Biology subjects

Geisbert, T. W.

Publications and source records attributed to Geisbert, T. W..

15 recordsLinked to original sources

bioRxiv2026

Oral 4`fluorouridine provides postexposure protection against lethal Nipah virus infection

There are no approved medical countermeasures for combatting Nipah virus (NiV) which causes regular outbreaks in humans and animals in South and Southeast Asia with mortality rates in humans ranging from 40% to more than 90%. Recently, it was shown that 4-fluorouridine (4-FlU; EIDD-2749), an orally available ribonucleoside analog, protected guinea pigs and nonhuman primates from lethal challenge with Lassa virus and that 4-FlU has in vitro antiviral activity against NiV. Here, we assessed the postexposure protective efficacy of 4-FlU in a lethal hamster model of NiV infection. Daily treatment with 4-FlU beginning 3 days after exposure to NiV resulted in complete protection from lethal infection. Our findings support the further development of 4-FlU as a therapy for NiV disease.

microbiology↗

bioRxiv2024

A Single-shot ChAd3 Vaccine Provides Protection from Intramuscular and Aerosol Sudan Virus Exposure

Infection with Sudan virus (SUDV) is characterized by an aggressive disease course with case fatality rates between 40-100% and no approved vaccines or therapeutics. SUDV causes sporadic outbreaks in sub-Saharan Africa, including a recent outbreak in Uganda which has resulted in over 100 confirmed cases in one month. Prior vaccine and therapeutic efforts have historically prioritized Ebola virus (EBOV), leading to a significant gap in available treatments. Two vaccines, Erbevo(R) and Zabdeno(R)/Mvabea(R), are licensed for use against EBOV but are ineffective against SUDV. Recombinant adenovirus vector vaccines have been shown to be safe and effective against filoviruses, but efficacy depends on having low seroprevalence to the vector in the target human population. For this reason, and because of an excellent safety and immunogenicity profile, ChAd3 was selected as a superior vaccine vector. Here, a ChAd3 vaccine expressing the SUDV glycoprotein (GP) was evaluated for immunogenicity and efficacy in nonhuman primates. We demonstrate that a single dose of ChAd3-SUDV confers acute and durable protection against lethal SUDV challenge with a strong correlation between the SUDV GP-specific antibody titers and survival outcome. Additionally, we show that a bivalent ChAd3 vaccine encoding the GP from both EBOV and SUDV protects against both parenteral and aerosol lethal SUDV challenge. Our data indicate that the ChAd3-SUDV vaccine is a suitable candidate for a prophylactic vaccination strategy in regions at high risk of filovirus outbreaks. One Sentence Summary: A single-dose of ChAd3 vaccine protected macaques from lethal challenge with Sudan virus (SUDV) by parenteral and aerosol routes of exposure.

immunology↗

bioRxiv2022

A highly attenuated Vesiculovax vaccine rapidly protects nonhuman primates against lethal Marburg virus challenge

BackgroundMarburg virus (MARV), an Ebola-like virus, remains an eminent threat to public health as demonstrated by its high associated mortality rate (23-90%) and recent emergence in West Africa for the first time. Although a recombinant vesicular stomatitis virus (rVSV)-based vaccine (Ervebo) is licensed for Ebola virus disease (EVD), no approved countermeasures exist against MARV. Results from clinical trials indicate Ervebo prevents EVD in 97.5-100% of vaccinees 10 days onwards post-immunization. Methodology/FindingsGiven the rapid immunogenicity of the Ervebo platform against EVD, we tested whether a similar, but highly attenuated, rVSV-based Vesiculovax vector expressing the glycoprotein (GP) of MARV (rVSV-N4CT1-MARV-GP) could provide swift protection against Marburg virus disease (MVD). Here, groups of cynomolgus monkeys were vaccinated 7, 5, or 3 days before exposure to a lethal dose of MARV (Angola variant). All subjects (100%) immunized one week prior to challenge survived; 80% and 20% of subjects survived when vaccinated 5- and 3-days pre-exposure, respectively. Lethality was associated with higher viral load and aberrant innate immunity signaling, whereas survival correlated with development of MARV GP-specific antibodies and early expression of NK cell-, B-cell-, and cytotoxic T-cell-related transcriptional signatures. Conclusions/SignificanceThese results emphasize the utility of Vesiculovax vaccines for MVD outbreak management. The highly attenuated nature of rVSV-N4CT1 vaccines, which are clinically safe in humans, may be preferable to vaccines based on the same platform as Ervebo (rVSV "delta G" platform), which in some trial participants induced vaccine-related adverse events in association with viral replication including arthralgia/arthritis, dermatitis, and cutaneous vasculitis. Author SummaryMarburg virus (MARV) is one of the deadliest viruses known to man. One of the most effective vaccines against this pathogen uses a recombinant vesicular stomatitis virus (rVSV) platform to express MARV glycoprotein (GP) immunogen. As rVSV-based vaccines may be used as medical interventions to mitigate or prevent outbreaks of MARV, defining the time window needed to elicit protection is vital. Here, a rVSV vector expressing MARV glycoprotein (rVSV-N4CT1-MARV-GP) fully protected nonhuman primates from lethality and disease when given as soon as 1 week prior to exposure. At 5- and 3-days pre-exposure, partial protection (80% and 20% survival, respectively) was achieved. Vaccination with rVSV-N4CT1-MARV-GP appears to "jump-start" the immune system to allow sufficient time for MARV-specific adaptive responses to form. This fast- acting vaccine is based on a similar platform as Ervebo, the only FDA- and EU-approved vaccine for preventing Ebola virus infection. The rVSV-N4CT1-MARV-GP vaccine features additional attenuations in the rVSV backbone that may contribute to a more acceptable safety profile in vaccinees, as Ervebo in some recipients induced vaccine- related adverse events including rashes and joint pain.

microbiology↗

bioRxiv2021

Natural history of nonhuman primates after conjunctival exposure to Ebola virus

Transmission of Ebola virus (EBOV) primarily occurs via contact exposure of mucosal surfaces with infected body fluids. Historically, nonhuman primate (NHP) challenge studies have employed intramuscular or small particle aerosol exposure, which are uniformly lethal routes of infection, but mimic worst-case scenarios such as a needlestick. When exposed by more likely routes of natural infection, limited NHP studies have shown delayed onset of disease and reduced mortality. Here we performed a series of systematic natural history studies in cynomolgus macaques with a range of conjunctival exposure doses. Challenge with 10,000 plaque forming units (PFU) of EBOV was uniformly lethal, whereas 5/6 subjects survived low and moderate dose challenges (100 or 500 PFU). Conjunctival challenge resulted in a protracted time-to death. Asymptomatic disease was observed in survivors with limited detection of EBOV replication. Inconsistent seropositivity in survivors may suggest physical or natural immunological barriers are sufficient to prevent widespread viral dissemination.

microbiology↗

bioRxiv2021

Rapid and Durable Protection Against Marburg Virus with a Single-Shot ChAd3-MARV GP Vaccine

Marburg virus (MARV) causes a severe hemorrhagic fever disease in primates with mortality rates in humans up to 90%. Since 2018, MARV has been identified as a priority pathogen by the WHO, needing urgent research and development of countermeasures due to the high public health risk it poses. Recently, the first case of MARV in West Africa underscored the significant outbreak potential of this virus. The potential for cross border spread as had occurred during the Ebola 2014-2016 outbreak illustrates the critical need for Marburg vaccines. To support regulatory approval of the ChAd3-Marburg vaccine that has completed Phase I trials, we show that a non-replicating chimpanzee-derived adenovirus vector with a demonstrated safety profile in humans (ChAd3) protected against a uniformly lethal challenge with Marburg-Angola. Protective immunity was achieved within 7 days of vaccination and was maintained through one year post vaccination, antigen-specific antibodies were a significant immune correlate of protection in the acute challenge model (p=0.0003), and predictive for protection with an AUC = 0.88. These results demonstrate that a single-shot ChAd3 MARV vaccine generated a protective immune response that was both rapid and durable with a significant immune correlate of protection that will support advanced clinical development. One Sentence SummaryA single-shot of non-replicating ChAd3-MARV vaccine demonstrated both rapid (within 1 week) and durable (12 months) protection against lethal Marburg virus infection in macaques.

immunology↗

bioRxiv2021

Protective pan-ebolavirus combination therapy by two multifunctional human antibodies

Ebolaviruses cause a severe and often fatal illness with the potential for global spread. Monoclonal antibody-based treatments that have become available recently have a narrow therapeutic spectrum and are ineffective against ebolaviruses other than Ebola virus (EBOV), including medically important Bundibugyo (BDBV) and Sudan (SUDV) viruses. Here we report the development of a therapeutic cocktail comprising two broadly neutralizing human antibodies rEBOV-515 and rEBOV-442 that recognize non-overlapping sites on the ebolavirus glycoprotein (GP). Antibodies in the cocktail exhibited synergistic neutralizing activity and resisted viral escape, and they were optimized for their Fc-mediated effector function activities. The cocktail protected non-human primates from ebolavirus disease caused by EBOV, BDBV, or SUDV with high therapeutic effectiveness. High-resolution structures of the cocktail antibodies in complex with GP revealed the molecular determinants for neutralization breadth and potency. This study provides advanced preclinical data to support clinical development of this cocktail for pan-ebolavirus therapy.

immunology↗

bioRxiv2021

LY-CoV1404 potently neutralizes SARS-CoV-2 variants

SARS-CoV-2 neutralizing monoclonal antibodies (mAbs) can reduce the risk of hospitalization when administered early during COVID-19 disease. However, the emergence of variants of concern has negatively impacted the therapeutic use of some authorized mAbs. Using a high throughput B-cell screening pipeline, we isolated a highly potent SARS-CoV-2 spike glycoprotein receptor binding domain (RBD)-specific antibody called LY-CoV1404 (also known as bebtelovimab). LY-CoV1404 potently neutralizes authentic SARS-CoV-2 virus, including the prototype, B.1.1.7, B.1.351 and B.1.617.2). In pseudovirus neutralization studies, LY-CoV1404 retains potent neutralizing activity against numerous variants including B.1.1.7, B.1.351, B.1.617.2, B.1.427/B.1.429, P.1, B.1.526, B.1.1.529, and the BA.2 subvariant and retains binding to spike proteins with a variety of underlying RBD mutations including K417N, L452R, E484K, and N501Y. Structural analysis reveals that the contact residues of the LY-CoV1404 epitope are highly conserved with the exception of N439 and N501. Notably, the binding and neutralizing activity of LY-CoV1404 is unaffected by the most common mutations at these positions (N439K and N501Y). The breadth of reactivity to amino acid substitutions present among current VOC together with broad and potent neutralizing activity and the relatively conserved epitope suggest that LY-CoV1404 has the potential to be an effective therapeutic agent to treat all known variants causing COVID-19. In BriefLY-CoV1404 is a potent SARS-CoV-2-binding antibody that neutralizes all known variants of concern and whose epitope is rarely mutated. HighlightsO_LILY-CoV1404 potently neutralizes SARS-CoV-2 authentic virus and known variants of concern including the B.1.1.529 (Omicron), the BA.2 Omicron subvariant, and B.1.617.2 (Delta) variants C_LIO_LINo loss of potency against currently circulating variants C_LIO_LIBinding epitope on RBD of SARS-CoV-2 is rarely mutated in GISAID database C_LIO_LIBreadth of neutralizing activity and potency supports clinical development C_LI

immunology↗

bioRxiv2021

Functional cooperativity mediated by rationally selected combinations of human monoclonal antibodies targeting the henipavirus receptor binding protein

Hendra virus (HeV) and Nipah virus (NiV), the prototypic members of the Henipavirus (HNV) genus, are emerging, zoonotic paramyxoviruses known to cause severe disease across six mammalian orders, including humans (Eaton et al., 2006). While several research groups have made strides in developing candidate vaccines and therapeutics against henipaviruses, such countermeasures have not been licensed for human use, and significant gaps in knowledge about the human immune response to these viruses exist. To address these gaps, we isolated a large panel of human monoclonal antibodies (mAbs) from the B cells of an individual with prior occupation-related exposure to the equine HeV vaccine (Equivac(R) HeV). Competition-binding and hydrogen-deuterium exchange mass spectrometry (HDX-MS) studies identified at least six distinct antigenic sites on the HeV/NiV receptor binding protein (RBP) that are recognized by human mAbs. Antibodies recognizing multiple antigenic sites potently neutralized NiV and/or HeV isolates in vitro. The most potent class of cross-reactive antibodies achieved neutralization by blocking viral attachment to the host cell receptors ephrin-B2 and ephrin-B3. Antibodies from this class mimic receptor binding by inducing a receptor-bound conformation to the HeV-RBP protein tetramer, exposing an epitope that appears to lie hidden in the interface between protomers within the HeV-RBP tetramer. Antibodies that recognize this cryptic epitope potently neutralized HeV and NiV. Flow cytometric studies using cell-surface-displayed HeV-RBP protein showed that cross-reactive, neutralizing mAbs from each of these classes cooperate for binding. In a highly stringent hamster model of NiVB infection, antibodies from both classes reduced morbidity and mortality and achieved synergistic protection in combination and provided therapeutic benefit when combined into two bispecific platforms. These studies identified multiple candidate mAbs that might be suitable for use in a cocktail therapeutic approach to achieve synergistic antiviral potency and reduce the risk of virus escape during treatment.

immunology↗

bioRxiv2020

Use of convalescent serum reduces severity of COVID-19 in nonhuman primates

Passive transfer of convalescent plasma or serum is a time-honored strategy for treating infectious diseases. Human convalescent plasma containing antibodies against SARS-CoV-2 is currently being used to treat COVID-19 patients. However, most patients have been treated outside of randomized clinical trials making it difficult to determine the efficacy of this approach. Here, we assessed the efficacy of convalescent sera in a newly developed African green monkey model of COVID-19. Groups of SARS-CoV-2-infected animals were treated with pooled convalescent sera containing either high or low to moderate anti-SARS-CoV-2 neutralizing antibody titers. Differences in viral load and disease pathology were minimal between monkeys that received the lower titer convalescent sera and untreated controls. However, and importantly, lower levels of SARS-CoV-2 in respiratory compartments, reduced gross and histopathological lesion severity in the lungs, and reductions in several parameters associated with coagulation and inflammatory processes were observed in monkeys that received convalescent sera versus untreated controls. Our data support human studies suggesting that convalescent plasma therapy is an effective strategy if donors with high level of antibodies against SARS-CoV-2 are employed and if recipients are at an early stage of disease.

microbiology↗

bioRxiv2020

LY-CoV555, a rapidly isolated potent neutralizing antibody, provides protection in a non-human primate model of SARS-CoV-2 infection

SARS-CoV-2 poses a public health threat for which therapeutic agents are urgently needed. Herein, we report that high-throughput microfluidic screening of antigen-specific B-cells led to the identification of LY-CoV555, a potent anti-spike neutralizing antibody from a convalescent COVID-19 patient. Biochemical, structural, and functional characterization revealed high-affinity binding to the receptor-binding domain, ACE2 binding inhibition, and potent neutralizing activity. In a rhesus macaque challenge model, prophylaxis doses as low as 2.5 mg/kg reduced viral replication in the upper and lower respiratory tract. These data demonstrate that high-throughput screening can lead to the identification of a potent antiviral antibody that protects against SARS-CoV-2 infection. One Sentence SummaryLY-CoV555, an anti-spike antibody derived from a convalescent COVID-19 patient, potently neutralizes SARS-CoV-2 and protects the upper and lower airways of non-human primates against SARS-CoV-2 infection.

immunology↗

bioRxiv2020

In plain sight: the role of alpha-1-antitrypsin in COVID-19 pathogenesis and therapeutics.

RationaleSARS-CoV-2 entry into host cells is facilitated by endogenous and exogenous proteases that proteolytically activate the spike glycoprotein and antiproteases inhibiting this process. Understanding the key actors in viral entry is crucial for advancing knowledge of virus tropism, pathogenesis, and potential therapeutic targets. ObjectivesWe aimed to investigate the role of naive serum and alpha-1-antitrypsin (AAT) in inhibiting protease-mediated SARS-CoV-2 entry and explore the implications of AAT deficiency on susceptibility to different SARS-CoV-2 variants. FindingsOur study demonstrates that naive serum exhibits significant inhibition of SARS-CoV-2 entry, with AAT identified as the major serum protease inhibitor potently restricting entry. Using pseudoparticles, replication-competent pseudoviruses, and authentic SARS-CoV-2, we show that AAT inhibition occurs at low concentrations compared with those in serum and bronchoalveolar tissues, suggesting physiological relevance. Furthermore, sera from subjects with an AAT-deficient genotype show reduced ability to inhibit entry of both Wuhan-Hu-1 (WT) and B.1.617.2 (Delta) but exhibit no difference in inhibiting B.1.1.529 (Omicron) entry. ConclusionsAAT may have a variant-dependent therapeutic potential against SARS-CoV-2. Our findings highlight the importance of further investigating the complex interplay between proteases, antiproteases, and spike glycoprotein activation in SARS-CoV-2 and other respiratory viruses to identify potential therapeutic targets and improve understanding of disease pathogenesis.

microbiology↗

bioRxiv2020

Establishment of an African green monkey model for COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for an unprecedented global pandemic of COVID-19. Animal models are urgently needed to study the pathogenesis of COVID-19 and to screen candidate vaccines and treatments. Nonhuman primates (NHP) are considered the gold standard model for many infectious pathogens as they usually best reflect the human condition. Here, we show that African green monkeys support a high level of SARS-CoV-2 replication and develop pronounced respiratory disease that may be more substantial than reported for other NHP species including cynomolgus and rhesus macaques. In addition, SARS-CoV-2 was detected in mucosal samples of all animals including feces of several animals as late as 15 days after virus exposure. Importantly, we show that virus replication and respiratory disease can be produced in African green monkeys using a much lower and more natural dose of SARS-CoV-2 than has been employed in other NHP studies.

microbiology↗

bioRxiv2020

Filovirus infection induces an anti-inflammatory state in Rousettus bats

The Marburg and Ebola filoviruses cause a severe, often fatal, disease in humans and nonhuman primates but have only subclinical effects in bats, including Egyptian rousettes, which are a natural reservoir of Marburg virus. A fundamental question is why these viruses are highly pathogenic in humans but fail to cause disease in bats. To understand how bats resist the disease caused by filoviruses, we infected one cohort of Egyptian rousette bats with Marburg virus and another cohort with Ebola virus and harvested multiple tissues for mRNA expression analysis. While virus transcripts were found primarily in the liver, Principal component analysis (PCA) revealed coordinated changes across multiple tissues. Gene signatures in kidney and liver pointed at induction of vasodilation, reduction of coagulation and changes in the regulation of iron metabolism. Signatures of immune response detected in spleen and liver indicated a robust anti-inflammatory state signified by macrophages in the M2 state and an active T cell response. Many of the responsive genes were found to be evolutionarily divergent, providing a framework for understanding the differences in outcomes of filovirus infections between bats and humans. In this study, we outline multiple interconnected pathways that respond to infection by MARV and EBOV, providing insights into the complexity of the mechanisms that enable bats to resist the disease caused by filoviral infections. The results have the potential to aid in the development of new strategies to effectively mitigate and treat the disease caused by these viruses in humans.

microbiology↗

bioRxiv2020

Prior vaccination with the rVSV-ZEBOV vaccine does not interfere with but improves the efficacy of postexposure antibody treatment in nonhuman primates exposed to Ebola virus

A replication-competent, vesicular stomatitis virus vaccine expressing the Ebola virus (EBOV) glycoprotein (GP) (rVSV-ZEBOV) was successfully used during the 2013-16 EBOV epidemic1. Additionally, chimeric and human monoclonal antibodies (mAb) against the EBOV GP showed promise in animals and EBOV patients when administered therapeutically2-6. Given the large number of at-risk humans being prophylactically vaccinated with rVSV-ZEBOV, there is uncertainty regarding whether vaccination would preclude use of antibody treatments in the event of a known exposure of a recent vaccinee. To model a worst-case scenario, we performed a study using rhesus monkeys vaccinated or unvaccinated with the rVSV-ZEBOV vaccine. One day after vaccination, animals were challenged with a uniformly lethal dose of EBOV. Five vaccinated animals and five unvaccinated animals were then treated with the anti-EBOV GP mAb-based therapeutic MIL77 starting 3 days postexposure. Additionally, five vaccinated macaques received no therapeutic intervention. All five macaques that were vaccinated and subsequently treated with MIL77 showed no evidence of clinical illness and survived challenge. In contrast, all five animals that only received the rVSV-ZEBOV vaccine became ill and 2/5 survived; all five macaques that only received MIL77 only also became ill and 4/5 survived. Enhanced efficacy of vaccinated animals that were treated with MIL77 was associated with delayed EBOV viremia attributed to the vaccine. These results suggest that rVSV-ZEBOV augments immunotherapy.

microbiology↗

bioRxiv2018

Two-antibody pan-ebolavirus cocktail confers broad therapeutic protection in ferrets and nonhuman primates

All available experimental vaccines and immunotherapeutics1,2 against Ebola virus (EBOV), including rVSV-ZEBOV3 and ZMappTM4, lack activity against other ebolaviruses associated with human disease outbreaks. This year, two separate outbreaks of EBOV in the Democratic Republic of Congo underscored the unpredictable nature of ebolavirus reemergence in a region that has historically experienced outbreaks of the divergent ebolaviruses Sudan virus (SUDV) and Bundibugyo virus (BDBV)5. Here we show that MBP134AF, a pan-ebolavirus therapeutic comprising two broadly neutralizing human antibodies (bNAbs)6,7(see companion manuscript, Wec et al.) could protect against lethal EBOV, SUDV, and BDBV infection in ferrets and nonhuman primates (NHPs). MBP134AF not only not only establishes a viable therapeutic countermeasure to outbreaks caused by antigenically diverse ebolaviruses but also affords unprecedented effectiveness and potency--a single 25-mg/kg dose was fully protective in NHPs. This best-in-class antibody cocktail is the culmination of an intensive collaboration spanning academia, industry and government in response to the 2013-2016 EBOV epidemic6,7 and provides a translational research model for the rapid development of immunotherapeutics targeting emerging infectious diseases.

microbiology↗