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At least 19 recordsLinked to original sources
PubMed2006

Conserved receptor-binding domains of Lake Victoria marburgvirus and Zaire ebolavirus bind a common receptor.

The GP(1,2) envelope glycoproteins (GP) of filoviruses (marburg- and ebolaviruses) mediate cell-surface attachment, membrane fusion, and entry into permissive cells. Here we show that a 151-amino acid fragment of the Lake Victoria marburgvirus GP1 subunit bound filovirus-permissive cell lines more efficiently than full-length GP1. An homologous 148-amino acid fragment of the Zaire ebolavirus GP1 subunit similarly bound the same cell lines more efficiently than a series of longer GP1 truncation variants. Neither the marburgvirus GP1 fragment nor that of ebolavirus bound a nonpermissive lymphocyte cell line. Both fragments specifically inhibited replication of infectious Zaire ebolavirus, as well as entry of retroviruses pseudotyped with either Lake Victoria marburgvirus or Zaire ebolavirus GP(1,2). These studies identify the receptor-binding domains of both viruses, indicate that these viruses utilize a common receptor, and suggest that a single small molecule or vaccine can be developed to inhibit infection of all filoviruses.

Amino Acid Sequence↗
PubMed2006

Assembly and budding of Ebolavirus.

Ebolavirus is responsible for highly lethal hemorrhagic fever. Like all viruses, it must reproduce its various components and assemble them in cells in order to reproduce infectious virions and perpetuate itself. To generate infectious Ebolavirus, a viral genome-protein complex called the nucleocapsid (NC) must be produced and transported to the cell surface, incorporated into virions, and then released from cells. To further our understanding of the Ebolavirus life cycle, we expressed the various viral proteins in mammalian cells and examined them ultrastructurally and biochemically. Expression of nucleoprotein alone led to the formation of helical tubes, which likely serve as a core for the NC. The matrix protein VP40 was found to be critical for transport of NCs to the cell surface and for the incorporation of NCs into virions, where interaction between nucleoprotein and the matrix protein VP40 is likely essential for these processes. Examination of virus-infected cells revealed that virions containing NCs mainly emerge horizontally from the cell surface, whereas empty virions mainly bud vertically, suggesting that horizontal budding is the major mode of Ebolavirus budding. These data form a foundation for the identification and development of potential antiviral agents to combat the devastating disease caused by this virus.

Animals↗
PubMed2005

Generation of eGFP expressing recombinant Zaire ebolavirus for analysis of early pathogenesis events and high-throughput antiviral drug screening.

Zaire ebolavirus causes large outbreaks of severe and usually fatal hemorrhagic disease in humans for which there is no effective treatment or cure. To facilitate examination of early critical events in viral pathogenesis and to identify antiviral compounds, a recombinant Zaire ebolavirus was engineered to express a foreign protein, eGFP, to provide a rapid and sensitive means to monitor virus replication in infected cells. This genetically engineered virus represents the first insertion of a foreign gene into ebolavirus. We show that Ebola-eGFP virus (EboZ-eGFP) infects known early targets of human infections and serves as an ideal model to screen antiviral compounds in less time than any previously published assay.

Animals↗
PubMed2004

A C-terminal basic amino acid motif of Zaire ebolavirus VP35 is essential for type I interferon antagonism and displays high identity with the RNA-binding domain of another interferon antagonist, the NS1 protein of influenza A virus.

The ebolavirus VP35 protein antagonizes the cellular type I interferon response by blocking phosphorylation of IRF-3, a transcription factor that turns on the expression of a large number of antiviral genes. To identify the domain of VP35 responsible for interferon antagonism, we generated mutations within the VP35 gene and found that a C-terminal basic amino acid motif is required for inhibition of ISG56 reporter gene expression as well as IFN-beta production. Remarkably, this basic amino acid motif displayed high sequence identity with part of the N-terminal RNA-binding domain of another interferon-antagonist, the NS1 protein of influenza A virus.

Amino Acid Motifs↗
PubMed2005

Homo-oligomerization facilitates the interferon-antagonist activity of the ebolavirus VP35 protein.

We have identified a putative coiled-coil motif within the amino-terminal half of the ebolavirus VP35 protein. Cross-linking studies demonstrated the ability of VP35 to form trimers, consistent with the presence of a functional coiled-coil motif. VP35 mutants lacking the coiled-coil motif or possessing a mutation designed to disrupt coiled-coil function were defective in oligomerization, as deduced by co-immunoprecipitation studies. VP35 inhibits signaling that activates interferon regulatory factor 3 (IRF-3) and inhibits (IFN)-alpha/beta production. Experiments comparing the ability of VP35 mutants to block IFN responses demonstrated that the VP35 amino-terminus, which retains the putative coiled-coil motif, was unable to inhibit IFN responses, whereas the VP35 carboxy-terminus weakly inhibited the activation of IFN responses. IFN-antagonist function was restored when a heterologous trimerization motif was fused to the carboxy-terminal half of VP35, suggesting that an oligomerization function at the amino-terminus facilitates an "IFN-antagonist" function exerted by the carboxy-terminal half of VP35.

Amino Acid Motifs↗
PubMed2006

Modulation of virion incorporation of Ebolavirus glycoprotein: effects on attachment, cellular entry and neutralization.

The filoviruses Ebolavirus (EBOV) and Marburgvirus (MARV) cause severe hemorrhagic fever in humans and are potential agents of biological warfare. The envelope glycoprotein (GP) of filoviruses mediates viral entry into cells and is an attractive target for therapeutic intervention and vaccine design. Here, we asked if the efficiency of virion incorporation of EBOV-GP impacts attachment and entry into target cells and modulates susceptibility to neutralizing antibodies. In order to control the level of EBOV-GP expression, we generated cell lines expressing the GPs of the four known EBOV subspecies in an inducible fashion. Regulated expression of GP on the cell surface allowed production of reporter viruses harboring different amounts of GP. A pronounced reduction of virion incorporation of EBOV-GP had relatively little effect on virion infectivity, suggesting that only a few copies of GP might be sufficient for efficient engagement of cellular receptors. In contrast, optimal interactions with cellular attachment factors like the DC-SIGN protein required incorporation of high amounts of GP. Antibody-mediated neutralization of virions bearing high amounts of GP was slightly more efficient than neutralization of virions harboring low amounts of GP, suggesting that the efficiency of GP incorporation into virions might modulate susceptibility to neutralizing antibodies. Finally, regulated expression of GP in permissive 293 cells did not reduce EBOV-GP-driven infection but diminished vesicular stomatitis virus GP (VSV-G) and amphotropic murine leukemia virus (A-MLV) GP mediated entry in a dose-dependent manner. Therefore, intracellular GP does not seem to downmodulate expression of its receptor(s) but might alter expression and/or function of molecules involved in VSV-G and A-MLV-GP-dependent entry. Our results suggest that the efficiency of virion incorporation of GP could impact EBOV attachment to target cells and might modulate control of viral spread by the humoral immune response.

Cell Line↗
PubMed2006

The signal peptide of the ebolavirus glycoprotein influences interaction with the cellular lectins DC-SIGN and DC-SIGNR.

The C-type lectins DC-SIGN and DC-SIGNR (collectively referred to as DC-SIGN/R) bind to the ebolavirus glycoprotein (EBOV-GP) and augment viral infectivity. DC-SIGN/R strongly enhance infection driven by the GP of EBOV subspecies. Zaire (ZEBOV) but have a much less pronounced effect on infection mediated by the GP of EBOV subspecies. Sudan (SEBOV). For this study, we analyzed the determinants of the differential DC-SIGN/R interactions with ZEBOV- and SEBOV-GP. The efficiency of DC-SIGN engagement by ZEBOV-GP was dependent on the rate of GP incorporation into lentiviral particles, while appreciable virion incorporation of SEBOV-GP did not allow robust DC-SIGN/R usage. Forced incorporation of high-mannose carbohydrates into SEBOV-GP augmented the engagement of DC-SIGN/R to the levels observed with ZEBOV-GP, indicating that appropriate glycosylation of SEBOV-GP is sufficient for efficient DC-SIGN/R usage. However, neither signals for N-linked glycosylation unique to SEBOV- or ZEBOV-GP nor the highly variable and heavily glycosylated mucin-like domain modulated the interaction with DC-SIGN/R. In contrast, analysis of chimeric GPs identified the signal peptide as a determinant of DC-SIGN/R engagement. Thus, ZEBOV- but not SEBOV-GP was shown to harbor high-mannose carbohydrates, and GP modification with these glycans was controlled by the signal peptide. These results suggest that the signal peptide governs EBOV-GP interactions with DC-SIGN/R by modulating the incorporation of high-mannose carbohydrates into EBOV-GP. In summary, we identified the level of GP incorporation into virions and signal peptide-controlled glycosylation of GP as determinants of attachment factor engagement.

Cell Adhesion Molecules↗
PubMed2026

The Re-Emergence of Bundibugyo Ebolavirus in Uganda and the Democratic Republic of Congo: Epidemiological Drivers, Response Strategies, and Implications for Global Health Security.

Bundibugyo ebolavirus (BDBV) is one of the least studied species within the genus Orthoebolavirus (family Filoviridae), despite its capacity to cause severe Ebola virus disease (EVD) with substantial mortality. First identified during a 2007-2008 outbreak in Bundibugyo District, western Uganda (149 reported cases, 37 deaths; case-fatality rate [CFR] approximately 25-36%), BDBV re-emerged in 2012 in Orientale Province, Democratic Republic of the Congo (DRC) (57-59 cases, 29-34 deaths; CFR 34-58%), before resurfacing in Ituri Province, DRC, in April-May 2026. By 11 August 2026, this third outbreak had grown to 4566 laboratory-confirmed cases and 2128 deaths (CFR ≈ 47%) across five DRC provinces and Uganda, becoming the largest, fastest-growing BDBV epidemic on record and the second-largest Ebola-family outbreak overall. This narrative review, not a systematic review or meta-analysis, summarizes peer-reviewed literature, preprints, and official situation reports from WHO, Africa CDC, US CDC, ECDC, and national health ministries, identified through PubMed, Scopus, Web of Science, Google Scholar, and Embase from inception to 12 August 2026, to examine BDBV historical evolution, virology and pathogenesis, drivers of re-emergence, surveillance and response, therapeutic and vaccine gaps, and global health security implications. The 2026 outbreak, unfolding amid conflict and mass displacement in eastern DRC, has been marked by an estimated basic reproduction number of 1.4-2.1 (central estimate 1.71), disproportionate infection among healthcare workers (7.2% of confirmed cases in DRC, 20% in Uganda), and the continued absence of licensed BDBV-specific vaccines or therapeutics. Findings underscore the need for sustained genomic and ecological surveillance, decentralized rapid diagnostics, broadly protective pan-filovirus vaccines, conflict-sensitive response strategies, and strengthened Uganda-DRC collaboration. Because the evidence base for the ongoing outbreak remains preliminary, findings should be interpreted cautiously and revisited as further peer-reviewed data emerge.

Bundibugyo ebolavirus↗
PubMed2005

RNA polymerase I-driven minigenome system for Ebola viruses.

In general, Ebola viruses are well known for their ability to cause severe hemorrhagic fever in both human and nonhuman primates. However, despite substantial sequence homology to other members of the family Filoviridae, Reston ebolavirus displays reduced pathogenicity for nonhuman primates and has never been demonstrated to cause clinical disease in humans, despite its ability to cause infection. In order to develop a tool to explore potential roles for transcription and replication in the reduced pathogenicity of Reston ebolavirus, we developed an RNA polymerase I (Pol I)-driven minigenome system. Here we demonstrate successful Reston ebolavirus minigenome rescue, including encapsidation, transcription, and replication, as well as the packaging of minigenome transcripts into progeny particles. The Pol I-driven Reston ebolavirus minigenome system provides a higher signal intensity with less background (higher signal-to-noise ratio) than a comparable T7-driven Reston ebolavirus minigenome system which was developed simultaneously. Successful Reston ebolavirus minigenome rescue was also achieved by the use of helper plasmids derived from the closely related Zaire ebolavirus or the more distantly related Lake Victoria marburgvirus. The use of heterologous helper plasmids in the Reston ebolavirus minigenome system yielded levels of reporter expression which far exceeded the level produced by the homologous helper plasmids. This comparison between minigenomes and helper plasmids from different filovirus species and genera indicates that inherent differences in the transcription and/or replication capacities of the ribonucleoprotein complexes of pathogenic and apathogenic filoviruses may exist, as these observations were confirmed in a Lake Victoria marburgvirus minigenome system.

Artificial Gene Fusion↗
PubMed2026

The 2026 Bundibugyo Ebola Outbreak: A Warning for Global Preparedness for Future Epidemics.

Dear Editor, The 2026 Bundibugyo Ebolavirus (BDBV) outbreak has once again demonstrated that the threat of emerging diseases remains a major global health challenge. The outbreak, first detected in the Democratic Republic of Congo (DRC) and spread to Uganda, is not only a regional crisis but also a test of the world's preparedness for pathogens with epidemic potential. Unlike Zaire Ebolavirus (EBOV), which has benefited from effective vaccines and treatments in recent years, BDBV still lacks a licensed vaccine or specific treatment[1]. As of June 6, a total of 515 laboratory-confirmed cases and 91 deaths have been reported in DRC, while Uganda has reported 19 laboratory-confirmed cases and two deaths. The occurrence of unexplained deaths among both the community and healthcare workers, along with prior reports of an unidentified hemorrhagic fever, suggest that the outbreak has been likely originated in March 2026 or even earlier. Accordingly, the virus is believed to have spread unnoticed for several weeks before being identified through genomic sequencing in mid-May 2026[2]. The resurgence of Ebola in Africa results from a complex interaction of environmental, social, and political factors. Deforestation, the development of mining activities, the expansion of agriculture, and increased human contact with wildlife have elevated the likelihood of spillovers from wildlife reservoirs, particularly fruit bats, which are considered the most likely natural hosts of ebolaviruses. Moreover, weak disease surveillance systems and limited access to health services have delayed the identification of early cases. The similarity of the initial symptoms of Ebola to other endemic diseases in the region, such as malaria, makes early diagnosis difficult and provides ample opportunity for transmission to spread. Insecurity, misinformation, attacks on healthcare facilities, and armed conflict in the region have also posed serious challenges to the implementation of contact tracing programs and rapid response to the epidemic[3,4]. One of the most critical challenges highlighted by this outbreak is the weakness of diagnostic capacities in the affected areas. The initial 2007 outbreak of BDBV proved that delayed lab confirmation paralyzes public health responses[5]. Now, dealing with a much larger outbreak in 2026, the persistence of this challenge highlights a dangerous failure to invest in diagnostic infrastructure over the last 19 years. Many health facilities do not have access to molecular laboratories, rapid sample transport systems, and biosafety infrastructure[6]. These limitations delay the diagnosis and isolation of patients, thus perpetuating disease transmission. Investment in the development of mobile laboratories, rapid point-of-care diagnostic tests, and digital reporting systems can dramatically reduce the time to diagnosis and response to an outbreak. The BDBV outbreak shows that laboratory preparedness must be considered an essential part of global health security. Furthermore, the early detection of emerging pathogens depends not only on diagnostic technologies but also on the expertise of local scientists who are able to recognize unusual epidemiological and laboratory patterns. During the current outbreak, suspected Ebola cases initially tested negative using common diagnostic tests (designed for Zaire Ebola Virus), which delayed the identification of the BDBV. Specifically, field-based diagnostics in Bunia were calibrated exclusively to detect the EBOV responsible for recent Congolese outbreaks. Consequently, patient samples collected throughout late April and early May yielded negative results, requiring cross-country transport to Kinshasa for genomic confirmation[2]. This experience revealed a major vulnerability in outbreak preparedness: diagnostic tools designed for known threats may be ineffective in detecting less common or unexpected pathogens. Therefore, strengthening local scientific capacities, developing genomic surveillance, and expanding access to flexible and adaptable diagnostic platforms should be considered as a top priority for global health security. The lack of a licensed vaccine for BDBV was one of the most significant challenges of this epidemic. While the rVSV-ZEBOV vaccine has played a significant role in controlling Zaire ebolavirus, there is no licensed vaccine for BDBV. In response to this outbreak, efforts to develop mRNA-based vaccines, adenoviral vectors, rVSV-based vaccines, and multipotent vaccines have been accelerated[7]. However, the experience of this epidemic has shown that the development of medical products for rare diseases continues to face financial and investment constraints. This challenge highlights the need for sustained support from governments and international institutions for research and development of pathogens with epidemic potential. The 2026 Bundibugyo outbreak provides several key lessons for the global community. First, early detection and rapid diagnosis are the most important factors in containing the epidemic. The 19-year interval between the 2007 BDBV outbreak and the 2026 outbreak underscores persistent shortcomings in investment toward decentralized, pan-ebolavirus diagnostic infrastructure, with diagnostic delays hindering timely outbreak identification in both instances. Second, the trust and active participation of local communities are as important as medical interventions. Additionally, the rapid cross-border transmission dynamics between the DRC and Uganda demonstrate that blanket travel restrictions and border closures are impractical. As communities in the Great Lakes region routinely cross national borders for trade and healthcare, coordinated regional surveillance and timely information sharing are likely to be more effective than broad border closures in mitigating disease transmission[8]. Third, the protection of health workers must be a priority in preparedness plans. Fourth, a "One Health" approach is essential for simultaneous monitoring of humans, animals, and the environment. Although BDBV is not a new pathogen, the lack of licensed medical interventions and limited investment in research reflect many of the vulnerabilities associated with the concept of "Disease X."[9]. Unlike Zaire Ebola Virus, for which licensed vaccines and monoclonal antibody therapies are available, BDBV forces public health responses to rely almost entirely on non-pharmaceutical interventions such as isolation and infection control[10]. This gap reflects the structural inequity in global health research and development funding, with pathogens affecting resource-limited regions receiving insufficient attention until they spark an international emergency[2]. The BDBV outbreak proves that global epidemic preparedness cannot be pathogen-selective; it requires proactive investment in broad-spectrum countermeasures and resilient frontline health systems[8]. In conclusion, the 2026 BDBV outbreak is a serious wake-up call for the global health system. The epidemic revealed that gaps in surveillance systems, diagnostic capacities, vaccine development, and preparedness for emerging diseases persist. Investing in health infrastructure, developing Pan-Ebolavirus vaccines, strengthening laboratories, expanding the One-Health approach, and supporting research on emerging zoonotic pathogens must be at the top of global health security priorities. Otherwise, the BDBV outbreak may be just a prelude to larger crises to come.

Ebolavirus↗
PubMed2004

Rapid diagnosis of Ebola hemorrhagic fever by reverse transcription-PCR in an outbreak setting and assessment of patient viral load as a predictor of outcome.

The largest outbreak on record of Ebola hemorrhagic fever (EHF) occurred in Uganda from August 2000 to January 2001. The outbreak was centered in the Gulu district of northern Uganda, with secondary transmission to other districts. After the initial diagnosis of Sudan ebolavirus by the National Institute for Virology in Johannesburg, South Africa, a temporary diagnostic laboratory was established within the Gulu district at St. Mary's Lacor Hospital. The laboratory used antigen capture and reverse transcription-PCR (RT-PCR) to diagnose Sudan ebolavirus infection in suspect patients. The RT-PCR and antigen-capture diagnostic assays proved very effective for detecting ebolavirus in patient serum, plasma, and whole blood. In samples collected very early in the course of infection, the RT-PCR assay could detect ebolavirus 24 to 48 h prior to detection by antigen capture. More than 1,000 blood samples were collected, with multiple samples obtained from many patients throughout the course of infection. Real-time quantitative RT-PCR was used to determine the viral load in multiple samples from patients with fatal and nonfatal cases, and these data were correlated with the disease outcome. RNA copy levels in patients who died averaged 2 log(10) higher than those in patients who survived. Using clinical material from multiple EHF patients, we sequenced the variable region of the glycoprotein. This Sudan ebolavirus strain was not derived from either the earlier Boniface (1976) or Maleo (1979) strain, but it shares a common ancestor with both. Furthermore, both sequence and epidemiologic data are consistent with the outbreak having originated from a single introduction into the human population.

Antigens, Viral↗
PubMed2004

Pathogenesis of filoviral haemorrhagic fevers.

The filoviruses, marburgvirus and ebolavirus, cause epidemics of haemorrhagic fever with high case-fatality rates. The severe illness results from a complex of pathogenetic mechanisms that enable the virus to suppress innate and adaptive immune responses, infect and kill a broad variety of cell types, and elicit strong inflammatory responses and disseminated intravascular coagulation, producing a syndrome resembling septic shock. Most experimental data have been obtained on Zaire ebolavirus, which causes uniformly lethal disease in experimentally infected non-human primates but produces a broader range of outcomes in naturally infected human beings. 10-30% of patients can survive the illness by mobilising adaptive immune responses, and there is limited evidence that mild or symptomless infections also occur. The other filoviruses that have caused human disease, Sudan ebolavirus, Ivory Coast ebolavirus, and marburgvirus, produce a similar illness but with somewhat lower case-fatality rates. Variations in outcome during an epidemic might be due partly to genetically determined differences in innate immune responses to the viruses. Recent studies in non-human primates have shown that blocking of certain host responses, such as the coagulation cascade, can result in reduced viral replication and improved host survival.

Africa↗
PubMed2005

The role of reverse genetics systems in determining filovirus pathogenicity.

The family Filoviridae is comprised of two genera: Marburgvirus and Ebolavirus. To date minigenome systems have been developed for two Ebola viruses (Reston ebolavirus and Zaire ebolavirus [ZEBOV]) as well as for Lake Victoria marburgvirus, the sole member of the Marburgvirus genus. The use of these minigenome systems has helped characterize functions for many viral proteins in both genera and have provided valuable insight towards the development of an infectious clone system in the case of ZEBOV. The recent development of two such infectious clone systems for ZEBOV now allow effective strategies for experimental mutagenesis to study the biology and pathogenesis of one of the most lethal human pathogens.

Animals↗
PubMed2026

Bundibugyo at the border: The 2026 Ebola outbreak and the case for pre-emptive countermeasure equity.

The 2026 Ebola outbreak caused by Bundibugyo ebolavirus in the Democratic Republic of the Congo and Uganda exposes a persistent structural flaw in global health security: preparedness remains overwhelmingly reactive and pathogen-specific. Despite the $518 million Africa CDC-WHO joint continental plan, no licensed BDBV vaccine or therapeutic is available; a 21-day (three-week) detection delay and cross-border transmission expose inadequate inter-epidemic investment in non-Zaire ebolavirus countermeasures. We argue for sustained, ring-fenced financing, institutionalised cross-border coordination, species-inclusive diagnostics, and real-time genomic data sharing to move African Ebola preparedness from reactive to pre-emptive.

Hemorrhagic Fever, Ebola↗
PubMed2004

Rescue of Ebola virus from cDNA using heterologous support proteins.

Using the infectious clone for Zaire ebolavirus, the functional specificity of viral proteins of the ribonucleoprotein complex in transcription/replication was investigated by substituting them with heterologous proteins derived from closely (Reston ebolavirus) and distantly related filoviruses (Marburgvirus). The data clearly demonstrated that transcription/replication are neither strictly species-specific nor genus-specific. Protein interactions between the nucleoprotein NP and the virion protein VP35 and the polymerase L and VP35 seemed to be the most critical steps. In contrast to previous data, viral proteins were able to target heterologous filovirus RNA. Together these results indicated that protein-protein interactions are more critical than protein-RNA interactions.

Animals↗
PubMed2006

Identification of two amino acid residues on Ebola virus glycoprotein 1 critical for cell entry.

Using site-directed mutagenesis and retroviral vector pseudotyping of the wild type or mutated glycoprotein of Zaire ebolavirus (ZEBOV), we analyzed 15 conserved residues in the N-terminus of the filovirus glycoprotein 1 (GP1) in order to identify residues critical for cell entry. Results from infectivity assays and Western blot analyses identified two phenylalanine residues at positions 88 and 159 that appear to be critical for ZEBOV entry in vitro. We extended this observation by introduction of alanines at either position 88 or 159 of Ivory Coast Ebolavirus (CIEBOV) and observed the same phenotype. Further, we showed that introduction of each of the two mutations in a recombinant full-length clone of ZEBOV (Mayinga strain) that also carried the coding sequence for GFP could not be rescued, suggesting the mutants rendered the virus non-infectious. The two phenylalanines that are critical for both ZEBOV and CIEBOV entry are found in two linear domains of GP1 that are highly conserved among filoviruses, and thus could provide a target for rational development of broadly cross-protective vaccines or antiviral therapies.

Amino Acid Sequence↗
PubMed2006

Development of a cAdVax-based bivalent ebola virus vaccine that induces immune responses against both the Sudan and Zaire species of Ebola virus.

Ebola virus (EBOV) causes a severe hemorrhagic fever for which there are currently no vaccines or effective treatments. While lethal human outbreaks have so far been restricted to sub-Saharan Africa, the potential exploitation of EBOV as a biological weapon cannot be ignored. Two species of EBOV, Sudan ebolavirus (SEBOV) and Zaire ebolavirus (ZEBOV), have been responsible for all of the deadly human outbreaks resulting from this virus. Therefore, it is important to develop a vaccine that can prevent infection by both lethal species. Here, we describe the bivalent cAdVaxE(GPs/z) vaccine, which includes the SEBOV glycoprotein (GP) and ZEBOV GP genes together in a single complex adenovirus-based vaccine (cAdVax) vector. Vaccination of mice with the bivalent cAdVaxE(GPs/z) vaccine led to efficient induction of EBOV-specific antibody and cell-mediated immune responses to both species of EBOV. In addition, the cAdVax technology demonstrated induction of a 100% protective immune response in mice, as all vaccinated C57BL/6 and BALB/c mice survived challenge with a lethal dose of ZEBOV (30,000 times the 50% lethal dose). This study demonstrates the potential efficacy of a bivalent EBOV vaccine based on a cAdVax vaccine vector design.

Adenoviridae↗
PubMed2006

Global suppression of the host antiviral response by Ebola- and Marburgviruses: increased antagonism of the type I interferon response is associated with enhanced virulence.

We studied the effect of filovirus infection on host cell gene expression by characterizing the regulation of gene expression responses in human liver cells infected with Zaire Ebolavirus (ZEBOV), Reston Ebolavirus (REBOV), and Marburgvirus (MARV), using transcriptional profiling and bioinformatics. Expression microarray analysis demonstrated that filovirus infection resulted in the up-regulation of immune-related genes and the down-regulation of many coagulation and acute-phase proteins. These studies further revealed that a common feature of filovirus virulence is suppression of key cellular antiviral responses, including TLR-, interferon (IFN) regulatory factor 3-, and PKR-related pathways. We further showed that ZEBOV and MARV were more potent antagonists of the IFN response and inhibited the expression of most of the IFN-stimulated genes (ISGs) observed in mock-infected IFN-alpha-2b treated cells, compared to REBOV infection, which activated more than 20% of these ISGs. Finally, we examined IFN-related gene expression in filovirus-infected cells treated with IFN-alpha-2b. These experiments revealed that a majority of genes induced in mock-infected cells treated with type I IFN were antagonized in treated ZEBOV- and MARV-infected cells, while in contrast, REBOV infection resulted in a significant increase in ISG expression. Analysis of STAT1 and -2 phosphorylation following IFN treatment showed a significant reduction of STAT phosphorylation for MARV but not for ZEBOV and REBOV, indicating that different mechanisms might be involved in antagonizing IFN signaling pathways by the different filovirus species. Taken together, these studies showed a correlation between antagonism of type I IFN responses and filovirus virulence.

Animals↗