Ebola Virus-infected Patients Research Articles

Early control of viral load by favipiravir promotes survival to Ebola virus challenge and prevents cytokine storm in non-human primates.

Ebola virus has been responsible for two major epidemics over the last several years and there has been a strong effort to find potential treatments that can improve the disease outcome. Antiviral favipiravir was thus tested on non-human primates infected with Ebola virus. Half of the treated animals survived the Ebola virus challenge, whereas the infection was fully lethal for the untreated ones. Moreover, the treated animals that did not survive died later than the controls. We evaluated the hematological, virological, biochemical, and immunological parameters of the animals and performed proteomic analysis at various timepoints of the disease. The viral load strongly correlated with dysregulation of the biological functions involved in pathogenesis, notably the inflammatory response, hemostatic functions, and response to stress. Thus, the management of viral replication in Ebola virus disease is of crucial importance in preventing the immunopathogenic disorders and septic-like shock syndrome generally observed in Ebola virus-infected patients.

Effect of Favipiravir on some epidemic infections: A mini review

Favipiravir is a modern antiviral drug that can be used in developing viral pandemics, such as the Ebola virus, H1N1 flu, Lassa fever, and haemorrhagic fever outbreaks in Argentina in 2009. A. Chain conclusion Favipiravir is transformed to favipiravir-RTP and inserted into the RNA strand that is elongating. Then, since favipiravir acts as a chain terminator, chain elongation slows down at incorporation site of favipiravir and does not continue. The proofreading enzyme cannot repair this complex of RNA-favipiravir and it will be discarded as excessive RNA, which causes the extinction of the viral genome. Mutagenesis with lethal consequences Ribavirin is used in the RNA elongating process until completion. The single strand of RNA with several ribavirin incorporation sites incorporates ribavirin or acts as mRNA for the production of viral proteins. Due to incorporation of ribavirin onto viral RNA, a mismatching of the base pairs (transition mutation) will occur. Translation of this mutated RNA will then cause mutations in the sequence of amino acid residues of the protein, result in impaired of protein function. Viral proteins that have lost their function are unable to replicate or generate infectious viral particles, and the virus is no longer infectious. As a result, lethal mutagenesis ends viral infection in a different way than chain termination. Favipiravir’s clinical trial against Ebola virus-infected patients has not yet been formally approved, and further research is required. Favipiravir, on the other hand, poses a risk of embryo toxicity and teratogenicity. As a result, the Japanese Ministry of Health, Welfare and Labor have been approved this medication with recommendations for more clinical use until August 15, 2014, when they approved the use of favipiravir due to the Ebola virus epidemic in West Africa. The aim of this review is to investigate the potential impact of favipiravir on infections espectially RNA-virus infections, according to previous published investigations, and thus to encourage rapid approval of this interesting antivirus in emergencies.

Human Diversity of Killer Cell Immunoglobulin-Like Receptors and Human Leukocyte Antigen Class I Alleles and Ebola Virus Disease Outcomes

We investigated the genetic profiles of killer cell immunoglobulin-like receptors (KIRs) in Ebola virus–infected patients. We studied the relationship between KIR–human leukocyte antigen (HLA) combinations and the clinical outcomes of patients with Ebola virus disease (EVD). We genotyped KIRs and HLA class I alleles using DNA from uninfected controls, EVD survivors, and persons who died of EVD. The activating 2DS4–003 and inhibitory 2DL5 genes were significantly more common among persons who died of EVD; 2DL2 was more common among survivors. We used logistic regression analysis and Bayesian modeling to identify 2DL2, 2DL5, 2DS4–003, HLA-B-Bw4-Thr, and HLA-B-Bw4-Ile as probably having a significant relationship with disease outcome. Our findings highlight the importance of innate immune response against Ebola virus and show the association between KIRs and the clinical outcome of EVD.

Insufficient Preparation of Ambulatory Physicians for Ebola Virus Disease in Germany

Globalization and climate change increase the likelihood of a global spread of high consequence infectious diseases. We analyzed how outpatient physicians in Germany were prepared to recognize and handle potential Ebola virus-infected patients during the recent Ebola outbreak in West Africa. Outpatient physicians participated in 2 anonymous surveys (n=166 and 129, respectively) and were asked, among others, about their knowledge of Ebola virus disease, their subjective perception of their own knowledge and the practical implementation in their daily routine. This was compared to a minimum standard defined by 14 members of the German "Permanent Working Group of Competence and Treatment Centres for high consequence infectious diseases" (STAKOB). The Ebola virus-specific knowledge of participants was significantly inferior compared to the defined minimum standard. Of 8 factual questions, an average of merely 5 was answered correctly. The physicians' subjective perception of knowledge presented as 'little'. Although 56% of participants indicated that they had received standard operation procedures, 64% had not implemented them into their daily routine. Merely 22% of surveyed medical doctors participated in Ebola virus-specific education programs. Yet participation led to a significantly better subjective knowledge perception. Contrary to the official assessment that Germany is well prepared for high consequence infectious diseases, this study suggests that there are deficits in this area. Despite the abundance of information about Ebola virus disease, preparation of outpatient physicians in Germany was inadequate. Yet nearly half of the participants indicated the potential risk of occurrence as 'likely' or 'very likely'. The presented data show the different consequences to be drawn regarding potential future crises and further research.

Implementation of a non-human primate model of Ebola disease: Infection of Mauritian cynomolgus macaques and analysis of virus populations

Ebola virus (EBOV) haemorrhagic fever remains a threat to global public health with an urgent need for an effective treatment. In order to achieve these goals, access to non-human primate (NHP) laboratory models is an essential requirement. Here, we present the first NHP-EBOV laboratory model readily available to the European scientific community, based on infection of Mauritian cynomolgus macaques using a Central-African EBOV strain and increasing virus challenge dose (10, 100, or 1000 focus forming units per animal). The outcome of these experiments was assessed using clinical, hematological, and biochemical criteria. All challenge doses resulted in fatal infections within 8–11 days. Symptoms appeared from day 5 after infection onwards and disease progression was slower than in previous reports based on Asian cynomolgus macaques. Thus, our model resembled human disease more closely than previous models (onset of symptoms estimated 2–21 days after infection) extending the period of time available for therapeutic intervention. To establish the dynamics of virus genome variation, the study included the first detailed analysis of major and minor genomic EBOV variants during the course of the disease. Major variants were scarce and the population of minor variants was shaped by selective pressure similar to genomic mutations observed in Nature. This primate model provides a robust baseline for future genomic studies in the context of therapeutic methods for treating Ebola virus-infected patients.

Does Disruption of Integrins Play a Role on Ebola Virus Hemorrhagic Fever Syndrome?

Heterodimeric receptors of the beta1 and beta3 integrin families are shown to play an important role in platelet adhesion and aggregation, which is critical for homeostasis and thrombosis [11]. In particular, GPIIb/IIIa integrant complex on platelets binds to collagen, fibrinogen and Von Willebrand Factor, resulting in platelet activation. This activation triggers the coagulation cascade resulting in blood clot formation and hemorrhage control. Ebola virus glycoprotein’s (GP) are shown to interact with Integrins (beta1) and may be involved in the virus entry. Ebola GP expression also led to the down regulation of integrins [12]. Integrand αV was required for efficient GP-mediated transduction and EBOV infection of macrophages [13]. Binding of Ebola virus GP to aVbIII integrins is also shown to prime the endosomal cathepsins, a necessary step in the Ebola virus entry [14]. VP35 protein (required for viral transcription) of Ebola virus contains RGD (Arg-Gly-Asp) and several RGD like motifs in the Table 1. Interestingly, RGD/KGD peptide motif is a conserved feature of low molecular weight non-enzymatic proteins called as “disinterring” present in snake venoms [15]. These molecules bind to the platelet surface integrins (such as alphaII-beta3), blocking the interaction of the platelets with the natural substrates such as fibrinogen and von Willebrand factor. This blockage results in potential inhibition of platelet aggregation [16] (and thus preventing fibrin clots), a crucial step in homeostasis. Due to the presence of conserved RGD and RGD like motifs in VP35, it is possible that VP35 protein might potentially block/delay platelet aggregation. Delayed platelet aggregation might inhibit blood clotting in response to vascular injury/altered vascular barrier observed in the Ebola virus infected patients, thus exacerbating hemorrhages. Significantly decreased platelet aggregation observed in experimentally infected rhesus macaques supports this theory [17]. Table 1: Arg-Gly-Asp (RGD) and similar motifs present in the VP35 protein of Ebola virus (Accession number AAM76032) with the amino acid residue numbers are shown in the figure. Amino acids are represented by single alphabets according to the standard nomenclature.

Decontamination of a field laboratory dedicated to Ebola virus-infected patients.

In 2015, the French Armed Forces deployed a biosafety level 3 (BSL3) field laboratory as a part of an Ebola treatment center in Guinea. When closing the center, laboratory decontamination operations were necessary. We present the decontamination protocols applied for the BSL3 field laboratory, making the entire module ready for a future use.

Plasmodium Parasitemia Associated With Increased Survival in Ebola Virus-Infected Patients.

The ongoing Ebola outbreak in West Africa has resulted in 28 646 suspected, probable, and confirmed Ebola virus infections. Nevertheless, malaria remains a large public health burden in the region affected by the outbreak. A joint Centers for Disease Control and Prevention/National Institutes of Health diagnostic laboratory was established in Monrovia, Liberia, in August 2014, to provide laboratory diagnostics for Ebola virus. All blood samples from suspected Ebola virus-infected patients admitted to the Médecins Sans Frontières ELWA3 Ebola treatment unit in Monrovia were tested by quantitative real-time polymerase chain reaction for the presence of Ebola virus and Plasmodium species RNA. Clinical outcome in laboratory-confirmed Ebola virus-infected patients was analyzed as a function of age, sex, Ebola viremia, and Plasmodium species parasitemia. The case fatality rate of 1182 patients with laboratory-confirmed Ebola virus infections was 52%. The probability of surviving decreased with increasing age and decreased with increasing Ebola viral load. Ebola virus-infected patients were 20% more likely to survive when Plasmodium species parasitemia was detected, even after controlling for Ebola viral load and age; those with the highest levels of parasitemia had a survival rate of 83%. This effect was independent of treatment with antimalarials, as this was provided to all patients. Moreover, treatment with antimalarials did not affect survival in the Ebola virus mouse model. Plasmodium species parasitemia is associated with an increase in the probability of surviving Ebola virus infection. More research is needed to understand the molecular mechanism underlying this remarkable phenomenon and translate it into treatment options for Ebola virus infection.

Clinical Chemistry of Patients With Ebola in Monrovia, Liberia.

The development of point-of-care clinical chemistry analyzers has enabled the implementation of these ancillary tests in field laboratories in resource-limited outbreak areas. The Eternal Love Winning Africa (ELWA) outbreak diagnostic laboratory, established in Monrovia, Liberia, to provide Ebola virus and Plasmodium spp. diagnostics during the Ebola epidemic, implemented clinical chemistry analyzers in December 2014. Clinical chemistry testing was performed for 68 patients in triage, including 12 patients infected with Ebola virus and 18 infected with Plasmodium spp. The main distinguishing feature in clinical chemistry of Ebola virus-infected patients was the elevation in alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and γ-glutamyltransferase levels and the decrease in calcium. The implementation of clinical chemistry is probably most helpful when the medical supportive care implemented at the Ebola treatment unit allows for correction of biochemistry derangements and on-site clinical chemistry analyzers can be used to monitor electrolyte balance.

State-of-the-Art Workshops on Medical Countermeasures Potentially Available for Human Use Following Accidental Exposures to Ebola Virus.

The ongoing outbreak of Ebola in West Africa has raised a general awareness that at present there are no Ebola-specific medical countermeasures (MCMs) with proven effectiveness. This paper recapitulates discussions held at the 6th International Filovirus Symposium in March 2014 as well as the subsequent design of a randomized clinical trial design for treating Ebola virus-infected patients evacuated from West Africa to the United States. A number of different drugs or biologics were critically reviewed and 3 different postexposure strategies were identified as being farthest along in development; passive immunotherapy with monoclonal antibodies, postexposure vaccination with constructs involving viral vectors (such as vesicular stomatitis virus), and antisense compounds directly targeting the viral genome such as modified phosphorodiamidate morpholino oligomer-based compounds and small interfering RNA products. At the time of the meetings, there were no investigational new drugs (INDs) in place for the candidate MCMs. Developers and sponsors of these candidate products were strongly encouraged to prepare pre-IND packets and submit pre-IND meeting requests to the Food and Drug Administration. Some of these investigational products have already been used under emergency authorizations to treat patients in Africa as well as patients evacuated to the United States or Western Europe.

Characterization of activated B cells, a novel antigen-specific B cell population that emerges in blood after infection and vaccination in humans (VAC11P.1062)

Abstract Plasma cells (PCs) and memory B cells (MBCs) provide a remarkably stable humoral immune memory. In humans, antigen-specific antibody secreting cells (ASCs) and MBCs are detected in peripheral blood shortly after infection and vaccination. While ASCs can be distinguished by surface staining, the phenotype of recently generated MBCs is unknown. Here, we defined the phenotype of the latter cells, and termed them activated B cells (ABCs). We confirmed the specificity of ABCs after influenza vaccination and infection by ELISPOT (after in vitro differentiation) and by HA-specific staining. Similarly to ASCs, ABCs actively proliferate, up-regulate CD27 and down-regulate CD21. In contrast to ASCs, ABCs do not spontaneously secrete antibodies and up-regulate CD20 expression. ABCs represent a distinct lineage from ASCs as they maintained Pax5 expression and showed only a slight increase in IRF4 expression compared to naive B cells. Using this characterization, we were able to clearly distinguish ABCs and ASCs in peripheral blood of two Ebola virus-infected patients who were being cared for at Emory University Hospital. Defining ABCs is critical for addressing basic questions regarding the fundamental differences between the memory and plasma cell compartments in humans and because ABCs could be used for procuring therapeutic monoclonal Abs that may be different in terms of their protective potential from those derived from ASCs.

Experience with Treating Ebola Virus–Infected Patients in U.S. Facilities

The devastating Ebola epidemic in Africa has claimed >10,000 lives so far and is only slowly abating. Occasionally healthcare workers from the U.S. and Europe caring for Ebola virus (EBOV)–infected patients in Africa have acquired the infection themselves and been evacuated for advanced medical care. This highly contagious and often deadly infection has raised concerns regarding the appropriateness and safety of providing life-saving or life-sustaining measures to such patients. Two recent papers now address this issue. Johnson and colleagues, from the University of Nebraska Medical Center, report their …

Treatment of Ebola virus infection with antibodies from reconvalescent donors.

Clinical evidence suggests that antibodies from reconvalescent donors (persons who have recovered from infection) may be effective in the treatment of Ebola virus infection. Administration of this treatment to Ebola virus–infected patients while preventing the transmission of other pathogenic viruses may be best accomplished by use of virus-inactivated reconvalescent plasma.

Ebola in pregnancy: risk and clinical outcomes.

The current Ebola virus disease (EVD) outbreak in West Africa—the worst since Ebola virus was identified in 1976—provides a stark reminder of the human consequences of EVD. There are great challenges, ethical dilemmas and uncertainty in providing safe obstetric interventions to Ebola virus-infected women in a humanitarian emergency setting. Although applying the precautionary principle is eminently sensible, especially when protecting healthcare staff, the limited evidence underpinning discussions regarding management of pregnant women with EVD should be acknowledged, with very few studies to date reporting on maternal and fetal outcomes. Much of our understanding of EVD comes from previous outbreaks in resource-limited settings in Africa, a very different healthcare context to the UK. Women in these settings are at high-risk for exposure to Ebola virus (because of their predominant caregiver role, both in domestic and healthcare settings), rather than women being more susceptible to Ebola virus. Ebola virus is transmitted from person to person through close and direct physical contact with body fluids from a symptomatic individual. In the early symptomatic phase, the virus is present in blood but thought to be at very low levels in other body fluids. Infectiousness increases with illness severity, and, in the late phase, all body fluids should be considered infectious, with blood, faeces and vomit being most infectious. Skin is almost certainly highly contaminated in late-stage disease, as maintaining good hygiene with diarrhoea, vomiting, incontinence and bleeding is near impossible (Public Health England; Ebola in pregnancy. 2014, https://www.gov.uk/government/publications/information-for-healthcare-workers-ebola-in-pregnancy). Bausch et al. isolated Ebola virus from breast milk in one lactating woman, in both the acute and convalescent phases of illness (after demonstrated viral clearance from blood), suggesting that the mammary glands may be an immunologically protected site with delayed viral clearance (Bausch et al. J Infect Dis 2007;196:S142–7). However, it is unknown if Ebola virus is transmitted routinely from mothers to infants through breastfeeding (Jamieson et al. Obstet Gynecol 2014;124:1005–10). It is likely that fetal infection occurs through the placenta. In the current outbreak in Guinea, Baggi et al. found a high Ebola virus load in the amniotic fluid of two pregnant women, and in one this was after viral clearance from blood in the convalescent phase. Placental samples in both were also positive for Ebola virus (Baggi et al. Euro Surv 2014;19(49)). In most previous EVD outbreaks, pregnancy-related information was not collected systematically or routinely reported. Data on pregnancy outcomes in the current Ebola outbreak are also relatively scarce, with some reports from Guinea (Baggi et al.; Baize et al. N Engl J Med 2014;371:1418–25), Sierra Leone (Schieffelin et al. N Engl J Med 2014;371:2092–100) and Liberia (Chertow et al. N Engl J Med 2014;371:2054–7). Only the report by Baggi et al. from Guinea specifically focuses on pregnancy outcomes, describing induced deliveries after intrauterine death in two 7-month gestation Ebola virus-infected pregnant women who were in the convalescent phase of illness; both women survived. In the other reports (Baize et al.; Chertow et al.; Schieffelin et al.), pregnancy-related outcomes are described among other clinical outcomes in Ebola virus-infected patients. Limited evidence suggests that pregnant women are at increased risk of spontaneous abortion (Baize et al.; Bull WHO 1978;56:271–93; Bwaka et al. J Infect Dis 1999;179:S1–7; Chertow et al.; Mupapa et al. J Infect Dis. 1999;179:S11–12; Schieffelin et al.), pregnancy-related haemorrhage (Mupapa et al.; Schieffelin et al.), stillbirth (Baggi et al.; Mupapa et al.) and death (Bull WHO; Mupapa et al.) when infected. However, although evidence to date suggests that maternal mortality is high among Ebola virus-infected pregnant women, there are also reports of maternal survival after fetal loss (Bull WHO; Baggi et al.; Baize et al.; Bwaka et al.; Mupapa et al.). High neonatal mortality rates have also been reported. Live infants born to Ebola virus-infected mothers have invariably died (Bull WHO; Mupapa et al.), but some have died in the late neonatal phase, and whether these deaths represented actual cases of EVD or resulted from the many other causes of high infant mortality has not always been known (Bull WHO). As we learn more about Ebola virus transmission and the clinical course of illness and recovery, we must continually revisit our approach to its control and treatment, based on best-quality evidence. Meeting maternal health needs in West Africa while better understanding and managing the risk to healthcare workers in the ongoing Ebola outbreak is the real challenge. AK has previously worked as a clinician with Médecins Sans Frontières in Liberia (2005/06) and currently works for Public Health England.

Diagnostic performances of clinical laboratory tests using Triton X-100 to reduce the biohazard associated with routine testing of Ebola virus-infected patients.

Ebola virus, an enveloped virus, is the cause of the largest and most complex Ebola virus disease (EVD) outbreak in West Africa. Blood or body fluids of an infected person may represent a biohazard to laboratory workers. Laboratory tests of virus containing specimens should be conducted in referral centres at biosafety level 4, but based on the severity of clinical symptoms, basic laboratories might be required to execute urgent tests for patients suspected of EVD. The aim of this work was to compare the analytical performances of laboratory tests when Triton X-100, a chemical agent able to inactivate other enveloped viruses, was added to specimens. Results of clinical chemistry, coagulation and haematology parameters on samples before and after the addition of 0.1% (final concentration) of Triton X-100 and 1 h of incubation at room temperature were compared. Overall, results showed very good agreement by all statistical analyses. Triton X-100 at 0.1% did not significantly affect the results for the majority of the analytes tested. Triton X-100 at 0.1% can be used to reduce the biohazard in performing laboratory tests on samples from patients with EVD without affecting clinical decisions.

Immunopathology of highly virulent pathogens: insights from Ebola virus

Ebola virus is a highly virulent pathogen capable of inducing a frequently lethal hemorrhagic fever syndrome. Accumulating evidence indicates that the virus actively subverts both innate and adaptive immune responses and triggers harmful inflammatory responses as it inflicts direct tissue damage. The host immune system is ultimately overwhelmed by a combination of inflammatory factors and virus-induced cell damage, particularly in the liver and vasculature, often leading to death from septic shock. We summarize the mechanisms of immune dysregulation and virus-mediated cell damage in Ebola virus–infected patients. Future approaches to prevention and treatment of infection will be guided by answers to unresolved questions about interspecies transmission, molecular mechanisms of pathogenesis, and protective adaptive and innate immune responses to Ebola virus.

Inflammatory responses in Ebola virus-infected patients.

Ebola virus subtype Zaire (Ebo-Z) induces acute haemorrhagic fever and a 60-80% mortality rate in humans. Inflammatory responses were monitored in victims and survivors of Ebo-Z haemorrhagic fever during two recent outbreaks in Gabon. Survivors were characterized by a transient release in plasma of interleukin-1beta (IL-1beta), IL-6, tumour necrosis factor-alpha (TNFalpha), macrophage inflammatory protein-1alpha (MIP-1alpha) and MIP-1beta early in the disease, followed by circulation of IL-1 receptor antagonist (IL-1RA) and soluble receptors for TNFalpha (sTNF-R) and IL-6 (sIL-6R) towards the end of the symptomatic phase and after recovery. Fatal infection was associated with moderate levels of TNFalpha and IL-6, and high levels of IL-10, IL-1RA and sTNF-R, in the days before death, while IL-1beta was not detected and MIP-1alpha and MIP-1beta concentrations were similar to those of endemic controls. Simultaneous massive activation of monocytes/macrophages, the main target of Ebo-Z, was suggested in fatal infection by elevated neopterin levels. Thus, presence of IL-1beta and of elevated concentrations of IL-6 in plasma during the symptomatic phase can be used as markers of non-fatal infection, while release of IL-10 and of high levels of neopterin and IL-1RA in plasma as soon as a few days after the disease onset is indicative of a fatal outcome. In conclusion, recovery from Ebo-Z infection is associated with early and well-regulated inflammatory responses, which may be crucial in controlling viral replication and inducing specific immunity. In contrast, defective inflammatory responses and massive monocyte/macrophage activation were associated with fatal outcome.

Lessons from the survivors of Ebola infection

Ebola virus, which causes viral hemorrhagic fever, is one of humankind’s most pathogenic infections, and has a mortality rate of 60–80%. Against such odds, do host or viral factors determine survival? In a study of two clusters in Gabon in 1996, Baize et al. 1 Baize S. et al. Defective humoral responses and extensive intravascular apoptosis are associated with fatal outcome in Ebola virus-infected patients. Nat. Med. 1999; 5: 423-426 Crossref PubMed Scopus (445) Google Scholar measured viral load, antibody responses, mRNA for T-cell-activation markers, T-cell apoptosis and circulating interferon γ (IFN-γ) levels in Ebola patients. Clear distinctions between individuals were evident, with survivors developing specific immunoglobulin G within five days of illness and cytotoxic T lymphocyte (CTL)-responses shortly afterwards. Those who did not survive, by contrast, had a poor immunoglobulin response, rising IFN-γ levels and dramatic T-cell apoptosis (consistent with the lymphoreticular damage characteristic of such patients at post mortem). Viral loads differed little between groups, suggesting that the early host response was critical in determining outcome. Specific antibodies were directed against a viral nucleoprotein and several smaller proteins rather than against transmembrane structures. Thus early T-cell responses determined survival, as has been found in rodent models of Ebola infection; such responses direct the production of appropriate antibodies. This information should help direct Ebola vaccine development, and raises questions as to how clinicians might enhance T-cell response times.

Defective humoral responses and extensive intravascular apoptosis are associated with fatal outcome in Ebola virus-infected patients.

Ebola virus is very pathogenic in humans. It induces an acute hemorrhagic fever that leads to death in about 70% of patients. We compared the immune responses of patients who died from Ebola virus disease with those who survived during two large outbreaks in 1996 in Gabon. In survivors, early and increasing levels of IgG, directed mainly against the nucleoprotein and the 40-kDa viral protein, were followed by clearance of circulating viral antigen and activation of cytotoxic T cells, which was indicated by the upregulation of FasL, perforin, CD28 and gamma interferon mRNA in peripheral blood mononuclear cells. In contrast, fatal infection was characterized by impaired humoral responses, with absent specific IgG and barely detectable IgM. Early activation of T cells, indicated by mRNA patterns in peripheral blood mononuclear cells and considerable release of gamma interferon in plasma, was followed in the days preceding death by the disappearance of T cell-related mRNA (including CD3 and CD8). DNA fragmentation in blood leukocytes and release of 41/7 nuclear matrix protein in plasma indicated that massive intravascular apoptosis proceeded relentlessly during the last 5 days of life. Thus, events very early in Ebola virus infection determine the control of viral replication and recovery or catastrophic illness and death.