Ebola Virus Infection of Flt3-Dependent, Conventional Dendritic Cells and Antigen Cross-presentation Leads to High Levels of T-Cell Activation.

BACKGROUND: Previous studies have described that Ebola virus (EBOV) infection of human monocyte-derived dendritic cells (moDCs) inhibits dendritic cell (DC) maturation, resulting in poor T-cell activation. However, it is unknown how other DC subsets distinct from moDCs respond to EBOV infection. METHODS: To better understand how DCs initiate T-cell activation during EBOV infection, we assessed the response of conventional mouse DCs (cDCs) to EBOV infection utilizing a recombinant EBOV expressing the model antigen ovalbumin. RESULTS: In contrast to moDCs, mouse cDC2s and cDC1s were poorly infected with EBOV but were highly activated. DCs were able to prime CD8 T cells via cross-presentation of antigens obtained from cell debris of EBOV-infected cells. EBOV infection further enhanced DC cross-presentation. CONCLUSIONS: Our findings indicate that EBOV infection of cDCs results in activation rather than inhibition, leading to high levels of T-cell activation. With that we propose a mechanistic explanation for the excess T-cell activation observed in human Ebola virus disease.

Machine learning-based analysis of Ebola virus' impact on gene expression in nonhuman primates.

Introduction: This study introduces the Supervised Magnitude-Altitude Scoring (SMAS) methodology, a novel machine learning-based approach for analyzing gene expression data from non-human primates (NHPs) infected with Ebola virus (EBOV). By focusing on host-pathogen interactions, this research aims to enhance the understanding and identification of critical biomarkers for Ebola infection. Methods: We utilized a comprehensive dataset of NanoString gene expression profiles from Ebola-infected NHPs. The SMAS system combines gene selection based on both statistical significance and expression changes. Employing linear classifiers such as logistic regression, the method facilitates precise differentiation between RT-qPCR positive and negative NHP samples. Results: The application of SMAS led to the identification of IFI6 and IFI27 as key biomarkers, which demonstrated perfect predictive performance with 100% accuracy and optimal Area Under the Curve (AUC) metrics in classifying various stages of Ebola infection. Additionally, genes including MX1, OAS1, and ISG15 were significantly upregulated, underscoring their vital roles in the immune response to EBOV. Discussion: Gene Ontology (GO) analysis further elucidated the involvement of these genes in critical biological processes and immune response pathways, reinforcing their significance in Ebola pathogenesis. Our findings highlight the efficacy of the SMAS methodology in revealing complex genetic interactions and response mechanisms, which are essential for advancing the development of diagnostic tools and therapeutic strategies. Conclusion: This study provides valuable insights into EBOV pathogenesis, demonstrating the potential of SMAS to enhance the precision of diagnostics and interventions for Ebola and other viral infections.

Reconceptualizing transcriptional slippage in plant RNA viruses.

RNA viruses have evolved sophisticated strategies to exploit the limited encoded information within their typically compact genomes. One of them, named transcriptional slippage (TS), is characterized by the appearance of indels in nascent viral RNAs, leading to changes in the open reading frame (ORF). Although members of unrelated viral families express key proteins via TS, the available information about this phenomenon is still limited. In potyvirids (members of the Potyviridae family), TS has been defined by the insertion of an additional A at An motifs (n ≥ 6) in newly synthesized transcripts at a low frequency, modulated by nucleotides flanking the A-rich motif. Here, by using diverse experimental approaches and a collection of plant/virus combinations, we discover cases not following this definition. In summary, we observe (i) a high rate of single-nucleotide deletions at slippage motifs, (ii) overlapping ORFs acceded by slippage at an U8 stretch, and (iii) changes in slippage rates induced by factors not related to cognate viruses. Moreover, a survey of whole-genome sequences from potyvirids shows a widespread occurrence of species-specific An/Un (n ≥ 6) motifs. Even though many of them, but not all, lead to the production of truncated proteins rather than access to overlapping ORFs, these results suggest that slippage motifs appear more frequently than expected and play relevant roles during virus evolution. Considering the potential of this phenomenon to expand the viral proteome by acceding to overlapping ORFs and/or producing truncated proteins, a re-evaluation of TS significance during infections of RNA viruses is required.IMPORTANCETranscriptional slippage (TS) is used by RNA viruses as another strategy to maximize the coding information in their genomes. This phenomenon is based on a peculiar feature of viral replicases: they may produce indels in a small fraction of newly synthesized viral RNAs when transcribing certain motifs and then produce alternative proteins due to a change of the reading frame or truncated products by premature termination. Here, using plant-infecting RNA viruses as models, we discover cases expanding on previously established features of plant virus TS, prompting us to reconsider and redefine this expression strategy. An interesting conclusion from our study is that TS might be more relevant during RNA virus evolution and infection processes than previously assumed.

Intracellular Ebola virus nucleocapsid assembly revealed by in situ cryo-electron tomography.

Filoviruses, including the Ebola and Marburg viruses, cause hemorrhagic fevers with up to 90% lethality. The viral nucleocapsid is assembled by polymerization of the nucleoprotein (NP) along the viral genome, together with the viral proteins VP24 and VP35. We employed cryo-electron tomography of cells transfected with viral proteins and infected with model Ebola virus to illuminate assembly intermediates, as well as a 9 Å map of the complete intracellular assembly. This structure reveals a previously unresolved third and outer layer of NP complexed with VP35. The intrinsically disordered region, together with the C-terminal domain of this outer layer of NP, provides the constant width between intracellular nucleocapsid bundles and likely functions as a flexible tether to the viral matrix protein in the virion. A comparison of intracellular nucleocapsids with prior in-virion nucleocapsid structures reveals that the nucleocapsid further condenses vertically in the virion. The interfaces responsible for nucleocapsid assembly are highly conserved and offer targets for broadly effective antivirals.

Rational design of self-amplifying virus-like vesicles with Ebola virus glycoprotein as vaccines.

As emerging and re-emerging pathogens, filoviruses, especially Ebola virus (EBOV), pose a great threat to public health and require sustained attention and ongoing surveillance. More vaccines and antiviral drugs are imperative to be developed and stockpiled to respond to unpredictable outbreaks. Virus-like vesicles, generated by alphavirus replicons expressing homogeneous or heterogeneous glycoproteins (GPs), have demonstrated the capacity of self-propagation and shown great potential in vaccine development. Here, we describe a novel class of EBOV-like vesicles (eVLVs) incorporating both EBOV GP and VP40. The eVLVs exhibited similar antigenicity as EBOV. In murine models, eVLVs were highly attenuated and elicited robust GP-specific antibodies with neutralizing activities. Importantly, a single dose of eVLVs conferred complete protection in a surrogate EBOV lethal mouse model. Furthermore, our VLVs strategy was also successfully applied to Marburg virus (MARV), the representative member of the genus Marburgvirus. Taken together, our findings indicate the feasibility of an alphavirus-derived VLVs strategy in combating infection of filoviruses represented by EBOV and MARV, which provides further evidence of the potential of this platform for universal live-attenuated vaccine development.

Inactivation Validation of Ebola, Marburg, and Lassa Viruses in AVL and Ethanol-Treated Viral Cultures.

High-consequence pathogens such as the Ebola, Marburg, and Lassa viruses are handled in maximum-containment biosafety level 4 (BSL-4) laboratories. Genetic material is often isolated from such viruses and subsequently removed from BSL-4 laboratories for a multitude of downstream analyses using readily accessible technologies and equipment available at lower-biosafety level laboratories. However, it is essential to ensure that these materials are free of viable viruses before removal from BSL-4 laboratories to guarantee sample safety. This study details the in-house procedure used for validating the inactivation of Ebola, Marburg, and Lassa virus cultures after incubation with AVL lysis buffer (Qiagen) and ethanol. This study's findings show that no viable virus was detectable when high-titer cultures of Ebola, Marburg, and Lassa viruses were incubated with AVL lysis buffer for 10 min, followed by an equal volume of 95% ethanol for 3 min, using a method with a sensitivity of ≤0.8 log10 TCID50 as the limit of detection.

A novel multi-epitope peptide vaccine targeting immunogenic antigens of Ebola and monkeypox viruses with potential of immune responses provocation in silico.

The emergence or reemergence of monkeypox (Mpox) and Ebola virus (EBOV) agents causing zoonotic diseases remains a huge threat to human health. Our study aimed at designing a multi-epitope vaccine (MEV) candidate to target both the Mpox and EBOV agents using immunoinformatics tools. Viral protein sequences were retrieved, and potential nonallergenic, nontoxic, and antigenic epitopes were obtained. Next, cytotoxic and helper T-cell (CTL and HTL, respectively) and B-cell (BCL) epitopes were predicted, and those potential epitopes were fused utilizing proper linkers. The in silico cloning and expression processes were implemented using Escherichia coli K12. The immune responses were prognosticated using the C-ImmSim server. The MEV construct (29.53 kDa) included four BCL, two CTL, and four HTL epitopes and adjuvant. The MEV traits were pertinent in terms of antigenicity, non-allergenicity, nontoxicity, physicochemical characters, and stability. The MEV candidate was also highly expressed in E. coli K12. The strong affinity of MEV-TLR3 was confirmed using molecular docking and molecular dynamics simulation analyses. Immune simulation analyses unraveled durable activation and responses of cellular and humoral arms alongside innate immune responses. The designed MEV candidate demonstrated appropriate traits and was promising in the prediction of immune responses against both Mpox and EBOV agents. Further experimental assessments of the MEV are required to verify its efficacy.

National burden of Ebola virus disease in Democratic Republic of the Congo: the urgency to act.

Ebola virus disease (EVD) has long been a major public health concern for Democratic Republic of the Congo (DR Congo). First identified in DR Congo in 1976, the country has witnessed more than 25 outbreaks of this deadly disease, which has a case fatality rate of nearly 90% and manifesting with symptoms such as diarrhoea, vomiting, stomachache and haemorrhagic fever. African fruit bats have been speculated to be the reservoir of this virus. DR Congo is currently facing another EVD outbreak simultaneously with other communicable diseases, rendering it vulnerable to a shortage of medical and paramedical staff along with distrust among remote communities towards local authorities due to armed conflict and political instability. Moreover, lack of ring vaccinations and inefficient surveillance of suspected individuals are some other significant hurdles in disease control. Despite the availability of rVSV-ZEBOV/Erbevo vaccine and many antibody-based vaccines, challenges including politicization, low access to remote communities, and illiteracy have limited their effectiveness. Recently, the Congolese govt. has put in efforts such as building local capacities at the health zone level, outbreak control intervention, community engagement and social mobilization to counter the rising EVD cases. Four successive Strategic Response Plans have been implemented to increase resource mobilization by DR Congo and her partners. The Spread of zoonotics such as EVD can be confronted by implementing the One Health approach, which involves medical staff, veterinarians and public health officials.

An update on nonhuman primate usage for drug and vaccine evaluation against filoviruses.

INTRODUCTION: Due to their faithful recapitulation of human disease, nonhuman primates (NHPs) are considered the gold standard for evaluating drugs against Ebolavirus and other filoviruses. The long-term goal is to reduce the reliance on NHPs with more ethical alternatives. In silico simulations and organoid models have the potential to revolutionize drug testing by providing accurate, human-based systems that mimic disease processes and drug responses without the ethical concerns associated with animal testing. However, as these emerging technologies are still in their developmental infancy, NHP models are presently needed for late-stage evaluation of filovirus vaccines and drugs, as they provide critical insights into the efficacy and safety of new medical countermeasures. AREAS COVERED: In this review, the authors introduce available NHP models and examine the existing literature on drug discovery for all medically significant filoviruses in corresponding models. EXPERT OPINION: A deliberate shift toward animal-free models is desired to align with the 3Rs of animal research. In the short term, the use of NHP models can be refined and reduced by enhancing replicability and publishing negative data. Replacement involves a gradual transition, beginning with the selection and optimization of better small animal models; advancing organoid systems, and using in silico models to accurately predict immunological outcomes.

A Review of the Interaction between miRNAs and Ebola Virus.

Ebola virus (EBOV) is a life-threatening and virulent pathogen that kills approximately 90 percent of infected individuals. Nowadays, microRNAs (miRNAs) have become a promising option for more efficient screening, diagnosis, monitoring, and therapy of numerous diseases such as cancer, stroke, Alzheimer's, and viral infections. Recent studies have revealed the role of EBOV and host-encoded miRNAs in Ebola virus disease (EVD), opening an avenue for developing novel drugs against EVD and diagnostic panels for EBOV infection. EBOV-encoded miRNAs such as miR-VP-3p and miR-1-5p and anti-EBOV host cell miRNAs such as has-miR-150-3p, has-miR-103b and has-miR-145-3p might be a possible diagnostic biomarker or druggable targets. This paper highlights the importance of viral and cellular miRNAs in EBOV infection and EVD.

Transport of Patients With High-Consequence Infectious Diseases: Development of European Capacity in Norway.

Infection of Western aid workers with Ebola virus disease during the 2014-2016 West African outbreak demonstrated the need for medical evacuation to high-level isolation units in Europe and the United States. In Norway, an ad hoc preparedness team was established for aeromedical evacuation in case of need. In October 2014, this team transported an infected aid worker from the military section of Oslo Airport to Oslo University Hospital. To maintain and strengthen the capacity for domestic ambulance transport on the ground and in the air, the Norwegian Medical Emergency Response Team for High Consequence Infectious Diseases (in Norway known as "Nasjonalt medisinsk utrykningsteam for høyrisikosmitte"), or NORTH, was established as a permanent service in 2017. Recognizing the expertise of this domestic team, Norway was subsequently entrusted with the task of enhancing the European aeromedical transport capacity for high-consequence infectious diseases and establishing the Norwegian rescEU Jet Air Ambulance for Transport of Highly Infectious Patients, or NOJAHIP, in 2022. In this case study, we present experiences and lessons learned from these 2 services and discuss how they can be further developed.

Fully human monoclonal antibodies against Ebola virus possess complete protection in a hamster model.

Ebola disease is a lethal viral hemorrhagic fever caused by ebolaviruses within the Filoviridae family with mortality rates of up to 90%. Monoclonal antibody (mAb) based therapies have shown great potential for the treatment of EVD. However, the potential emerging ebolavirus isolates and the negative effect of decoy protein on the therapeutic efficacy of antibodies highlight the necessity of developing novel antibodies to counter the threat of Ebola. Here, 11 fully human mAbs were isolated from transgenic mice immunized with GP protein and recombinant vesicular stomatitis virus-bearing GP (rVSV-EBOV GP). These mAbs were divided into five groups according to their germline genes and exhibited differential binding activities and neutralization capabilities. In particular, mAbs 8G6, 2A4, and 5H4 were cross-reactive and bound at least three ebolavirus glycoproteins. mAb 4C1 not only exhibited neutralizing activity but no cross-reaction with sGP. mAb 7D8 exhibited the strongest neutralizing capacity. Further analysis on the critical residues for the bindings of 4C1 and 8G6 to GPs was conducted using antibodies complementarity-determining regions (CDRs) alanine scanning. It has been shown that light chain CDR3 played a crucial role in binding and neutralization and that any mutation in CDRs could not improve the binding of 4C1 to sGP. Importantly, mAbs 7D8, 8G6, and 4C1 provided complete protections against EBOV infection in a hamster lethal challenge model when administered 12 h post-infection. These results support mAbs 7D8, 8G6, and 4C1 as potent antibody candidates for further investigations and pave the way for further developments of therapies and vaccines.

Proximal fleximer analogues of 2'-deoxy-2'-fluoro-2'-methyl purine nucleos(t)ides: Synthesis and preliminary pharmacokinetic and antiviral evaluation.

In this study, proximal fleximer nucleos(t)ide analogues of Bemnifosbuvir were synthesized and evaluated for their potential to serve as antiviral therapeutics. The final parent flex-nucleoside and ProTide modified flex-nucleoside analogues were tested against several viral families including flaviviruses, filoviruses, and coronaviruses. Modest activity against Zaire Ebola virus was observed at 30 µM for compound ProTide modified analogue. Neither compound exhibited activity for any of the other viruses tested. The parent flex-nucleoside analogue was screened for toxicity in CD-1 mice and showed no adverse effects up to 300 mg/kg, the maximum concentration tested.

Afucosylated anti-EBOV antibody MIL77-3 engages sGP to elicit NK cytotoxicity.

MIL77-3 is one component of antibody cocktail that is produced in our lab and represents an effective regimen for animals suffering from Zaire Ebolavirus (EBOV) infection. MIL77-3 is engineered to increase its affinity for the FcγRIIIa (CD16a) by deleting the fucose in the framework region. The potential effects of this modification on host immune responses, however, remain largely unknown. Herein, we demonstrated that MIL77-3 recognized secreted glycoproptein (sGP), produced by EBOV, and formed the immunocomplex to potently augment antibody-dependent cytotoxicity of human peripheral blood-derived natural killer cells (pNKs), including CD56dim and CD56bright subpopulations, in contrast to the counterparts (Mab114, rEBOV548, fucosylated MIL77-3). Intriguingly, this effect was not observed when NK92-CD16a cell line was utilized and restored by the addition of beads-coupled or membrane-anchored sGP in combination with MIL77-3. Furthermore, sGP bound to unrecognized receptors on T cells contaminated in pNKs rather than NK92-CD16a cells. Administration of beads-coupled sGP/MIL77-3 complex in mice elicited NK activation. Overall, this work reveals an immune-stimulating function of sGP/MIL77-3 complex by triggering cytotoxic activity of NK cells, highlighting the necessity to evaluate the potential impact of MIL77-3 on host immune reaction in clinical trials. IMPORTANCE: Zaire Ebolavirus (EBOV) is highly lethal and causes sporadic outbreaks. The passive administration of monoclonal antibodies (mAbs) represents a promising treatment regimen against EBOV. Mounting evidence has shown that the efficacy of a subset of therapeutic mAbs in vivo is intimately associated with its capacity to trigger NK activity, supporting glycomodification of Fc region of anti-EBOV mAbs as a putative strategy to enhance Fc-mediated immune effector function as well as protection in vivo. Our work here uncovers the potential harmful influence of this modification on host immune responses, especially for mAbs with cross-reactivity to secreted glycoproptein (sGP) (e.g., MIL77-3), and highlights it is necessary to evaluate the NK-stimulating activity of a fucosylated mAb engaged with sGP when a new candidate is developed.

Assessment of prevalence and determinants of anxiety and psychological distress symptoms in Ebola child and adolescent survivors and orphans in Eastern Democratic Republic of the Congo during the COVID-19 pandemic.

BACKGROUND: To date, only three studies investigated the mental health of youth affected by Ebola virus disease (EVD). None explored anxiety and psychological distress symptoms in survivors or orphans. This study aimed to investigate the prevalence and determinants of anxiety and psychological distress symptoms among survivors and orphans of the 2018-2020 Ebola epidemic in Eastern Democratic Republic of the Congo (DRC) during the COVID-19 pandemic. METHODS: A representative sample of 416 participants (mean age = 13.37, SD = 2.79, 51.20 % girls, 146 survivors, 233 orphans, and 34 orphan-survivor participants) completed measures evaluating anxiety, psychological distress, exposure, resilience, stigmatization related to Ebola and COVID-19. RESULTS: 55.88 % and 55.96 % of survivors and orphans experienced severe symptoms of anxiety and psychological distress. Participants who were both survivors and orphans presented higher prevalence of anxiety and psychological distress (94.12 % and 100 %) compared to survivors (74.03 % and 81.82 %) or orphans (37.99 % and 33.33 %), χ2 = 70.63, p < .001; χ2 = 113.50, p < .001. Ebola and COVID-19 related stigmatization were the most important determinants of anxiety (B = 0.40, p < .001; B = 0.37, p < .001) and psychological distress (B = 0.48, p < .001; B = 0.44, p < .001). Resilience was negatively associated with both anxiety and psychological distress. The final regression models explained 49 % and 85 % of the variance of anxiety and psychological distress. LIMITATIONS: The cross-sectional design used prevents to establish causal link. CONCLUSIONS: Ebola children and adolescents' survivors and orphans are at major risk of experiencing anxiety and psychological distress in Eastern RDC affected by years of armed conflict. Massive resources are needed to develop and implement programs to reduce stigma and support mental health.

Novel proteolytic activation of Ebolavirus glycoprotein GP by TMPRSS2 and cathepsin L at an uncharted position can compensate for furin cleavage.

A multistep priming process involving furin and endosomal cathepsin B and L (CatB/L) has been described for the Orthoebolavirus zairense (EBOV) glycoprotein GP. Inhibition or knockdown of either furin or endosomal cathepsins, however, did not prevent virus multiplication in cell cultures. Moreover, an EBOV mutant lacking the furin cleavage motif (RRTRR→AGTAA) was able to replicate and cause fatal disease in nonhuman primates, indicating that furin cleavage may be dispensable for virus infectivity. Here, by using protease inhibitors and EBOV GP-carrying recombinant vesicular stomatitis virus (VSV) and transcription and replication-competent virus-like particles (trVLPs) we found that processing of EBOV GP is mediated by different proteases in different cell lines depending on the protease repertoire available. Endosomal cathepsins were essential for EBOV GP entry in Huh-7 but not in Vero cells, in which trypsin-like proteases and stably expressed trypsin-like transmembrane serine protease 2 (TMPRSS2) supported wild-type EBOV GP and EBOV GP_AGTAA mutant entry. Furthermore, we show that the EBOV GP_AGTAA mutant is cleaved into fusion-competent GP2 by TMPRSS2 and by CatL at a so far unknown site. Fluorescence microscopy co-localization studies indicate that EBOV GP cleavage by TMPRSS2 may occur in the TGN prior to virus release or in the late endosome at the stage of virus entry into a new cell. Our data show that EBOV GP must be proteolytically activated to support virus entry but has even greater flexibility in terms of proteases and the precise cleavage site than previously assumed.

"If I die for touching him, let me die": a rapid ethnographic assessment of cultural practices and Ebola transmission in high-risk border regions of Tanzania.

BACKGROUND: Ebola Virus Disease (EVD) is a rare but contagious disease caused by Ebola Virus (EBOV). The first Ebola outbreaks were reported in the Democratic Republic of Congo (DRC) before subsequent reported cases in Western and East African countries, including Uganda, which borders Tanzania. Proximity to EVD-infected countries raises the prospect of cross-border transmission, raising alarm in Tanzania. This study aimed to explore the cultural practices likely to prevent or escalate EVD transmission in the event of its outbreak in the country. METHODS: This rapid ethnographic assessment employed observation, interviews, and focus group discussions to collect data from people with diverse characteristics in five regions of Tanzania Mainland namely, Kagera, Kigoma, Mwanza and Songwe regions and Zanzibar Island. The qualitative data was then subjected to thematic analysis. FINDINGS: Cultural practices may escalate the transmission of EVD and hinder its prevention and control. These cultural practices include caring sick people at home, confirmation of death, mourning, and body preparation for burial. Communal life, ceremonies, and social gatherings were other aspects observed to have the potential for compounding EVD transmission and hindering its containment in case of an outbreak. CONCLUSION: Cultural practices may escalate EVD transmission as identified in the study settings. As such, Risk Communication and Community Engagement (RCCE) activities should be interventionist in transforming cultural practices that may escalate the spread of EVD as part of preparedness, prevention, and control efforts in the event of an outbreak.

Prevention and control of Ebola virus transmission: mathematical modelling and data fitting.

The Ebola virus disease (EVD) has been endemic since 1976, and the case fatality rate is extremely high. EVD is spread by infected animals, symptomatic individuals, dead bodies, and contaminated environment. In this paper, we formulate an EVD model with four transmission modes and a time delay describing the incubation period. Through dynamical analysis, we verify the importance of blocking the infection source of infected animals. We get the basic reproduction number without considering the infection source of infected animals. And, it is proven that the model has a globally attractive disease-free equilibrium when the basic reproduction number is less than unity; the disease eventually becomes endemic when the basic reproduction number is greater than unity. Taking the EVD epidemic in Sierra Leone in 2014-2016 as an example, we complete the data fitting by combining the effect of the media to obtain the unknown parameters, the basic reproduction number and its time-varying reproduction number. It is shown by parameter sensitivity analysis that the contact rate and the removal rate of infected group have the greatest influence on the prevalence of the disease. And, the disease-controlling thresholds of these two parameters are obtained. In addition, according to the existing vaccination strategy, only the inoculation ratio in high-risk areas is greater than 0.4, the effective reproduction number can be less than unity. And, the earlier the vaccination time, the greater the inoculation ratio, and the faster the disease can be controlled.

Low-Input, High-Resolution 5' Terminal Filovirus RNA Sequencing with ViBE-Seq.

Although next-generation sequencing (NGS) has been instrumental in determining the genomic sequences of emerging RNA viruses, de novo sequence determination often lacks sufficient coverage of the 5' and 3' ends of the viral genomes. Since the genome ends of RNA viruses contain the transcription and genome replication promoters that are essential for viral propagation, a lack of terminal sequence information hinders the efforts to study the replication and transcription mechanisms of emerging and re-emerging viruses. To circumvent this, we have developed a novel method termed ViBE-Seq (Viral Bona Fide End Sequencing) for the high-resolution sequencing of filoviral genome ends using a simple yet robust protocol with high fidelity. This technique allows for sequence determination of the 5' end of viral RNA genomes and mRNAs with as little as 50 ng of total RNA. Using the Ebola virus and Marburg virus as prototypes for highly pathogenic, re-emerging viruses, we show that ViBE-Seq is a reliable technique for rapid and accurate 5' end sequencing of filovirus RNA sourced from virions, infected cells, and tissue obtained from infected animals. We also show that ViBE-Seq can be used to determine whether distinct reverse transcriptases have terminal deoxynucleotidyl transferase activity. Overall, ViBE-Seq will facilitate the access to complete sequences of emerging viruses.

Comparison of Routes of Administration, Frequency, and Duration of Favipiravir Treatment in Mouse and Guinea Pig Models of Ebola Virus Disease.

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.