Search Results (96)

The ongoing 2026 Bundibugyo ebolavirus outbreak in eastern Democratic Republic of the Congo highlights the continued vulnerability of Central Africa to recurrent Ebola emergence. This outbreak emerged less than six months after the previous one ended, appears to represent one of the shortest documented inter-epidemic intervals in the Democratic Republic of the Congo based on currently available outbreak reports. Current surveillance systems remain largely reactive, focusing on the detection of human cases after zoonotic spillover has occurred. While strengthening health systems, diagnostic capacity, and early case detection remains the cornerstone of Ebola preparedness, growing research suggests that environmental and climatic information may eventually contribute to a broader understanding of spillover risk within a One Health framework. However, current evidence remains insufficient to identify validated environmental indicators or operational thresholds capable of predicting Ebola spillover events. Recent modeling studies have demonstrated that environmental drivers of Ebola emergence remain highly context-dependent and cannot yet support operational early warning systems. This commentary argues that continued research integrating environmental monitoring, remote sensing, ecological observations, and epidemiological data may improve understanding of Ebola emergence and eventually contribute to future preparedness strategies. Rather than proposing climate-informed preparedness approaches as an operational prediction tool, we emphasize its potential as a complementary research priority requiring further validation before any operational implementation. Full article

Bundibugyo virus disease, caused by Bundibugyo virus (Orthoebolavirus bundibugyoense), is a severe human Ebola disease with substantial mortality, unresolved reservoir ecology, limited diagnostic implementation, and no licensed vaccines or therapeutics specifically approved for this Orthoebolavirus species. The May 2026 public health emergency in the Democratic Republic of the Congo and Uganda renewed the need for a focused synthesis of Bundibugyo virus-specific diagnostics and medical countermeasures. This review synthesizes the peer-reviewed literature, preprints, and official public-health documents on diagnostics, antivirals, therapeutics, vaccines, and post-exposure prophylaxis. Comparative evidence from the Ebola virus, Sudan virus, Marburg virus, and pan-filovirus platforms is included only where it clarifies Bundibugyo virus-specific evidence, exposes unsupported extrapolation, or defines preparedness gaps. The 2007–2008 outbreak showed that assays optimized for known filoviruses can miss divergent ebolaviruses; the 2026 outbreak underscored the importance of diagnostic breadth, sequencing-based confirmation, decentralized laboratory capacity, and regional coordination. Clinical and immunological data indicate that Bundibugyo virus cannot be reduced to an Ebola virus-like model. Countermeasure evidence remains largely preclinical: recombinant vesicular stomatitis virus vaccines expressing Bundibugyo virus glycoprotein provide the strongest direct animal protection data, whereas antiviral and antibody-based evidence varies widely and requires careful separation of direct Bundibugyo virus data from platform-based extrapolation. Full article

This review describes a novel method for increasing the effectiveness of inactivated enveloped whole-virus vaccines by targeting them for extensive uptake by antigen-presenting cells (APCs). Several inactivated whole-virus vaccines with dense glycan shields display suboptimal effectiveness because the multiple carbohydrate chains (glycans) on the virus mask immunogenic peptides and surround the virus with a negative electrostatic charge that decreases uptake by APCs. It is postulated that engineering such vaccinating viruses to present the carbohydrate antigen “α-gal epitope” on the glycan shields will immunocomplex them with the anti-Gal antibody; thus, it will target them for robust uptake by APCs. Anti-Gal is an abundant natural antibody in humans, constituting ~1% of human circulating immunoglobulins. The ligand of anti-Gal is the α-gal epitope, which is naturally synthesized in non-primate mammals and New World monkeys by the glycosylation enzyme α1,3galactosyltransferase. This enzyme is encoded by the GGTA1-gene. Viral vaccines presenting multiple α-gal epitopes on their glycan shield bind anti-Gal and activate the complement system to produce complement chemotactic cleavage peptides C5a and C3a that induce extensive recruitment of APCs to vaccine injection sites. The virion-bound anti-Gal further targets the viral vaccine for robust uptake by APCs, following binding of its Fc “tail” to Fcγ-receptors on APCs. The efficacy of this method was studied in anti-Gal-producing mice with α-gal presenting inactivated influenza virus vaccine and with gp120 of HIV presenting this epitope. These studies indicated that virus vaccines engineered to present α-gal epitopes increase anti-virus antibody production and virus-specific T-cell activation by 15- to 100-fold in comparison to the same vaccines lacking α-gal epitopes. It is suggested that α-gal presenting inactivated SARS-CoV-2 virus vaccines can induce a similar protective long-term immune memory against S- M-, E-, and N-viral proteins. Furthermore, immune-escaping variants of the mutated S-protein may be destroyed by antibodies to M and E proteins, and cells infected with such variants may be killed by cytotoxic T cells specific to peptides of the N-protein. Such an anti-M-, E-, and N-protein immune protection may prevent expansion of these variants and thus may avoid the need for immunization with COVID-19 vaccines every 6 months or following the appearance of new variants. A similar potent immunization may be achieved with an inactivated Ebolavirus vaccine engineered to present α-gal epitopes on the glycan shield. The resulting immune response to the various Ebolavirus proteins also may contribute to cross-reactive protection against other Ebolavirus species containing proteins with evolutionarily conserved structures. An effective method for the preparation of a whole-virus vaccine presenting α-gal epitopes is by arming it with the GGTA1-gene inserted into the viral genome. Such virions will present multiple α-gal epitopes on their glycan shield, which will amplify their immunogenicity instead of reducing it in the wild-type virus. Full article

In May 2026, two outbreaks occurred at once: an Andes virus outbreak aboard the MV Hondius expedition cruise ship (13 cases (12 laboratory-confirmed and 1 probable), 3 deaths, and more than 600 contacts traced across 32 countries and territories; passengers and crew from 23 countries; data as of 22 June 2026) and a Bundibugyo virus disease (BDBV) outbreak in Central Africa (more than 1000 laboratory-confirmed cases and more than 250 confirmed deaths in the Democratic Republic of the Congo and Uganda; data as of 22 June 2026). The two pathogens diverge sharply in their transmission epidemiology. Aboard the MV Hondius, person-to-person transmission was sustained across three generations from a single index case, and one asymptomatic, PCR-positive contact later developed symptoms, indicating pre-symptomatic ANDV RNA detection, although the extent to which this corresponds to infectiousness and onward transmission remains uncertain. BDBV, on current evidence, has not been documented to sustain pre-symptomatic transmission as a major driver of its outbreaks, which allows for contact tracing of different timing and intensity. This Perspective draws together the epidemiological data from the MV Hondius outbreak, the endemic-region experience (Chile’s 2021–2025 secondary attack rate of 5.7%; Argentina’s 1996 El Bolsón and 2018 Epuyén outbreaks), the molecular pathogenesis, the diagnostic platforms, the therapeutic pipeline (favipiravir, tocilizumab, Icatibant) and the vaccine strategies (USAMRIID DNA vaccine, phase 1 completed). We set the contact-tracing and active-surveillance protocols applied to ANDV against the less stringent protocols that may suffice for BDBV. Full article

In 2025, tropical medicine was shaped by advances in diagnostic technology, expanding arboviral epidemics, rapid progress in filovirus vaccine development, evolving regulatory responses to newly licensed vaccines, and translational breakthroughs addressing neglected tropical diseases. This review discusses five select developments that significantly influenced clinical practice and global health policy over the past year, highlighting the implications of each for clinicians, researchers, and public health systems. Full article

Background: Despite repeated re-emergence of Sudan ebolavirus (SUDV), its long-term human toll remains under-characterised. We assessed multisystem clinical, biochemical, and psychosocial outcomes ~25 years after the 2000 Gulu outbreak. Methods: We conducted a cross-sectional evaluation of 45 survivors of laboratory-confirmed SUDV and 30 age- and gender-matched community controls from the same region. Symptoms were assessed as current at the study visit using a structured checklist; for each symptom present, we recorded severity and duration from onset to the visit date. Standardised clinical examinations, haematological and biochemical assessments, anxiety and depression screening, and structured interviews on social support and stigma were performed. Group comparisons were assessed with Wilcoxon rank-sum and χ²/Fisher’s exact tests; correlations were assessed with Spearman’s ρ. Findings: Core physiological indices (vital signs, BMI, blood pressure, and body temperature) and mental health were comparable between survivors and controls. Nevertheless, survivors reported ongoing symptoms, including joint pain and visual impairment each in 36% (16/45), fatigue in 18% (8/45), and neurological symptoms in 13% (6/45). Subclinical laboratory deviations centred on hepatic and platelet biology: elevated total bilirubin occurred in 14% of survivors versus 6.7% of controls; thrombocytopenia or platelet morphological abnormalities in 12% versus 3.3%; haemoglobin abnormalities in 6% versus 0%. Among survivors, albumin and mean platelet volume declined with age (both p ≤ 0.03). Psychological morbidity was low (normal anxiety 82% (37/45; and normal depression 80% (36/45). Yet a social paradox emerged, despite universal post-outbreak support, 98% (44/45) described enduring stigma. To minimise differential recall bias, symptom inventories were not collected from controls; consequently, between-group comparisons for symptom prevalence were not performed, and symptom inferences are restricted to survivors and framed descriptively. Interpretation: A quarter-century after infection, SUDV survivors show preserved systemic physiology but carry chronic musculoskeletal, sensory, and neurological sequelae, alongside a discrete subclinical profile implicating hepatic function and platelet biology. Psychological resilience coexists with near-universal, persistent stigma, indicating that material support did not achieve full psychosocial reintegration. Given the lack of virological and deep immune profiling, proposed pathogenetic mechanisms, such as antigen persistence or immune-mediated injury, remain speculative and hypotheses-generating only. These findings argue for survivor-centred long-term care, embedded with epidemic preparedness frameworks that integrate musculoskeletal rehabilitation, ophthalmic and neurological services with comprehensive mental health care, and sustained anti-stigma community engagement. This dissociation, including short-lived support alongside enduring stigma, indicates that humanitarian relief alone does not secure durable psychosocial reintegration and should be complemented by long-horizon, survivor-centred services and community engagement. Funding: This study was supported by the Coalition for Epidemic Preparedness Innovations (CEPI) under the Universal Protocol for Standardising Assays and Advancing Vaccine Immunogenicity Assessments for Emerging and Re-emerging Viral Threats, implemented through the Uganda Virus Research Institute (UVRI) as part of CEPI’s Centralised Laboratory Network (CLN). Full article

Filoviruses are among the most lethal viral human pathogens known, with significant relevance to public health, yet their evolutionary history remains poorly resolved. This study applied a multiprotein molecular phylogenetic approach to investigate the evolutionary and temporal dynamics of the family Filoviridae. Amino acid sequences from the proteome and seven individual proteins (NP, VP35, VP40, GP, VP30, VP24, L) were analyzed using MEGA 12, with RelTime inference anchored on uniform calibrations, and integration of epidemiological data (cases, fatalities, case fatality). The phylogenetic reconstructions revealed robust topologies for most proteins, though selective pressures on GP, VP30 and VP40 generated more variable patterns. Temporal inferences supported the classification of filoviruses into three groups: an ancestral lineage (>1 MYA, fish- and reptile-associated), an intermediate lineage (BCE–1 MYA, bat-associated), and a contemporary lineage (CE, ebolaviruses and marburgviruses). VP30 and VP40 showed consistent associations with epidemiological outcomes in Orthoebolavirus zairense, suggesting their interplay may underlie enhanced dispersal and virulence. Contrariwise, Orthoebolavirus restonense emerged as a natural counterpoint for comparison with other potential human pathogenic filoviruses. Taken together, these findings highlight that filoviral evolution is intrinsically linked not only to viral biology but also to the ecology and history of their hosts. Full article

Recent outbreaks of highly pathogenic human RNA viruses from probable zoonotic origin have highlighted the relevance of epidemic preparedness as a society. However, research in vaccinology and virology, as well as epidemiologic surveillance, is often constrained by the biological risk that live virus experimentation entails. These also involve expensive costs, time-consuming procedures, and advanced personnel expertise, hampering market access for many drugs. Most of these drawbacks can be circumvented with the use of pseudotyped viruses, which are surrogate, non-pathogenic recombinant viral particles bearing the surface envelope protein of a virus of interest. Pseudotyped viruses significantly expand the research potential in virology, enabling the study of non-culturable or highly infectious pathogens in a safer environment. Most are derived from lentiviral vectors, which confer a series of advantages due to their superior efficiency. During the past decade, many studies employing pseudotyped viruses have evaluated the efficacy of vaccines or monoclonal antibodies for relevant pathogens such as HIV-1, Ebolavirus, Influenza virus, or SARS-CoV-2. In this review, we aim to provide an overview of the applications of pseudotyped viruses when evaluating the neutralization capacity of exposed individuals, or candidate vaccines and antivirals in both preclinical models and clinical trials, to further help develop effective countermeasures against emerging neutralization-escape phenotypes. Full article

Zaire Ebolavirus (EBOV) is one type of filovirus that causes the deadly EBOV disease, with an average fatality rate of around 50%. EBOV outbreaks are devastating and unpredictable and may emerge as the next global pandemic. As a BSL-4 pathogen, EBOV is inaccessible to regular biological laboratories. Therefore, EBOV virus-like particles (EBOV-VLPs) and EBOV pseudoviruses (EBOV-PVs) are utilized in the initial development of many potential therapies, for safety reasons and ease of procurement, as opposed to using infectious viruses. To investigate the host cell entry of EBOV and develop viral entry blockers, the EBOV model virions must accurately represent the morphological and mechanical properties of infectious EBOV virions. Due to the nanometer scale and irregular shape of EBOVs, these properties are challenging to characterize. In this research, state-of-the-art nanoscale characterization techniques are employed to examine the mechanical and structural elements of a selection of commonly used EBOV-approximating model virions. This study comprehensively determines the accuracy of EBOV approximation with a variety of model virions and the uniformity of mechanical and structural traits across different model virion types and preparation methods. This provides important implications for developing therapeutic treatments against EBOV using these model virions. Full article

The recombinant vesicular stomatitis virus-Zaire Ebolavirus envelope glycoprotein vaccine (rVSVΔG-ZEBOV-GP) was highly effective against Ebola virus disease in a ring vaccination trial conducted during the 2014–2016 outbreak in Guinea and is licensed by regulatory agencies including US FDA, EMA, and prequalified by WHO. Vaccination studies in a nonhuman primate (NHP) model guided initial dose selection for clinical trial evaluation. We summarize two dose-ranging studies with the clinical-grade rVSVΔG-ZEBOV-GP vaccine candidate to assess the impact of dose level on immune responses and efficacy in an NHP Ebola virus (EBOV) challenge model. Forty-six cynomolgus macaques were vaccinated with a wide range of rVSVΔG-ZEBOV-GP doses and challenged 42 days later intramuscularly with 1000 pfu EBOV. Vaccination with rVSVΔG-ZEBOV-GP induced relatively high levels of EBOV-specific IgG and neutralizing antibodies, measured using the same validated assays as used in rVSVΔG-ZEBOV-GP clinical trials. Similar responses were observed across dose groups from 1 × 10⁸ to 1 × 10² pfu. A single vaccination conferred 98% protection from lethal intramuscular EBOV challenge across all dose groups. These results demonstrate that robust antibody titers are induced in NHPs across a wide range of rVSVΔG-ZEBOV-GP vaccine doses, correlating with high levels of protection against death from EBOV challenge. Full article

Filoviruses, mainly consisting of the two genera of Ebolavirus and Marburgvirus, are enveloped negative-strand RNA viruses that can infect humans to cause severe hemorrhagic fevers and outbreaks with high mortality rates. However, we still do not have effective medicines for treating these diseases. To search for effective drugs, we have identified three marine indole alkaloids that exhibit potent activities against filovirus infection. Thus, it is suggested that marine indole alkaloids can be a valuable compound source for filovirus drug screening and development. Since marine indole alkaloids comprise a large diverse group of secondary metabolites, their biological properties would be helpful for pharmaceutical drug development to treat various filovirus infections. Full article

The Ebola virus (EBOV) causes severe disease in humans, and animal models are needed to evaluate the efficacy of vaccines and therapeutics. While non-human primate (NHP) and rodent EBOV infection models have been well characterized, there is a growing need for an intermediate model. Here, we provide the first report of a small-particle aerosol (AE) EBOV ferret model and disease progression compared with the intramuscular (IM) EBOV ferret model. EBOV infection of ferrets by either route resulted in uniform lethality in 5–6.5 days post infection (dpi) in a dose-dependent manner, with IM-infected ferrets succumbing significantly earlier than AE-infected ferrets. EBOV disease progression differed between AE and IM routes, with significant viremia and presence of virus in target organs occurring earlier in the AE model. In contrast, significant fever, clinical signs of disease, liver pathology, and systemic inflammation occurred earlier in the IM EBOV model. Hepatocellular damage and splenic pathology were noted in both models, while pronounced lung pathology and renal impairment were exclusive to the AE and IM models, respectively. These results demonstrate that small-particle AE and IM ferret EBOV models share numerous common features with NHP and human EBOV infection by these routes and will therefore be useful for the development of vaccine and therapeutic countermeasures. Full article

Sequence analysis of the Zaire ebolavirus (EBOV) polymerase (L gene) mRNA, using online tools, identified a highly ranked −1 programmed ribosomal frameshift (FS) signal including an ideal slippery sequence heptamer (UUUAAAA), with an overlapping coding region featuring two tandem UGA codons, immediately followed by an RNA region that is the inverse complement (antisense) to a region of the mRNA of the selenoprotein iodothyronine deiodinase II (DIO2). This antisense interaction was confirmed in vitro via electrophoretic gel shift assay, using cDNAs at the EBOV and DIO2 segments. The formation of a duplex between the two mRNAs could trigger the ribosomal frameshift, by mimicking the enhancing role of a pseudoknot structure, while providing access to the selenocysteine insertion sequence (SECIS) element contained in the DIO2 mRNA. This process would allow the −1 frame UGA codons to be recoded as selenocysteine, forming part of a C-terminal module in a low abundance truncated isoform of the viral polymerase, potentially functioning in a redox role. Remarkably, 90 bases downstream of the −1 FS site, an active +1 FS site can be demonstrated, which, via a return to the zero frame, would enable the attachment of the entire C-terminal of the polymerase protein. Using a construct with upstream and downstream reporter genes, spanning a wildtype or mutated viral insert, we show significant +1 ribosomal frameshifting at this site. Acting singly or together, frameshifting at these sites (both of which are highly conserved in EBOV strains) could enable the expression of several modified isoforms of the polymerase. The 3D modeling of the predicted EBOV polymerase FS variants using the AI tool, AlphaFold, reveals a peroxiredoxin-like active site with arginine and threonine residues adjacent to a putative UGA-encoded selenocysteine, located on the back of the polymerase “hand”. This module could serve to protect the viral RNA from peroxidative damage. Full article

Bombali virus (BOMV) is a novel Orthoebolavirus that has been detected in free-tailed bats in Sierra Leone, Guinea, Kenya, and Mozambique. We screened our collection of 349 free-tailed bat lungs collected in Côte d’Ivoire and Tanzania for BOMV RNA and tested 228 bat blood samples for BOMV antibodies. We did not detect BOMV-specific antibodies but found BOMV RNA in a Mops condylurus bat from Tanzania, marking the first detection of an ebolavirus in this country. Our findings further expand the geographic range of BOMV and support M. condylurus’ role as a natural BOMV host. Full article

Favipiravir is a ribonucleoside analogue that has been explored as a therapeutic for the treatment of Ebola Virus Disease (EVD). Promising data from rodent models has informed nonhuman primate trials, as well as evaluation in patients during the 2013–2016 West African EVD outbreak of favipiravir treatment. However, mixed results from these studies hindered regulatory approval of favipiravir for the indication of EVD. This study examined the influence of route of administration, duration of treatment, and treatment schedule of favipiravir in immune competent mouse and guinea pig models using rodent-adapted Zaire ebolavirus (EBOV). A dose of 300 mg/kg/day of favipiravir with an 8-day treatment was found to be fully effective at preventing lethal EVD-like disease in BALB/c mice regardless of route of administration (oral, intraperitoneal, or subcutaneous) or whether it was provided as a once-daily dose or a twice-daily split dose. Preclinical data generated in guinea pigs demonstrates that an 8-day treatment of 300 mg/kg/day of favipiravir reduces mortality following EBOV challenge regardless of route of treatment or duration of treatments for 8, 11, or 15 days. This work supports the future translational development of favipiravir as an EVD therapeutic. Full article