need to build national and worldwide capacity to provide care for patients with highly infectious diseases. Specialized biocontainment units were successful in treating several critically ill patients with Ebola virus disease both in the United States and Europe. Several key principles underlie the care of critically ill patients in a high-containment environment. Environmental factors, staffing, equipment, training, laboratory testing, procedures, and waste management each present unique challenges. A multidisciplinary approach is key to developing effective systems and protocols to maintain the safety of patients, staff, and communities.

Clinical Evaluation of Ebola Virus Disease Therapeutics

Ebola virus disease (EVD) was first described over 40 years ago, but no treatment has been approved for humans. The 2013-2016 EVD outbreak in West Africa has expedited the clinical evaluation of several candidate therapeutics that act through different mechanisms, but with mixed results. Nevertheless, these studies are important because the accumulation of clinical data and valuable experience in conducting efficacy trials under emergency circumstances will lead to better implementation of similar studies in the future. Here, we summarize the results of EVD clinical trials, focus on the discussion of factors that may have potentially impeded the effectiveness of existing candidate therapeutics, and highlight considerations that may help meet the challenges ahead in the quest to develop clinically approved drugs.

Longitudinal peripheral blood transcriptional analysis of a patient with severe Ebola virus disease

The 2013-2015 outbreak of Ebola virus disease in Guinea, Liberia, and Sierra Leone was unprecedented in the number of documented cases, but there have been few published reports on immune responses in clinical cases and their relationships with the course of illness and severity of Ebola virus disease. Symptoms of Ebola virus disease can include severe headache, myalgia, asthenia, fever, fatigue, diarrhea, vomiting, abdominal pain, and hemorrhage. Although experimental treatments are in development, there are no current U.S. Food and Drug Administration-approved vaccines or therapies. We report a detailed study of host gene expression as measured by microarray in daily peripheral blood samples collected from a patient with severe Ebola virus disease. This individual was provided with supportive care without experimental therapies at the National Institutes of Health Clinical Center from before onset of critical illness to recovery. Pearson analysis of daily gene expression signatures revealed marked gene expression changes in peripheral blood leukocytes that correlated with changes in serum and peripheral blood leukocytes, viral load, antibody responses, coagulopathy, multiple organ dysfunction, and then recovery. This study revealed marked shifts in immune and antiviral responses that preceded changes in medical condition, indicating that clearance of replicating Ebola virus from peripheral blood leukocytes is likely important for systemic viral clearance.

Neurological Complications and Sequelae of Ebola Virus Disease

PURPOSE OF REVIEW

The recent 2014-2016 outbreak of Ebola virus disease (EVD) has led to many discoveries regarding Ebola. Although neurological symptoms during EVD had been previously described, many reports since this outbreak have made clear that EVD can lead to neurological issues. This article will review the various neurological manifestations of EVD.

RECENT FINDINGS

Recently, many neurological symptoms have been described during acute EVD, including altered mental status, seizures, and meningoencephalitis, among others; survivors of EVD also may develop neurological sequelae, such as persistent headache and memory loss and can exhibit abnormalities on neurological exam. Additionally, it is now evident that in rare cases, survivors may experience relapses of EVD months after recovery, including the central nervous system (CNS). EVD can result in many clinical neurological manifestations, both acutely and after recovery. Research is ongoing to further clarify the nature of Ebola in the CNS.