scholarly journals Attenuated Replication of Lassa Virus Vaccine Candidate ML29 in STAT-1-/- Mice

Pathogens ◽  
2019 ◽  
Vol 8 (1) ◽  
pp. 9 ◽  
Author(s):  
Dylan Johnson ◽  
Jenny Jokinen ◽  
Igor Lukashevich
Keyword(s):  
Vaccine Development ◽  
Vaccine Candidate ◽  
Small Animal ◽  
Vero Cells ◽  
Lassa Fever ◽  
Effective Vaccine ◽  
Cell Mediated Immunity ◽  
Lassa Virus ◽  
Cell Responses ◽  
Fold Reduction

Lassa virus (LASV), a highly prevalent mammalian arenavirus endemic in West Africa, can cause Lassa fever (LF), which is responsible for thousands of deaths annually. LASV is transmitted to humans from naturally infected rodents. At present, there is not an effective vaccine nor treatment. The genetic diversity of LASV is the greatest challenge for vaccine development. The reassortant ML29 carrying the L segment from the nonpathogenic Mopeia virus (MOPV) and the S segment from LASV is a vaccine candidate under current development. ML29 demonstrated complete protection in validated animal models against a Nigerian strain from clade II, which was responsible for the worst outbreak on record in 2018. This study demonstrated that ML29 was more attenuated than MOPV in STAT1-/- mice, a small animal model of human LF and its sequelae. ML29 infection of these mice resulted in more than a thousand-fold reduction in viremia and viral load in tissues and strong LASV-specific adaptive T cell responses compared to MOPV-infected mice. Persistent infection of Vero cells with ML29 resulted in generation of interfering particles (IPs), which strongly interfered with the replication of LASV, MOPV and LCMV, the prototype of the Arenaviridae. ML29 IPs induced potent cell-mediated immunity and were fully attenuated in STAT1-/- mice. Formulation of ML29 with IPs will improve the breadth of the host’s immune responses and further contribute to development of a pan-LASV vaccine with full coverage meeting the WHO requirements.

scholarly journals Pichinde Virus Infection of Outbred Hartley Guinea Pigs as a Surrogate Animal Model for Human Lassa Fever: Histopathological and Immunohistochemical Analyses

Pathogens ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 579 ◽  
Author(s):  
Wun-Ju Shieh ◽  
Shuiyun Lan ◽  
Sherif R. Zaki ◽  
Hinh Ly ◽  
Yuying Liang
Keyword(s):  
Animal Model ◽  
Surrogate Model ◽  
Guinea Pigs ◽  
Virulent Strain ◽  
Small Animal ◽  
Immunohistochemical Analysis ◽  
Lassa Fever ◽  
Lassa Virus ◽  
Pichinde Virus ◽  
Guinea Pig Model

Lassa virus (LASV) is a mammarenavirus (arenavirus) that causes zoonotic infection in humans that can lead to fatal hemorrhagic Lassa fever (LF) disease. Currently, there are no FDA-approved vaccines or therapeutics against LASV. Development of treatments against LF and other related arenavirus-induced hemorrhagic fevers (AHFs) requires relevant animal models that can recapitulate clinical and pathological features of AHF diseases in humans. Laboratory mice are generally resistant to LASV infection, and non-human primates, while being a good animal model for LF, are limited by their high cost. Here, we describe a small, affordable, and convenient animal model that is based on outbred Hartley guinea pigs infected with Pichinde virus (PICV), a mammarenavirus that is non-pathogenic in humans, for use as a surrogate model of human LF. We conducted a detailed analysis of tissue histopathology and immunohistochemical analysis of different organs of outbred Hartley guinea pigs infected with different PICV strains that show differential disease phenotypes and pathologies. Comparing to infection with the avirulent PICV strain (P2 or rP2), animals infected with the virulent strain (P18 or rP18) show extensive pathological changes in different organs that sustain high levels of virus replication. The similarity of tissue pathology and viral antigen distribution between the virulent PICV–guinea pig model and lethal human LASV infection supports a role of this small animal model as a surrogate model of studying human LF in order to understand its pathogenesis and for evaluating potential preventative and therapeutic options against AHFs.

scholarly journals Identification of Common CD8+ T Cell Epitopes from Lassa Fever Survivors in Nigeria and Sierra Leone

2020 ◽  
Vol 94 (12) ◽  
Author(s):  
Saori Sakabe ◽  
Jessica N. Hartnett ◽  
Nhi Ngo ◽  
Augustine Goba ◽  
Mambu Momoh ◽  
...  
Keyword(s):  
T Cell ◽  
West Africa ◽  
Sierra Leone ◽  
T Cell Responses ◽  
Lassa Fever ◽  
Health Concern ◽  
Lassa Virus ◽  
T Cell Epitopes ◽  
Virus Surface ◽  
Cell Responses

ABSTRACT Early and robust T cell responses have been associated with survival from Lassa fever (LF), but the Lassa virus-specific memory responses have not been well characterized. Regions within the virus surface glycoprotein (GPC) and nucleoprotein (NP) are the main targets of the Lassa virus-specific T cell responses, but, to date, only a few T cell epitopes within these proteins have been identified. We identified GPC and NP regions containing T cell epitopes and HLA haplotypes from LF survivors and used predictive HLA-binding algorithms to identify putative epitopes, which were then experimentally tested using autologous survivor samples. We identified 12 CD8-positive (CD8+) T cell epitopes, including epitopes common to both Nigerian and Sierra Leonean survivors. These data should be useful for the identification of dominant Lassa virus-specific T cell responses in Lassa fever survivors and vaccinated individuals as well as for designing vaccines that elicit cell-mediated immunity. IMPORTANCE The high morbidity and mortality associated with clinical cases of Lassa fever, together with the lack of licensed vaccines and limited and partially effective interventions, make Lassa virus (LASV) an important health concern in its regions of endemicity in West Africa. Previous infection with LASV protects from disease after subsequent exposure, providing a framework for designing vaccines to elicit similar protective immunity. Multiple major lineages of LASV circulate in West Africa, and therefore, ideal vaccine candidates should elicit immunity to all lineages. We therefore sought to identify common T cell epitopes between Lassa fever survivors from Sierra Leone and Nigeria, where distinct lineages circulate. We identified three such epitopes derived from highly conserved regions within LASV proteins. In this process, we also identified nine other T cell epitopes. These data should help in the design of an effective pan-LASV vaccine.

scholarly journals A Single-Cycle Influenza A Virus-Based SARS-CoV-2 Vaccine Elicits Potent Immune Responses in a Mouse Model

Vaccines ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 850
Author(s):  
Surapong Koonpaew ◽  
Challika Kaewborisuth ◽  
Kanjana Srisutthisamphan ◽  
Asawin Wanitchang ◽  
Theeradej Thaweerattanasinp ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Immune Responses ◽  
Influenza A ◽  
Vaccine Development ◽  
Vaccine Candidate ◽  
Mdck Cells ◽  
Chimeric Gene ◽  
Cell Mediated Immunity ◽  
Single Cycle ◽  
Virus Envelope

The use of virus-vectored platforms has increasingly gained attention in vaccine development as a means for delivering antigenic genes of interest into target hosts. Here, we describe a single-cycle influenza virus-based SARS-CoV-2 vaccine designated as scPR8-RBD-M2. The vaccine utilizes the chimeric gene encoding 2A peptide-based bicistronic protein cassette of the SARS-CoV-2 receptor-binding domain (RBD) and influenza matrix 2 (M2) protein. The C-terminus of the RBD was designed to link with the cytoplasmic domain of the influenza virus hemagglutinin (HA) to anchor the RBD on the surface of producing cells and virus envelope. The chimeric RBD-M2 gene was incorporated in place of the HA open-reading frame (ORF) between the 3′ and 5′ UTR of HA gene for the virus rescue in MDCK cells stably expressing HA. The virus was also constructed with the disrupted M2 ORF in segment seven to ensure that M2 from the RBD-M2 was utilized. The chimeric gene was intact and strongly expressed in infected cells upon several passages, suggesting that the antigen was stably maintained in the vaccine candidate. Mice inoculated with scPR8-RBD-M2 via two alternative prime-boost regimens (intranasal-intranasal or intranasal-intramuscular routes) elicited robust mucosal and systemic humoral immune responses and cell-mediated immunity. Notably, we demonstrated that immunized mouse sera exhibited neutralizing activity against pseudotyped viruses bearing SARS-CoV-2 spikes from various variants, albeit with varying potency. Our study warrants further development of a replication-deficient influenza virus as a promising SARS-CoV-2 vaccine candidate.

scholarly journals Immunogenicity of low dose prime-boost vaccination of mRNA vaccine CV07050101 in non-human primates

2021 ◽  
Author(s):  
Neeltje van Doremalen ◽  
Robert Fischer ◽  
Jonathan Schulz ◽  
Myndi Holbrook ◽  
Brian Smith ◽  
...  
Keyword(s):  
Immune Responses ◽  
Neutralizing Antibodies ◽  
Vaccine Candidate ◽  
Small Animal ◽  
S Protein ◽  
Cell Responses ◽  
Cellular Immune Responses ◽  
Boost Vaccination ◽  
Human Volunteers ◽  
Cellular Immune

Many different vaccine candidates against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the etiological agent of COVID-19, are currently approved and under development. Vaccine platforms vary from mRNA vaccines to viral-vectored vaccines, and several candidates have been shown to produce humoral and cellular responses in small animal models, non-human primates and human volunteers. In this study, six non-human primates received a prime-boost intramuscular vaccination with 4 μg of mRNA vaccine candidate CV07050101, which encodes a pre-fusion stabilized spike (S) protein of SARS-CoV-2. Boost vaccination was performed 28 days post prime vaccination. As a control, six animals were similarly injected with PBS. Humoral and cellular immune responses were investigated at time of vaccination, and two weeks afterwards. No antibodies could be detected two and four weeks after prime vaccination. Two weeks after boost vaccination, binding but no neutralizing antibodies were detected in 4 out of 6 non-human primates. SARS-CoV-2 S protein specific T cell responses were detected in these 4 animals. In conclusion, prime-boost vaccination with 4 μg of vaccine candidate CV07050101 resulted in limited immune responses in 4 out of 6 non-human primates.

scholarly journals Protection From Lethal Lassa Disease Can Be Achieved Both Before and After Virus Exposure by Administration of Single-Cycle Replicating Lassa Virus Replicon Particles

2019 ◽  
Vol 220 (8) ◽  
pp. 1281-1289 ◽  
Author(s):  
Markus H Kainulainen ◽  
Jessica R Spengler ◽  
Stephen R Welch ◽  
JoAnn D Coleman-McCray ◽  
Jessica R Harmon ◽  
...  
Keyword(s):  
Vaccine Candidate ◽  
Lassa Fever ◽  
Stable Cell Line ◽  
Lassa Virus ◽  
Single Cycle ◽  
Before And After ◽  
Chronic Morbidity ◽  
Virus Exposure ◽  
High Yields ◽  
Guinea Pig Model

AbstractLassa fever is a frequently severe human disease that is endemic to several countries in West Africa. To date, no licensed vaccines are available to prevent Lassa virus (LASV) infection, even though Lassa fever is thought to be an important disease contributing to mortality and both acute and chronic morbidity. We have previously described a vaccine candidate composed of single-cycle LASV replicon particles (VRPs) and a stable cell line for their production. Here, we refine the genetic composition of the VRPs and demonstrate the ability to reproducibly purify them with high yields. Studies in the guinea pig model confirm efficacy of the vaccine candidate, demonstrate that single-cycle replication is necessary for complete protection by the VRP vaccine, and show that postexposure vaccination can confer protection from lethal outcome.

scholarly journals A Lassa Virus Live-Attenuated Vaccine Candidate Based on Rearrangement of the Intergenic Region

mBio ◽  
2020 ◽  
Vol 11 (2) ◽  
Author(s):  
Yingyun Cai ◽  
Masaharu Iwasaki ◽  
Daisuke Motooka ◽  
David X. Liu ◽  
Shuiqing Yu ◽  
...  
Keyword(s):  
Intergenic Region ◽  
Guinea Pigs ◽  
Cultured Cells ◽  
Vaccine Candidate ◽  
Lassa Fever ◽  
Lassa Virus ◽  
Wild Type ◽  
Live Attenuated Vaccine ◽  
Attenuated Vaccine ◽  
Western Africa

ABSTRACT Lassa virus (LASV) poses a significant public health problem within the regions of Lassa fever endemicity in Western Africa. LASV infects several hundred thousand individuals yearly, and a considerable number of Lassa fever cases are associated with high morbidity and lethality. No approved LASV vaccine is available, and current therapy is limited to an off-label usage of ribavirin that is only partially effective and associated with significant side effects. The impact of Lassa fever on human health, together with the limited existing countermeasures, highlights the importance of developing effective vaccines against LASV. Here, we present the development and characterization of a recombinant LASV (rLASV) vaccine candidate [rLASV(IGR/S-S)], which is based on the presence of the noncoding intergenic region (IGR) of the small (S) genome segment (S-IGR) in both large (L) and S LASV segments. In cultured cells, rLASV(IGR/S-S) was modestly less fit than wild-type rLASV (rLASV-WT). rLASV(IGR/S-S) was highly attenuated in guinea pigs, and a single subcutaneous low dose of the virus completely protected against otherwise lethal infection with LASV-WT. Moreover, rLASV(IGR/S-S) was genetically stable during serial passages in cultured cells. These findings indicate that rLASV(IGR/S-S) can be developed into a LASV live-attenuated vaccine (LAV) that has the same antigenic composition as LASV-WT and a well-defined mechanism of attenuation that overcomes concerns about increased virulence that could be caused by genetic changes in the LAV during multiple rounds of multiplication. IMPORTANCE Lassa virus (LASV), the causative agent of Lassa fever, infects several hundred thousand people in Western Africa, resulting in many lethal Lassa fever cases. No U.S. Food and Drug Administration-licensed countermeasures are available to prevent or treat LASV infection. We describe the generation of a novel LASV live-attenuated vaccine candidate rLASV(IGR/S-S), which is based on the replacement of the large genomic segment noncoding intergenic region (IGR) with that of the small genome segment. rLASV(IGR/S-S) is less fit in cell culture than wild-type virus and does not cause clinical signs in inoculated guinea pigs. Importantly, rLASV(IGR/S-S) protects immunized guinea pigs against an otherwise lethal exposure to LASV.

scholarly journals Systemic viral spreading and defective host responses are associated with fatal Lassa fever in macaques

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Nicolas Baillet ◽  
Stéphanie Reynard ◽  
Emeline Perthame ◽  
Jimmy Hortion ◽  
Alexandra Journeaux ◽  
...  
Keyword(s):  
T Cell ◽  
Multiorgan Failure ◽  
Severe Disease ◽  
T Cell Responses ◽  
Hemorrhagic Fever ◽  
Lassa Fever ◽  
Diagnostic Tools ◽  
Lassa Virus ◽  
Full Characterization ◽  
Cell Responses

AbstractLassa virus (LASV) is endemic in West Africa and induces a viral hemorrhagic fever (VHF) with up to 30% lethality among clinical cases. The mechanisms involved in control of Lassa fever or, in contrast, the ensuing catastrophic illness and death are poorly understood. We used the cynomolgus monkey model to reproduce the human disease with asymptomatic to mild or fatal disease. After initial replication at the inoculation site, LASV reached the secondary lymphoid organs. LASV did not spread further in nonfatal disease and was rapidly controlled by balanced innate and T-cell responses. Systemic viral dissemination occurred during severe disease. Massive replication, a cytokine/chemokine storm, defective T-cell responses, and multiorgan failure were observed. Clinical, biological, immunological, and transcriptomic parameters resembled those observed during septic-shock syndrome, suggesting that similar pathogenesis is induced during Lassa fever. The outcome appears to be determined early, as differentially expressed genes in PBMCs were associated with fatal and non-fatal Lassa fever outcome very early after infection. These results provide a full characterization and important insights into Lassa fever pathogenesis and could help to develop early diagnostic tools.

scholarly journals Lassa Virus Vaccine Candidate ML29 Generates Truncated Viral RNAs Which Contribute to Interfering Activity and Attenuation

Viruses ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 214
Author(s):  
Dylan M. Johnson ◽  
Beatrice Cubitt ◽  
Tia L. Pfeffer ◽  
Juan Carlos de la Torre ◽  
Igor S. Lukashevich
Keyword(s):  
Matrix Protein ◽  
Fluorescent Protein ◽  
Vaccine Candidate ◽  
Small Animal ◽  
Lymphocytic Choriomeningitis ◽  
Lassa Virus ◽  
Defective Interfering Particles ◽  
Persistently Infected ◽  
Viral Genomes ◽  
Infected Cells

Defective interfering particles (DIPs) are naturally occurring products during virus replication in infected cells. DIPs contain defective viral genomes (DVGs) and interfere with replication and propagation of their corresponding standard viral genomes by competing for viral and cellular resources, as well as promoting innate immune antiviral responses. Consequently, for many different viruses, including mammarenaviruses, DIPs play key roles in the outcome of infection. Due to their ability to broadly interfere with viral replication, DIPs are attractive tools for the development of a new generation of biologics to target genetically diverse and rapidly evolving viruses. Here, we provide evidence that in cells infected with the Lassa fever (LF) vaccine candidate ML29, a reassortant that carries the nucleoprotein (NP) and glycoprotein (GP) dominant antigens of the pathogenic Lassa virus (LASV) together with the L polymerase and Z matrix protein of the non-pathogenic genetically related Mopeia virus (MOPV), L-derived truncated RNA species are readily detected following infection at low multiplicity of infection (MOI) or in persistently-infected cells originally infected at high MOI. In the present study, we show that expression of green fluorescent protein (GFP) driven by a tri-segmented form of the mammarenavirus lymphocytic choriomeningitis virus (r3LCMV-GFP/GFP) was strongly inhibited in ML29-persistently infected cells, and that the magnitude of GFP suppression was dependent on the passage history of the ML29-persistently infected cells. In addition, we found that DIP-enriched ML29 was highly attenuated in immunocompetent CBA/J mice and in Hartley guinea pigs. Likewise, STAT-1-/- mice, a validated small animal model for human LF associated hearing loss sequelae, infected with DIP-enriched ML29 did not exhibit any hearing abnormalities throughout the observation period (62 days).

scholarly journals An mRNA vaccine against SARS-CoV-2: Lyophilized, liposome-based vaccine candidate EG-COVID induces high levels of virus neutralizing antibodies

2021 ◽  
Author(s):  
H. Christian Hong ◽  
Kwang Sung Kim ◽  
Shin Ae Park ◽  
Min Jeong Chun ◽  
Eun Young Hong ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Vaccine Candidate ◽  
Vero Cells ◽  
Vaccine Platform ◽  
New Era ◽  
European Variant ◽  
Cellular Immune ◽  
And Storage

AbstractIn addition to the traditional method of vaccine development, the mRNA coronavirus vaccine, which is attractive as a challenging vaccination, recently opened a new era in vaccinology. Here we describe the EG-COVID which is a novel liposome-based mRNA candidate vaccine that encodes the spike (S) protein of SARS-CoV-2 with 2P-3Q substitution in European variant. We developed the mRNA vaccine platform that can be lyophilized using liposome-based technology. Intramuscular injection of the EG-COVID elicited robust humoral and cellular immune response to SARS-CoV-2. Furthermore, sera obtained from mice successfully inhibited SARS-CoV-2 viral infection into Vero cells. We developed EG-COVID and found it to be effective based on in vitro data, and we plan to initiate a clinical trial soon. Since EG-COVID is a lyophilized mRNA vaccine that is convenient for transportation and storage, accessibility to vaccines will be significantly improved.

scholarly journals A prefusion SARS-CoV-2 spike RNA vaccine is highly immunogenic and prevents lung infection in non-human primates

2020 ◽  
Author(s):  
Annette B. Vogel ◽  
Isis Kanevsky ◽  
Ye Che ◽  
Kena A. Swanson ◽  
Alexander Muik ◽  
...  
Keyword(s):  
Vaccine Candidate ◽  
Rhesus Macaques ◽  
Geometric Mean ◽  
Effective Vaccine ◽  
Phase 2 ◽  
Preclinical Development ◽  
Pivotal Phase ◽  
Cell Responses ◽  
Large Populations ◽  
The One

AbstractTo contain the coronavirus disease 2019 (COVID-19) pandemic, a safe and effective vaccine against the new severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is urgently needed in quantities sufficient to immunise large populations. In this study, we report the design, preclinical development, immunogenicity and anti-viral protective effect in rhesus macaques of the BNT162b2 vaccine candidate. BNT162b2 contains an LNP-formulated nucleoside-modified mRNA that encodes the spike glycoprotein captured in its prefusion conformation. After expression of the BNT162b2 coding sequence in cells, approximately 20% of the spike molecules are in the one-RBD ‘up’, two-RBD ‘down’ state. Immunisation of mice with a single dose of BNT162b2 induced dose level-dependent increases in pseudovirus neutralisation titers. Prime-boost vaccination of rhesus macaques elicited authentic SARS-CoV-2 neutralising geometric mean titers 10.2 to 18.0 times that of a SARS-CoV-2 convalescent human serum panel. BNT162b2 generated strong TH1 type CD4+ and IFNγ+ CD8+ T-cell responses in mice and rhesus macaques. The BNT162b2 vaccine candidate fully protected the lungs of immunised rhesus macaques from infectious SARS-CoV-2 challenge. BNT162b2 is currently being evaluated in a global, pivotal Phase 2/3 trial (NCT04368728).

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