Recombinant vaccine against COVID-19 based on a paramyxovirus viral vector

Abstract

An active or inactivated recombinant vaccine against COVID-19 is described that comprises a Newcastle disease viral vector and a pharmaceutically acceptable carrier, adjuvant and/or excipient, characterized in that the viral vector is a virus capable of generating a cellular immune response that has a SARS-COV-2 exogenous nucleotide sequence inserted.

Claims

1. A recombinant Newcastle disease virus (NDV) comprising a NDV viral vector comprising SEQ ID NO:6 or SEQ ID NO:14 and an exogenous nucleotide sequence encoding for antigenic sites of severe acute respiratory syndrome coronavirus 2 (SARS-COV-2), wherein the exogenous nucleotide sequence comprises an ectodomain of a spike (S) protein of SARS-COV-2 fused to a transmembrane domain and a cytoplasmic domain of a NDV fusion (F) protein, wherein the polybasic cleavage site of the ectodomain of the S protein is mutated to an alanine and amino acids that correspond to amino acids 817, 892, 899, 942, 986 and 987 of the ectodomain of the S protein of SEQ ID NO:11 are mutated to prolines, whereby the NDV viral vector and the antigenic sites are stable after at least 3 consecutive passages in chicken embryo.

2. The recombinant NDV according to claim 1, wherein the recombinant NDV is used in an active form.

3. The recombinant NDV according to claim 1, wherein the recombinant NDV is used in an inactivated form.

4. The recombinant NDV according to claim 1, wherein the NDV viral vector comprises SEQ ID NO:6.

5. The recombinant NDV according to claim 1, wherein the NDV viral vector comprises SEQ ID NO:14.

6. The recombinant NDV according to claim 1, wherein the S protein ectodomain nucleotide sequence is a sequence having at least 80% identity with any sequence that translates into the amino acid sequence of the exodomain of the S protein of SEQ ID NO: 11 and still comprises all of the S protein mutations of claim 1.

7. The recombinant NDV according to claim 1, wherein the S protein ectodomain nucleotide sequence is any sequence that translates into the amino acid sequence of the exodomain of the S protein of SEQ ID NO: 11.

8. A coronavirus disease 2019 (COVID-19) vaccine comprising: a recombinant Newcastle disease virus (NDV) comprising an NDV viral vector comprising SEQ ID NO:6 or SEQ ID NO:14 and an exogenous nucleotide sequence encoding for antigenic sites of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), wherein the exogenous nucleotide sequence comprises an ectodomain of a spike (S) protein of SARS-COV-2 fused to a transmembrane domain and a cytoplasmic domain of a NDV fusion (F) protein, wherein the polybasic cleavage site of the ectodomain of the S protein is mutated to an alanine and amino acids that correspond to amino acids 817, 892, 899, 942, 986 and 987 of the ectodomain of the S protein of SEQ ID NO:11 are mutated to prolines, whereby the NDV viral vector and the antigenic sites are stable after at least 3 consecutive passages in chicken embryo, and a pharmaceutically acceptable carrier, adjuvant and/or excipient.

9. The COVID-19 vaccine according to claim 8, wherein the recombinant NDV is live.

10. The COVID-19 vaccine according to claim 8, wherein the recombinant NDV is inactivated.

11. The COVID-19 vaccine according to claim 8, wherein the NDV viral vector comprises SEQ ID NO:6.

12. The COVID-19 vaccine according to claim 8, wherein the NDV viral vector comprises SEQ ID NO:14.

13. The COVID-19 vaccine according to claim 8, wherein the S protein ectodomain nucleotide sequence is a sequence having at least 80% identity with any sequence that translates into the amino acid sequence of the exodomain of the S protein of SEQ ID NO: 11 and still comprises all of the S protein mutations of claim 12.

14. The COVID-19 vaccine according to claim 8, wherein the S protein ectodomain nucleotide sequence is any sequence that translates into the amino acid sequence of the exodomain of the S protein of SEQ ID NO: 11.

15. The COVID-19 vaccine according to claim 8, wherein the pharmaceutically acceptable carrier comprises an aqueous solution or an emulsion.

16. The COVID-19 vaccine according to claim 15, wherein the emulsion is a water-oil emulsion, an oil-water emulsion, or a water-oil-water emulsion.

17. The COVID-19 vaccine according to claim 15, wherein the emulsion is a water-oil-water emulsion.

18. The COVID-19 vaccine according to claim 8, wherein the recombinant NDV is an active virus in a concentration between 10.sup.6.0 and 10.sup.10.0 CEID50%/mL per volume dose.

19. The COVID-19 vaccine according to claim 8, wherein the recombinant NDV is an active virus in a concentration between 10.sup.6.0 and 10.sup.8.5 CEID50%/mL per dose.

20. The COVID-19 vaccine according to claim 18, wherein the volume per dose is 0.2 to 2 mL.

21. The COVID-19 vaccine according to claim 8, wherein the COVID-19 vaccine is adapted to be administrable intramuscularly, intranasally, subcutaneously, by spraying, or by nebulization.

22. The COVID-19 vaccine according to claim 21, wherein the COVID-19 vaccine is adapted to be administrable intramuscularly or intranasally.

23. A method for treating or preventing coronavirus disease 2019 (COVID-19) in a subject, the method comprising administering to the subject an effective amount of the recombinant Newcastle disease virus (NDV) of claim 1.

24. The method of claim 23, wherein the recombinant NDV is administered in a dose between 10.sup.6.0 and 10.sup.10.0 CEID50%/mL in a volume between 0.2 and 2 mL.

25. The method of claim 24, wherein the recombinant NDV is administered in a dose between 10.sup.6.5 and 10.sup.8.5 CEID50%/mL.

26. The method of claim 23, wherein the recombinant NDV is administered intramuscularly, intranasally, subcutaneously, by spraying, or by nebulization.

27. The method of claim 24, wherein the recombinant NDV is administered intranasally in a dose between 10.sup.7.5 and 10.sup.8.5 CEID50%/mL.

28. The method of claim 24, wherein the recombinant NDV is administered intramuscularly in a dose between 10.sup.7.0 and 10.sup.8.5 CEID50%/mL.

29. The method of claim 26, wherein the recombinant NDV is administered in a first dose and a second dose.

30. The method of claim 29, wherein the recombinant NDV is administered 7 to 35 days apart between the first dose and the second dose.

31. The method of claim 30, wherein the recombinant NDV is administered 21 to 28 days apart between the first dose and the second dose.

32. The method of claim 29, wherein the first dose is administered intranasally and the second dose is administered intramuscularly.

33. The method of claim 23, wherein the recombinant NDV generates mucosal immunity against infection by SARS-COV-2.

34. A method for treatment or prevention of coronavirus disease 2019 (COVID-19) caused by SARS-COV-2 in a subject, the method comprising administering a first dose, followed by a second dose, of an effective amount of the recombinant NDV of claim 1 to the subject, wherein the first dose is an active recombinant NDV administered intranasally and the second dose is an active recombinant NDV or an inactivated recombinant NDV administered intramuscularly.

35. The method of claim 34, wherein the second dose is the active recombinant NDV.

36. The method of claim 34, wherein the second dose is the inactivated recombinant NDV.

Description

BRIEF DESCRIPTION OF THE INVENTION

(1) For this, a recombinant vaccine has been invented that comprises a viral vector based on Newcastle disease virus having inserted an exogenous nucleotide sequence of severe acute respiratory syndrome coronavirus 2 (SARS-COV-2), capable of generating a cellular immune response, and a pharmaceutically acceptable carrier, adjuvant, and/or excipient.

DETAILED DESCRIPTION OF THE INVENTION

(2) During development of the present invention, it has been unexpectedly found that a recombinant vaccine comprising a paramyxovirus viral vector capable of generating a cellular immune response, having inserted an exogenous nucleotide sequence encoding for antigenic sites of syndrome acute respiratory disease coronavirus 2 (SARS-COV-2), and a pharmaceutically acceptable carrier, adjuvant and/or excipient, provides a suitable protection against coronavirus disease 2019 (COVID-19).

(3) The used viral vector can be active (live) or inactivated (dead), by inactivated being understood that the recombinant virus that functions as a viral vector and contains the nucleotide sequence encoding for antigenic sites of SARS-COV-2 has lost the property of replicate. Inactivation is achieved by physical or chemical procedures well known in the art, preferably by chemical inactivation with formaldehyde or beta-propiolactone (Office International des Epizooties 2008, Newcastle Disease. OIE Manual of Diagnostic Tests and Vaccines for Terrestrial Animals. Office International des Epizooties, France, p. 576-589). On the other hand, it is understood that an active or live virus maintains its ability to replicate.

(4) Preferably, the used viral vector is a paramyxovirus which is selected from any paramyxovirus including any serotype, genotype or genetic class, including lentogenic, mesogenic and velogenic viruses. Likewise, it is preferred to use paramyxoviruses to which reverse genetic techniques can be performed to eliminate phenylalanine in position 117 and the basic amino acids in position close to position Q114 that give pathogenicity to paramyxoviruses, or paramyxoviruses included in the genus Avulavirus that infect birds, such as Newcastle disease virus (NDV) or Sendai virus. More preferably, the viral vector is NDV and said viral vector is preferably selected from lentogenic or mesogenic strains, such as LaSota, B1, QV4, Ulster, Roakin, Komarov strains, Preferably, the recombinant virus is from LaSota strain. Even more preferably, the NDV viral vector comprises SEQ ID NO:6 or SEQ ID NO:14.

(5) With regard to the exogenous nucleotide sequence encoding for antigenic sites of SARS-COV-2, in the case of the present invention the used nucleotide sequence is preferably selected from a sequence encoding the SARS-COV-2 spike glycoprotein S or a sequence encoding a sequence derived thereof. The SARS-COV-2 spike glycoprotein S comprises two functional subunits responsible for binding to the host cell receptor (S1 subunit) and fusion of viral and cellular membranes (S2 subunit). In a preferred embodiment of the invention, the exogenous nucleotide sequence encoding for antigenic sites of SARS-COV-2 is selected from a sequence encoding the S1 subunit of SARS-COV-2 spike glycoprotein S, a sequence encoding the S2 subunit of SARS-COV-2 spike glycoprotein S, a sequence encoding the two of S1 and S2 subunits of SARS-COV-2 spike glycoprotein S, a sequence encoding at least one fragment of S1 or S2 subunits of SARS-Cov-2 spike glycoprotein S, a sequence having at least 80% of identity with the sequence encoding the S1 subunit of SARS-Cov-2 spike glycoprotein S, a sequence having at least 80% of identity with the sequence encoding the S2 subunit of SARS-COV-2 spike glycoprotein S, a sequence having at least 80% of identity with the sequence encoding the two of S1 and S2 subunits of SARS-COV-2 spike glycoprotein S, a sequence having at least 80% of identity with a sequence encoding at least one fragment of S1 or S2 subunits of SARS-CoV-2 spike glycoprotein S, a sequence encoding the two of S1 and S2 subunits of SARS-COV-2 spike glycoprotein S lacking of at least one epitope located between nucleotides corresponding to amino acids 1 to 460 of the sequence of S1, a sequence encoding the S1 subunit of SARS-COV-2 spike glycoprotein S lacking of at least one epitope located between nucleotides corresponding to amino acids 1 to 460 of the sequence of S1, or a sequence encoding the two of S1 and S2 subunits of SARS-CoV-2 spike glycoprotein S, stabilized in its prefusion form by including at least two substitutions of proline in S2 subunit. In a preferred embodiment, the epitope located between nucleotides corresponding to amino acids 1 to 460 of the sequence of S1 is selected from amino acid sequences SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9 or SEQ ID NO:10. In other preferred embodiment, the exogenous nucleotide sequence encoding for antigenic sites of SARS-COV-2 is selected from a sequence with an identity of at least 80% with any of the sequences SEQ ID NO:1, SEQ ID NO:2, SEQ ID NO: 3, SEQ ID NO:4 or SEQ ID NO:5. In a further preferred embodiment, the sequence encoding the two of S1 and S2 subunits of SARS-COV-2 spike glycoprotein S stabilized in its prefusion form by including at least two substitutions of proline in S2 subunit, is selected from a sequence having at least 80% of identity with any sequence that translates into any of the amino acid sequences SEQ ID NO:11, SEQ ID NO:12 or SEQ ID NO:13.

(6) The exogenous nucleotide sequence encoding the antigenic sites of SARS-COV-2 of the vaccine of the present invention can be prepared by chemical synthesis of the nucleotide sequence of interest so that it can subsequently be inserted into the NDV viral vector. The insertion of the exogenous nucleotide sequence is carried out using standard cloning techniques of molecular biology and can be inserted into any intergenic regions of NDV genome. The thus produced infectious clone is transfected into a cell culture for generating recombinant virus or parent virus.

(7) The virus replicates through consecutive passages in any system suitable for growing, such as SPF chicken embryo, or commercial cell lines or expressly designed for growing of viruses, until reaching the concentration of the virus that is required to achieve the antigenic response, preferably between 10.sup.6.0 and 10.sup.10.0 CEID50% (Chicken Embryo Infectious Dose 50%)/mL. It is preferred that the virus be stable after at least three consecutive passages in the system used for growth once rescued from the cell culture, so that a stable production is achieved on an industrial scale. For virus isolation, the virus is removed from the system appropriate for growing and is separated from cellular or other components, typically by well-known clarification procedures such as filtration, ultrafiltration, gradient centrifugation, ultracentrifugation, and column chromatography, and can be further purified as desired using well known procedures, e.g., plaque assays.

(8) In the embodiment in which the vaccine is active, it is a natural lentogenic active vaccine virus or one attenuated by methods already known in the art. On the other hand, when the vaccine is inactivated, once the viral concentration required to achieve the antigenic response has been reached, the virus is inactivated. Preferably, the inactivation is carried out by physical or chemical procedures well known in the art, preferably by chemical inactivation with formaldehyde, beta-propiolactone or binary ethyleneimine (BEI).

(9) Pharmaceutically acceptable carriers for the vaccines of the present invention are preferably aqueous solutions or emulsions. More particularly, in the case of active virus vaccines aqueous solutions are preferred, and in the case of inactivated vaccines preferably the used carrier is compatible with an immune adjuvant used to enhance the immune response to the inactivated vaccine. In a further embodiment in which the vaccine is inactivated, the vaccine is preferably accompanied by a pharmaceutically acceptable adjuvant. In an embodiment in which an adjuvant is used, adjuvants based on squalenes are preferred; preferably those referred as MF-59 or AddaVax or AS03, TLR-9 receptor agonists, such as CpG-1018, or cationic lipids such as R-DOTAP.

(10) Regarding the administration of the vaccine, it can be administered intramuscularly, intranasally, subcutaneously, by spraying or nebulization, using the appropriate means and forms for each case and depending on whether it is an active vaccine or an inactivated vaccine. Preferably, the vaccine administration is carried out at least once intramuscularly and/or intranasally.

(11) In a particularly preferred embodiment, the vaccine is administered at least twice to generate a higher immune response, either by maintaining the route of administration or changing the route of administration, with a virus concentration preferably between 10.sup.6.0 and 10.sup.8.5 CEID50%/mL per dose, according to the volume of vaccine to be applied according to the selected route of administration. Preferably the vaccine is administered twice intramuscularly either in active or inactivated form, twice intranasally in its active form, or once intranasally, followed by once intramuscularly. Administration of vaccines in an embodiment which is administered twice, can be carried out within a period of 7 to 35 days between the first and second administration, preferably within a period of 14 to 28 days between the first and second administration, and more preferably it is administered the first time by intranasal route in its active form and the second time by intramuscular route, either in its active or inactivated form.

(12) In another aspect of the present invention, it has been found that it is possible to administer intranasally a dose of an active virus comprising antigenic sites of the severe acute respiratory syndrome coronavirus 2 (SARS-COV-2), preferably the recombinant paramyxovirus of the present invention, followed by a second intramuscular dose of a SARS-COV-2 antigen, achieving a highly efficient immune response. Preferably, the antigen of the second dose is the same active virus of the first dose, but once the immunization has been carried out by intranasal route, a skilled in the art can infer that it is possible to deliver intramuscularly any other SARS-COV-2 antigen. Still more preferably, the antigen of the second dose is the same virus of the first dose in its inactivated form.

(13) Preferably, the vaccine of the present invention is formulated with a volume of 0.5 mL per dose that contains the virus concentration corresponding to its intramuscular application, either in its active or inactivated form. In an embodiment where the route of administration is intranasal, the preferred volume per dose is 0.2 mL.

(14) The vaccine according to the principles of the present invention, additionally, does not cause adverse events in mammals.

(15) The present invention will be better understood from the following examples, which are presented only for illustrative purposes to allow a thorough understanding of the preferred embodiments of the present invention, not implying that there are no other, non-illustrated embodiments that may be implemented based on the above detailed description.

Example 1

(16) Generation of NDV LaSota Vectors

(17) To clone the RNA genome of NDV strain LaSota and thus generate a viral vector in the form of plasmid DNA referred as pLS11801140 (SEQ ID NO:6), firstly extraction of total viral RNA from NDV strain LaSota was carried out by triazole method. From the purified RNA, the synthesis of cDNA (complementary DNA) of the viral genome was carried out, using the previously purified total RNA as a template. In order to clone all of the genes of NDV genome (15,183 base pairs (bp)), 7 fragments with overlapping ends and cohesive restriction sites were amplified by PCR. Fragment 1 (F1) spans from nucleotide (nt) 1-1755, F2 goes from nt 1-3321, F3 comprises from nt 1755-6580, F4 goes from 6,151-10,210, F5 spans from nt 7,381-11,351, F6 goes from 11,351-14,995 and F7 comprises from nt 14,701-15,186. The 7 fragments were assembled within the cloning vector referred as pLS11801140 (SEQ ID NO:6) using standard ligation techniques, which allowed reconstruct the NDV LaSota genome, which after cloning contains a unique SacII restriction site between the P and M genes, which serves for cloning of any gene of interest in this viral region of the vector. In addition, another vector referred as pLS11801140_L289A (SEQ ID NO:14) was generated, for which the same process above described for pLS11801140 was followed, but including the amino acid L289A in the F gene of the NDV genome.

Example 2

(18) Cloning of Various Exogenous Nucleotide Sequences of SARS-COV-2 in SacII Site of Vector pNDVLS11801140

(19) To clone various exogenous nucleotide sequences derived from the SARS-COV-2 spike glycoprotein S, the following 6 versions of the SARS-COV-2 spike glycoprotein S gene were assembled in silico using the software Vector NTI, based on the Wuhan-Hu-1 strain (accession number NC_045512.2): Spike S1/S2 SARS-COV-2: Sequence of SARS-COV-2 spike glycoprotein S (with S1 and S2 subunits) not modified (SEQ ID NO:1). Spike S1 SARS-COV-2/TMCyto: Sequence of S1 subunit of SARS-COV-2 spike glycoprotein S fused to the transmembrane and cytoplasmic sequence (TMCyto) of F gene of NDV (SEQ ID NO:2). Spike S1/S2 SARS-COV-2/TMCyto: Sequence of ectodomain of SARS-COV-2 spike glycoprotein S fused to the transmembrane and cytoplasmic sequence (TMCyto) of F gene of NDV (SEQ ID NO:3). Spike S1/S2 SARS-COV-2/PreF: Sequence of ectodomain of SARS-COV-2 spike glycoprotein S fused to the transmembrane and cytoplasmic sequence (TMCyto) of F gene of NDV, modified so that the NDV protein F acquired the pre-fusion conformation. The cleavage site of spike glycoprotein S was mutated from RRAR to A and 2 mutations of proline were introduced in amino acids K986P and V987P (SEQ ID NO:4). Spike S1/S2 SARS-COV-2/PreF/-ADE: Sequence of ectodomain of SARS-COV-2 spike glycoprotein S fused to the transmembrane and cytoplasmic sequence (TMCyto) of F gene of NDV, modified so that the NDV protein F acquired the pre-fusion conformation and avoid antibody dependent infection (ADE) amplification. The cleavage site of spike glycoprotein S was mutated from RRAR to A and 2 mutations of proline were introduced in amino acids K986P and V987P, and a deletion of the epitope corresponding to amino acids located in positions 363 to 368 was synthetically introduced (SEQ ID NO:5). Spike S1/S2 SARS-COV-2/Hexapro: Sequence of ectodomain of SARS-COV-2 spike glycoprotein S stabilized in its prefusion form and four additional prolines distributed in the synthetic gene to give greater stability to spike protein expressed by NDV (SEQ ID NO:11).

(20) The above sequences were initially independently cloned into a pUC vector. The pUC inserts were then subcloned by standard genetic engineering techniques into the unique restriction site SacII, located between the P and M genes of genome of NDV LaSota contained in the plasmid pLS11801140 (SEQ ID NO:6). The plasmid pLS11801140 (SEQ ID NO:6) also contains all the transcription and translation signal sequences so that each of the five versions of the genes can be transcribed and translated and thus generate 6 different versions of the SARS-COV-2 spike glycoprotein S. As a result of the cloning process six NDV DNA. (complementary DNA) clones were generated, referred as, respectively: pNDVLS/Spike S1/S2 SARS-Cov-2. pNDVLS/Spike S1 SARS-COV-2/TMCyto. pNDVLS/Spike S1/S2 SARS-COV-2/TMCyto. pNDVLS/Spike S1/S2 SARS-COV-2/PreF. pNDVLS/Spike S1/S2 SARS-COV-2/PreF/-ADE. pNDVLS/Spike S1/S2 SARS-COV-2/Hexapro.

(21) Each of the generated plasmids was characterized by PCR to detect the presence of each version of the SARS-COV-2 spike glycoprotein S. They were also characterized by restriction enzyme digestion, obtaining the expected restriction patterns. Stability and sequence of the PCR product of each version of SARS-COV-2 spike glycoprotein S were confirmed by sequencing.

Example 4

(22) Generation of Recombinant Viruses

(23) Each of the plasmids generated in the above example was transformed by a chemical method and then was independently propagated in E. coli for 16 hours under continuous stirring at 37 C. DNA of each clone was purified by standard molecular biology procedures. Ten micrograms (g) of purified DNA were used in transfection experiments by using lipofectamine in Hep2 and A-549 cells. Forty-eight hours after transfection, each of the recombinant viruses generated from the 6 transfections was recovered from the supernatant and used in viral propagation assays in specific pathogen-free (SPF) embryonated chicken eggs for the subsequent preparation of the vaccines.

Example 5

(24) Propagation of Recombinant Viruses

(25) SPF embryonated chicken eggs were inoculated with the production seeds, with the infecting dose previously determined for each of the recombinant viruses prepared in the previous example. The embryos were incubated at 37 C. for a period of 48 hours, checking mortality daily. After this period, the live embryos were refrigerated from one day to the next, preferably for 24 hours; the amnio-allantoic fluid (FAA) was harvested under aseptic conditions and clarified by centrifugation. The FAA was used to characterize by hemagglutination the generation of recombinant virus rescued from the E. coli cellular culture and by RT-PCR, using specific primers to amplify the sequence located between the P and M genes, and demonstrate the presence of the various versions of the SARS-COV-2 spike glycoprotein S cloned in each of the recovered recombinant viruses. Once the identity was established by RT-PCR, the stability of the various inserts was established by sequencing each of them. From the transfection and propagation assays in SPF chicken embryonated eggs, the following 6 recombinant viruses were generated: rNDVLS/Spike S1/S2 SARS-Cov-2. rNDVLS/Spike S1 SARS-COV-2/TMCyto. rNDVLS/Spike S1/S2 SARS-COV-2/TMCyto. rNDVLS/Spike S1/S2 SARS-COV-2/PreF. rNDVLS/Spike S1/S2 SARS-COV-2/PreF/-ADE. rNDVLS/Spike S1/S2 SARS-COV-2/Hexapro.

Example 6

(26) Manufacture of Active and Inactivated Vaccines Against COVID-19

(27) The viruses prepared in the previous example were purified from FAA as previously described in the art (SANTRY, Lisa A., et al. Production and purification of high-titer Newcastle disease virus for use in preclinical mouse models of cancer. Molecular TherapyMethods & Clinical Development, 2018, vol. 9, p. 181-191; and NESTOLA, Piergiuseppe, et al. Improved virus purification processes for vaccines and gene therapy. Biotechnology and Bioengineering, 2015, vol. 112, no. 5, p. 843-857.).

(28) The active vaccines were prepared to be administered by intramuscular and intranasal routes in aqueous solution. For this, the FAA was mixed with a stabilizing solution (TPG) so that three vaccines were obtained with four different concentrations depending on the volume required to be applied in the vaccine: providing a minimum of 10.sup.7.0 CEID50%/mL per dose, providing a minimum of 10.sup.7.5 CEID50%/mL per dose, providing a minimum of 10.sup.8.0 CEID50%/mL per dose, and providing a minimum of 10.sup.8.5 CEID50%/mL per dose.

(29) Table 1 shows the composition of 1 L of TPG stabilizing solution.

(30) TABLE-US-00001 TABLE 1 Component Amount Trehalose Dihydrate 75.0 g Dibasic Sodium Phosphate 1.30 g Monobasic Potassium Phosphate 0.50 g Monosodium glutamate 0.90 g Water for injection 1,000 mL

(31) Similarly, viruses purified with the same technique used for active vaccines were inactivated by chemical inactivation with a 10% formaldehyde solution in PBS added dropwise, and a water-oil-water type emulsion was made as an adjuvant to perform a test on pigs. The oil phase corresponds to 25% of formulation, the internal aqueous phase to 25% of formulation, and the external aqueous phase to 50% of formulation. Sterile purified water and Span 80 and Tween 80 type surfactants were used for preparing the aqueous phase. Mineral oil and Span 80 and Tween 80 type surfactants were used for preparing the oily phase. Thus, four vaccines with four different concentrations were obtained: providing a minimum of 10.sup.7.0 CEID50%/mL per dose, providing a minimum of 10.sup.7.5 CEID50%/mL per dose, providing a minimum of 10.sup.8.0 CEID50%/mL per dose, and providing a minimum of 10.sup.8.5 CEID50%/mL per dose. To make the emulsion, the aqueous phase was slowly added to the oil phase under constant stirring. To achieve the specified particle size a homogenizer was used.

Example 7

(32) Stability Tests of Constructs in Consecutive Passages

Example 7AStabilization of Protein S (Spike) with Two Prolines

(33) Two of the constructs made according to example 5 were subjected to consecutive passages in SPF embryos as described in such example 5, and the recovered viruses were tested to confirm their stability and identity, particularly with regard to the obtained viral titer and permanency and integrity of the inserted SARS-COV-2 antigen.

(34) The construct of example 5 referred as rNDVLS/Spike S1/S2 SARS-COV-2/PreF comprises the gene ectodomain, which will be fused to the Transmembrane and Cytoplasmic region (TMC or TMCyto) of the F (Fusion) gene of Newcastle virus. This fusion ensures that the Spike protein encoded by this chimeric gene (Ectodomain+TMCyto), is incorporated into the Newcastle capsid and is exposed on the viral surface as the main antigen. The nucleotide sequence of the chimeric gene in this version has codon usage optimized for human. The cleavage site for Furin (F) was removed and two prolines were introduced to the sequence to ensure the pre-fusion structure of the final protein.

(35) According to literature and previous studies based on the SARS-COV virus, this structure with two prolines is able to stabilize the structure of the Spike protein for generating antibodies with the correct conformation to neutralize SARS-COV-2 virus.

(36) Once generated, the obtained parent virus was characterized by RT-PCR to ensure the presence of the cloned Spike gene within the NDV genome. The identity and stability of Spike gene within the Newcastle genome were also confirmed by sequencing. Expression of the Spike protein expressed by the parent virus was also confirmed by immunoperoxidase.

(37) This parent virus was propagated by two consecutive passages in a 10 days old SPF chicken embryo in order to increase the titer and generate the Master Seed, and one more passage in a chicken embryo to generate the Production Seed from which an experimental vaccine was formulated.

(38) Characterization tests by RT-PCR of the master seed, production seed and generated experimental vaccine, resulted positive, with the band corresponding to the inserted Spike gene amplified. However, when the recombinant virus of each passage was sequenced, three mutations in the Spike gene were identified. A transcription stop codon was located in the coding sequence in subunit 2, and two more mutations in the carboxy terminal region.

(39) In the immunoperoxidase analysis to detect expression of the Spike protein in the master seed, production seed and experimental vaccine, a gradual decrease in expression was observed. The more passages, the smaller amount of protein was detected by anti-Spike antibody, to such a degree that the experimental vaccine results in an almost zero percentage of Spike protein. These results indicated that the Spike gene may be detected by RT-PCR and remained inserted into the vector; however, with each passage in the chicken embryo the stability of the gene was disrupted.

(40) Still, since the master seed had a good result of Spike expression by immunoperoxidase, this material was used to formulate the vaccine used in the pre-clinical trial in pigs.

(41) However, the analysis of the sera of the 0 and 21 days old vaccinated pigs indicated that the Spike protein, expressed by the recombinant virus of rNDVLS/Spike S1/S2 SARS-COV-2/PreF version of the example 5, did not induce specific IgG antibodies, nor specific neutralizing antibodies against SARS-COV-2.

(42) This result clearly shows that, despite the structure designed with two prolines in the sequence, the generation of the Spike protein was compromised, resulting in the expression of Spike protein with a three-dimensional structure not suitable for induction of neutralizing antibodies, contrary to what was expected.

Example 7BStabilization of Protein S (Spike) with 6 Prolines

(43) The Spike gene of the rNDVLS/Spike S1/S2 SARS-COV-2/Hexapro version preserve the ectodomain of the Spike gene fused to Transmembrane and Cytoplasmic region (TMC or TMCyto) of the F (Fusion) gene of Newcastle virus. The nucleotide sequence of the chimeric gene has codon usage optimized for human. The cleavage site for Furin (F) was removed and six prolines were introduced into the sequence to ensure the Hexa-pro structure of the final protein.

(44) The same process methodology was applied to generate the Hexa-pro parent virus and subsequent master seeds, production seed and experimental vaccine. With this design, the same tests conducted in accordance to example 7A, RT-PCR, sequencing, immunoperoxidase and SDS-PAGE (Coomassie), resulted positive for identity and stability of quimeric Spike Hexa-Pro protein, different from the construct of such example 7A.

(45) The recombinant virus rNDVLS/Spike S1/S2 SARS-COV-2/Hexapro from example 5 was used in pre-clinical trials in SPF pigs, with positive results for detection of IgG antibodies and neutralizing antibodies against SARS-COV-2.

Example 8

(46) Study to Assess the Safety and Immunogenicity Level Produced in Pigs by the Active Vaccine Against COVID-19

(47) A study was carried out to evaluate the safety and immunogenicity of the vaccine in accordance to the principles of the present invention in SPF pigs.

(48) For this study, a virus was designed using the plasmid pLS11801140_L289A (SEQ ID NO: 14) generated in example 1 with the Spike S1/S2 SARS-COV-2/Hexapro version, following the process previously described in examples 2-6.

(49) The vaccine was formulated in four doses of 10.sup.7.0 CEID50%/mL, 10.sup.7.5 CEID50%/mL, 10.sup.8.0 CEID50%/mL, 10.sup.8.5 CEID50%/mL of live or active virus per dose by different routes of administration (oral, intramuscular and its combination) with two applications of the doses. The safety level was determined by measuring the presence or absence of adverse reactions after the vaccine application. The immunogenicity was evaluated by comparing the immune response generated after the application of the two doses of vaccine by means of an ELISA test for detecting neutralizing antibodies (GenScript) against the RBD protein of SARS-COV-2 (28 dpv). Table 3 shows the study design.

(50) TABLE-US-00002 TABLE 3 Route Application Number of Vaccine IN IM volume applications Group Pigs 10.sup.8.0 CEID50%/mL XX 2.0 mL 2 (0 and 21 1 8 active virus days) 10.sup.7.5 CEID50%/mL XX 2.0 mL 2 (0 and 21 2 6 active virus days) 10.sup.7.0 CEID50%/mL XX 2.0 mL 2 (0 and 21 3 6 active virus days) 10.sup.8.5 CEID50%/mL XX 1.0 mL 2 (0 and 21 4 6 active virus days) 10.sup.8.0 CEID50%/mL XX 1.0 mL 2 (0 and 21 5 6 active virus days) 10.sup.7.5 CEID50%/mL XX 1.0 mL 2 (0 and 21 6 6 active virus days) 10.sup.7.0 CEID50%/mL XX 1.0 mL 2 (0 and 21 7 6 active virus days) 10.sup.7.5 CEID50%/mL X X 2.0 mL/1.0 2 (0 days) 8 6 active virus mL 10.sup.7.5 CEID50%/mL X X 2.0 mL/1.0 2 (0 and 21 9 6 active virus mL days) 10.sup.8.0 CEID50%/mL XX 1.0 mL 2 (0 and 21 10 6 active virus days) wherein: IN = Intranasal, IM = Intramuscular, X = 1 dose

(51) A total of 62 SPF pigs of similar age/body weight (3-4 weeks old) were used in the study in different experimental groups. Animals were randomly placed according to their weight in isolation cubicles. No relevant adverse reactions were observed in any of the animals.

(52) Animals were observed for clinical signs throughout the study period. The monitored clinical signs were abnormal respiration, abnormal behavior, and rectal temperature each morning. For animal welfare reasons the animals were observed more than once a day.

(53) In the clinical report only in group 10 (inactivated vaccine) was observed that one of the piglets presented an adverse reaction 30 seconds post vaccination, showing salivation, depression and muscle tremors; the piglet was immediately treated, damped with cold water and the response was evaluated; 5 minutes after the adverse reaction, the pig did not show serious clinical manifestations, remained depressed for 1 hour and returned to normal. With the second vaccine application this pig did not show any kind of post vaccinal adverse reaction.

(54) There were no evident clinical manifestations in the daily check-ups in any of the piglets in all groups throughout the test. This indicates that the used vaccines, with different titles and routes of application, were safe and complied with the safety test.

(55) To determine the viral load, samples (nasal swabs on day 0 pre vaccination, 1 day after the first vaccination and 1 day after the second vaccination) were taken to assess the vaccine presence based on the load of genetic material of the vaccine virus. The genetic load was also assessed after sacrifice in lung tissue samples by RT-PCRtrq against the vector virus (NDV) and detecting the insert encoding the SARS-COV-2 Spike protein in the same vector.

(56) All samples were negative for detection of genetic material against the vector virus (NDV), both in the baseline sampling and 24 hours after the first vaccination.

(57) For the assessment of antibodies against SARS-COV-2 Spike, a commercial ELISA kit (GenScript) authorized by the FDA was used, which detects in a non-functional way neutralizing antibodies against RBD of SARS-COV-2 virus.

(58) The degree of immunogenicity induced by vaccination was assessed by production of neutralizing antibodies (GenScript cPass) against RBD protein of SARS-COV-2. Serological samples were taken at day 0, 21, and 28 after the first vaccination. The results for the groups at 35 days after the first vaccination are shown in the following table 4.

(59) TABLE-US-00003 TABLE 4 Elisa-Serum Virus- Mean Mean Title Neutralization Inhibition (ELISA- Group (+) () (%) Positive % VSN) Group 1 8 0 100 79.29 1:190 (log.sub.2 = 7.57) Group 2 4 2 66.66 55.52 Group 3 5 1 83.33 59.98 Group 4 6 10 100 95.39 Group 5 6 0 100 92.10 1:1,667 (log.sub.2 = 10.70) Group 6 6 0 100 92.85 1:700 (log.sub.2 = 9.45) Group 7 6 0 100 91.06 1:200 (log2 = 7.64) Group 8 4 1 80 32.06 Group 9 6 0 100 94.90 1:1,100 (log.sub.2 = 10.10) Group 10 6 10 100 96.04 1:1,800 (log.sub.2 = 10.81) Cx (+) Hum two 10 100 94.21 1:600 (log.sub.2 = 9.22 Cx (+) Kit NA NA NA 94.42 1 = 900 (log.sub.2 = 9.81)

(60) It should be noted that in order to compare these results, serum from a patient affected by SARS-COV-2 who had the disease at the same time the test conducting was included, identified as Cx (+), and it was observed that for several groups the mean titers were even higher than those of the convalescent patient.

(61) Additionally, for Group 1 which received two intranasal vaccines, the same test was conducted using oral fluids in order to detect the possibility of local immunity, the synergistic effect of which is observed in Group 9 which received the first dose by intranasal route and the second dose by intramuscular route. In this regard, although there are no comparable results, the antibody levels in oral fluids positive for Group 1 at day 28 and 35 suggest the possibility of prevention of infection by SARS-COV-2 virus in the primary infection route (upper respiratory mucosa) when two doses are administered intranasally.

(62) Similarly, fourteen days after the second application, day 35 after the first vaccination, all surviving animals were humanitarily sacrificed and lung, lymph nodes, liver, kidney and spleen samples were collected to determine the presence of the vaccine virus by RT-PCRtrq, as well as for histopathologic assessment of possible pulmonary lesions using the planimetry technique and macro- and microscopic changes of the lung, present in the lung for the intranasal route, and in the area of intramuscular application.

(63) After humanitarian sacrifice and necropsy of the pigs it was detected that the lungs of all the animals did not show lesions suggestive of viral infection and therefore from the used active vaccine. In the area of intramuscular vaccine application, no active or chronic inflammatory processes were detected, nor the presence of areas of fibrosis or abscesses, so indicating that the application of the vaccine by intranasal or intramuscular route did not generate lesions in the lung level or tissue level in the area of vaccine application.

(64) From this example it can be seen that, in accordance with the principles of the present invention, it is possible to obtain a stable recombinant virus for large-scale industrial production, which can exhibit safety and immunogenicity in a mammalian animal model by various routes of administration in its active or inactivated form.

(65) In this same example it is demonstrated that it is possible to administer by intranasal route a dose of an active virus comprising antigenic sites of SARS-COV-2, such as in the embodiment tested in example 8, followed by a second dose by intramuscular route of the same recombinant virus. From this experiment, a person skilled in the art can infer that it is possible to administer any other SARS-COV-2 antigen by intramuscular route to obtain protection, since it has been shown that application of the vaccine by intranasal route with a first dose was sufficient to stimulate a systemic response to the virus antigen by intramuscular route, which could be achieved by administering a different vaccine.

(66) Therefore, even when specific embodiments of the invention have been illustrated and described, it should be emphasized that numerous modifications are possible, such as the used virus as the viral vector, and the used exogenous viral sequence. Therefore, the present invention should not be construed as restricted except as required by the prior art and appended claims.