埃博拉病毒病疫苗研究进展

埃博拉病毒病(Ebola virus disease, EVD)是由埃博拉病毒引起的一种急性出血性传染病. 自2014年3月以来, EVD在西非多个国家暴发,引起全球关注,WHO已将此疫情列为国际关注的突发公共卫生事件.虽然有很多因素限制了EVD疫苗的发展,目前无可用于人的疫苗获批上市,但当前的严峻形式促进了疫苗研究的发展. 本文着重介绍EVD疫苗相关的研究进展,包括评价疫苗所用的动物模型、疫苗种类和进入临床试验的疫苗.     

Filoviruses: One of These Things is (not) Like the Other

The family Filoviridae contains several of the most deadly pathogens known to date and the current Ebola virus disease (EVD) outbreak in Western Africa, due to Ebola virus (EBOV) infection, highlights the need for active and broad research into filovirus pathogenesis. However, in comparison, the seven other known filovirus family members are significantly understudied. Many of these, including Marburgviruses and Ebolaviruses other than EBOV, are also highly virulent and fully capable of causing widespread epidemics. This review places the focus on these non-EBOV filoviruses, including known immunological and pathological data. The available animal models, research tools and currently available therapeutics will also be discussed along with an emphasis in the large number of current gaps in knowledge of these less highlighted filoviruses. It is evident that much research is yet to be done in order to bring the non-EBOV filovirus field to the forefront of current research and, importantly, to the development of more effective vaccines and therapeutics to combat potential future outbreaks.     

Ebola virus disease: Recent advances in diagnostics and therapeutics

Ebola virus disease(EVD)is associated with haemorrhagic fever in humans and nonhuman primates,with a high rate of fatality(up to 90%).Some outbreaks in human history have proven the lethality of EVD.The recent epidemic of 2014 and 2015 in West Africa was the deadliest of all time(11 284 deaths).To understand the transmission dynamics,we have reviewed the epidemiology of EVD to date.The absence of any licensed vaccines or approved drugs against Ebola virus(EBOV)further highlights the severity and crisis level of EVD.Some organizations(public and private)are making considerable efforts to develop novel therapeutic approaches or vaccines to contain the outbreak of EBOV shortly.Here,we summarized the various potential drugs and vaccines(undergoing multiple phases of clinical trials)that have arisen as an alternative against EBOV,and we highlighted the numerous issues and limitations hindering this process.Alternatively,an increasing focus on strengthening the medical and civic health structure could provide speedy benefits in containing the spread of EVD,as well as offer a resilient foundation for the deployment of novel drugs and vaccines to the affected countries,once such drugs and vaccines become available.     

Immunogenicity of rVSVΔG-ZEBOV-GP Ebola vaccination in exposed and potentially exposed persons in the Democratic Republic of the Congo

Despite more than 300,000 rVSVΔG-ZEBOV-glycoprotein (GP) vaccine doses having been administered during Ebola virus disease (EVD) outbreaks in the Democratic Republic of the Congo (DRC) between 2018 and 2020, seroepidemiologic studies of vaccinated Congolese populations are lacking. This study examines the antibody response at 21 d and 6 mo postvaccination after single-dose rVSVΔG-ZEBOV-GP vaccination among EVD-exposed and potentially exposed populations in the DRC. We conducted a longitudinal cohort study of 608 rVSVΔG-ZEBOV-GP–vaccinated individuals during an EVD outbreak in North Kivu Province, DRC. Participants provided questionnaires and blood samples at three study visits (day 0, visit 1; day 21, visit 2; and month 6, visit 3). Anti-GP immunoglobulin G (IgG) antibody titers were measured in serum by the Filovirus Animal Nonclinical Group anti-Ebola virus GP IgG enzyme-linked immunosorbent assay. Antibody response was defined as an antibody titer that had increased fourfold from visit 1 to visit 2 and was above four times the lower limit of quantification at visit 2; antibody persistence was defined as a similar increase from visit 1 to visit 3. We then examined demographics for associations with follow-up antibody titers using generalized linear mixed models. A majority of the sample, 87.2%, had an antibody response at visit 2, and 95.6% demonstrated antibody persistence at visit 3. Being female and of young age was predictive of a higher antibody titer postvaccination. Antibody response and persistence after Ebola vaccination was robust in this cohort, confirming findings from outside of the DRC.

Since the rVSVΔG-ZEBOV-glycoprotein (GP) vaccine completed clinical trials in West Africa, over 300,000 doses of the vaccine have been deployed in response to the multiple Ebola virus disease (EVD) outbreaks in the Democratic Republic of the Congo (DRC). While initially deployed under a “compassionate use/expanded access” protocol (1, 2), as of December 19, 2019, the vaccine was officially licensed by both the American (Food and Drug Administration, FDA) and European (European Medicines Agency) regulatory agencies (3, 4). Wide use of this vaccine was supported by evidence gathered in clinical trials and other studies, including those postlicensure conducted in North America and West Africa, which demonstrated short-term vaccine efficacy (5–16). In addition to short-term protection, clinical trials and other studies have provided evidence of Ebolavirus Zaire (EBOV)–specific antibody persistence up to 2 y postvaccination, suggesting that the vaccine may continue to offer protective immunity over time (5, 7, 8, 14, 15). While promising, observations of successful rVSVΔG-ZEBOV-GP vaccine performance in outbreak settings have mostly come from studies conducted at the end of the 2014 to 2016 West African EVD outbreak (7, 13, 14, 17). Such studies in the DRC are lacking.Furthermore, recent evidence of breakthrough infections within the DRC has highlighted the need for DRC-specific vaccine research, including magnitude and durability of serological response after rVSVΔG-ZEBOV-GP vaccination in Congolese populations. In April 2019, the World Health Organization (WHO) released a preliminary report of rVSVΔG-ZEBOV-GP efficacy in the 2018 to 2020 Beni outbreak. Among 93,965 people at risk who were vaccinated, there were 15 confirmed EVD cases with onset of symptoms 10 d or more postvaccination (18). Another report describes an individual who presented with EVD 6 mo after vaccination, initiating a chain of transmission resulting in 91 subsequent infections (19), prompting questions around the duration of protection. These recent events highlight both the consequences of breakthrough infections and the possibility of waning immunity postvaccination.When considering rVSVΔG-ZEBOV-GP performance in the DRC, there are several factors that may impact the effect of vaccination in Congolese populations. First, an increase in vaccination dose could have resulted in increased immunogenicity in the DRC. Vaccination deployment during the EVD outbreak of 2018 initially included double the plaque-forming units (PFUs) in the vaccine dosage compared to what was used in West Africa (20 million PFU/mL versus 10 million PFU/mL, respectively) (20). As previous studies have identified varying immunogenicity after different vaccine doses in different locations, this variation in vaccine dose could lead to differing antibody responses from previously studied cohorts (15). Second, an important component of the vaccine deployment was the requirement for an ultracold chain (storage of vaccine at −70 °C), which poses extreme logistical challenges in resource-constrained environments. Despite considerable efforts to avoid cold chain failures, it is plausible that fluctuations could have occurred and caused changes in vaccine effectiveness (21). Third, populations in this region may have a baseline level of filovirus seroreactivity that may enable a more robust response to Ebola vaccination (15, 22). Previous serologic studies in the DRC have indicated that Congolese populations may not be naive to filovirus exposures, with individuals presenting evidence of robust antibody responses to various filoviruses in the absence of a known history of EVD (23–26). While there had never been a reported EVD outbreak in North Kivu prior to 2018, this province is known for highly mobile populations; proximity to large forested areas, which may harbor filovirus or filovirus-like pathogens; and access to cross-border populations, including those from Uganda, which have had previous filovirus outbreaks (27–29). Finally, the underlying prevalence of immunosuppressive conditions, such as HIV infection and poor nutritional status, could hinder vaccine immunogenicity in Congolese populations (30).Given the DRC’s unique landscape, which includes evidence of breakthrough infections, a more thorough region-specific understanding of serologic response to Ebola vaccination is needed. Various factors such as vaccine dose, storage conditions, current infections, and previous exposure may alter the magnitude and durability of antibody response after vaccination in Congolese populations (7, 31, 32). To better understand rVSVΔG-ZEBOV-GP performance in the DRC, we conducted a seroepidemiologic study of postvaccination antibody persistence in Congolese populations, who may have meaningfully different experiences than those in West Africa. Here, we provide a preliminary report of antibody response and persistence, along with potential predictors, after single-dose rVSVΔG-ZEBOV-GP vaccination among EVD-exposed and potentially exposed populations in the DRC.     

Identification of a New Ribonucleoside Inhibitor of Ebola Virus Replication

The current outbreak of Ebola virus (EBOV) in West Africa has claimed the lives of more than 15,000 people and highlights an urgent need for therapeutics capable of preventing virus replication. In this study we screened known nucleoside analogues for their ability to interfere with EBOV replication. Among them, the cytidine analogue β-d-N4-hydroxycytidine (NHC) demonstrated potent inhibitory activities against EBOV replication and spread at non-cytotoxic concentrations. Thus, NHC constitutes an interesting candidate for the development of a suitable drug treatment against EBOV.     

埃博拉出血热研究现状及2014年疫情进展

发现于1976年的埃博拉出血热具有高传染性、高致病性和高病死率的特点,曾多次在非洲中西部暴发流行,病死率高达50％-90％。然而目前仍然未研制出有效的疫苗和抗病毒药物。始于2014年初的非洲西部暴发疫情是该病历史上最严重的疫情,感染和死亡人数已经超过了该病发现以来的总和,WHO宣布本次疫情为“国际关注的突发公共卫生事件”。国际公共卫生和医疗部门正在通力合作抗击这一烈性传染病。本文就该病研究现状及本次疫情暴发以来的一些特点进行回顾。     

Ebola Virus GP Activates Endothelial Cells via Host Cytoskeletal Signaling Factors

Ebola virus disease (EVD) is a lethal disease caused by the highly pathogenic Ebola virus (EBOV), and its major symptoms in severe cases include vascular leakage and hemorrhage. These symptoms are caused by abnormal activation and disruption of endothelial cells (ECs) whose mediators include EBOV glycoprotein (GP) without the need for viral replication. However, the detailed molecular mechanisms underlying virus–host interactions remain largely unknown. Here, we show that EBOV-like particles (VLPs) formed by GP, VP40, and NP activate ECs in a GP-dependent manner, as demonstrated by the upregulation of intercellular adhesion molecules-1 (ICAM-1) expression. VLPs-mediated ECs activation showed a different kinetic pattern from that of TNF-α-mediated activation and was associated with apoptotic ECs disruption. In contrast to TNF-α, VLPs induced ICAM-1 overexpression at late time points. Furthermore, screening of host cytoskeletal signaling inhibitors revealed that focal adhesion kinase inhibitors were found to be potent inhibitors of ICAM-1 expression mediated by both TNF-α and VLPs. Our results suggest that EBOV GP stimulates ECs to induce endothelial activation and dysfunction with the involvement of host cytoskeletal signaling factors, which represent potential therapeutic targets for EVD.     

On-Demand Patient-Specific Phenotype-to-Genotype Ebola Virus Characterization

Biosafety, biosecurity, logistical, political, and technical considerations can delay or prevent the wide dissemination of source material containing viable virus from the geographic origin of an outbreak to laboratories involved in developing medical countermeasures (MCMs). However, once virus genome sequence information is available from clinical samples, reverse-genetics systems can be used to generate virus stocks de novo to initiate MCM development. In this study, we developed a reverse-genetics system for natural isolates of Ebola virus (EBOV) variants Makona, Tumba, and Ituri, which have been challenging to obtain. These systems were generated starting solely with in silico genome sequence information and have been used successfully to produce recombinant stocks of each of the viruses for use in MCM testing. The antiviral activity of MCMs targeting viral entry varied depending on the recombinant virus isolate used. Collectively, selecting and synthetically engineering emerging EBOV variants and demonstrating their efficacy against available MCMs will be crucial for answering pressing public health and biosecurity concerns during Ebola disease (EBOD) outbreaks.     

Filovirus Research in Gabon and Equatorial Africa: The Experience of a Research Center in the Heart of Africa

Health research programs targeting the population of Gabon and Equatorial Africa at the International Center for Medical Research in Franceville (CIRMF), Gabon, have evolved during the years since its inception in 1979 in accordance with emerging diseases. Since the reemergence of Ebola virus in Central Africa, the CIRMF “Emerging Viral Disease Unit” developed diagnostic tools and epidemiologic strategies and transfers of such technology to support the response of the National Public Health System and the World Health Organization to epidemics of Ebola virus disease. The Unit carries out a unique investigation program on the natural history of the filoviruses, emergence of epidemics, and Ebola virus pathogenesis. In addition, academic training is provided at all levels to regional and international students covering emerging conditions (host factors, molecular biology, genetics) that favor the spread of viral diseases.     

The Baboon (Papio spp.) as a Model of Human Ebola Virus Infection

Baboons are susceptible to natural Ebola virus (EBOV) infection and share 96% genetic homology with humans. Despite these characteristics, baboons have rarely been utilized as experimental models of human EBOV infection to evaluate the efficacy of prophylactics and therapeutics in the United States. This review will summarize what is known about the pathogenesis of EBOV infection in baboons compared to EBOV infection in humans and other Old World nonhuman primates. In addition, we will discuss how closely the baboon model recapitulates human EBOV infection. We will also review some of the housing requirements and behavioral attributes of baboons compared to other Old World nonhuman primates. Due to the lack of data available on the pathogenesis of Marburg virus (MARV) infection in baboons, discussion of the pathogenesis of MARV infection in baboons will be limited.     

Ebola Virus Disease: Rapid Diagnosis and Timely Case Reporting are Critical to the Early Response for Outbreak Control

Ebola virus disease (EVD) is a life-threatening zoonosis caused by infection with the Ebola virus. Since the first reported EVD outbreak in the Democratic Republic of the Congo, several small outbreaks have been reported in central Africa with about 2,400 cases occurring between 1976 and 2013. The 2013–2015 EVD outbreak in west Africa is the first documented outbreak in this region and the largest ever with over 27,000 cases and more than 11,000 deaths. Although EVD transmission rates have recently decreased in west Africa, this crisis continues to threaten global health and security, particularly since infected travelers could spread EVD to other resource-limited areas of the world. Because vaccines and drugs are not yet licensed for EVD, outbreak control is dependent on the use of non-pharmaceutical interventions (e.g., infection control practices, isolation of EVD cases, contact tracing with follow-up and quarantine, sanitary burial, health education). However, delays in diagnosing and reporting EVD cases in less accessible rural areas continue to hamper control efforts. New advances in rapid diagnostics for identifying presumptive EVD cases and in mobile-based technologies for communicating critical health-related information should facilitate deployment of an early response to prevent the amplification of sporadic EVD cases into large-scale outbreaks.We live in a globally interconnected world where the rapidity of modern travel allows us, and the microbes that infect us, to be virtually anywhere within only hours. In earlier times, weeks or months were often needed to traverse the barriers that were imposed by geography and distance. The lengthiness of travel afforded some protection against the introduction of virulent pathogens to new locales because many who were infected either recovered or succumbed before reaching their final destination. This is no longer the case. Several tropical viral diseases (e.g., dengue, Middle East respiratory syndrome, chikungunya, and Ebola virus disease [EVD]) have expanded their geographical range due in part to transit of infected humans.¹ Of these diseases, EVD has received the lion''s share of international attention. This is because of the 2013–2015 EVD outbreak in west Africa where over 27,000 cases with more than 11,000 deaths have been reported.² Although EVD transmission rates have decreased and Liberia was recently declared free of EVD transmission by the World Health Organization (WHO), this crisis continues to threaten global health and security.EVD is caused by infection with a single-stranded, negative-sense RNA virus of the genus Ebolavirus.³ Zaire ebolavirus (EBOV) was first identified in humans in an outbreak that occurred in 1976 near the Ebola River in the Democratic Republic of the Congo (DRC, formerly Zaire).⁴ Three additional African species, Sudan, Tai Forest, and Bundibugyo ebolavirus, also cause disease in humans, but the case fatality rates due to infection with these viruses are not as high as that due to EBOV, which can reach 90%. Although the natural reservoir of Ebola virus has not been definitively determined, serological and molecular data indicate that this virus is present in some species of African frugivorous and insectivorous bats.^5–7 Zoonotic transmission of Ebola virus may occur in humans who are exposed during hunting and butchering of infected bats.^5,8 Increases in human population, coupled with changes in land use, enhance the risk of contact with reservoirs of Ebola virus.⁸ Pigott and others⁶ mapped the zoonotic niche of EVD in central and west Africa and reported that 22 million humans inhabit at-risk areas. It is possible that EVD could spread more readily in these areas because of increasing population growth and mobility.Human-to-human transmission of EVD occurs primarily via direct contact with bodily fluids of an infected human after fever has developed or with the body of a human who has recently died of EVD.³ The incubation period usually lasts about 1 week, but can be 3 weeks or possibly longer. Thus, humans who are incubating disease, but not yet symptomatic, can travel a considerable distance before they begin to shed the virus as demonstrated by the introduction of EVD via ground travel (e.g., Guinea to Liberia, Sierra Leone, and Senegal) and via air travel (e.g., Guinea to the United States; Liberia to Nigeria, the United States, and the United Kingdom; Sierra Leone to Italy).^2,9,10Although the current EVD outbreak has waned, infections are still occurring in some hot spots in west Africa. Because of the international connectivity of west Africa, there is concern that EVD could spread to other densely populated, resource-limited areas of the world that are ill-prepared to control this disease for which there is as yet no licensed vaccine or proven curative therapy.^10–13 Halting EVD transmission is critical to prevent further spread of EVD within and beyond west Africa. The use of multifaceted non-pharmaceutical interventions (e.g., infection control practices, EVD treatment units for case isolation, contact tracing with follow-up and quarantine, sanitary burial, health education) has decreased EVD transmission in many areas of west Africa. Nevertheless, delays in diagnosing and reporting new EVD cases in less accessible rural areas continue to hamper control efforts.¹⁴If control interventions had been deployed early on, the EVD outbreak in west Africa may have been contained in a relatively short time similar to some EVD outbreaks that occurred previously in central Africa.^15,16 Unfortunately, the lack of surveillance for EVD in west Africa, a region that was largely unfamiliar with this disease, and the lack of adequate public health capacity, impeded an early response and allowed the establishment of multiple foci of EVD in Guinea. However, there is hope that new advances in rapid diagnostics and mobile-based communication technology will expedite the deployment of resources to control EVD outbreaks.^1,17,18 Rapid diagnosis of EVD is critical because the early symptoms of EVD (i.e., high fever, malaise, fatigue, body aches) can be confused with those of some other endemic infectious diseases (e.g., malaria, influenza, typhoid, dengue, yellow fever, Lassa fever).^19,20 The WHO recently approved the ReEBOV Antigen Rapid Test, developed by Tulane University researchers (New Orleans, LA) in partnership with Corgenix Inc. (Broomfield, CO), for procurement in EVD-affected countries.²¹ This lateral flow immunochromatographic assay can provide results within 15–25 minutes and is based on the qualitative detection of EBOV VP40 antigen in serum, plasma, or finger-stick whole blood.²² Although less accurate (92% sensitivity; 85% specificity) than “gold standard” nucleic acid amplification tests (NAATs), the ReEBOV Antigen Rapid Test is less expensive, easier to perform, and does not require electricity. With appropriate infection control precautions, the ReEBOV Antigen Rapid Test can be used by trained personnel as a screening tool in rural health clinic settings for presumptive detection of EBOV in patients whose signs and symptoms, in conjunction with epidemiological risk factors, are consistent with EVD. Rapid diagnosis of presumptive EVD cases allows for 1) isolation of symptomatic individuals while they await confirmatory NAAT to prevent health-care-associated EVD; 2) quarantine and monitoring of contacts to prevent spread of EVD to the community; 3) early administration of supportive treatments (i.e., rehydration, electrolytes, antibiotics, antimalarials) to improve patient outcome; and 4) timely engagement of affected communities to reduce fear and to encourage cooperation with control interventions. However, because of the lower specificity of the ReEBOV Antigen Rapid Test, further refinements will be necessary to improve its positive predictive value when EVD case numbers are low to reduce exposure of patients with false positive test results to patients with EVD. The U.K.''s Defense Science and Technology Laboratory (DSTL) has developed a rapid diagnostic test (RDT) that is similar in principle to the ReEBOV Antigen Rapid Test, but is based on detection of an undisclosed Ebola virus antigen.²³ The DSTL EVD RDT can produce a semiquantitative result by scoring the test (T) line on color intensity (2–10). Although the DSTL EVD RDT appears to have high sensitivity (100%) with a specificity of (∼92–97%) compared with NAAT (i.e., when the control and T line (CT) score is above 2, 4, or 6), further studies are needed before this test can be approved for screening purposes. Other RDTs for EVD are in various stages of development. For example, researchers at the Massachusetts Institute of Technology (Cambridge, MA) and Harvard Medical School (Boston, MA) engineered a multiplexed pathogen detection platform that uses multicolored silver nanoparticles conjugated to monoclonal antibodies directed against EBOV, dengue virus, or yellow fever virus to detect the presence of these agents in human serum.²⁴ Further development of this experimental device, with inclusion of monoclonal antibodies directed against malaria, a common endemic infection, may result in a rapid screening test that could aid differential diagnosis of febrile patients who are suspected to have EVD.Once presumptive EVD cases have been identified, they must be promptly reported to public health authorities to quickly mobilize resources for outbreak control. Advances in mobile-based communication technology are enabling faster, cheaper, and more reliable reporting of EVD cases with expanded geographic coverage. One of several promising examples is mHero (mobile Health Worker Electronic Response and Outreach), a new, two-way, mobile communication platform.²⁵ IntraHealth International (Chapel Hill, NC), in partnership with the United Nations Children''s Fund and Liberia''s Ministry of Health and Social Welfare (MOHSW), has deployed mHero to help frontline health workers (HWs) respond to EVD outbreaks. mHero enables Liberia''s MOHSW to instantly send critical information to thousands of HWs'' mobile phones and HWs to send time-sensitive information to the MOHSW. This powerful tool allows for reporting and tracking of new EVD cases, communicating laboratory test results, sharing reference and training materials, testing and improving HWs'' knowledge, and coordinating with rural health clinics. IntraHealth is introducing mHero in Guinea and discussions are underway to roll out mHero to other countries in west Africa.In addition to expediting EVD case reporting, advances in mobile-based communication technology could help to track the spread of EVD. Accurate, near real-time information on population mobility in west Africa, one of the most highly connected and densely populated regions of Africa, could show where people have gone after leaving an area of EVD transmission, thus suggesting where new cases might appear. This information is valuable because it enables public health authorities to rapidly focus intervention efforts to interrupt EVD transmission. Only a decade ago, obtaining detailed and comprehensive data for this region would have been impossible. Today, call data records (CDRs) that contain mobility data are stored on cell phone carrier servers. Although CDRs have yet to be released for Guinea, Liberia, and Sierra Leone, the west African countries most affected by the EVD outbreak, mobility pattern models have been generated for Côte d''Ivoire and Senegal to demonstrate the feasibility of this approach, which has been previously used to track the spread of malaria in Kenya and cholera in Haiti.²⁶Thus far, more than 24 outbreaks of EVD have occurred in Africa since the first documented outbreak in the DRC in 1976. The 2013–2015 EVD outbreak in west Africa is a stark reminder that an emerging infectious disease can exact a terrible toll on human life, severely affect health-care systems, devastate fragile economies, and destabilize governments. Because Ebola virus has an animal reservoir, it cannot be eradicated. Zoonotic introduction of Ebola virus into the African population will continue to occur and must be detected and tackled early on at the source to prevent amplification of sporadic EVD cases into large-scale outbreaks that are driven by human to human transmission.^7,27 Improved rapid diagnostics and mobile-based communication technology are critical to enable a swift response to EVD and must be included in the EVD preparedness response. Finally, the current EVD outbreak has highlighted the urgent need to rebuild the greatly weakened public health infrastructure of EVD-affected west Africa. This will require a long-term international commitment of significant financial and technical resources. Nonetheless, investments along these lines will surely pay off many times over for global health by strengthening west Africa''s capacity to mount an early response to control outbreaks of EVD and other emerging infectious diseases.     

中医药防治埃博拉病毒病的军民融合机制初探

本文通过总结2014年西非国家埃博拉疫情暴发期间,北京地区军地联合抗击埃博拉病毒病过程中中医药的干预治疗情况,初步探索中医药防治埃博拉病毒病的军民融合机制。     

Tolerance and Persistence of Ebola Virus in Primary Cells from Mops condylurus,a Potential Ebola Virus Reservoir

Although there have been documented Ebola virus disease outbreaks for more than 40 years, the natural reservoir host has not been identified. Recent studies provide evidence that the Angolan free-tailed bat (Mops condylurus), an insectivorous microbat, is a possible ebolavirus reservoir. To investigate the potential role of this bat species in the ecology of ebolaviruses, replication, tolerance, and persistence of Ebola virus (EBOV) were investigated in 10 different primary bat cell isolates from M. condylurus. Varying EBOV replication kinetics corresponded to the expression levels of the integral membrane protein NPC1. All primary cells were highly tolerant to EBOV infection without cytopathic effects. The observed persistent EBOV infection for 150 days in lung primary cells, without resultant selective pressure leading to virus mutation, indicate the intrinsic ability of EBOV to persist in this bat species. These results provide further evidence for this bat species to be a likely reservoir of ebolaviruses.     

Being Ready to Treat Ebola Virus Disease Patients

As the outbreak of Ebola virus disease (EVD) in West Africa continues, clinical preparedness is needed in countries at risk for EVD (e.g., United States) and more fully equipped and supported clinical teams in those countries with epidemic spread of EVD in Africa. Clinical staff must approach the patient with a very deliberate focus on providing effective care while assuring personal safety. To do this, both individual health care providers and health systems must improve EVD care. Although formal guidance toward these goals exists from the World Health Organization, Medecin Sans Frontières, the Centers for Disease Control and Prevention, and other groups, some of the most critical lessons come from personal experience. In this narrative, clinicians deployed by the World Health Organization into a wide range of clinical settings in West Africa distill key, practical considerations for working safely and effectively with patients with EVD.An unprecedented number of health care professionals from a variety of clinical settings, in a wide range of countries are thinking about, preparing for and caring for Ebola virus disease (EVD) patients. Guidance documents on infection prevention and control (IPC) practice and clinical care have been produced by organizations with EVD experience.^1–3 The World Health Organization (WHO) produces guidance for implementation across a wide range of resource settings. Medecin Sans Frontières produces guidance for medical team activities across the outbreak. The Centers for Disease Control and Prevention (CDC) focus on measures which can be taken by the United States health system and extrapolated by others involved in preparedness and response. There are no short cuts to clinical preparedness for EVD. These documents and their revisions should be reviewed carefully.As important as guidance documents are, many lessons must be learned from specific hands-on experience. The WHO has mobilized clinical consultants in support of EVD response in each of the affected countries in West Africa. This short list of key points attempts to consolidate practical lessons learned that do not always percolate into technical documents. Having landed in unconstrained, resource-limited settings at the start of local EVD clinical operations in an outbreak, and more established EVD care centers, we hope that others might adopt some of these lessons and avoid some of the risks inherent to the steep learning curve associated with delivering EVD care. The points are geared toward the daily care of patients as opposed to the critical mechanics of establishing a care center and developing its procedures. They are focused on the outbreak setting and also have relevance to the referral hospital setting.     

From the Cover: Human Ebola virus infection results in substantial immune activation

Four Ebola patients received care at Emory University Hospital, presenting a unique opportunity to examine the cellular immune responses during acute Ebola virus infection. We found striking activation of both B and T cells in all four patients. Plasmablast frequencies were 10–50% of B cells, compared with less than 1% in healthy individuals. Many of these proliferating plasmablasts were IgG-positive, and this finding coincided with the presence of Ebola virus-specific IgG in the serum. Activated CD4 T cells ranged from 5 to 30%, compared with 1–2% in healthy controls. The most pronounced responses were seen in CD8 T cells, with over 50% of the CD8 T cells expressing markers of activation and proliferation. Taken together, these results suggest that all four patients developed robust immune responses during the acute phase of Ebola virus infection, a finding that would not have been predicted based on our current assumptions about the highly immunosuppressive nature of Ebola virus. Also, quite surprisingly, we found sustained immune activation after the virus was cleared from the plasma, observed most strikingly in the persistence of activated CD8 T cells, even 1 mo after the patients’ discharge from the hospital. These results suggest continued antigen stimulation after resolution of the disease. From these convalescent time points, we identified CD4 and CD8 T-cell responses to several Ebola virus proteins, most notably the viral nucleoprotein. Knowledge of the viral proteins targeted by T cells during natural infection should be useful in designing vaccines against Ebola virus.Ebola virus is a member of the Filoviridae family, which are filamentous, negative-stranded RNA viruses that are known to cause severe human disease (1). An ongoing outbreak of Ebola virus in West Africa has brought this virus and the disease it causes (Ebola virus disease; EVD) to the forefront. The World Health Organization has reported over 20,000 cases and 8,000 deaths in West Africa, with Sierra Leone, Guinea, and Liberia the most affected.Our knowledge of the human immune response to Ebola virus has been severely limited due to the lack of infrastructure to perform such analyses in high containment levels (biosafety level 4; BSL-4). Minimal data exist regarding the human cellular immune response during acute Ebola virus infection, which indicate that aberrant cytokine responses (2–6), decreased CD4 and CD8 T cells, and increased CD95 expression on T cells are all associated with fatal outcomes (4). In vivo studies have revealed an association between apoptosis of lymphocytes and fatal outcome (3), and lymphocyte apoptosis has been seen both in vitro in infected human cells and in vivo in mouse and nonhuman primate models (7–9).The natural serologic response to Ebola virus infection has been well-characterized, with specific IgM responses detected as early as 2 d after symptom onset but generally occurring 10–29 d after symptom onset in most patients. Ebola virus-specific IgG responses have been detected as early as 6 d post symptom onset, occurring ∼19 d after symptom onset in most individuals (10, 11). Serological responses to Ebola virus have been reported as absent or diminished in fatal cases; however, sample sizes have been very limited (3).Data from in vitro studies have demonstrated that Ebola virus-infected dendritic cells are impaired in their ability to produce cytokines and activate autologous T cells (12), whereas infected macrophages exhibit impaired maturation (13). Ebola virus also encodes several proteins that can interfere with the innate immune response in infected cells (14). These in vitro studies, combined with the limited human data showing T-cell apoptosis, lymphopenia, and absent antibody responses in fatal cases, have led to the assumption that Ebola virus infection is immunosuppressive.Here we examine the immune responses of four survivors of EVD who received care at Emory University Hospital. This first look, to our knowledge, at the human adaptive immune response during the acute phase of Ebola virus infection shows striking levels of T- and B-cell activation in all four patients.     

Effects of the USA PATRIOT Act and the 2002 Bioterrorism Preparedness Act on select agent research in the United States

A bibliometric analysis of the Bacillus anthracis and Ebola virus archival literature was conducted to determine whether negative consequences of the Uniting and Strengthening America by Providing Appropriate Tools Required to Intercept and Obstruct Terrorism” (USA PATRIOT) Act and the 2002 Bioterrorism Preparedness Act on US select agent research could be discerned. Indicators of the health of the field, such as number of papers published per year, number of researchers authoring papers, and influx rate of new authors, indicated an overall stimulus to the field after 2002. As measured by interorganizational coauthorships, both B. anthracis and Ebola virus research networks expanded after 2002 in terms of the number of organizations and the degree of collaboration. Coauthorship between US and non US scientists also grew for Ebola virus but contracted for the subset of B. anthracis research that did not involve possession of viable, virulent bacteria. Some non-US institutions were dropped, and collaborations with others intensified. Contrary to expectations, research did not become centralized around a few gatekeeper institutions. Two negative effects were detected. There was an increased turnover rate of authors in the select agent community that was not observed in the control organism (Klebsiella pneumoniae) research community. However, the most striking effect observed was not associated with individual authors or institutions; it was a loss of efficiency, with an approximate 2- to 5-fold increase in the cost of doing select agent research as measured by the number of research papers published per millions of US research dollars awarded.     

埃博拉疫苗临床试验研究进展

埃博拉病毒病以往被人们称作埃博拉病毒性出血热,目前尚无针对该病的特异性治疗措施与药物,疫苗成为最有可能预防控制病毒传播的手段。目前,多种埃博拉候选疫苗已经进入了临床试验,包括减毒水疱性口炎病毒载体埃博拉疫苗(rVSV-ZEBOV)、复制缺陷型黑猩猩3型腺病毒载体埃博拉疫苗(cAd3-EBO或ChAd3-EBO-Z)、复制缺陷型人5型腺病毒载体埃博拉疫苗(Ad5-EBOV)和人3型副流感病毒载体埃博拉疫苗(HPIV3)等。ChAd3-EBO-Z和Ad5-EBOV等在早期的临床试验中均表现出较好的安全性和免疫原性。rVSV-ZEBOV率先完成了Ⅲ期临床试验,已证实其对埃博拉病毒病的预防具有很高的保护效力,但是研究数据也提示了该疫苗可能存在的安全性问题。本文旨在回顾2014年以来埃博拉疫苗在临床试验研究方面的重大进展,讨论尚存的问题和挑战以及未来的发展方向。     

Filovirus RefSeq Entries: Evaluation and Selection of Filovirus Type Variants,Type Sequences,and Names

Sequence determination of complete or coding-complete genomes of viruses is becoming common practice for supporting the work of epidemiologists, ecologists, virologists, and taxonomists. Sequencing duration and costs are rapidly decreasing, sequencing hardware is under modification for use by non-experts, and software is constantly being improved to simplify sequence data management and analysis. Thus, analysis of virus disease outbreaks on the molecular level is now feasible, including characterization of the evolution of individual virus populations in single patients over time. The increasing accumulation of sequencing data creates a management problem for the curators of commonly used sequence databases and an entry retrieval problem for end users. Therefore, utilizing the data to their fullest potential will require setting nomenclature and annotation standards for virus isolates and associated genomic sequences. The National Center for Biotechnology Information’s (NCBI’s) RefSeq is a non-redundant, curated database for reference (or type) nucleotide sequence records that supplies source data to numerous other databases. Building on recently proposed templates for filovirus variant naming [<virus name> (<strain>)/<isolation host-suffix>/<country of sampling>/<year of sampling>/<genetic variant designation>-<isolate designation>], we report consensus decisions from a majority of past and currently active filovirus experts on the eight filovirus type variants and isolates to be represented in RefSeq, their final designations, and their associated sequences.