Patent Application
20230414745
The present invention refers to a recombinant influenza virus encoding a fusion protein comprising a truncated NS1 protein and a SARS-CoV receptor binding domain and its use for prophylactic treatment, a pharmaceutical preparation comprising said virus for use in prime boost vaccination and a two-component vaccine for prime boost vaccination.
The emergence of newly identified viruses highlights the need for the development of novel antiviral strategies. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a newly emerged coronavirus which causes a severe acute respiratory disease, COVID-19. COVID-19 first appeared in Wuhan, a city in China, in December 2019. SARS-CoV is an animal virus, perhaps bats are the reservoir of the virus, which spread to other animals including humans. The transmission of SARS-CoV is primarily from human to human. These viruses generally target the respiratory system of a patient and lead to influenza-like symptoms.
As of Oct. 30, 2020, the World Health Organization has reported about 45 million confirmed cases worldwide, resulting in 1.18 million deaths.
Symptoms of COVID-19 can range from mild-illness to pneumonia, renal dysfunction, respiratory and multi-organ failure. Unlike the previous SARS-CoV, COVID-19 has proved to be more lethal. Patients infected with COVID-19 rely on their natural immunity and generally seek supportive care to help relieve symptoms. In severe cases, treatment involves mechanical ventilation and vital organ function support.
Thus far, there has been no vaccine or therapeutic agent to prevent or successfully treat SARS-CoV-2 infection. In view of the continuing threat to human health, there is an urgent need for preventive and therapeutic antiviral therapies for SARS-CoV-2 control.
Thus, there is a need for a composition for the prevention of SARS-CoV infections and their associated complications.
It is the objective of the present invention to provide a composition for preventing SARS-CoV infections.
The objective is solved by the subject matter of the present invention.
The present invention discloses a recombinant influenza virus comprising a modified NS segment, encoding
Specifically, the present invention provides an isolated fusion protein comprising from its N to C-terminus
Specifically, the SARS-CoV receptor binding domain is SARS-CoV-2 receptor binding domain.
Specifically, the recombinant influenza virus encoding the fusion protein and NS2 protein (NS1-SARS-CoV-2RBD/NS2) is a live attenuated influenza virus. Influenza virus attenuated live vaccines based on reverse genetics technology of influenza virus have been shown to be safe and effective, also when expressing foreign genes. However, life attenuated influenza virus expressing SARS-CoV2 RBD as part of a fusion protein has not been reported. Major obstacles in this connection are lack of stability of the chimeric NS1 gene, insufficient expression of the inserted antigen and that replication of the chimeric virus is affected by the chimeric NS1 gene. Said obstacles are overcome by the present invention.
Specifically, the recombinant influenza virus is an influenza B virus, specifically a human influenza B virus.
Vaccine candidates against SARS-CoV-2 based on the RBD are under development, however, in contrast to all other approaches, expression of the RBD by an influenza virus would permit to immunize and protect against influenza and Covid-19 at the same time. Moreover, intranasal application would allow to induce mucosal immunity with the potential to block and eliminate the virus directly at the site of entry of the virus. Thus induction of sterilizing immunity would be feasible. In contrast to other approaches which usually do not provide mucosal immunity, this immunization route has the potential not only to protect from disease but also from infection. The expression of the RBD is achieved by influenza viruses, specifically influenza B viruses, which grow to high titers in tissue culture, an important prerequisite for industrial production of viral vaccine vectors.
According to an embodiment of the invention, the truncated NS1 protein comprises its N-terminal 10 to 18 amino acids, specifically the NS1 protein comprises up to 16 amino acids.
According to an embodiment, the recombinant influenza virus further comprises up to 40, specifically up to 30, specifically up to 27 amino acids of the SARS-CoV S1 subunit C-terminal of the RBD.
According to a specific embodiment, the recombinant influenza virus described herein comprises SEQ ID NOs.1-6 or 54-57.
According to an embodiment, there is a linker between the NS1 fragment and the encoding 2A cleavage peptide and/or the signal peptide, specifically having a length of 2 to 10 amino acids. Specifically, the linker sequence comprises glycine, alanine and/or serine residues.
According to a further specific embodiment, the recombinant influenza virus comprises modifications of the NA and/or HA proteins.
Herein provided is also the recombinant influenza virus described herein for use in the preparation of a medicament for prophylactic treatment of a disease condition caused by or associated with an infection by a coronavirus and/or an influenza virus specifically inducing immunity against a coronavirus and/or an influenza virus.
Further provided is a pharmaceutical formulation such as a vaccine, comprising the recombinant influenza virus encoding NS1-SARS-CoV-2-RBD/NS2 as described herein in an effective amount.
Further provided herein is a pharmaceutical formulation comprising the recombinant influenza virus, and a physiologically acceptable excipient.
Specifically, the pharmaceutical preparation is for inducing immunity to prevent infection and/or disease by a coronavirus and/or influenza virus, wherein the effective amount is effective in inducing immunity for preventing infection of susceptible cells by the virus.
Specifically, the pharmaceutical preparation is formulated for local administration, preferably for application to the upper and lower respiratory tract, nasal, pulmonary, intraoral, ocular, or dermal use, or for systemic administration, preferably for parenteral administration.
Specifically, the pharmaceutical preparation is administered to a subject as a spray, a powder, a gel, an ointment, a cream, a foam, or a liquid solution, a lotion, a patch, a gargle solution, an aerosolized powder, an aerosolized liquid formulation, granules, capsules, specifically comprising a preparation for parenteral administration.
Specifically, the coronavirus is a β-coronavirus, preferably selected from the group consisting of SARS-CoV-2, MERS-CoV, SARS-CoV-1, HCoV-0043, and HCoV-HKU1, or mutants thereof.
Specifically, the influenza virus is influenza A or B virus, more specifically it is influenza B virus.
Herein provided is also an isolated nucleic acid sequence expressing the recombinant influenza virus encoding NS1-SARS-CoV-2-RBD/NS2 as described herein. Specifically, the nucleic acid sequence comprises one or more artificial splice sites within the gene encoding the truncated NS1 protein.
According to a further embodiment of the invention, a two-component vaccine is provided herein, comprising the recombinant influenza virus encoding NS1-SARS-CoV-2RBD/NS2 as described herein with native hemagglutinin (HA) from Victoria or Yamagata lineages, for use in the vaccination of a subject, wherein a priming composition, comprising one, two or three recombinant influenza virus strains comprising the NS1-SARS-CoV-2-RBD fusion protein described herein, is formulated for prime-administration prior to a boosting composition, comprising one, two or three recombinant influenza virus strains comprising the NS1-SARS-CoV-2-RBD fusion protein in the priming composition but antigenically differing in the HA, formulated for boost-administration. Specifically, the HA head is antigenically different.
According to an embodiment, the boosting composition is administered 2 to 8 weeks after the priming composition, specifically 2, 3, 4, 5, 6, 7, or 8 weeks after the priming composition.
According to an alternative embodiment, the boosting composition is administered about 3 weeks after the priming composition.
According to a specific embodiment, the recombinant influenza virus of the priming composition, encoding the NS1-SARS-CoV-2-RBD fusion protein, comprises a native HA with a B/Victoria derived HA, and the recombinant influenza virus of the boosting composition, also comprising the NS1-SARS-CoV-2-RBD fusion protein, comprises a native HA with a B/Yamagata lineage HA, or wherein the recombinant influenza virus of the priming composition comprises a native HA with a B/Victoria lineage derived HA, and the recombinant influenza virus of the boosting composition comprises a native HA with a B/Yamagata lineage derived HA.
According to an embodiment, vaccination is for the prevention of corona virus related disease or infection and can further be simultaneously used for prevention of influenza virus infection.
Further provided herein is a kit for prime-boost vaccination comprising at least two vials, wherein a first vial contains a priming composition comprising one, two or three recombinant influenza virus strains comprising the NS1-SARS-CoV-2-RBD fusion protein, and a second vial contains a boosting composition comprising one, two or three deINS1 influenza virus strains of the same group as in the priming composition but with an antigenically different HA head.
a: B/Florida Delta-19 P7 growth curve on serum free Vero cells. b: B/Murmansk Delta-19 P4 Growth Curve on serum free Vero cells. Samples were collected at 28, 72 and 96 hours post infection and titered by multiplex FFA assay.
Unless indicated or defined otherwise, all terms used herein have their usual meaning in the art, which will be clear to the skilled person. Reference is for example made to the standard handbooks, such as Sambrook et al, “Molecular Cloning: A Laboratory Manual” (4th Ed.), Vols. 1-3, Cold Spring Harbor Laboratory Press (2012); Krebs et al., “Lewin's Genes XI”, Jones & Bartlett Learning, (2017), and Murphy & Weaver, “Janeway's Immunobiology” (9th Ed., or more recent editions), Taylor & Francis Inc, 2017.
The subject matter of the claims specifically refers to artificial products or methods employing or producing such artificial products, which may be variants of native (wild-type) products. Though there can be a certain degree of sequence identity to the native structure, it is well understood that the materials, methods and uses of the invention, e.g., specifically referring to isolated nucleic acid sequences, amino acid sequences, fusion constructs, expression constructs, transformed host cells and modified proteins, are “man-made” or synthetic, and are therefore not considered as a result of “laws of nature”.
The terms “comprise”, “contain”, “have” and “include” as used herein can be used synonymously and shall be understood as an open definition, allowing further members or parts or elements. “Consisting” is considered as a closest definition without further elements of the consisting definition feature. Thus “comprising” is broader and contains the “consisting” definition.
The term “about” as used herein refers to the same value or a value differing by +/−5% of the given value.
As used herein and in the claims, the singular form, for example “a”, “an” and “the” includes the plural, unless the context clearly dictates otherwise.
As used herein, amino acids refer to twenty naturally occurring amino acids encoded by sixty-one triplet codons. These 20 amino acids can be split into those that have neutral charges, positive charges, and negative charges:
The “neutral” amino acids are shown below along with their respective three-letter and single-letter code and polarity: Alanine (Ala, nonpolar, neutral), Asparagine (Asn, N; polar, neutral), Cysteine (Cys, nonpolar, neutral), Glutamine (Gln, Q; polar, neutral), Glycine (Gly, nonpolar, neutral), Isoleucine (Ile, I; nonpolar, neutral), Leucine (Leu, L; nonpolar, neutral), Methionine (Met, M; nonpolar, neutral), Phenylalanine (Phe, nonpolar, neutral), Proline (Pro, P; nonpolar, neutral), Serine (Ser, S; polar, neutral), Threonine (Thr, T; polar, neutral), Tryptophan (Trp, W; nonpolar, neutral), Tyrosine (Tyr, Y; polar, neutral), Valine (Val, V; nonpolar, neutral), and Histidine (His, H; polar, positive (10%) neutral (90%)).
The “positively” charged amino acids are: Arginine (Arg, R; polar, positive), and Lysine (Lys, K; polar, positive).
The “negatively” charged amino acids are: Aspartic acid (Asp, ID, polar, negative), and Glutamic acid (Glu, E; polar, negative).
The influenza virion consists of an internal ribonucleoprotein core (a helical nucleocapsid) containing the single-stranded RNA genome, and an outer lipoprotein envelope lined inside by a matrix protein (M1). The segmented genome of influenza A and B virus consists of eight segments, seven for influenza C, of linear, negative polarity, single-stranded RNAs which encode eleven, some influenza A strains ten, polypeptides, including the RNA-dependent RNA polymerase proteins (PB2, PB1 and PA) and nucleoprotein (NP) which form the nucleocapsid; the matrix membrane proteins (M1, M2 or BM2 for influenza B, respectively); two surface glycoproteins which project from the lipid containing envelope: hemagglutinin (HA) and neuraminidase (NA); the nonstructural protein (NS1) and the nuclear export protein (NEP, also: NS2). Influenza B viruses encode also NB, a membrane protein which might have ion channel activity and most influenza A strains also encode an eleventh protein (PB1-F2) believed to have proapoptotic properties. Transcription and replication of the genome takes place in the nucleus and assembly occurs via budding on the plasma membrane. The viruses can reassort genes during mixed infections. Influenza virus adsorbs via HA to sialyloligosaccharides in cell membrane glycoproteins and glycolipids. Following endocytosis of the virion, a conformational change in the HA molecule occurs within the cellular endosome which facilitates membrane fusion, thus triggering uncoating. The nucleocapsid migrates to the nucleus where viral mRNA is transcribed. Viral mRNA is transcribed and processed by a unique mechanism in which viral endonuclease cleaves the capped 5′-terminus from cellular heterologous mRNAs which then serve as primers for transcription from viral RNA templates by the viral transcriptase. Transcripts terminate at sites 15 to 22 bases from the ends of their templates, where oligo(U) sequences act as signals for the addition of poly(A) tracts. Of the eight viral RNA molecules of influenza A virus so produced, six are monocistronic messages that are translated directly into the proteins representing HA, NA, NP and the viral polymerase proteins, PB2, PB1 and PA. The other two transcripts undergo splicing, each yielding two mRNAs which are translated in different reading frames to produce M1, M2, NS1 and NS2. In most of influenza A viruses, segment 2 also encodes for a second protein (PB1-F2), expressed from an overlapping reading frame. In other words, the eight viral RNA segments code for eleven proteins: nine structural and 2 non-structural (NS1, PB1-F2) proteins.
A “recombinant” virus is one which has been manipulated in vitro, e.g., using recombinant DNA techniques, to introduce changes to the viral genome, or otherwise artificially generated.
Through combining specific elements such as splice donor and acceptor sites a protease cleavage site and leader peptide with the RBD sequence, high levels of the RBD protein can be expressed and secreted out of the infected cells. This can be a further important prerequisite for inducing sufficient levels of neutralizing antibodies resulting in protection against infection with Sars-Covid-2.
Furthermore, according to a specific embodiment of this invention, the NS gene segment contains the natural splice donor and/or acceptor splice site. Alternatively, the sequences downstream of the splice donor and/or upstream of the acceptor site can be altered, preferably by introducing synthetic sequences in order to modify splicing activity. For example, it can be modified in that either the sequence surrounding the splice donor site is altered to increase the homology to the 5′end of the human U1 snRNA and/or the sequence upstream of the splice acceptor site containing the branch point is altered (Plotch and Krug, 1986, Nemeroff et al., 1992) and the pyrimidine stretch is replaced by a sequence that enhances splicing of the NS segment.
For example, the sequence surrounding the 5′ splice site can be changed from GATTG (SEQ ID NO:10, as found in the influenza A PR8 NS segment) to
(SEQ ID NO:11) or
ATTG (SEQ ID NO:12, nucleotides complementary to the 5′ end of the U1 snRNA are shown in bold italic letters, the splice donor site is indicated by “/”).
For example, the sequence surrounding the 5′ splice site can be changed from GGG
CC (SEQ ID NO:13, as found in the influenza B/Thueringen NS segment) to G
G
CC (SEQ ID NO:14, nucleotides complementary to the 5′ end of the U1 snRNA are shown in bold italic letters, the splice donor site is indicated by “/”).
In order to optimize splicing, the preferred synthetic acceptor site comprises a lariat consensus sequence and a pyrimidine stretch.
For example, the sequence upstream of the synthetic splice acceptor site can be as follows
TACTAAC
GAC/AG.
The lariat consensus sequence is underlined, the pyrimidine stretch is bold, the splice acceptor site is indicated by “/”.
In view of stability of the virus vector and the expression rate of the heterologous sequence it can be important to introduce the synthetic/modified sequence containing a lariat consensus sequence and a pyrimidine stretch at a specific position within the NS gene, e.g. directly upstream of the slice acceptor site.
Furthermore, it may be necessary to vary the distance between the lariat consensus sequence and the pyrimidine stretch to modify the splicing rate of the NS segment (Plotch S. and Krug R., 1986, Nemeroff M. et al., 1992).
The truncated NS1 protein of the herein described recombinant influenza virus consists of only about 10 to 20 amino acids of its N-terminus and thus the virus lacks a functional NS1 protein. It may be referred to it as deINS1 influenza virus. Deletion of the functional NS1 protein leads to a significant attenuation of influenza virus due to lack of replication in interferon competent cells or organisms (replication deficient phenotype). Viruses lacking the functional NS1 protein are not able to antagonize cytokine production of infected cells, therefore inducing self-adjuvanting and immune modulating effects. The hallmark of immune response after immunization with the inventive recombinant influenza virus is triggering of Th1 type of immune response associated with predominant IgG2A antibody isotype response (Ferko B. et al., 2004). The use of NS1 depleted influenza virus is highly advantageous due to increased T-cell response. Enhanced T-cell response may positively affect cross-reactivity of the HA stalk domain thus leading to increased memory effect of the cells and optimized vaccination effect. These improved T-cell responses are due to the release of interferon due to the lack of functional NS1 of the inventive virus comprising the NS1-SARS-CoV-2-RBD fusion protein.
Recall responses by memory cells was not only stronger but also appeared faster with deINS1 vaccine viruses. (Mueller et al, J Virol., 2010).
The lack of NS1 activity achieves highly advantageous properties for the life attenuated virus (LAIV). Specifically, when delivered intranasally, it infects cells of the upper respiratory tract and expresses viral antigens, but it does not form viral progeny and the vaccine strains are not shed by the recipient, making LAIV vaccines lacking functional NS1 protein very safe; and, additionally, since NS1 depleted strains are unable to counteract the host interferon (IFN) response, infection induces high levels of interferon, achieving a natural adjuvant effect that activates B and T cell-mediated immune responses.
Moreover, virus lacking functional NS1 protein stimulates cross-neutralizing serum antibodies against drift variants (Wachek V. et al., 2010), and cross-neutralizing mucosal IgA against different influenza A subtypes (Morokutti A. et al., 2014). Clinical data also indicate that pandemic deltaNS1 has potential for superior immunity (Nicolodi et al., 2019).
According to the invention, the term “replication deficient” is defined as replication rate in interferon competent host cells that is at least reduced by 95%, preferably 99%, preferably 99.9% compared to wild type influenza virus replication rate, determined by hemagglutination assay, TCID50 assay or plaque assay as well known in the art. Specifically, the influenza virus is completely replication deficient.
The influenza virus described herein can be human or animal influenza virus, such as, but not limited to avian, equine, swine. Preferably, it is human influenza virus.
Specifically, the recombinant influenza virus encodes a fusion protein which comprises from its N to C-terminus
Specifically, the truncated NS1 protein consists of 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 amino acids of the N-terminus of the NS1-wt protein.
Coronaviruses are enveloped spherical particles, the spike glycoproteins (S protein) of which form a crown-like surface. The S protein consists of two subunits: S1 and S2. The fragment located in the middle of the S1 subunit (amino acids (aa) 318-510 with respect to the S1 subunit sequence) is the minimum receptor-binding domain (RBD) in SARS-CoV, which binds to the host cell receptor angiotensin converting enzyme 2 (ACE2). The RBD is about 192 amino acids long and comprises the receptor binding motif (RBM). The binding of RBD and ACE2 triggers the conformational change of the S2 subunit and virus particle invasion. The crystal structure of the RBD bound to ACE2 peptidase indicates that RBD presents a flat concave surface at the N-terminus of the receptor peptidase on which amino acids 445-460 anchor the entire receptor-binding loop of the RBD core This loop of about 70 amino acids (aa 424-494) makes complete contact with the ACE2 receptor and is called the receptor binding motif (RBM). Specifically, the RBD including the RBM comprises the sequence of any one of SEQ ID NOs:1 to 6 or 54-57 or is at least 95%, specifically 96, 97, 98, 99, 99.9% identical with SEQ ID NOs:1-6 or 54-57.
In an alternative embodiment, the RBD including the RBM comprises the sequence of any one of SEQ ID NOs:1 to 6 with 1, 2, 3, 4, or 5 amino acid substitutions, deletions or insertions.
The virus can encode the NS1-SARS-CoV-2-RBD fusion protein comprising additional 10 to 50 amino acids of the SARS-CoV S1 subunit linked to the C-terminus of RBD. Specifically, the RBD can comprise 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50 amino acids (NS1-SARS-CoV-2-RBD-S1-fragment).
Specifically, the S1 subunit is of 27 amino acids.
Specifically, the fusion protein comprises SEQ ID NO:6 or SEQ ID NO:54, SEQ ID NO:55, SEQ ID NO:56 or SEQ ID NO:57.
The recombinant influenza virus encoding the NS1-SARS-CoV-2-RBD fusion protein can comprise one or more linker sequences of the same or different lengths, located between the truncated NS1 protein (NS1 fragment) and the 2A cleavage peptide and/or the signal peptide and/or the SARS-CoV receptor binding domain.
According to an embodiment, the linker has a length of 2 to 10 amino acids. Specifically, the linker sequence comprises glycine, serine and/or alanine residues. Specifically, the linker comprises at least one glycine and serine residue, more specifically the linker is GS, GSG, GGSGG (SEQ ID NO:17), GSGSG (SEQ ID NO:18), GSGSGSGS (SEQ ID NO:19), GG, GGG, or GGGG (SEQ ID NO:21). Preferably, the linker is a GSG linker.
According to a specific embodiment, the fusion protein also comprises a self-cleaving peptide, specifically located between the linker and the signal peptide. 2A self-cleaving peptides, or 2A peptides, is a class of 18-22 aa-long peptides, which can induce ribosomal skipping during translation of a protein in a cell. These peptides share a core sequence motif of DxExNPGP (SEQ ID NO:9), and are found in a wide range of viral families. They help generating polyproteins by causing the ribosome to fail at making a peptide bond.
Specifically, the peptide comprises the sequence ATNFSLLKQAGDVEENPGP (SEQ ID NO: 8).
The recombinant influenza virus encoding the NS1-SARS-CoV-2-RBD fusion protein was shown to be stable for at least 6 passages.
According to the embodiment of the present invention, the recombinant influenza virus disclosed herein is a reassortant virus, specifically wherein said virus comprises at least two gene segments of a seasonal or pandemic strain origin.
According to the invention, the recombinant influenza virus comprises modified hemagglutinin (HA) and/or neuraminidase (NA) polypeptides.
On account of their external localization the HA and NA antigens represent the most important viral target structures for the host immune system. Of antibodies which bind specifically to HA, it is thought that they neutralize the viral infectivity, probably by blocking the early steps of infection (Kida et al., 1983). NA-specific antibodies normally do not prevent the initial infection of a target cell but precisely the spread of the virus. In addition, due to competition mechanisms, the immunologic response to NA appears to be partly suppressed in favor of the more frequently occurring HA antigen (Kilbourne, 1976).
The neuraminidase (NA) assembles as a tetramer of four identical polypeptides and, when embedded in the envelope of the virus, accounts for approximately 10-20% of the total glycoproteins on the virion surface, with about 40-50 NA spikes and 300-400 HA spikes on an average sized virion of 120 nm (McAuley J. L. et al., 2019, Varghese et al., 1983; Ward et al., 1983; Moules et al., 2010). The four monomers, each of approximately 470 amino acids, fold into four distinct structural domains: the cytoplasmic tail, the transmembrane region, the stalk, and the catalytic head. Suggesting that the NA cytoplasmic tail is involved in critical viral functions, the N-terminal domain sequence is nearly 100% conserved across all IAV subtypes and consists of the sequence MNPNQK (SEQ ID NO:49; Blok and Air, 1982). Reverse engineered viruses containing site-specific mutations in this domain exhibit altered virion morphology and reduced replicative yields (Mitnaul et al., 1996; Jin et al., 1997; Barman et al., 2004). IAV engineered to encode an NA lacking a cytoplasmic tail could still be rescued but with a markedly attenuated phenotype (Garcia-Sastre and Palese, 1995). The altered morphology and attenuated infectivity of viruses expressing NA lacking the cytoplasmic tail domain are thought to be due to a lack of interaction with the membrane-associated matrix M1 viral protein (McAuley J. L. et al., 2019, Enami and Enami, 1996), which ultimately alters the efficiency of budding from the infected host cell (Jin et al., 1997; Ali et al., 2000; Barman et al., 2001; Mintaev et al., 2014). Determinants in both the cytoplasmic tail domain and the transmembrane domain contribute to the transport of the glycoprotein to the apical plasma membrane. However, the role of the tail domain in packaging the surface NA into virions remains unclear. A complete loss of the tail domain (Garcia-Sastre and Palese, 1995) resulted in a 50% reduction in the amount of NA in infected cells. The absence of all tail amino acids except for the initiating methionine gave rise to virus that also showed markedly less incorporation of NA into virions, but in this case, NA was present at the plasma membrane at similar levels to wild-type virus (McAuley J. L. et al., 2019, Mitnaul et al., 1996).
The terms “hemagglutinin” and “HA” refer to any influenza virus hemagglutinin. In certain embodiments, the hemagglutinin is influenza hemagglutinin, such as an influenza A hemagglutinin, an influenza B hemagglutinin, or an influenza C hemagglutinin. A typical hemagglutinin comprises domains known to those of skill in the art including a signal peptide (optional), a stem domain (also referred to as a “stalk domain”), a globular head domain, a luminal domain (optional), a transmembrane domain (optional) and a cytoplasmic domain (optional). Functionally, the hemagglutinin glycoprotein is composed of an immunodominant globular head domain involved in virus attachment to the host cell and the membrane proximal stalk/stem domain mediating fusion of the viral and cell membrane in the host endosome. The terms “stalk” and “stem” can be used interchangeably herein. The stalk domain is more conserved among influenza A (group 1 and 2) and B viruses allowing antibodies that target this region to neutralize a wide spectrum of influenza virus subtypes and is identified to harbor neutralizing B-cell epitopes. The immunodominant HA head domains undergo constant antigenic drift or shift The HA stalk domain is composed of three helical bundles and is functionally required for the pH induced conformational changes involved in membrane fusion during viral entry and exit from the host cell. In contrast to the HA-head variability, the stalk domain displays a much higher level of conservation across influenza strains with some central residues being identical across all subtypes (Krystal M, et al., 1982). The stalk domain is evolving at a rate that is significantly slower than that of the head domain. Additionally, the cross-reactive epitopes in the stalk domain targeted by broadly neutralizing monoclonal antibodies are evolving at an even slower rate compared to the full head and stalk regions of the protein (Kirkpatrick E. et al., 2018). Three protective epitopes, with varying levels of cross-reactivity between group 1 and 2 influenza strains, have been identified within the stalk portion of influenza A HA. Epitope 1 is centered on the α-helix of the HA2 region of HA. Targeting this epitope is also protective against B strains, but the antibody must have unique properties to accommodate key modifications helping to obscure the epitope surface (Dreyfus C, et al, 2012). Epitopes 2 and 3 are protective across group 2 influenza A subtypes. Epitope 2 includes the upper portion of the long alpha helix CD in HA2 (Wang T T, et al., 2010) whereas epitope 3 is located at the base of the HA2 stalk spanning regions of the fusion peptide and helix-capping loops (Ekiert D C, et al., 2011). The fourth protective stalk epitope is located in the C terminal portion of HA1 and offers broad protection across both B strain lineages (Yasugi M, et al., 2013) Generating a strong antibody response against any of these conserved epitopes can offer broader and more durable protection against influenza by circumventing reliance on epitopes prone to antigenic drift.
Specifically, the influenza virus is a high growth influenza virus specifically comprising one or more amino acid substitutions in the PB1, M and NS2 proteins as described in WO2020152318A. Specifically, the influenza virus described herein comprises a D67N amino acid substitution in the PB1 protein (according to the numbering of SEQ ID NO:22), a K93R substitution in the M protein (according to the numbering of SEQ ID NO:23) and a Y117H substitution in NS2/NEP protein (according to the numbering of SEQ ID NO:24).
Specifically, the influenza virus expressing the fusion protein described herein comprises any one or more of SEQ ID NOs 22, 23 or 24. More specifically, the influenza virus comprises all of SEQ ID NOs 22 to 24.
As an example, but not limited to it, influenza/SARS-CoV-2 chimeric viruses can be created by reverse genetics whereby the HA and NA genes can be derived from strains such as B/Florida/04/2006 (B-Yamagata lineage) and B/Murmansk/3/2010 (B Victoria lineage) while the internal genes are derived from B/Thüringen/02/2006 a B/Jiangsu/10/2003-like virus from the B Yamagata lineage. The NS gene is genetically modified to have a complete deletion of the NS1 gene. The NS1 deletion is replaced by 219 amino acids from the SARS-CoV-2 receptor binding domain (RBD) sequence which is flanked by sequences allowing efficient expression and secretion from infected cells. 6:2 reassortant viruses can be created using both unmodified internal genes: PB2. PB1, PA, NP, M and NS2/NEP as well as amino acid substitutions described above.
The term “transmembrane domain” (TMD) refers to any polypeptide which is hydrophobic and can be inserted or is anchored in the cellular membrane. Transmembrane domains (TMDs) consist predominantly of nonpolar amino add residues and may traverse the bilayer once or several times. Examples for TMDs can be, but are not limited to viral TMDs, Influenza TMD, tyrosine kinase TMD, G-protein-coupled receptors, EGF like domains SAE like domains or the transmembrane domain M2.
The term “antigenically different” as used herein refers to the presence of different antigenic sites being target by antibody response. Different antigenicity can be due to amino acid substitutions in the HA head domains due to antigenic drifts and shifts of the influenza virus. The ‘classical’ antigenic sites were historically determined using murine mAbs and analysis of changes in amino acid sequences connected to antigenic drift (as measured by reduction of HI activity (Wiley et al., N1981). The majority of mutations in the head were focused on sites related to immune escape, while the majority of mutations in the stalk seem to be evenly dispersed throughout the domain. (Kirkpatrick et al., 2018).
As used herein, the term “infection” means the invasion by, multiplication and/or presence of a virus in a cell or a subject. An infection can be an “active” infection, i.e., an infection in which the virus is replicating in a cell or a subject. Such an infection is characterized by the spread of the virus to other cells, tissues, and/or organs, from the cells, tissues, and/or organs initially infected by the virus. An infection may also be a latent infection, i.e. an infection in which the virus is not replicating. In certain embodiments, an infection refers to the pathological state resulting from the presence of the virus in a cell or a subject, or by the invasion of a cell or subject by the virus. Herein, infection is infection with coronavirus, or infection with both, coronavirus and influenza virus.
As used herein, the term “influenza virus disease” refers to the pathological state resulting from the presence of an influenza (e.g., influenza A or B) virus in a cell or subject or the invasion of a cell or subject by an influenza virus. In specific embodiments, the term refers to a respiratory illness caused by an influenza virus.
As used herein, the term “corona virus disease” refers to the pathological state resulting from the presence of a coronavirus (e.g., β-coronavirus, such as but not limited to SARS-CoV-2, MERS-CoV, SARS-CoV-1, HCoV-OC43, and HCoV-HKU1) virus in a cell or subject or the invasion of a cell or subject by a coronavirus. In specific embodiments, the term refers to a respiratory illness caused by a coronavirus.
As used herein, the term “nucleic acid” includes DNA molecules (e.g., cDNA) and RNA molecules (e.g., mRNA or pre-mRNA) and analogs of the DNA or RNA generated using nucleotide analogs. The nucleic acid can be single-stranded or double-stranded.
As used herein, the terms “prevent”, “preventing” and “prevention” in the context of the administration of a therapy to a subject to prevent a coronavirus infection and/or an influenza virus infection refer to one or more of the prophylactic/beneficial effects resulting from the administration of a therapy or a combination of therapies. In a specific embodiment, the term “prevent” in the context of the administration of a therapy to a subject to prevent a coronavirus disease and optionally also an influenza virus disease refer to one or more of the following effects resulting from the administration of a therapy or a combination of therapies: (i) the inhibition of the development or onset of a coronavirus/an influenza virus disease or a symptom thereof; (ii) the inhibition of the recurrence of a coronavirus/an influenza virus disease or a symptom associated therewith; and (iii) the reduction or inhibition in coronavirus/influenza virus infection and/or replication.
Specifically, the term “prophylaxis” or “prophylactic” refers to preventive measures which are intended to reduce the risk of disease occurrence, or recurrence of disease. When provided prophylactically, the pharmaceutical preparation described herein which is a vaccine is provided before any symptom or clinical sign of a pathogen infection becomes manifest. The prophylactic administration of the preparation serves to prevent or attenuate any subsequent infection. When provided prophylactically, the preparation of the invention is provided before any symptom or clinical sign of a disease becomes manifest. The prophylactic administration of the preparation serves to prevent or attenuate one or more symptoms or clinical signs associated with the disease.
As used herein, the terms “treat,” “treatment,” and “treating” refer to prophylactic treatment, i.e. to the immunization or vaccination of a subject.
The “protection” provided need not be absolute, i.e., a corona infection need not be totally prevented or eradicated, as long as there is a statistically significant improvement compared with a control population or set of mammals, specifically of humans. Protection may be limited to reducing the severity or rapidity of onset of symptoms or clinical signs of the coronavirus infection.
As used herein, the terms “subject” or “patient” are used interchangeably to refer to an animal (e.g., birds, reptiles, and mammals). In a specific embodiment, the subject is a mammal including a non-primate (e.g., a camel, donkey, zebra, cow, pig, horse, goat, sheep, cat, dog, rat, and mouse) and a primate (e.g., a monkey, chimpanzee, and a human). In certain embodiments, the subject is a non-human animal. In some embodiments, the subject is a farm animal or pet. In another embodiment, the subject is a human.
According to a specific embodiment, the vaccine comprising the inventive recombinant influenza virus encoding the NS1-SARS-CoV-2-RBD fusion protein, or the two-component vaccine containing said virus can further comprise one or more adjuvants. As used herein, an “adjuvant” refers to a substance or mixture that enhances the body's immune response to an antigen, in the present disclosure an adjuvant enhances the cell mediated immune response induced by the combination of the first composition, second composition and/or third composition. As used herein, an adjuvant is combined into any or all of the priming composition and/or boosting composition.
The term “stabilizers” refers to any agent that can increase the stability of the virus, for example it can be bovine serum albumin, sugars, chitosan, dextrans, PEGs etc.
By “administration” is meant introducing the pharmaceutical preparation (vaccine) or two-component vaccine (herein referred to as preparation) of the present disclosure into a subject; it may also refer to the act of providing the preparation/vaccine of the present disclosure to a subject (e.g., by prescribing). The preparation can be administered to a human or animal subject in vivo using a variety of known routes and techniques. For example, the preparation may be provided as an injectable solution, suspension or emulsion and administered via parenteral, subcutaneous, oral, epidermal, intradermal, intramuscular, intraarterial, intraperitoneal, intravenous injection using a conventional needle and syringe, or using a liquid jet injection system. The preparation may be administered topically to skin or mucosal tissue, such as nasally, intratracheally, intestinally, sublingually, rectally or vaginally, or provided as a finely divided spray, such as a mist, suitable for respiratory or pulmonary administration. In certain embodiments, the preparations are administered intramuscularly or intranasally.
The term “effective amount” refers to that amount of the compound being administered which will produce a reaction that is distinct from a reaction that would occur in the absence of the compound. In reference to embodiments of the disclosure including the immunotherapy compounds of the disclosure, an “effective amount” is the amount which increases the immunological response in the recipient over the response that would be expected without administration of the compound.
The terms “pharmaceutical preparation” or “pharmaceutical composition” or “pharmaceutical formulation” refer to the recombinant influenza virus comprising a modified NS1 segment and encoding the NS1-SARS-CoV-2-RBD fusion protein as described herein, with other chemical components, such as pharmaceutically acceptable carriers and excipients. One purpose of a pharmaceutical composition is to facilitate administration of a compound to the organism.
As used herein, a “pharmaceutically acceptable carrier” refers to a carrier or diluent that does not cause significant irritation to an organism and does not abrogate the biological activity and properties of the administered vaccine compositions. It refers to a diluent, adjuvant, excipient, or vehicle with which the pharmaceutical composition (e.g., immunogenic or vaccine formulation) is administered. Saline solutions and aqueous dextrose and glycerol solutions can also be employed as liquid carriers, particularly for injectable solutions. Suitable excipients include starch, glucose, lactose, sucrose, gelatine, malt, rice, flour, chalk, silica gel, sodium stearate, glycerol monostearate, talc, sodium chloride, dried skim milk, glycerol, propylene, glycol, water, ethanol and the like. Examples of suitable pharmaceutical carriers are described in “Remington's Pharmaceutical Sciences” by E. W. Martin. The formulation should be selected according to the mode of administration. The particular formulation may also depend on whether the virus is live or inactivated.
The general concept of a prime-boost regimen is well known to the skilled person in the vaccine field. Thus, in one embodiment, the recombinant influenza virus comprising a modified NS1 segment, encoding the NS1-SARS-CoV-2-RBD fusion protein described herein can be part of a priming composition of a two-component vaccine composition used for priming an immune response, the boosting composition is a booster vaccine used for boosting an immune response. Because the prime boost effect is due to different antigenicity, the recombinant influenza virus comprising a modified NS1 segment, encoding the NS1-SARS-CoV-2-RBD fusion protein can also be part of the boosting vaccine composition.
As described herein, the first, priming composition is administered as a prime dose and the second boosting composition is administered as a boost dose, provided both the first and second compositions are administered. In embodiments, the prime and boost dose are administered 2 to 4 weeks, specifically at least 7 days, at least 14 days, at least 21 days, specifically at least 28 days apart, or longer. In embodiments, the prime dose and boost dose are administered about 7 days, about 14 days, about 21 days apart, about 28 days apart, about 35 days apart, about 42 days apart, about 49 days apart, 56 days, 63 days, 70 days, 77 days, 84 days, 91 days, 98 days, 105 days, 112, 119 days, 126 days, 133 days, 140 days, 147 days, 154 days, 161 days, 168 days, about 175 days, or about 183 days apart.
In certain embodiments, the prime administration and boost administration are administered about 1 week apart, about 2 weeks apart, about 3 weeks apart, about 4 weeks apart, about 5 weeks apart, about 6 weeks apart, about 7 weeks apart, about 8 weeks apart, about 9 weeks apart, about 10 weeks apart, about 11 weeks apart, about 12 weeks apart, about 13 weeks apart, about 14 weeks apart, about 15 weeks apart, about 16 weeks apart, about 17 weeks apart, about 18 weeks apart, about 19 weeks apart, about 20 weeks apart, about 21 weeks apart, about 22 weeks apart, about 23 weeks apart, about 24 weeks apart, about 25 weeks apart, about 26 weeks apart, about 27 weeks apart, about 28 weeks apart, about 29 weeks apart, or about 30 weeks apart In certain other embodiments, the prime dose and boost dose are administered about 1 month apart, about 2 months apart, about 3 months apart, about 4 months apart, about months apart, about 6 months apart, about 7 months apart, about 8 months apart, about 9 months apart, about 10 months apart, about 11 months apart, or about 12 months apart.
As general guidance, an immunologically effective amount when used with reference to a viral vaccine can range from about 1×107 viral particles per dose to about 1×1012 viral particles per dose. An immunologically effective amount can be about 6×1010, about 7×1010, about 8×1010, about 9×1010, about 1×1011, viral particles per dose.
The kit for prime-boost vaccination as referred herein comprises at least two separate vials:
The influenza virus as described herein can be also useful to prepare reassortant viruses including 6:1:1 reassortants, 6:2 reassortants and 7:1 reassortants. A 6:1:1 reassortant according to the present invention is an influenza virus with 6 internal gene segments, an NA gene segment from a different, second, viral isolate, and a HA gene segment from a third isolate; a 6:2 reassortant is an influenza virus with 6 internal gene segments, and an NA gene segment and a HA gene segment from a different (second) viral isolate; and a 7:1 reassortant is an influenza virus with 6 internal gene segments and an NA gene segment from a vaccine virus, and a HA gene segment from a different viral source than the vaccine virus, or an influenza virus with 6 internal gene segments and a HA gene segment, and an NA gene segment is from a different viral source than the vaccine virus. As an alternative, 5:1:2 reassortants are also encompassed herein.
In some embodiments, a plurality of vectors incorporating at least the 6 internal genome segments of a one influenza B strain along with one or more genome segments encoding immunogenic influenza surface antigens of a different influenza strain are introduced into a population of host cells. For example, at least the 6 internal genome segments (“the backbone”) of a selected influenza A or B strain, e.g., an artificially engineered influenza A or B backbone strain encoding the recombinant influenza virus comprising a modified NS1 segment, encoding the NS1-SARS-CoV-2-RBD fusion protein as described herein, e.g. but not limited to B/Thüringen/02/06, B/Colorado, B/Iowa, B/Maryland, B/Phuket/3073/2013, a B/Jiangsu/10/03-like virus from the B Yamagata lineage, B/Murmansk/3/2010, or A/IVR-116 are introduced into a population of host cells along with one or more segments encoding immunogenic antigens derived from another virus strain. Typically, the immunogenic surface antigens include either or both of the hemagglutinin (HA) and/or neuraminidase (NA) antigens. In embodiments where a single segment encoding an immunogenic surface antigen is introduced, the 7 complementary segments of the selected virus are also introduced into the host cells.
In a further embodiment, herein provided is a plurality of influenza virus vectors for preparing a reassortant influenza B virus comprising a modified NS1 segment, encoding the NS1-SARS-CoV-2-RBD fusion protein described herein, comprising
In a further embodiment, herein provided is a plurality of influenza virus vectors, comprising
In a further embodiment, herein provided is a plurality of influenza virus vectors, comprising
According to yet a further embodiment of the invention, herein provided is a method for preparing an influenza virus B described herein, by contacting a cell with
Further provided in an embodiment is a method for preparing an influenza virus B of the present invention, by contacting a cell with
In a further aspect, provided herein is a method for preparing an influenza virus A described herein, by contacting a cell with
The examples described herein are illustrative of the present invention and are not intended to be limitations thereon. Different embodiments of the present invention have been described according to the present invention. Many modifications and variations may be made to the techniques described and illustrated herein without departing from the scope of the invention. Accordingly, it should be understood that the examples are illustrative only and are not limiting upon the scope of the invention.
A) Soluble Expression of Sars-CoV-2 RBD by Influenza deINS1 Virus.
Several variants of the Delta-19 SARS-CoV-2 strains with Influenza B (Delta-19: deltaNS, Covid 19; Table 1) were constructed. All strains express a secreted, soluble form of the SARS-CoV-2 Receptor Binding Domain (RBD) All strains were passaged at least 7 times and SARS-COV-2 RBD stability was confirmed. SARS-CoV-2 expression has been measured by sandwich ELISA and western blot for some of the vaccine strains. The three highlighted strains were used in the pre-clinical animal study.
The influenza/SARS-CoV-2 chimeric viruses were created by reverse genetics: The HA and NA genes were derived from B/Florida/04/2006 (B-Yamagata lineage) and B/Murmansk/3/2010 (B Victoria lineage) while the internal genes were derived from B/Thüringen/02/2006 a B/Jiangsu/10/2003-like virus from the B Yamagata lineage. The NS gene is genetically modified to have a complete deletion of the NS1 gene. The NS1 deletion is replaced by 219 amino acids from the SARS-CoV-2 receptor binding domain (RBD) sequence which was flanked by sequences allowing efficient expression and secretion from infected cells. A schematic drawing is depicted in
B) Anchored expression of Sars-CoV-2 RBD by influenza deINS1 virus. To anchor the RBD sequence into the viral envelope, the RBD sequence is fused to a transmembrane sequence. A schematic drawing of the construct is shown in
A cDNA coding for the RBD of SARS-CoV-2 virus was inserted into a modified NS segment of influenza B/Thueringen/2/06 that does not code for a functional NS1 protein. The NS1 protein was C-terminally truncated after amino acid 16. A cDNA coding for a fusion protein consisting of (from N-terminus to C-terminus) a linker (GSG), a 19 amino acid self-cleaving P2A sequence, a 20 amino acid signal peptide, and 219 amino acids from the SARS-CoV-2 receptor binding domain (RBD) was fused in frame to the C-terminus of the 16 amino acid NS1 protein resulting in the following protein:
SASFSTFKCYGVSPTKLNDLCFTNVYADSFVIRGDEVRQIAPGQTGKIA
DYNYKLPDDFTGCVIAWNSNNLDSKVGGNYNYLYRLFRKSNLKPFERDI
STEIYQAGSTPCNGVEGFNCYFPLQSYGFQPTNGVGYQPYRVVVLSFEL
LHAPATVCGPKKSTNLVKNKCVNFNFNGLTGT.
NITNLCPFGEVENATRFASVYAWNRKRISNCVADYSVLYNSASFSTFKC
YGVSPTKLNDLCFTNVYADSFVIRGDEVRQIAPGQTGKIADYNYKLPDD
FTGCVIAWNSNNLDSKVGGNYNYLYRLFRKSNLKPFERDISTEIYQAGS
TPCNGVEGFNCYFPLQSYGFQPTNGVGYQPYRVVVLSFELLHAPATVCG
PKKSTNLVKNKCVNFNFNGLTGT is the SARS-CoV-2 RBD
SARS-CoV-2 Receptor Binding Domain may have the following sequence:
Transmembrane Domain Sequence Information:
Flu B (B/Phuket/3073/2013) HA2 Transmembrane domain and Cytoplasmic Tail
Amino Acid Sequence:
Nucleotide Sequence:
Flu A (A/Texas/04/2009) HA2 Transmembrane domain and Cytoplasmic Tail
Amino Acid Sequence:
Nucleotide Sequence:
Examples for transmembrane sequences which can be used according to the invention
GGAGAGGTGTTCAATGCTACCCGCTTTGCTTCAGTGTACGCTTGGAATA
GGAAACGGATCAGTAATTGCGTGGCTGATTATTCTGTGCTGTACAATAG
CGCAAGCTTCAGCACATTCAAATGCTATGGAGTGAGCCCCACAAAACTG
AATGATCTGTGCTTCACTAATGTTTACGCCGATTCATTTGTGATACGCG
GAGATGAGGTGAGACAGATTGCCCCTGGCCAAACAGGAAAAATCGCGGA
TTACAATTACAAACTGCCAGATGATTTCACTGGATGCGTGATTGCATGG
AATTCAAATAATCTGGATAGTAAAGTTGGAGGCAATTACAATTACCTGT
ACAGACTGTTCAGAAAAAGCAATCTGAAACCCTTTGAGCGAGATATCAG
CACCGAAATCTACCAGGCTGGCTCTACGCCTTGCAATGGAGTGGAGGGA
TTCAATTGTTATTTTCCTCTGCAGAGTTACGGATTCCAACCGACCAATG
GTGTGGGATATCAGCCCTACAGAGTGGTGGTGCTGAGCTTCGAACTGCT
TCACGCTCCAGCAACAGTGTGCGGACCCAAAAAATCTACTAATCTGGTG
AAAAATAAGTGCGTGAATTTCAATTTCAATGGACTGACGGGAACGGGA
CTGCTTTACTACTCAACTGCTGCCTCCAGTT
TGGCTGTAACACTGATGATAGCTATCTTTGTTGTTTATATGGTCTCCAG
BGHB deINS1-RBD219 BSMBI plus Flu B HA2 linker, transmembrane domain, and cytoplasmic tail from B/Phuket/3073/2013 (Codon optimized) amino acid sequence
GGAGAGGTGTTCAATGCTACCCGCTTTGCTTCAGTGTACGCTTGGAATA
GGAAACGGATCAGTAATTGCGTGGCTGATTATTCTGTGCTGTACAATAG
CGCAAGCTTCAGCACATTCAAATGCTATGGAGTGAGCCCCACAAAACTG
AATGATCTGTGCTTCACTAATGTTTACGCCGATTCATTTGTGATACGCG
GAGATGAGGTGAGACAGATTGCCCCTGGCCAAACAGGAAAAATCGCGGA
TTACAATTACAAACTGCCAGATGATTTCACTGGATGCGTGATTGCATGG
AATTCAAATAATCTGGATAGTAAAGTTGGAGGCAATTACAATTACCTGT
ACAGACTGTTCAGAAAAAGCAATCTGAAACCCTTTGAGCGAGATATCAG
CACCGAAATCTACCAGGCTGGCTCTACGCCTTGCAATGGAGTGGAGGGA
TTCAATTGTTATTTTCCTCTGCAGAGTTACGGATTCCAACCGACCAATG
GTGTGGGATATCAGCCCTACAGAGTGGTGGTGCTGAGCTTCGAACTGCT
TCACGCTCCAGCAACAGTGTGCGGACCCAAAAAATCTACTAATCTGGTG
AAAAATAAGTGCGTGAATTTCAATTTCAATGGACTGACGGGAACGGGT
CTGCTTTACTACTCAACTGCTGCCT
CCAGTTTGGCTGTAACACTGATGATAGCTATCTTTGTTGTTTATATGGT
CTCCAGAGACAATGTTTCTTGCTCCATCTGTCTATAATGATGAGCGGCC
BGHB deINS1-RBD219 BSMBI plus generic linker, Flu B HA2 transmembrane domain, and cytoplasmic tail from B/Phuket/3073/2013 (Codon optimized) amino acid sequence
NEP/NS2 (spliced)
Serum free Vero cells were infected for 16 hours in infection media containing 500 ng/ml Amphotericin and 0.5% 10×TrypLE. Supernatant was collected, centrifuged at 200×g for 10 minutes and run on 4-20% SDS-PAGE gel with 2× Laemmli sample loading buffer with 2-Mercaptoethanol and boiling at 99° C. for 10 minutes. Proteins are transferred to nitrocellulose membrane using methanol free transfer buffer. Membranes are blocked with 5% milk and stained with either a mouse monoclonal antibody (SARS-COV-2 Spike RBD Mab Clone 1034522, RND Systems) and Goat anti Moue HRP secondary antibody or a Rabbit polyclonal antibody (SARS CoV-2/2019-nCoV Spike/RBD Antibody, Rabbit PAb, antigen affinity purified, Sino Biological) and Goat anti Rabbit IgG HRP (RND Systems). Membranes were washed with PBST and developed with Super Chemiluminescent substrate (Pierce). Protein bands were visualized using a Bio Rad Chem+ gel doc. Concentration of secreted RBD is estimated by comparing to a known control and using the Image Lab Quantitative Software from Bio Rad (
Serum free Vero cells were infected with a 1:5 serial dilution of undiluted virus in media containing 500 ng/ml Amphotericin. Infected cells were incubated at 33° C. overnight and fixed after 16-20 h with 4% formaldehyde. Cells were washed with PBS, permeabilized with 1% triton and washed with PBST. Two primary antibodies were added simultaneously: anti influenza B NP (clone B017, mouse, Invitrogen) and anti-SARS CoV-2 Neutralizing Antibody (4C6, mAB, rabbit, Genscript) in 5% mill in PBST, washed 3 times with PBST and incubated with 2 secondary antibodies: Goat anti Mouse IgG conjugated with Dylight 488 (Pierce) and Goat anti rabbit IgG AlexaFluor 647 (Jackson Immuno Research Laboratories). Cells were then washed 3 times with PBST and fluorescent cells were imaged using the Celigo Imaging Cytometer (Nexcelom). Each well was counted in both the green (NP) and red channel (RBD) and titers were calculated. The titers shown below in Table 2 represent the number of cells expressing NP and RBD upon infection with the indicated viral vectors each derived from passage 8. This result indicates that almost every cell infected with the virus (=NP titer) expresses the inserted RBD antigen. Importantly, the ratio of NP versus RBD expression remained in the same range during the passages, indicating that expression of the RBD is stable. Moreover, the results show that the titers are sufficiently high (>8 log 10) to permit vaccine production on an industrial scale. The RBD ratios of the seed viruses are shown below. The RBD ratios of the different passages are shown in
Stability
Each vaccine virus was passaged 7 times (P1-7) in serum free Vero Cells in media containing 0.5% 10×TrypLE and 500 ng/ml Amphotericin B. Genetic stability was assessed by RT-PCR. Briefly, RNA was extracted from each passage and RT-PCR was performed using One step RT-PCR kit (Qiagen) using NS non-coding region primers. PCR products were run on a 0.8% agarose gel (
Growth Kinetics of Chimeric Vaccine Viruses
Growth of the viruses were assessed by infecting serum free Vero cells in T25 flasks with cells seeded at 80,000 cells/cm2 at an MOI of 0.005 in media containing 0.5% 10×TrypLE and 500 ng/ml Amphotericin B at a ratio of 0.22 ml/cm2. At 48 hours post infection, the supernatants were spiked with 0.5% 10×TrypLE. Supernatant was harvested at 48, 72 and 96 hours post infection and supernatants were titered by FFA assay. The results are shown in
a shows the B/Florida Delta-19 P7 growth curve on serum free Vero cells seeded at 80,000 C/Cm2 were infected at an MOI of 0.005 in 0.22 ml virus growth media/cm2. Virus growth media contains 0.5% 10× TrypLE and 500 ng/ml AmphB. Samples were collected at 28, 72 and 96 hours post infection and titered by FFA assay.
b shows B/Murmansk Delta-19 P4 Growth Curve on serum free Vero cells seeded at 80,000 C/Cm2 were infected at an MOI of 0.005 in 0.22 ml virus growth media/cm2. Virus growth media contains 0.5% 10×TrypLE and 500 ng/ml AmphB. Samples were collected at 28, 72 and 96 hours post infection and titered by multiplex FFA assay.
Animal Study. Immunogenicity and Protection Efficacy of Delta-19 Against SARS-CoV-2 Wild-Type Challenge
The immunogenic properties and protection efficacy of the Delta-19 vaccine in the ferret model was evaluated. Three Delta-19 strains with different Influenza B backbones were used in this study: B/Florida/04/06-like (B-Yamagata), B/Phuket/3073/2013 (B-Yamagata) and B/Murmansk/3/10 (B-Victoria) that all express a 219 amino acid region of the SARS-CoV-2 S1 protein, the Receptor Binding Domain (RBD) (Amino Acids:331-524 in the S protein of hCov-19/Wuhan/Hu-1/2019/reference strain). All strains used in the pre-clinical study contained the wild-type NS splice mutant. Each animal received prime and booster inoculations of these three strains at a dose of 108.0-108.7). Sera was collected at various points throughout the study. The ferrets were challenged with 5e4 pfu/500 ul IN with SARS-CoV-2/WA01, CSU V2 from BEI, 3/5/21 21 days post boost 3. Plaque Reduction Neutralizing Titers (PRNT) were measured against SARS-CoV-2 in sera (Table 3). Nasal wash and oral swab samples were collected at days 1, 3, 5 and 7 post challenge. SARS-CoV-2 levels were measured in these samples by traditional plaque assay (Tables 4 and 5). The sera was also used to measure the serum IgG levels against SARS-CoV-2 RBD (Table 6), Influenza HA0 (Table 7) and neutralizing titers against the three influenza strains (Table 8) were measured by Fluorescent Microneutralization Assay (fMNA). Weight, temperature, and clinical symptoms were measured in all ferrets throughout the study. Six out of eight ferrets immunized developed neutralizing antibodies and were protected against challenge with SARS COV-2. All immunized ferrets had also neutralizing antibodies against influenza virus indicating that dual protection against Covid19 and influenza is possible with the chimeric constructs that were generated and described.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2021/059788 | 11/17/2021 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63114941 | Nov 2020 | US |
