Pulmonary Involvement during the Ebola Virus Disease

PET imaging of TSPO expression in immune cells can assess organ-level pathophysiology in high-consequence viral infections

Ebola virus (EBOV) disease is characterized by lymphopenia, breach in vascular integrity, cytokine storm, and multiorgan failure. The pathophysiology of organ involvement, however, is incompletely understood. Using [18F]-DPA-714 positron emission tomography (PET) imaging targeting the translocator protein (TSPO), an immune cell marker, we sought to characterize the progression of EBOV-associated organ-level pathophysiology in the EBOV Rhesus macaque model. Dynamic [18F]-DPA-714 PET/computed tomography imaging was performed longitudinally at baseline and at multiple time points after EBOV inoculation, and distribution volumes (Vt) were calculated as a measure of peripheral TSPO binding. Using a mixed-effect linear regression model, spleen and lung Vt decreased, while the bone marrow Vt increased over time after infection. No clear trend was found for liver Vt. Multiple plasma cytokines correlated negatively with lung/spleen Vt and positively with bone marrow Vt. Multiplex immunofluorescence staining in spleen and lung sections confirmed organ-level lymphoid and monocytic loss/apoptosis, thus validating the imaging results. Our findings are consistent with EBOV-induced progressive monocytic and lymphocytic depletion in the spleen, rather than immune activation, as well as depletion of alveolar macrophages in the lungs, with inefficient reactive neutrophilic activation. Increased bone marrow Vt, on the other hand, suggests hematopoietic activation in response to systemic immune cell depletion and leukocytosis and could have prognostic relevance. In vivo PET imaging provided better understanding of organ-level pathophysiology during EBOV infection. A similar approach can be used to delineate the pathophysiology of other systemic infections and to evaluate the effectiveness of newly developed treatment and vaccine strategies.

Modulation of immune response in Ebola virus disease

Ebola virus disease targets and destroys immune cells, including macrophages and dendritic cells, leading to impairment of host response. After infection, a combination of strategies including alteration and evasion of immune response culminating in a strong inflammatory response can lead to multi-organ failure and death in most infected patients. This review discusses immune response dynamics, mainly focusing on how Ebola manipulates innate and adaptive immune responses and strategizes to thwart host immune responses. We also discuss the challenges and prospects of developing therapeutics and vaccines against Ebola.

Structural risk analysis of a potential Ebola outbreak with respect to infrastructural aspects amid the current COVID-19 pandemic

Due to the ease and increased volume of global interaction, it remains unclear whether the current coronavirus disease (COVID-19) pandemic will be a one-off event or whether the world is at risk of recurrent pandemics as a result of globalization. To address this important issue, the present study assessed the risk of a possible future Ebola pandemic. The risk profile of Hubei province in China was compared with that of the Democratic Republic of Congo (DRC) in terms of travel and infrastructure, since DRC is considered a major epicenter for Ebola outbreaks. Recurrence patterns of previous Ebola outbreaks were analyzed in a cumulative outbreak model. Internationally available data on air traffic, flight destinations, passenger numbers, population density, distribution and domestic traffic routes were all analyzed and compared between the DRC and Hubei province. DRC is a major epicenter for Ebola outbreaks, with 13 recorded outbreaks from 1976 until 2020. International airports at both Kinshasa, the capital city of the DRC and Wuhan, the capital city of Hubei province, are heavily frequented destinations and represent major transfer hubs on their respective continents. Volumes of flights to and from extracontinental destinations account for <25% of total flights at both airports with similar total international passenger volumes. However, the volume of domestic commuting by aviation is >30-fold higher at Hubei province compared with that of the DRC. This finding is also reflected by the higher population density and homogeneity in terms of population per square kilometer in Hubei. Following the analysis of decades of Ebola reports, it became evident that the DRC remains a hotspot for potential Ebola outbreaks in the future due to constantly recurrent local outbreaks. In terms of the international aviation network, numerous important similarities between Kinshasa and Hubei Province were observed as regards connectivity. The present comparative analysis extends beyond biological factors underlying Ebola and COVID-19 transmissions and confirms that the DRC, Kinshasa in particular, is not a remote location. Although internal commuting and population density may be lower in the DRC compared with those in Hubei province, integration into the international aviation network is similarly extensive. The international community must increase its focus and efforts in preventing another possible global pandemic commencing in Africa, and in particular the DRC.

Review of Ebola virus disease in children - how far have we come?

Ebola virus (EBOV) causes an extremely contagious viral haemorrhagic fever associated with high mortality. While, historically, children have represented a small number of total cases of Ebolavirus disease (EVD), in recent outbreaks up to a quarter of cases have been in children. They pose unique challenges in clinical management and infection prevention and control. In this review of paediatric EVD, the epidemiology of past EVD outbreaks with specific focus on children is discussed, the clinical manifestations and laboratory findings are described and key developments in clinical management including specific topics such as viral persistence and breastfeeding while considering unique psychosocial and anthropological considerations for paediatric care including of survivors and orphans and the stigma they face are discussed. In addition to summarising the literature, perspectives based on the authors' experience of EVD outbreaks in the Democratic Republic of the Congo (DRC) are described.Abbreviations: ARDS: acute respiratory distress syndrome; aOR: adjusted odds ratio; ALT: alanine transferase; ALIMA: Alliance for International Medical Action; AST: aspartate transaminase; BUN: blood urea nitrogen; CNS: central nervous system; CUBE: chambre d'urgence biosécurisée pour épidémie; COVID-19: coronavirus disease 2019; C_t: cycle threshold; DRC: Democratic Republic of Congo; ETC: ebola treatment centre; ETU: ebola treatment unit; EBOV: ebola virus; EVD: ebolavirus disease; FEAST: fluid expansion as supportive therapy; GP: glycoprotein; IV: intravenous; MEURI: monitored emergency use of unregistered interventions; NETEC: National Ebola Training and Education Centre; NP: nucleoprotein; ORS: oral rehydration solution; PALM: Pamoja Tulinde Maisha; PREVAIL: Partnership for Research on Ebola Virus in Liberia; PPE: personal protective equipment; PCR: polymerase chain reaction; PEP: post-exposure prophylaxis; RDTs: rapid diagnostic tests; RT: reverse transcriptase; RNA: ribonucleic acid; UNICEF: United Nations International Children's Emergency Fund; USA: United States of America; WHO: World Health Organization.

Immunological Perspective for Ebola Virus Infection and Various Treatment Measures Taken to Fight the Disease

Ebolaviruses, discovered in 1976, belongs to the Filoviridae family, which also includes Marburg and Lloviu viruses. They are negative-stranded RNA viruses with six known species identified to date. Ebola virus (EBOV) is a member of Zaire ebolavirus species and can cause the Ebola virus disease (EVD), an emerging zoonotic disease that results in homeostatic imbalance and multi-organ failure. There are three EBOV outbreaks documented in the last six years resulting in significant morbidity (> 32,000 cases) and mortality (> 13,500 deaths). The potential factors contributing to the high infectivity of this virus include multiple entry mechanisms, susceptibility of the host cells, employment of multiple immune evasion mechanisms and rapid person-to-person transmission. EBOV infection leads to cytokine storm, disseminated intravascular coagulation, host T cell apoptosis as well as cell mediated and humoral immune response. In this review, a concise recap of cell types targeted by EBOV and EVD symptoms followed by detailed run-through of host innate and adaptive immune responses, virus-driven regulation and their combined effects contributing to the disease pathogenesis has been presented. At last, the vaccine and drug development initiatives as well as challenges related to the management of infection have been discussed.