Search Results (73)

Filoviruses, including Ebola (EBOV) and Marburg (MARV) viruses, are zoonotic pathogens that cause severe hemorrhagic fever in humans, with mortality rates reaching up to 90%. Filovirus egress and spread are driven by the viral matrix protein VP40 and regulated both positively and negatively by a growing number of specific host interactors. Here, we identify tetraspanin protein CD9, a plasma membrane organizing and scaffolding protein, as playing a role in facilitating efficient egress of EBOV and MARV. Indeed, we observed a significant decrease in viral egress of VLPs and live filoviruses from CD9-KD cells as compared to that from WT cells. Moreover, exogenous expression of CD9 rescued egress of VP40 VLPs close to WT levels in the CD9-KD cells. These findings identify tetraspanin CD9 as a positive regulator of filovirus egress, and thus CD9 may represent a potential new target for antiviral therapies targeting the late stage of the filovirus lifecycle. Full article

In human and non-human primates, filoviruses, e.g., Ebolaviruses, cause severe hemorrhagic fever for which there are few therapeutic options. While there are licensed vaccines and therapeutics for Ebola virus disease, there is no approved vaccine or treatment for other Ebola diseases. There is a need for broad-spectrum antivirals to treat Ebola virus (EBOV), Sudan virus (SUDV), and Marburg virus (MARV). We have previously demonstrated that probenecid, an FDA-approved drug with a safety profile spanning over 7 decades, is safe and effective in preventing the replication of influenza A viruses, SARS-CoV-2, and other RNA respiratory viruses, such as HMPV and RSV, both in vitro and in vivo. In this study, probenecid was shown to inhibit the replication of infectious EBOV, SUDV, and MARV in Vero E6 cells, with IC50 Values of 3 μM, 8 μM, and 13 μM, respectively. It also reduced plaque size in infected Vero cell lawns, suggesting reduced virus spread. These studies show that probenecid is an effective, broad-spectrum, host-directed antiviral drug. 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

Crimean–Congo hemorrhagic fever virus (CCHF-V) and Ebola virus are lethal pathogens that cause widespread outbreaks of hemorrhagic fever. Both diseases can be transmitted through contact with the bodily fluids of infected individuals, but as an arbovirus, CCHF-V is primarily transmitted through tick bites. Both of these viruses are classified as Risk Group 4 due to the appreciable health threat they pose. To date, there are few effective treatments available to combat these deadly hemorrhagic fevers. Consequently, identifying and characterizing ion channels (viroporins) encoded in the viral genomes may lead to potential targeted drug development. Therefore, using bacteria-based genetic assays, two viroporin candidates from CCHF-V and Ebola have been examined, and their proposed structures have been modeled to aid in further drug discovery. The results indicate that CCHF-V-gp exhibits channel activity, which is indistinguishable from established viroporins found in other viruses. In contrast, our experimental approach was unable to uncover a viroporin candidate in the Ebola virus. Full article

Ebola virus (EBOV) causes severe hemorrhagic fevers in humans, and effective countermeasures remain limited. The EBOV-encoded major matrix protein VP40 is essential for viral assembly, budding, and particle release, making it a promising target for antiviral drug development. However, no approved drugs currently target the viral particle formation process. In this study, we established a simple and highly sensitive screening system to evaluate VP40-mediated virus-like particle (VLP) formation under biosafety level −2 conditions. The system uses the HiBiT luminescence-based reporter fused to VP40, allowing for the detection of VP40 release. Our results demonstrate that the HiBiT sequence fused at the N-terminus [HiBiT-VP40 (N)] retains VP40′s ability to form VLPs, supporting its use as a functional reporter. Furthermore, we validated the system by assessing the role of Rab11-dependent trafficking in VP40-mediated budding and by evaluating the effect of nocodazole, a microtubule depolymerizer, on VLP release. This novel screening system provides a convenient and reliable platform for screening potential inhibitors targeting the late stages of EBOV infection, including viral particle formation and release. Additionally, its potential adaptability to other filoviruses suggests wide applicability in the discovery and development of additional novel therapeutic agents. Full article

Handling cultured isolates and clinical, environmental, or wildlife surveillance samples containing Risk Group 3 and 4 pathogens presents considerable biosafety challenges in minimizing human exposure during processing and transport. Safe handling typically requires high- or maximum-containment facilities, demanding substantial logistical planning and resources. We evaluated PrimeStore Molecular Transport Medium (PS-MTM), a guanidine-based solution created to kill pathogens and preserve nucleic acids at ambient temperatures, for inactivating Crimean-Congo hemorrhagic fever, eastern equine encephalitis, Ebola, Hendra, Japanese encephalitis, Lassa, Marburg, Nipah, Rift Valley fever, and West Nile viruses. To mimic diagnostic conditions, human whole blood spiked with any of these viruses was incubated with PS-MTM for 20-, 30-, or 60-min. Samples with titers up to 10⁷ PFU/mL exposed to PS-MTM at all time points resulted in complete loss of infectivity judged by plaque assays. A 30-min incubation provided a 50% safety margin over the minimum inactivation time and was used for quantification with the tissue culture infectious dose (TCID₅₀) assay, enabling evaluation of PS-MTM’s activity for viruses that do or do not produce well-defined plaques. Results confirmed that PS-MTM inactivated all tested viruses at titers up to 10⁷ TCID₅₀/mL, underscoring its reliability for enhancing biosafety in diagnostics, outbreak management, and surveillance. Full article

The Ebola virus (EBOV), a highly lethal pathogen causing hemorrhagic fever, poses a persistent public health threat, with devastating multi-organ complications and high transmission potential through bodily fluids. EBOV’s pathogenesis is marked by severe oxidative stress and immune dysregulation, where increased reactive oxygen species (ROS) levels foster cellular damage, hinder immune defenses, and facilitate viral replication. Through immune evasion and suppression of cellular stress responses, EBOV affects both innate and adaptive immunity, activating pyroptosis, PANoptosis, necroptosis, and lymphocyte apoptosis, thereby amplifying inflammation and disease severity. Recent research suggests that bioactive molecules, including quercetin, curcumin, eugenol, and p-anisaldehyde, may offer therapeutic potential due to their antioxidant, anti-inflammatory, and immunomodulatory effects. This review also underscores the potential of conventional treatments, including amiodarone, favipiravir, remdesivir, azithromycin, chloroquine, and nitazoxanide, as therapeutic agents against EBOV, thanks to their antiviral and anti-inflammatory properties, although their efficacy varies across experimental models. These natural compounds could enhance immune resilience by scavenging ROS, modulating inflammation, and mitigating immune dysregulation, presenting promising adjunctive strategies to support conventional EBOV therapies. Full article

Ebola virus (EBOV) causes Ebola virus disease (EVD), a severe and often fatal hemorrhagic fever. Although much research has focused on host miRNA expression during EBOV infection, it has been discovered that EBOV itself also produces miRNAs. However, further studies are needed to fully comprehend the role of these EBOV-encoded miRNAs in infection and disease development. This study aimed to identify known and novel EBOV-encoded miRNAs and their potential functions in the pathogenic mechanisms of EBOV. We reanalyzed previously available small RNASeq data to identify the miRNAs and predict their cellular targets and functions. We identified four EBOV-encoded miRNAs—EBOV-mir-M1 (4390–4414), EBOV-mir-M4, EBOV-mir-M2 (8288–8309), and EBOV-mir-M3 (9885–9906)—expressed specifically in Ebola-infected human adult retinal pigment epithelial (ARPE) cells. EBOV-mir-M1 (4390–4414) was expressed up to 19 times more than the other three miRNAs. The identified miRNAs were predicted to target genes associated with pathways such as calcium signaling, MAPK signaling, type I interferon signaling, and cytokine-mediated signaling, which play critical roles in Ebola infection and pathogenesis. This study contributes to our understanding of the role of EBOV-encoded miRNAs in infection and pathogenesis by demonstrating the expression of these miRNAs in human ARPE cells, providing insights into the mechanisms underlying EBOV pathogenesis. Full article

Background/Objectives: Orthoebolaviruses and orthomarburgviruses are filoviruses that can cause viral hemorrhagic fever and significant morbidity and mortality in humans. The evaluation and deployment of vaccines to prevent and control Ebola and Marburg outbreaks must be informed by an understanding of the transmission and natural history of the causative infections, but little is known about the burden of asymptomatic infection or undiagnosed disease. This systematic review of the published literature examined the seroprevalence of antibodies to orthoebolaviruses and orthomarburgviruses in sub-Saharan Africa. Methods: The review protocol was registered on PROSPERO (ID: CRD42023415358) and previously published. Eighty-seven articles describing 85 studies were included, of which seventy-six measured antibodies to orthoebolaviruses and forty-one measured antibodies to orthomarburgviruses. Results: The results highlight three central findings that may have implications for vaccine development and deployment. First, substantial antibody seropositivity to Ebola virus (EBOV) and Sudan virus (SUDV) was observed in populations from outbreak-affected areas (≤33% seroprevalence among general populations; ≤41% seroprevalence among healthcare workers and close contacts of disease cases). Second, antibody seropositivity to EBOV, SUDV, and Marburg virus (MARV) was observed among populations from areas without reported outbreaks, with seroprevalence ranging from <1 to 21%. Third, in Central and East Africa, MARV antibody seroprevalence was substantially lower than EBOV or SUDV antibody seroprevalence, even in outbreak-affected areas and in populations at a moderate or high risk of infection (with MARV seroprevalence mostly ranging from 0 to 3%). Conclusions: Whilst gaps remain in our understanding of the significance of antibody seropositivity in some settings and contexts, these findings may be important in considering target indications for novel filovirus vaccines, in defining study designs and strategies for demonstrating vaccine efficacy or effectiveness, and in planning and evaluating vaccine deployment strategies to prevent and control outbreaks. Full article

Filoviruses, like the Marburg (MARV) and Ebola (EBOV) viruses, have caused outbreaks associated with significant hemorrhagic morbidity and high fatality rates. Vaccines offer one of the best countermeasures for fatal infection, but to date only the EBOV vaccine has received FDA licensure. Given the limited cross protection between the EBOV vaccine and Marburg hemorrhagic fever (MHF), we analyzed the protective efficacy of a similar vaccine, rVSV-MARV, in the lethal cynomolgus macaque model. NHPs vaccinated with a single dose (as little as 1.6 × 10⁷ pfu) of rVSV-MARV seroconverted to MARV G-protein prior to challenge on day 42. Vaccinemia was measured in all vaccinated primates, self-resolved by day 14 post vaccination. Importantly, all vaccinated NHPs survived lethal MARV challenge, and showed no significant alterations in key markers of morbid disease, including clinical signs, and certain hematological and clinical chemistry parameters. Further, apart from one primate (from which tissues were not collected and no causal link was established), no pathology associated with Marburg disease was observed in vaccinated animals. Taken together, rVSV-MARV is a safe and efficacious vaccine against MHF in cynomolgus macaques. Full article

Filoviruses are negative-sense single-stranded RNA viruses often associated with severe and highly lethal hemorrhagic fever in humans and nonhuman primates, with case fatality rates as high as 90%. Of the known filoviruses, Ebola virus (EBOV), the prototype of the genus Orthoebolavirus, has been a major public health concern as it frequently causes outbreaks and was associated with an unprecedented outbreak in several Western African countries in 2013–2016, affecting 28,610 people, 11,308 of whom died. Thereafter, filovirus research mostly focused on EBOV, paying less attention to other equally deadly orthoebolaviruses (Sudan, Bundibugyo, and Taï Forest viruses) and orthomarburgviruses (Marburg and Ravn viruses). Some of these filoviruses have emerged in nonendemic areas, as exemplified by four Marburg disease outbreaks recorded in Guinea, Ghana, Tanzania, and Equatorial Guinea between 2021 and 2023. Similarly, the Sudan virus has reemerged in Uganda 10 years after the last recorded outbreak. Moreover, several novel bat-derived filoviruses have been discovered in the last 15 years (Lloviu virus, Bombali virus, Měnglà virus, and Dehong virus), most of which are poorly characterized but may display a wide host range. These novel viruses have the potential to cause outbreaks in humans. Several gaps are yet to be addressed regarding known and emerging filoviruses. These gaps include the virus ecology and pathogenicity, mechanisms of zoonotic transmission, host range and susceptibility, and the development of specific medical countermeasures. In this review, we summarize the current knowledge on non-Ebola filoviruses (Bombali virus, Bundibugyo virus, Reston virus, Sudan virus, Tai Forest virus, Marburg virus, Ravn virus, Lloviu virus, Měnglà virus, and Dehong virus) and suggest some strategies to accelerate specific countermeasure development. Full article

The Ebola virus (EBOV) is a lethal pathogen causing hemorrhagic fever syndrome which remains a global health challenge. In the EBOV, two multifunctional proteins, VP35 and VP40, have significant roles in replication, virion assembly, and budding from the cell and have been identified as druggable targets. In this study, we employed in silico methods comprising molecular docking, molecular dynamic simulations, and pharmacological properties to identify prospective drugs for inhibiting VP35 and VP40 proteins from the myxobacterial bioactive natural product repertoire. Cystobactamid 934-2, Cystobactamid 919-1, and Cittilin A bound firmly to VP35. Meanwhile, 2-Hydroxysorangiadenosine, Enhypyrazinone B, and Sorangiadenosine showed strong binding to the matrix protein VP40. Molecular dynamic simulations revealed that, among these compounds, Cystobactamid 919-1 and 2-Hydroxysorangiadenosine had stable interactions with their respective targets. Similarly, molecular mechanics Poisson–Boltzmann surface area (MMPBSA) calculations indicated close-fitting receptor binding with VP35 or VP40. These two compounds also exhibited good pharmacological properties. In conclusion, we identified Cystobactamid 919-1 and 2-Hydroxysorangiadenosine as potential ligands for EBOV that target VP35 and VP40 proteins. These findings signify an essential step in vitro and in vivo to validate their potential for EBOV inhibition. Full article

Nipah virus (NiV) is a virulent zoonotic disease whose natural host is the fruit bat (Pteropus medius), which can coexist with and transmit the virus. Due to its high pathogenicity, wide host range, and pandemic potential, establishing a sensitive, specific, and rapid diagnostic method for NiV is key to preventing and controlling its spread and any outbreaks. Here, we established a luciferase immunosorbent assay (LISA) based on the NiV attachment glycoprotein (G) to detect NiV-specific immunoglobulin G by expressing a fusion protein of nanoluciferase (NanoLuc) and the target antigen. Sensitivity analysis was performed and compared to an indirect enzyme-linked immunosorbent assay (ELISA), and specificity and cross-reactivity assessments were performed using NiV-positive horse serum and Ebola virus-, Crimean–Congo hemorrhagic fever virus-, and West Nile virus-positive horse sera. The optimal structural domain for NiV detection was located within amino acids 176–602 of the NiV G protein head domain. Moreover, the LISA showed at least fourfold more sensitivity than the indirect ELISA, and the cross-reactivity results suggested that the LISA had good specificity and was capable of detecting NiV-specific immunoglobulin G in both mouse and horse serum. In conclusion, the establishment of a rapid, simple NiV LISA using the G protein head domain provides a resource for NiV monitoring. Full article

Orthohantaviruses may cause hemorrhagic fever with renal syndrome or hantavirus cardiopulmonary syndrome. Andes virus (ANDV) is the only orthohantavirus associated with human–human transmission. Therefore, emergency vaccination would be a valuable public health measure to combat ANDV-derived infection clusters. Here, we utilized a promising vesicular stomatitis virus (VSV)-based vaccine to advance the approach for emergency applications. We compared monovalent and bivalent VSV vectors containing the Ebola virus (EBOV), glycoprotein (GP), and ANDV glycoprotein precursor (GPC) for protective efficacy in pre-, peri- and post-exposure immunization by the intraperitoneal and intranasal routes. Inclusion of the EBOV GP was based on its favorable immune cell targeting and the strong innate responses elicited by the VSV-EBOV vaccine. Our data indicates no difference of ANDV GPC expressing VSV vectors in pre-exposure immunization independent of route, but a potential benefit of the bivalent VSVs following peri- and post-exposure intraperitoneal vaccination. Full article

Infection with Ebola virus (EBOV) is responsible for hemorrhagic fever in humans with a high mortality rate. Combined efforts of prevention and therapeutic intervention are required to tackle highly variable RNA viruses, whose infections often lead to outbreaks. Here, we have screened the 2P2I_3D chemical library using a nanoluciferase-based protein complementation assay (NPCA) and isolated two compounds that disrupt the interaction of the EBOV protein fragment VP35IID with the N-terminus of the dsRNA-binding proteins PKR and PACT, involved in IFN response and/or intrinsic immunity, respectively. The two compounds inhibited EBOV infection in cell culture as well as infection by measles virus (MV) independently of IFN induction. Consequently, we propose that the compounds are antiviral by restoring intrinsic immunity driven by PACT. Given that PACT is highly conserved across mammals, our data support further testing of the compounds in other species, as well as against other negative-sense RNA viruses. Full article