Community Research and Development Information Service - CORDIS


EVIDENT Report Summary

Project ID: 666100
Funded under: H2020-EU.3.1.

Periodic Reporting for period 1 - EVIDENT (Ebola Virus Disease - correlates of protection, determinants of outcome, and clinical management)

Reporting period: 2014-11-01 to 2016-04-30

Summary of the context and overall objectives of the project

EVIDENT is a Research and Innovation project that focuses on the Ebola virus (EBOV) disease (EVD) epidemic in West Africa. As of March 2016, a total of 28,639 confirmed cases with 11,316 deaths were reported by the World Health Organization (WHO) from affected countries in West Africa — Guinea, Liberia, Nigeria, Senegal, and Sierra Leone. In terms of reported morbidity and mortality, the current epidemic is far larger than all known EVD epidemics. EVIDENT is closely linked with and builds on the European Mobile Laboratory (EMLab) project, which has deployed three laboratory units to the affected countries in West Africa and performed EVD diagnostics for more than 20,000 samples from 2014 to 2016. EVIDENT has immediate, mid-term and long-term objectives to combat the current and future EVD epidemics.

The specific objectives of EVIDENT are:
- Providing key information needed to implement efficient convalescent plasma treatment and a toolkit to determine the suitability of plasma for treatment.
- Providing key information on immunity of survivors needed to estimate the efficacy of experimental vaccines.
- Improving supportive treatment of patients and reducing hospital case fatality rate by providing information on biomarkers and relevant co-infections.
- Providing information on pathophysiological changes and immunological determinants to infer new strategies for treatment of EVD.
- Monitoring development of mutations in EBOV genomes during the epidemic and enhancing our preparedness to determine the relevance of these changes in experimental systems.
- Protecting health care workers and communities by providing information on virus shedding and estimation of infectiousness in various stages of EVD.
- Support to operational research projects of other partners in the field, specifically vaccine and drug trails.
- Strengthening cooperation of biosafety level 4 (BSL-4) facilities and building a pan-European research area in the field of highly pathogenic viruses.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

EVIDENT has achieved the following results:

1. Immune response of survivors:
We have assessed the antibody titers, including neutralising antibodies, in survivors. We found a broad range of neutralising activity in their plasma; some survivors have very high titers, while in others neutralising antibodies are barely detectable. These data demonstrate that it is important to determine the titer of antibodies before plasma treatment trials to ensure that a therapeutic effect can be observed at all. The neutralising antibody titers remain stable after discharge for long periods of time (at least a year). Therefore, plasma can be obtained from survivors up to several months or perhaps even years after recovery. We found a good correlation between antibodies directed against the glycoprotein as measured in ELISA and the neutralising titer, demonstrating that reactivity in ELISA can serve as a surrogate for neutralising activity. Therefore, we propose the easy-to-perform ELISA rather than the neutralisation assay requiring BSL4 facilities as the method of choice for pre-screening of plasma. In addition, we have assessed T cell reactivity in survivors. As survivors are supposedly protected from re-infection, the observed level of antibody and T cell response should be considered protective. The data are presented to groups studying the efficacy of vaccines for comparison with antibody and T cell data generated with vaccinees. In conclusion, our data provide key information needed to implement efficient convalescent plasma treatment and to estimate the efficacy of experimental vaccines.

2. Management of patients:
To improve treatment of patients and support clinical trials, we have set up clinical chemistry measurement in the field. The analysis revealed frequent renal failure, electrolyte disturbance, and evidence for bacterial super-infection. Some of the pathologic clinical chemistry parameters can be corrected (such as electrolytes and glucose), which has immediate impact on patient management and may improve outcome. Main co-infection detected was malaria, while chronic virus infections were rare. The analysis of various pathogen and host factors revealed that age, virus load, and co-infection with malaria in children 5-14 years of age are independent predictors of poor outcome. Our results have implications for antimalaria and antibacterial therapy and assist in improving supportive treatment.

3. Ebola virus evolution:
We have implemented two sequencing programs. First, using deep sequencing technology, we have retrospectively sequenced 180 genomes covering the period March 2014 to January 2015. This program revealed the evolutionary history and molecular clock of the virus during the epidemic and multiple spreading events of the virus across country borders. Secondly, we have established nanopore sequencing technology in Guinea using the MinION technology. This program allowed us to follow the molecular epidemiology of the virus in the country in real-time and to support the field epidemiology and contact tracing efforts. In the laboratory, we have established replicon and reverse genetics systems that allow us to study the consequences of virus mutations that emerged during the epidemic.

4. Pathophysiology and immunology of EVD:
To provide information on pathophysiological changes and immunological determinants of EVD, we have measured a wide range of soluble cytokines, chemokines and growth factors, and studied the T cell response during the acute phase of infection. Analysis of soluble factors substantiated the notion that human EVD is associated with an overwhelming immune activation rather than immune suppression, and pointed at a discrete subset of cytokines as early markers of disease outcome. Fatal and surviving EVD patients showed robust T cell activation in consistence with the biomarker analysis. However, in fatal patients we observed significant up-regulation of markers of T cell ‘exhaustion’, in particular CTLA-4 and PD-1. These results demonstrated that defects in the mechanisms that control T cell homeostasis are associated to EVD and that high CTLA-4 and PD-1 co-expression in T cells mark fatal EVD. Biomarker and T cell analysis highlight pathways that might be amenable to therapeutic intervention.

5. Virus persistence and shedding:
We have implemented several sub-projects to provide information on virus shedding and estimation of infectiousness of patients and survivors in various stages of EVD. First, various body fluids were sampled from patients while they were treated on the EVD treatment units. We found that essentially all body fluids contain virus RNA until convalescence. Second, we have followed a cohort of male survivors and tested for virus persistence in seminal fluid. We found that the time to clearance of EBOV RNA from seminal fluid is variable and may be >10 months. Third, we have tested samples from the very early phase of EVD and noticed that in rare cases even highly sensitive detection techniques may not be able to detect the virus at this stage. Our predictions will assist in decision-making regarding contact management, surveillance, and preventive measures in EVD outbreaks. Health care workers, midwifes, and sexual partners of survivors are at risk of contracting the disease due to virus persisting in body fluids of male and female survivors.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The project generated data on various aspects of Ebola virus disease (EVD), which go beyond the current knowledge and have implications for patient and outbreak management. Specifically, the data on the frequency of patients with neutralising antibody titer, the time window for harvesting convalescent serum, and the tools for measuring surrogates of neutralising antibodies outside BSL-4 laboratories are expected to have an impact on the production and quality of convalescent serum production and treatment in West Africa. The data on T cell response shall allow vaccine producers to estimate the efficacy of the vaccines. These data may also facilitate the licensing of the current and future EBOV vaccines — in particular if phase 2 studies in humans can demonstrate that the immune response in vaccinated individuals to the EBOV GP antigen (part of the vaccine) corresponds to the survivors’ immune response to this antigen.
We expect that the data on biomarkers, co-infections and virus load will improve supportive clinical care and eventually help reducing the case fatality rate of EVD. First, they provide prognostic information on the course of the disease and predict complications, such as liver or renal failure. Second, clinical chemistry parameters can be measured in treatment units in West Africa, which has immediate impact on patient management and may improve outcome. Several pathologic clinical chemistry parameters can be corrected (such as electrolytes, glucose) even in resource-poor settings. Other parameters indicating bacterial super-infection call for improved antibacterial therapy.
The development of mutations in the virus genome, which may change transmissibility or virulence, has been a matter of concern. Our sequencing data have shown to which extent and in which regions the virus changes during an epidemic. In conjunction with the experimental systems we established, i.e. replicon and reverse genetics systems for the Makona strain of EBOV, we and others have now tools at hand to explore the consequences of mutations of concern. The set-up of a sequencing facility in the field demonstrated the great value of combining field and molecular epidemiology in outbreak situations. This concept is a blueprint for future epidemics.
The project also includes areas with a more long-term impact on research and innovation. This concerns the studies on pathogenesis of the acute infection, including the pathophysiology of the immune response and analysis of relevant pathways and mediators of disease. Our work on immunology of EVD revealed a unique immune signature suggesting serious dysregulation of the T cell response in particular in fatalities. This knowledge will facilitate the design of therapeutic strategies interfering with this pathophysiological cascade.
Our studies on virus shedding will improve the safety of HCW and family members, who are in contact with patients in early phase and after discharge. We now know that a large variety of body fluids contains virus and patients are potentially infectious after discharge for long time. We also observed that sensitive PCR assays might not be able to detect the virus in a few patients at early stage. This information will help optimising contact and patient management. Most importantly, given our data, it is essential to follow-up and potentially treat survivors or vaccinate thier contacts to prevent spread of the virus after discharge in health facilities and families, including sexual partners. However, great care is needed in the use of the data to prevent further stigmatization of EVD survivors.
With the long-term presence of our teams and mobile units (EMLab) in the field, which were crucial to implement the EVIDENT program, we have significantly contributed to the outbreak response. EVIDENT work also supported operational research projects of other partners in the field, such as vaccine and drug trials. Finally, based on EVIDENT achievements, we have obtained funding to support research and surveillance in the affected countries in the future. The novelty of our data is evidenced by publication in high-ranking scientific journals, including NATURE.

Related information

Record Number: 190340 / Last updated on: 2016-11-15
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