Safe and effective two-in-one replicon-and-VLP minispike vaccine for COVID-19

SummaryThe large SARS-CoV-2 spike (S) protein is the main target of current COVID-19 vaccine candidates but can induce non-neutralizing antibodies, which may cause vaccination-induced complications or enhancement of COVID-19 disease. Besides, encoding of a functional S in replication-competent virus vector vaccines may result in the emergence of viruses with altered or expanded tropism. Here, we have developed a safe single round rhabdovirus replicon vaccine platform for enhanced presentation of the S receptor-binding domain (RBD). Structure-guided design was employed to build a chimeric minispike comprising the globular RBD linked to a transmembrane stem-anchor sequence derived from rabies virus (RABV) glycoprotein (G). Vesicular stomatitis virus (VSV) and RABV replicons encoding the minispike not only allowed expression of the antigen at the cell surface but also incorporation into the envelope of secreted non-infectious particles, thus combining classic vector-driven antigen expression and particulate virus-like particle (VLP) presentation. A single dose of a prototype replicon vaccine, VSVΔG-minispike-eGFP (G), stimulated high titers of SARS-CoV-2 neutralizing antibodies in mice, equivalent to those found in COVID-19 patients. Boost immunization with the identical replicon further enhanced neutralizing activity. These results demonstrate that rhabdovirus minispike replicons represent effective and safe alternatives to vaccination approaches using replication-competent viruses and/or the entire S antigen.HighlightsSARS-CoV-2 S RBD antigen is preferred over entire S to preclude potential disease enhancing antibodiesconstruction of a chimeric rhabdovirus minispike protein presenting RBD in native conformationconstruction of single round VSV and rabies virus replicon vaccinespresentation of minispike antigen on cells and on noninfectious VLPsstrong induction of SARS-CoV-2 neutralizing antibodies by the VSV replicon/VLP system in vaccinated mice

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Safe and effective two-in-one replicon-and-VLP minispike vaccine for COVID-19: Protection of mice after a single immunization

PLoS Pathogens ◽

10.1371/journal.ppat.1009064 ◽

2021 ◽

Vol 17 (4) ◽

pp. e1009064

Author(s):

Alexandru A. Hennrich ◽

Bevan Sawatsky ◽

Rosalía Santos-Mandujano ◽

Dominic H. Banda ◽

Martina Oberhuber ◽

...

Keyword(s):

Neutralizing Antibodies ◽

Antigen Expression ◽

Vaccine Platform ◽

Dna And Rna ◽

Glycoprotein G ◽

Virus Like Particle ◽

Main Target ◽

Boost Immunization ◽

Vesicular Stomatitis ◽

Anchor Sequence

Vaccines of outstanding efficiency, safety, and public acceptance are needed to halt the current SARS-CoV-2 pandemic. Concerns include potential side effects caused by the antigen itself and safety of viral DNA and RNA delivery vectors. The large SARS-CoV-2 spike (S) protein is the main target of current COVID-19 vaccine candidates but can induce non-neutralizing antibodies, which might cause vaccination-induced complications or enhancement of COVID-19 disease. Besides, encoding of a functional S in replication-competent virus vector vaccines may result in the emergence of viruses with altered or expanded tropism. Here, we have developed a safe single round rhabdovirus replicon vaccine platform for enhanced presentation of the S receptor-binding domain (RBD). Structure-guided design was employed to build a chimeric minispike comprising the globular RBD linked to a transmembrane stem-anchor sequence derived from rabies virus (RABV) glycoprotein (G). Vesicular stomatitis virus (VSV) and RABV replicons encoding the minispike not only allowed expression of the antigen at the cell surface but also incorporation into the envelope of secreted non-infectious particles, thus combining classic vector-driven antigen expression and particulate virus-like particle (VLP) presentation. A single dose of a prototype replicon vaccine complemented with VSV G, VSVΔG-minispike-eGFP (G), stimulated high titers of SARS-CoV-2 neutralizing antibodies in mice, equivalent to those found in COVID-19 patients, and protected transgenic K18-hACE2 mice from COVID-19-like disease. Homologous boost immunization further enhanced virus neutralizing activity. The results demonstrate that non-spreading rhabdovirus RNA replicons expressing minispike proteins represent effective and safe alternatives to vaccination approaches using replication-competent viruses and/or the entire S antigen.

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Safety, Immunogenicity and Efficacy of a Recombinant Vesicular Stomatitis Virus Vectored Vaccine Against Severe Fever with Thrombocytopenia Syndrome and Heartland Bandaviruses

10.1101/2021.11.29.470508 ◽

2021 ◽

Author(s):

Phillip Hicks ◽

Jonna B. Westover ◽

Tomaz B Manzoni ◽

Brianne Roper ◽

Gabrielle L Rock ◽

...

Keyword(s):

Vesicular Stomatitis Virus ◽

Neutralizing Antibodies ◽

Genetic Manipulation ◽

Case Fatality ◽

Vaccine Platform ◽

Vesicular Stomatitis ◽

Immunocompetent Mice ◽

Vectored Vaccine ◽

Severe Fever ◽

Promising Vaccine Candidate

Severe fever with thrombocytopenia syndrome virus (SFTSV) is a recently emerged tickborne virus in east Asia with over 8,000 confirmed cases. With a high case fatality ratio, SFTSV has been designated a high priority pathogen by the WHO and the NIAID. Despite this, there are currently no approved therapies or vaccines to treat or prevent SFTS. Vesicular stomatitis virus (VSV) represents an FDA-approved vaccine platform that has been considered for numerous viruses due to its low sero-prevalence in humans, ease in genetic manipulation and promiscuity in incorporating foreign glycoproteins into its virions. In this study, we developed a recombinant VSV (rVSV) expressing the SFTSV glycoproteins Gn/Gc (rVSV-SFTSV) and assessed its safety, immunogenicity and efficacy in mice. We demonstrate that rVSV-SFTSV is safe when given to immunocompromised animals and is not neuropathogenic when injected intracranially into young immunocompetent mice. Immunization of Ifnar-/- mice with rVSV-SFTSV resulted in high levels of neutralizing antibodies and protection against lethal SFTSV challenge. Additionally, passive transfer of sera from immunized IFNAR-/- mice into naïve animals was protective when given pre- or post-exposure. Finally, we demonstrate that immunization with rVSV-SFTSV cross protects mice against challenge with the closely related Heartland virus despite low neutralizing titers to the virus. Taken together, these data suggest that rVSV-SFTSV is a promising vaccine candidate.

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Deficient Incorporation of Rabies Virus Glycoprotein into Virions Enhances Virus-Induced Immune Evasion and Viral Pathogenicity

Viruses ◽

10.3390/v11030218 ◽

2019 ◽

Vol 11 (3) ◽

pp. 218 ◽

Cited By ~ 2

Author(s):

Chunfu Li ◽

Hongliang Zhang ◽

Lina Ji ◽

Xiao Wang ◽

Yongjun Wen ◽

...

Keyword(s):

Immune Response ◽

Rabies Virus ◽

Recombinant Virus ◽

Neutralizing Antibodies ◽

Single Copy ◽

Wild Type ◽

Antiviral Immune Response ◽

Glycoprotein G ◽

Lethal Infection ◽

Infected Cells

Previous studies have shown that wild-type (wt) rabies virus (RABV) evades the host immune response by restricting expression of glycoprotein (G), which blocks activation of dendritic cells (DCs) and induces production of virus-neutralizing antibodies (VNAs). In the present study, wt RABVs not only restricted G expression but also reduced incorporation of G into mature virions compared with laboratory-adapted viruses. A recombinant RABV expressing triple G was used to further determine whether G expression relates to incorporation. The recombinant virus showed higher expression and incorporation of G and activated more DCs than the virus that expressed a single copy of G. Removal of G from viruses using subtilisin or Dithiothreitol (DTT)/ Nonidet P-40 (NP40) almost completely abolishes DC activation and VNA production. Consequently, these G-depleted viruses cause lethal infection in mice. Thus, wt RABVs can subvert DC-induced antiviral immune response and maintain pathogenicity by decreasing G expression in infected cells and G incorporation into virions.

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Virus-Like Particle Based Vaccines Elicit Neutralizing Antibodies against the HIV-1 Fusion Peptide

Vaccines ◽

10.3390/vaccines8040765 ◽

2020 ◽

Vol 8 (4) ◽

pp. 765

Author(s):

Alemu Tekewe Mogus ◽

Lihong Liu ◽

Manxue Jia ◽

Diane T. Ajayi ◽

Kai Xu ◽

...

Keyword(s):

Neutralizing Antibodies ◽

Vaccination Strategy ◽

Fusion Peptide ◽

Linear Epitope ◽

Broadly Neutralizing Antibodies ◽

Virus Like Particle ◽

Boost Immunization ◽

Potential Vaccine ◽

Hiv Envelope ◽

Hiv 1

Broadly neutralizing antibodies (bnAbs) isolated from HIV-infected individuals delineate vulnerable sites on the HIV envelope glycoprotein that are potential vaccine targets. A linear epitope within the N-terminal region of the HIV-1 fusion peptide (FP8) is the primary target of VRC34.01, a bnAb that neutralizes ~50% of primary HIV isolates. FP8 has attracted attention as a potential HIV vaccine target because it is a simple linear epitope. Here, platform technologies based on RNA bacteriophage virus-like particles (VLPs) were used to develop multivalent vaccines targeting the FP8 epitope. Both recombinant MS2 VLPs displaying the FP8 peptide and Qβ VLPs displaying chemically conjugated FP8 peptide induced high titers of FP8-specific antibodies in mice. Moreover, a heterologous prime-boost-boost regimen employing the two FP8-VLP vaccines and native envelope trimer was the most effective approach for eliciting HIV-1 neutralizing antibodies. Given the potent immunogenicity of VLP-based vaccines, this vaccination strategy—inspired by bnAb-guided epitope mapping, VLP bioengineering, and prime-boost immunization approaches—may be a useful strategy for eliciting bnAb responses against HIV.

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A Mycobacteriophage-Based Vaccine Platform: SARS-CoV-2 Antigen Expression and Display

Microorganisms ◽

10.3390/microorganisms9122414 ◽

2021 ◽

Vol 9 (12) ◽

pp. 2414

Author(s):

Krista G. Freeman ◽

Katherine S. Wetzel ◽

Yu Zhang ◽

Kira M. Zack ◽

Deborah Jacobs-Sera ◽

...

Keyword(s):

Single Particle ◽

High Purity ◽

Neutralizing Antibodies ◽

Vaccine Development ◽

Antigen Expression ◽

Spike Protein ◽

Infectious Agents ◽

Protein Antigens ◽

Vaccine Platform ◽

Excellent Safety Profile

The explosion of SARS-CoV-2 infections in 2020 prompted a flurry of activity in vaccine development and exploration of various vaccine platforms, some well-established and some new. Phage-based vaccines were described previously, and we explored the possibility of using mycobacteriophages as a platform for displaying antigens of SARS-CoV-2 or other infectious agents. The potential advantages of using mycobacteriophages are that a large and diverse variety of them have been described and genomically characterized, engineering tools are available, and there is the capacity to display up to 700 antigen copies on a single particle approximately 100 nm in size. The phage body may itself be a good adjuvant, and the phages can be propagated easily, cheaply, and to high purity. Furthermore, the recent use of these phages therapeutically, including by intravenous administration, suggests an excellent safety profile, although efficacy can be restricted by neutralizing antibodies. We describe here the potent immunogenicity of mycobacteriophage Bxb1, and Bxb1 recombinants displaying SARS-CoV-2 Spike protein antigens.

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RSV Vaccine Based on Rhabdoviral Vector Protects after Single Immunization

Vaccines ◽

10.3390/vaccines7030059 ◽

2019 ◽

Vol 7 (3) ◽

pp. 59 ◽

Cited By ~ 2

Author(s):

Wilmschen ◽

Schneider ◽

Peters ◽

Bayer ◽

Issmail ◽

...

Keyword(s):

Neutralizing Antibodies ◽

Lymphocytic Choriomeningitis ◽

Effective Vaccine ◽

Vector Vaccine ◽

Viral Loads ◽

Glycoprotein G ◽

Infected Cells ◽

Vesicular Stomatitis ◽

Syncytial Virus ◽

Tract Infections

The respiratory syncytial virus (RSV) is one major cause of lower respiratory tract infections in childhood and an effective vaccine is still not available. We previously described a new rhabdoviral vector vaccine, VSV-GP, a variant of the vesicular stomatitis virus (VSV), where the VSV glycoprotein G is exchanged by the glycoprotein GP of the lymphocytic choriomeningitis virus. Here, we evaluated VSV-GP as vaccine vector for RSV with the aim to induce RSV neutralizing antibodies. Wild-type F (Fwt) or a codon optimized version (Fsyn) were introduced at position 5 into the VSV-GP genome. Both F versions were efficiently expressed in VSV-GP-F infected cells and incorporated into VSV-GP particles. In mice, high titers of RSV neutralizing antibodies were induced already after prime and subsequently boosted by a second immunization. After challenge with RSV, viral loads in the lungs of immunized mice were reduced by 2–3 logs with no signs of an enhanced disease induced by the vaccination. Even a single intranasal immunization significantly reduced viral load by a factor of more than 100-fold. RSV neutralizing antibodies were long lasting and mice were still protected when challenged 20 weeks after the boost. Therefore, VSV-GP is a promising candidate for an effective RSV vaccine.

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Immunogenicity Study of Glycoprotein-Deficient Rabies Virus Expressing Simian/Human Immunodeficiency Virus SHIV89.6P Envelope in a Rhesus Macaque

Journal of Virology ◽

10.1128/jvi.78.24.13455-13459.2004 ◽

2004 ◽

Vol 78 (24) ◽

pp. 13455-13459 ◽

Cited By ~ 12

Author(s):

Philip M. McKenna ◽

Pyone Pyone Aye ◽

Bernhard Dietzschold ◽

David C. Montefiori ◽

Louis N. Martin ◽

...

Keyword(s):

Human Immunodeficiency Virus ◽

Rhesus Macaque ◽

Rabies Virus ◽

Neutralizing Antibodies ◽

Transmembrane Domain ◽

Cell Loss ◽

Glycoprotein G ◽

Immunodeficiency Virus ◽

Hiv 1

ABSTRACT Rabies virus (RV) has recently been developed as a novel vaccine candidate for human immunodeficiency virus type 1 (HIV-1). The RV glycoprotein (G) can be functionally replaced by HIV-1 envelope glycoprotein (Env) if the gp160 cytoplasmic domain (CD) of HIV-1 Env is replaced by that of RV G. Here, we describe a pilot study of the in vivo replication and immunogenicity of an RV with a deletion of G (ΔG) expressing a simian/human immunodeficiency virus SHIV89.6P Env ectodomain and transmembrane domain fused to the RV G CD (ΔG-89.6P-RVG) in a rhesus macaque. An animal vaccinated with ΔG-89.6P-RVG developed SHIV89.6P virus-neutralizing antibodies and SHIV89.6P-specific cellular immune responses after challenge with SHIV89.6P. There was no evidence of CD4+ T-cell loss, and plasma viremia was controlled to undetectable levels by 6 weeks postchallenge and has remained suppressed out to 22 weeks postchallenge.

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Glycoprotein B switches conformation during murid herpesvirus 4 entry

Journal of General Virology ◽

10.1099/vir.0.83519-0 ◽

2008 ◽

Vol 89 (6) ◽

pp. 1352-1363 ◽

Cited By ~ 27

Author(s):

Laurent Gillet ◽

Susanna Colaco ◽

Philip G. Stevenson

Keyword(s):

Neutralizing Antibodies ◽

Structural Changes ◽

Glycoprotein B ◽

Cell Binding ◽

Glycoprotein G ◽

Late Endosomes ◽

Endosomal Acidification ◽

Infected Cells ◽

Vesicular Stomatitis ◽

Herpesvirus 4

Herpesviruses are ancient pathogens that infect all vertebrates. The most conserved component of their entry machinery is glycoprotein B (gB), yet how gB functions is unclear. A striking feature of the murid herpesvirus 4 (MuHV-4) gB is its resistance to neutralization. Here, we show by direct visualization of infected cells that the MuHV-4 gB changes its conformation between extracellular virions and those in late endosomes, where capsids are released. Specifically, epitopes on its N-terminal cell-binding domain become inaccessible, whilst non-N-terminal epitopes are revealed, consistent with structural changes reported for the vesicular stomatitis virus glycoprotein G. Inhibitors of endosomal acidification blocked the gB conformation switch. They also blocked capsid release and the establishment of infection, implying that the gB switch is a key step in entry. Neutralizing antibodies could only partially inhibit the switch. Their need to engage a less vulnerable, upstream form of gB, because its fusion form is revealed only in endosomes, helps to explain why gB-directed MuHV-4 neutralization is so difficult.

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A vesicular stomatitis virus-based prime-boost vaccination strategy induces potent and protective neutralizing antibodies against SARS-CoV-2

PLoS Pathogens ◽

10.1371/journal.ppat.1010092 ◽

2021 ◽

Vol 17 (12) ◽

pp. e1010092

Author(s):

Gyoung Nyoun Kim ◽

Jung-ah Choi ◽

Kunyu Wu ◽

Nasrin Saeedian ◽

Eunji Yang ◽

...

Keyword(s):

Vesicular Stomatitis Virus ◽

Neutralizing Antibodies ◽

Transmembrane Domain ◽

Vaccination Strategy ◽

Protein S ◽

Full Length ◽

Cell Responses ◽

Boost Immunization ◽

Vesicular Stomatitis ◽

Protein Incorporation

The development of safe and effective vaccines to prevent SARS-CoV-2 infections remains an urgent priority worldwide. We have used a recombinant vesicular stomatitis virus (rVSV)-based prime-boost immunization strategy to develop an effective COVID-19 vaccine candidate. We have constructed VSV genomes carrying exogenous genes resulting in the production of avirulent rVSV carrying the full-length spike protein (SF), the S1 subunit, or the receptor-binding domain (RBD) plus envelope (E) protein of SARS-CoV-2. Adding the honeybee melittin signal peptide (msp) to the N-terminus enhanced the protein expression, and adding the VSV G protein transmembrane domain and the cytoplasmic tail (Gtc) enhanced protein incorporation into pseudotype VSV. All rVSVs expressed three different forms of SARS-CoV-2 spike proteins, but chimeras with VSV-Gtc demonstrated the highest rVSV-associated expression. In immunized mice, rVSV with chimeric S protein-Gtc derivatives induced the highest level of potent neutralizing antibodies and T cell responses, and rVSV harboring the full-length msp-SF-Gtc proved to be the superior immunogen. More importantly, rVSV-msp-SF-Gtc vaccinated animals were completely protected from a subsequent SARS-CoV-2 challenge. Overall, we have developed an efficient strategy to induce a protective response in SARS-CoV-2 challenged immunized mice. Vaccination with our rVSV-based vector may be an effective solution in the global fight against COVID-19.

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Rabies virus-based COVID-19 vaccine CORAVAX™ induces high levels of neutralizing antibodies against SARS-CoV-2

npj Vaccines ◽

10.1038/s41541-020-00248-6 ◽

2020 ◽

Vol 5 (1) ◽

Cited By ~ 1

Author(s):

Drishya Kurup ◽

Christoph Wirblich ◽

Holly Ramage ◽

Matthias J. Schnell

Keyword(s):

Global Health ◽

Infectious Diseases ◽

Rabies Virus ◽

Causative Agent ◽

Neutralizing Antibodies ◽

Rapid Development ◽

Emerging Infectious Diseases ◽

Vaccine Platform ◽

The World ◽

Further Development

Abstract The recently emerged coronavirus SARS-CoV-2, the causative agent of COVID-19, is rapidly spreading in the world. The exponentially expanding threat of SARS-CoV-2 to global health highlights the urgent need for a vaccine. Herein we show the rapid development of a novel, highly efficient, and safe COVID-19 vaccine using a rabies virus-based vector that has proven to be an efficient vaccine against several emerging infectious diseases. This study reports that both a live and an inactivated rabies virus containing the SARS-CoV-2 spike S1 protein induces potent virus-neutralizing antibodies at much higher levels than seen in the sera of convalescent patients. In summary, the results provided here warrant further development of this safe and established vaccine platform against COVID-19.

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