CN116785421B

CN116785421B - mRNA vaccine of bovine respiratory syncytial virus and application thereof

Info

Publication number: CN116785421B
Application number: CN202311047978.9A
Authority: CN
Inventors: 太万博; 尹鑫; 常继涛; 黄鹤
Original assignee: Beijing Hemu Biotechnology Co ltd; Harbin Veterinary Research Institute of CAAS
Current assignee: Beijing Hemu Biotechnology Co ltd; Harbin Veterinary Research Institute of CAAS
Priority date: 2023-08-21
Filing date: 2023-08-21
Publication date: 2024-01-09
Anticipated expiration: 2043-08-21
Also published as: CN116785421A

Abstract

The invention discloses an mRNA vaccine of bovine respiratory syncytial virus and application thereof, belonging to the technical field of nucleic acid vaccines. In order to improve the immunoprotection of bovine respiratory syncytial virus mRNA vaccine. The invention provides an mRNA vaccine of bovine respiratory syncytial virus, which codes an F protein mutant of the respiratory syncytial virus, and the amino acid sequence of the F protein mutant of the respiratory syncytial virus is shown as SEQ ID NO.13. Realizes the improvement of the immunity effect of the bovine respiratory syncytial virus.

Description

mRNA vaccine of bovine respiratory syncytial virus and application thereof

Technical Field

The invention belongs to the technical field of nucleic acid vaccines, and particularly relates to an mRNA vaccine of bovine respiratory syncytial virus and application thereof.

Background

Bovine respiratory syncytial virus (Bovine respiratory syncytial virus, BRSV) belongs to a member of the subfamily Pneumovirinae (Pneumovirus) of the Paramyxoviridae family (paramyxovirinae) and is one of the core causative agents of the respiratory disease syndrome in cattle. It has been shown that BRSV infection is widespread worldwide, with higher BRSV antibody positive rates in bovine populations in many countries, switzerland, japan, belgium, uk, canada, and the united states, reported 45% to 100% in the united states, 36% to 53% in canada, 52% to 90.8% in mexico, 54% in denmark. In China, BRSV infection of cattle groups in each province area is detected by detection methods such as RT-PCR, ELISA, neutralization test and the like, and the BRSV is found to be widely popular in China, however, no effective prevention and control vaccine is available in China at present, so that the demand of China on the BRSV vaccine is urgent.

The currently used BRSV vaccines abroad mainly include three types: attenuated live vaccine Rispoval RS (RB-94 attenuated strain), attenuated live vaccine Bayovac BRSV (Lehmkuhl 375 attenuated strain), and inactivated vaccine Vacores (220/69 strain). However, the existing vaccine has a certain defect in protection effect, the immunization of the inactivated vaccine only induces limited production of neutralizing antibodies, so that immune cattle cannot be effectively protected from infection, and part of cattle have side effects such as serious severity of respiratory diseases due to the enhancement of antibody dependence. Attenuated live vaccines can induce stronger immunoprotection, but have the risk of virulence reversion and lack safety.

Disclosure of Invention

The invention aims to improve the immunoprotection of bovine respiratory syncytial virus mRNA vaccine.

The invention provides an mRNA vaccine of bovine respiratory syncytial virus (Bovine respiratory syncytial virus), which codes for an F protein mutant of the respiratory syncytial virus, and the amino acid sequence of the F protein mutant of the respiratory syncytial virus is shown as SEQ ID NO. 9.

Further defined, the mRNA vaccine is composed of: the coding RNA gene of the F protein mutant of the respiratory syncytial virus, the 3' untranslated region and the poly-A.

Further defined is that the T7 promoter has a DNA sequence shown in SEQ ID NO.4, a 5 '-terminal untranslated region has a DNA sequence shown in SEQ ID NO.2, a 3' -terminal untranslated region has a DNA sequence shown in SEQ ID NO.3, a signal peptide has a DNA sequence shown in SEQ ID NO.5, and a sequence of the RNA gene encoding an F protein mutant of respiratory syncytial virus has a sequence shown in SEQ ID NO. 21.

The invention provides an application of an F protein mutant of bovine respiratory syncytial virus in preparing an mRNA vaccine for preventing or treating bovine respiratory disease syndrome, wherein the amino acid sequence of the F protein mutant of bovine respiratory syncytial virus is shown as SEQ ID NO.13.

The invention provides an application of a recombinant plasmid containing a DNA molecule for encoding the mRNA vaccine in preparing the mRNA vaccine for preventing or treating bovine respiratory disease syndrome.

The invention provides an application of a recombinant microbial cell containing the mRNA vaccine in preparing the mRNA vaccine for preventing or treating bovine respiratory disease syndrome.

The invention provides an application of lipid nano particles containing the mRNA vaccine in preparing the mRNA vaccine for preventing or treating bovine respiratory disease syndrome.

Further defined, the virus that causes the bovine respiratory disease syndrome is bovine respiratory syncytial virus.

The invention provides an application of the mRNA vaccine in preparing an antibody of bovine respiratory syncytial virus.

The invention provides an F protein mutant of bovine respiratory syncytial virus, which is characterized in that serine of 155 th and 290 th amino acids of an amino acid sequence of SEQ ID NO.11 is mutated into cysteine, the amino acid sequence of a transmembrane region is replaced by the amino acid sequence of a trimer structural domain of T4-bacteriophage fibrin, and the amino acid sequence of the transmembrane region is shown as SEQ ID NO. 9; the amino acid sequence of the trimer domain of the T4-phage fibrin is shown in SEQ ID NO. 14.

The beneficial effects are that:

1. vaccine design

The research is based on the amino acid sequence of F protein of BRSV Chinese strain LJX strain F, adopts bioinformatics and structural biology methods to carry out structural modification on the LJX strain F protein on a three-dimensional level, so that the strain F protein can be fixed in a pre-fusion state, forms a trimer structure and designs an mRNA vaccine.

First, the expressed protein is maintained in a pre-fusion state by site mutation: the mutation of the cysteine of the 155 th amino acid and the mutation of the cysteine of the 290 th amino acid are both S to C mutation, so that disulfide bonds which are not possessed by the original protein are formed, and the transformation of the conformation of the protein from fusion to fusion in the folding process is prevented; mutations at positions 190S to F and mutations at positions 207V to L stabilize the structure of the protein. The BRSV F protein modified as described above is immobilized in a pre-fusion state and is able to bind to the pre-fusion specific monoclonal antibody 58C 5.

The second aspect stabilizes its original trimeric conformation by deleting the transmembrane region and the trimeric structural design. The transmembrane region sequence after the 514 amino acid of the LJX strain F protein was deleted, and the trimeric domain of the T4-phage fibrin was introduced, and the amino acid sequence of the finally obtained mutated pre-fusion F protein was SEQ ID NO.13.

In the third aspect, the expression level of F protein is improved by two modifications of signal peptide design and single chain to improve the immune effect. In signal peptide selection, we selected prolactin signal peptide from animals protected cattle as signal peptide in BRSV F mRNA to increase F protein expression yield. Also, the LJX strain F protein has two protease cleavage sites removed to maintain F protein stability and increase yield.

2. Evaluation of vaccine Effect

The coding sequence of the F protein modified in the three aspects is subjected to codon optimization and sequence synthesis, and mRNA is prepared through in vitro transcription. Western Blot and Dot-ELISA detection were performed using specific monoclonal antibodies directed against pre-fusion and trimers of the F protein, both of which showed that the plasmid and the F protein expressed by mRNA had been immobilized in a pre-fusion state and a trimeric structure was formed. The BRSV mRNA vaccine is prepared by mass analysis such as lipid nanoparticle packaging, particle size detection and the like, and is named as BRSV-preF mRNA vaccine. Immunization of mice and calves with the prepared BRSV-preF mRNA vaccine induces the production of high-level IgG antibodies and neutralizing antibodies against BRSV. Safety experiments show that the prepared mRNA vaccine has immune protection on calves and safety.

Drawings

FIG. 1 is a diagram showing the antigen expression vectors pCAGGS-prolactin-EGFP and pCAGGS-prolactin-F;

FIG. 2 is a diagram showing agarose gel electrophoresis for the restriction enzyme digestion identification of the antigen expression vector pCAGGs-probactatin-F;

FIG. 3 is a graph of Western Blot detection results in a BRSV-F protein expression validation experiment;

FIG. 4 is a graph showing the detection result of Dot-ELISA in BRSV-F protein expression verification experiments;

FIG. 5 is a schematic representation of in vitro transcribed BRSV-preF mRNA sequences;

FIG. 6 is a graph of Western Blot detection results in a BRSV-preF mRNA protein expression validation experiment;

FIG. 7 is a graph showing the results of electron microscopy of BRSV-preF mRNA vaccine;

FIG. 8 is a graph showing the results of particle size detection of BRSV-preF mRNA vaccine;

FIG. 9 is a graph showing the detection results of specific IgG antibodies on mice for BRSV-preF mRNA vaccine;

FIG. 10 is a graph showing the results of detection of specific neutralizing antibodies in mice by BRSV-preF mRNA vaccine;

FIG. 11 is a graph showing the results of detection of antibodies in murine sera at 8 and 19 weeks after boost of BRSV-preF mRNA vaccine.

Detailed Description

Example 1 construction of an antigen expression vector for bovine respiratory syncytial Virus mRNA vaccine

The bovine respiratory syncytial virus mRNA vaccine sequence comprises the following elements: t7 promoter, 5 'untranslated region (5' UTR), signal peptide sequence, mRNA sequence encoding pre-fusion F antigen, 3 'untranslated region (3' UTR) and poly ( A).

The construction method of the antigen expression vector plasmid is as follows:

the following gene sequences were synthesized by the golden srey biosystems: the recombinant plasmid comprises polyA (SEQ ID NO. 1), 5'UTR (SEQ ID NO. 2), 3' UTR (SEQ ID NO. 3), T7 promoter (SEQ ID NO. 4), prosapon signal peptide sequence (SEQ ID NO. 5) and F protein gene sequence (SEQ ID NO. 6) of BRSV after codon optimization, and is connected to a pCAGGS vector, and the synthetic plasmid is named pCAGGS-prosapon-F; polyA (SEQ ID NO. 1), 5'UTR (SEQ ID NO. 2), 3' UTR (SEQ ID NO. 3), T7 promoter (SEQ ID NO. 4), prosapon signal peptide sequence (SEQ ID NO. 5) and EGFP protein gene sequence (SEQ ID NO. 7), and the synthetic plasmid named pCAGGS-prosapon-EGFP, which is ligated to pCAGGS vector, the map of the recombinant vector is shown in FIG. 1;

the synthetic plasmid pCAGGS-prolactin-F, pCAGGS-prolactin-EGFP is added to competent DH5 alpha competent cells of the Optimago company respectively, ice-bath is carried out for 30min, heat shock is carried out at 42 ℃ for 90s, ice-bath is carried out for 2min, 1mL LB culture solution is added, shaking table is carried out at 200rpm at 37 ℃ for 30min, 100uL bacterial solution is coated on a carbana resistant solid agar culture plate, and colonies are picked up the next day. The following day, the monoclonal was picked into LB medium.

Plasmids in 200 mL bacterial liquid are respectively extracted through a plasmid maxi kit product of Qiagen company, and the plasmids are pCAGGS-prolactin-EGFP and pCAGGS-prolactin-F. Using New England Biolabs CoXhoI andKpni restriction enzyme was subjected to double restriction identification, and the extracted plasmid was sequenced by Harborborui Corp to confirm that the sequence was correct (FIG. 2).

Example 2 expression verification experiments on pCAGGs-probactin-F plasmid vector

The pCAGGs-prolactin-F plasmid was transfected into HEK-293T cells by PEI reagent for verification of expression. And (3) paving the 293T cells into six-well plate cells on the previous day, and performing transfection experiments until the cell density reaches 80% -90% on the next day. 2ug of plasmid was transfected per well of 293T cells, and after 48 h transfection, cell lysates and supernatants were collected. Cell lysates and supernatants were subjected to sample treatment by adding DDT-containing 5×loading buffer, and subjected to reducing SDS-PAGE electrophoresis using specific BRSV F-specific antibodies to obtain Western Blot results (FIG. 3). As a result, as shown in FIG. 3, protein bands conforming to the expected sizes appeared in the test group transfected with pCAGGS-probactatin-F plasmid, compared with the vector control group, demonstrating secretory expression of the BRSV-F target antigen sequence carrying the probactatin signal peptide.

Cell lysates and supernatant samples were verified for expression and trimer structure by Dot-ELISA experiments (FIG. 4). Lysates and supernatants of 293T cells transfected with pCAGGS-prolactin-EGFP vector control and pCAGGS-prolactin-F experimental groups were loaded on NC membranes, and after blocking, were examined using a specific anti-F protein-specific monoclonal antibody (58C 5) before fusion, a specific monoclonal antibody (SC 5) against F protein before fusion and a specific monoclonal antibody (30D 8) against F protein after fusion, respectively (see International patent WO2012/006596 and US20110076268A 1).

The Dot-ELISA experimental result shows that the F protein coded by the antigen expression plasmid pCAGGS-probactatin-F can be effectively secreted, and the F protein conformation before fusion is maintained, and the F protein has a trimer structure.

EXAMPLE 3 preparation of mRNA vaccine

1. In vitro transcription of mRNA

The plasmids obtained in example 1 (pCAGGS-prolactin-EGFP; pCAGGS-prolactin-F) were each prepared by using New England Biolabs companyBsaI restriction endonuclease was cut to linearize the plasmid. Next, purification of linearized DNA was performed, 1/10 volume of 3M sodium acetate (pH=5.2) and 3 volume of absolute ethanol were added, the system was placed at-20℃for 1 hour, centrifuged at 15000 rpm for 30 minutes at 4℃by the centrifuge, the supernatant was discarded, and the DNA was resuspended in DEPC water to determine the DNA concentration.

In vitro transcription was performed using the mMESSAGE mMACHINE ™ T7 Transcription Kit product of Thermofisher company. The reaction was carried out in a PCR apparatus at 37℃for 2 hours. Adding TURBO DNase 1uL into the kit, mixing, and reacting at 37deg.C for 15min in a PCR instrument. Purification was performed using Qiagen's RNA purification kit, RNA on the adsorption column was eluted using DEPC water, the concentration of RNA was measured by a Nanodrop instrument, and RNA was stored at-80 ℃. The schematic diagram of the transcribed RNA is shown in FIG. 5, and the RNA sequence is shown as SEQ ID NO.22 and SEQ ID NO. 23.

293T cells were plated uniformly in six well plates and RNA transfected using the Mirus company TransIT ™ -mRNA Transfection Kits kit with 2. Mu.g mRNA per well. After 48 h transfection, cell lysates and supernatants were collected, and were subjected to sample treatment by adding a DDT-containing 5×loading buffer, respectively, and Western Blot results were obtained by reducing SDS-PAGE electrophoresis using a specific BRSV F-specific antibody (FIG. 5). Western Blot results indicate that in vitro transcribed BRSV-preF mRNA can correctly express F protein and is secreted efficiently.

The nucleotide sequence of the poly A is shown as SEQ ID NO.1, and contains 50-150 bases A: AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA (SEQ ID NO. 1).

The 5' UTR sequence is:

GAAATAAGAGAGAAAAGAAGAGTAAGAAGAAATATAAGAGCCACCGCTAGCCTCGAG（SEQ ID NO.2）。

the 3' UTR sequence is:

GATATCTGATAATAGGCTGGAGCCTCGGTGGCCATGCTTCTTGCCCCTTGGGCCTCCCCCCAGCCCCTCCTCCCCTTCCTGCACCCGTACCCCCGTGGTCTTTGAATAAAGTCTGA（SEQ ID NO.3）。

the T7 promoter sequence is:

TAATACGACTCACTATAGG（SEQ ID NO.4）。

the prosactin signal peptide sequence is:

ATGGATTCTAAGGGTTCCAGCCAGAAAGGTTCCAGGCTGCTGCTGCTGCTGGTGGTGAGCAATCTGCTGCTGCCTCAGGGAGTGGTGGGA（SEQ ID NO.5）。

the optimized F protein sequence is as follows:

CAGAACATCACCGAGGAGTTCTACCAGTCAACCTGCAGCGCCGTGAGCCGGGGCTACCTGAGCGCACTGAGAACCGGATGGTATACATCCGTGGTCACTATTGAGCTGTCTAAGATCCAGAAAGACGTGTGTAAGTCTACAGATAGTAAGGTCAAGCTGATCAAACAGGAGCTGGAAAAGTATAACAATGCTGTGACCGAGCTGCAGTCCCTGATGCAGAACGTGCCTGCCAGCGGCAGCGGCAGCGCCATCGCTTCTGGGGTGGCAGTCTGCAAGGTGCTGCATCTGGAGGGAGAAGTCAACAAGATCAAAAATGCACTGCTGAGTACTAACAAAGCCGTGGTCAGTCTGTCAAATGGGGTGAGCGTCCTGACCTTTAAGGTGCTGGACCTGAAAAACTACATCGATAAGGAGCTGCTGCCCAAACTGAACAATCACGACTGTCGGATCCCCAATATTGAGACTGTGATTGAGTTCCAGCAGAAGAACAATCGCCTGCTGGAGATCGCCCGGGAGTTCAGCGTGAACGCAGGCATTACCACACCACTGTCCACCTACATGCTGACAAATAGTGAGCTGCTGTCACTGATTAACGACATGCCCATCACCAATGATCAGAAGAAACTGATGAGTTCAAACGTGCAGATCGTCAGGCAGCAGAGCTATTCCATTATGTGCATCGTCAAGGAGGAAGTGATCGCCTACGTGGTCCAGCTGCCTATCTACGGCGTGATCGATACACCATGCTGGAAGCTGCATACTTCACCCCTGTGTACTACCGACAACAAAGAGGGGAGCAATATCTGCCTGACAAGAACTGACAGGGGATGGTACTGTGATAACGCTGGCTCTGTGAGTTTCTTTCCTCAGGCAGAAACCTGCAAGGTGCAGTCTAACCGCGTCTTCTGTGATACAATGAATAGTCTGACCCTGCCAACAGACGTGAACCTGTGCAATACAAACATCTTTAATACCAAGTACGACTGTAAGATTATGACTTCCAAGACCGACATCAGCTCCTCTGTGATCACTTCTATTGGGGCCATCGTCAGTTGCTACGGAAAGACAAAATGTACTGCTAGCAACAAGAATCGGGGCATCATCAAGACATTCAGTAACGGGTGTGATTATGTGTCAAATAAGGGCGTGGACACTGTGAGCGTCGGGAACACCCTGTACTATGTGAATAAGGTGGAGGGAAAAGCTCTGTACATCAAGGGCGAACCTATCATTAACTACTATGATCCACTGGTGTTCCCCTCAGACGAGTTTGATGCAAGCATTGCCCAGGTGAACGCCAAAATCAATCAGTCTCTGGCTTTTATTAGGCGCAGCGACGAGCTGCTGAGCGCAATTGGAGGTTACATCCCTGAAGCCCCTAGAGATGGCCAGGCATATGTGAGGAAGGATGGCGAATGGGTGCTGCTGAGCACCTTTCTGGGAGGTCTGGTGCCTAGAGGATCT（SEQ ID NO.6）。

EGFP sequence is:

ATGGTGAGCAAGGGCGAGGAGCTGTTCACCGGGGTGGTGCCCATCCTGGTCGAGCTGGACGGCGACGTAAACGGCCACAAGTTCAGCGTGTCCGGCGAGGGCGAGGGCGATGCCACCTACGGCAAGCTGACCCTGAAGTTCATCTGCACCACCGGCAAGCTGCCCGTGCCCTGGCCCACCCTCGTGACCACCCTGACCTACGGCGTGCAGTGCTTCAGCCGCTACCCCGACCACATGAAGCAGCACGACTTCTTCAAGTCCGCCATGCCCGAAGGCTACGTCCAGGAGCGCACCATCTTCTTCAAGGACGACGGCAACTACAAGACCCGCGCCGAGGTGAAGTTCGAGGGCGACACCCTGGTGAACCGCATCGAGCTGAAGGGCATCGACTTCAAGGAGGACGGCAACATCCTGGGGCACAAGCTGGAGTACAACTACAACAGCCACAACGTCTATATCATGGCCGACAAGCAGAAGAACGGCATCAAGGTGAACTTCAAGATCCGCCACAACATCGAGGACGGCAGCGTGCAGCTCGCCGACCACTACCAGCAGAACACCCCCATCGGCGACGGCCCCGTGCTGCTGCCCGACAACCACTACCTGAGCACCCAGTCCGCCCTGAGCAAAGACCCCAACGAGAAGCGCGATCACATGGTCCTGCTGGAGTTCGTGACCGCCGCCGGGATCACTCTCGGCATGGACGAGCTGTACAAGTAG（SEQ ID NO.7）。

the original LJX strain F gene sequence is:

ATGGCGGCAATAGCCATAAGGATGATCATCAGCATTATCTTCATCTCTACCTATATGACACATATCACTCTATGCCAAAACATAACAGAAGAATTTTATCAATCAACATGCAGTGCAGTTAGTAGAGGTTACCTTAGTGCATTAAGAACTGGATGGTATACAAGTGTGGTAACAATAGAGTTGAGCAAAATACAAAAAGATGTGTGTAAAAGTACTGATTCAAAAGTGAAATTAATAAAGCAAGAACTAGAAAAATACAACAATGCAGTAACAGAATTGCAGTCACTTATGCAAAATGTACCGGCCTCCTTTAATAGAGCAAAAAGAGGGATACCAGAGTTGATGCATTATACAAGAAACTCTACAAAAAGGTTTTATGGACTAATGGGCAAGAAGAGAAAAAGGAGATTTTTAGGATTCTTGCTAGGCATTGGATCTGCTATTGCAAGTGGTGTAGCAGTGTCCAAAGTACTACACCTGGAGGGAGAGGTGAATAAAATTAAAAATGCACTGCTATCCACAAATAAAGCAGTAGTTAGTCTATCCAATGGAGTTAGTGTCCTTACTAGCAAAGTACTTGATCTAAAGAACTATATAGACAAAGAGCTTCTACCTAAAGTTAACAATCATGATTGTAGGATATCCAACATAGAAACTGTGATAGAATTCCAACAAAAGAACAATAGATTGTTAGAAATCGCTAGGGAATTTAGTGTAAATGCTGGTATTACCACACCCCTCAGTACATACATGTTAACCAATAGTGAATTACTATCACTAATTAATGATATGCCTATAACTAATGACCAAAAAAAGCTAATGTCAAGTAATGTTCAAATAGTCAGGCAACAGAGTTATTCCATTATGTCAATTGTCAAAGAAGAGGTCATAGCTTATGTTGTACAATTACCTATTTATGGAGTTATAGACACCCCCTGTTGGAAACTGCACACCTCTCCATTATGCACCACTGATAATAAAGAAGGGTCAAACATCTGCTTAACTAGGACAGATCGTGGGTGGTATTGTGACAATGCAGGCTCTGTGTCCTTTTTCCCACAGGCAGAAACGTGTAAGGTACAATCAAATAGGGTGTTCTGTGACACAATGAACAGTTTAACTCTGCCTACTGATGTTAATTTATGTAACACTAACATATTCAATACAAAGTATGACTGTAAAATAATGACATCTAAAACTGATATAAGTAGTTCTGTGATAACTTCAATTGGAGCTATTGTATCGTGCTATGGGAAGACAAAATGTACAGCTTCTAATAAAAATCGTGGAATCATAAAGACTTTTTCCAATGGGTGTGATTATGTATCAAACAAAGGAGTTGACACTGTATCCGTTGGGAATACACTATATTATGTGAACAAGGTAGAGGGGAAAGCACTCTATATAAAGGGTGAACCAATTATTAATTACTATGATCCACTAGTGTTTCCTTCCGATGAGTTTGATGCATCAATTGCCCAAGTAAATGCTAAAATAAATCAAAGCCTGGCTTTCATACGTCGATCTGATGAGTTACTTCACAGTGTAGATGTAGGAAAGTCCACCACAAATGTAGTAATTACTACTATTATCATAGTGATAGTTGTAGTGATATTAATGTTAATAGCTGTAGGATTACTGTTTTACTGTAAGACTAGAAGTACTCCTATCATGTTAGGAAAGGATCAGCTTAGTGGTATCAACAATCTTTCTTTTAGTAAA（SEQ ID NO.8）

the original LJX strain F protein transmembrane region gene sequence is as follows:

CACAGTGTAGATGTAGGAAAGTCCACCACAAATGTAGTAATTACTACTATTATCATAGTGATAGTTGTAGTGATATTAATGTTAATAGCTGTAGGATTACTGTTTTACTGTAAGACTAGAAGTACTCCTATCATGTTAGGAAAGGATCAGCTTAGTGGTATCAACAATCTTTCTTTTAGTAAA（SEQ ID NO.9）

the gene sequence of the trimeric domain of T4-phage fibrin is:

AGCGCAATTGGAGGTTACATCCCTGAAGCCCCTAGAGATGGCCAGGCATATGTGAGGAAGGATGGCGAATGGGTGCTGCTGAGCACCTTTCTGGGAGGTCTGGTGCCTAGAGGATCT（SEQ ID NO.10）

the amino acid sequence corresponding to the original LJX strain F protein is as follows:

MDSKGSSQKGSRLLLLLVVSNLLLPQGVVGQNITEEFYQSTCSAVSRGYLSALRTGWYTSVVTIELSKIQKDVCKSTDSKVKLIKQELEKYNNAVTELQSLMQNVPASGSGSAIASGVAVCKVLHLEGEVNKIKNALLSTNKAVVSLSNGVSVLTFKVLDLKNYIDKELLPKLNNHDCRIPNIETVIEFQQKNNRLLEIAREFSVNAGITTPLSTYMLTNSELLSLINDMPITNDQKKLMSSNVQIVRQQSYSIMCIVKEEVIAYVVQLPIYGVIDTPCWKLHTSPLCTTDNKEGSNICLTRTDRGWYCDNAGSVSFFPQAETCKVQSNRVFCDTMNSLTLPTDVNLCNTNIFNTKYDCKIMTSKTDISSSVITSIGAIVSCYGKTKCTASNKNRGIIKTFSNGCDYVSNKGVDTVSVGNTLYYVNKVEGKALYIKGEPIINYYDPLVFPSDEFDASIAQVNAKINQSLAFIRRSDELLSAIGGYIPEAPRDGQAYVRKDGEWVLLSTFLGGLVPRGS（SEQ ID NO.11）

the amino acid sequence corresponding to the optimized prosactin signal peptide is as follows:

MDSKGSSQKGSRLLLLLVVSNLLLPQGVVG（SEQ ID NO.12）。

the amino acid sequence corresponding to the optimized F protein is as follows:

QNITEEFYQSTCSAVSRGYLSALRTGWYTSVVTIELSKIQKDVCKSTDSKVKLIKQELEKYNNAVTELQSLMQNVPASGSGSAIASGVAVCKVLHLEGEVNKIKNALLSTNKAVVSLSNGVSVLTFKVLDLKNYIDKELLPKLNNHDCRIPNIETVIEFQQKNNRLLEIAREFSVNAGITTPLSTYMLTNSELLSLINDMPITNDQKKLMSSNVQIVRQQSYSIMCIVKEEVIAYVVQLPIYGVIDTPCWKLHTSPLCTTDNKEGSNICLTRTDRGWYCDNAGSVSFFPQAETCKVQSNRVFCDTMNSLTLPTDVNLCNTNIFNTKYDCKIMTSKTDISSSVITSIGAIVSCYGKTKCTASNKNRGIIKTFSNGCDYVSNKGVDTVSVGNTLYYVNKVEGKALYIKGEPIINYYDPLVFPSDEFDASIAQVNAKINQSLAFIRRSDELLSAIGGYIPEAPRDGQAYVRKDGEWVLLSTFLGGLVPRGS（SEQ ID NO.13）。

the amino acid sequence of the trimeric domain of the optimized T4-phage fibrin is:

SAIGGYIPEAPRDGQAYVRKDGEWVLLSTFLGGLVPRGS（SEQ ID NO.14）

the EGFP protein has the amino acid sequence corresponding to:

MVSKGEELFTGVVPILVELDGDVNGHKFSVSGEGEGDATYGKLTLKFICTTGKLPVPWPTLVTTLTYGVQCFSRYPDHMKQHDFFKSAMPEGYVQERTIFFKDDGNYKTRAEVKFEGDTLVNRIELKGIDFKEDGNILGHKLEYNYNSHNVYIMADKQKNGIKVNFKIRHNIEDGSVQLADHYQQNTPIGDGPVLLPDNHYLSTQSALSKDPNEKRDHMVLLEFVTAAGITLGMDELYK（SEQ ID NO.15）。

the RNA sequence of the 5 '-untranslated region (5' UTR) is:

GAAAUAAGAGAGAAAAGAAGAGUAAGAAGAAAUAUAAGAGCCACCGCUAGCCUCGAG（SEQ ID NO.16）

the RNA sequence of the 3 '-terminal untranslated region (3' UTR) is:

GAUAUCUGAUAAUAGGCUGGAGCCUCGGUGGCCAUGCUUCUUGCCCCUUGGGCCUCCCCCCAGCCCCUCCUCCCCUUCCUGCACCCGUACCCCCGUGGUCUUUGAAUAAAGUCUGA（SEQ ID NO.17）

the RNA sequence of poly a is:

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA（SEQ ID NO.18）

the RNA sequence of the prosactin signal peptide is:

AUGGAUUCUAAGGGUUCCAGCCAGAAAGGUUCCAGGCUGCUGCUGCUGCUGGUGGUGAGCAAUCUGCUGCUGCCUCAGGGAGUGGUGGGA（SEQ ID NO.19）

the RNA sequence corresponding to the optimized trimer structural domain is as follows:

AGCGCAAUUGGAGGUUACAUCCCUGAAGCCCCUAGAGAUGGCCAGGCAUAUGUGAGGAAGGAUGGCGAAUGGGUGCUGCUGAGCACCUUUCUGGGAGGUCUGGUGCCUAGAGGAUCU（SEQ ID NO.20）

the F protein RNA sequence after codon optimization is as follows:

CAGAACAUCACCGAGGAGUUCUACCAGUCAACCUGCAGCGCCGUGAGCCGGGGCUACCUGAGCGCACUGAGAACCGGAUGGUAUACAUCCGUGGUCACUAUUGAGCUGUCUAAGAUCCAGAAAGACGUGUGUAAGUCUACAGAUAGUAAGGUCAAGCUGAUCAAACAGGAGCUGGAAAAGUAUAACAAUGCUGUGACCGAGCUGCAGUCCCUGAUGCAGAACGUGCCUGCCAGCGGCAGCGGCAGCGCCAUCGCUUCUGGGGUGGCAGUCUGCAAGGUGCUGCAUCUGGAGGGAGAAGUCAACAAGAUCAAAAAUGCACUGCUGAGUACUAACAAAGCCGUGGUCAGUCUGUCAAAUGGGGUGAGCGUCCUGACCUUUAAGGUGCUGGACCUGAAAAACUACAUCGAUAAGGAGCUGCUGCCCAAACUGAACAAUCACGACUGUCGGAUCCCCAAUAUUGAGACUGUGAUUGAGUUCCAGCAGAAGAACAAUCGCCUGCUGGAGAUCGCCCGGGAGUUCAGCGUGAACGCAGGCAUUACCACACCACUGUCCACCUACAUGCUGACAAAUAGUGAGCUGCUGUCACUGAUUAACGACAUGCCCAUCACCAAUGAUCAGAAGAAACUGAUGAGUUCAAACGUGCAGAUCGUCAGGCAGCAGAGCUAUUCCAUUAUGUGCAUCGUCAAGGAGGAAGUGAUCGCCUACGUGGUCCAGCUGCCUAUCUACGGCGUGAUCGAUACACCAUGCUGGAAGCUGCAUACUUCACCCCUGUGUACUACCGACAACAAAGAGGGGAGCAAUAUCUGCCUGACAAGAACUGACAGGGGAUGGUACUGUGAUAACGCUGGCUCUGUGAGUUUCUUUCCUCAGGCAGAAACCUGCAAGGUGCAGUCUAACCGCGUCUUCUGUGAUACAAUGAAUAGUCUGACCCUGCCAACAGACGUGAACCUGUGCAAUACAAACAUCUUUAAUACCAAGUACGACUGUAAGAUUAUGACUUCCAAGACCGACAUCAGCUCCUCUGUGAUCACUUCUAUUGGGGCCAUCGUCAGUUGCUACGGAAAGACAAAAUGUACUGCUAGCAACAAGAAUCGGGGCAUCAUCAAGACAUUCAGUAACGGGUGUGAUUAUGUGUCAAAUAAGGGCGUGGACACUGUGAGCGUCGGGAACACCCUGUACUAUGUGAAUAAGGUGGAGGGAAAAGCUCUGUACAUCAAGGGCGAACCUAUCAUUAACUACUAUGAUCCACUGGUGUUCCCCUCAGACGAGUUUGAUGCAAGCAUUGCCCAGGUGAACGCCAAAAUCAAUCAGUCUCUGGCUUUUAUUAGGCGCAGCGACGAGCUGCUGAGCGCAAUUGGAGGUUACAUCCCUGAAGCCCCUAGAGAUGGCCAGGCAUAUGUGAGGAAGGAUGGCGAAUGGGUGCUGCUGAGCACCUUUCUGGGAGGUCUGGUGCCUAGAGGAUCU（SEQ ID NO.21）；

the BRSV-preF mRNA molecule RNA sequence contained in the mRNA vaccine is as follows:

5’cap-GAAAUAAGAGAGAAAAGAAGAGUAAGAAGAAAUAUAAGAGCCACCGCUAGCCUCGAGGCCACCAUGGAUUCUAAGGGUUCCAGCCAGAAAGGUUCCAGGCUGCUGCUGCUGCUGGUGGUGAGCAAUCUGCUGCUGCCUCAGGGAGUGGUGGGACAGAACAUCACCGAGGAGUUCUACCAGUCAACCUGCAGCGCCGUGAGCCGGGGCUACCUGAGCGCACUGAGAACCGGAUGGUAUACAUCCGUGGUCACUAUUGAGCUGUCUAAGAUCCAGAAAGACGUGUGUAAGUCUACAGAUAGUAAGGUCAAGCUGAUCAAACAGGAGCUGGAAAAGUAUAACAAUGCUGUGACCGAGCUGCAGUCCCUGAUGCAGAACGUGCCUGCCAGCGGCAGCGGCAGCGCCAUCGCUUCUGGGGUGGCAGUCUGCAAGGUGCUGCAUCUGGAGGGAGAAGUCAACAAGAUCAAAAAUGCACUGCUGAGUACUAACAAAGCCGUGGUCAGUCUGUCAAAUGGGGUGAGCGUCCUGACCUUUAAGGUGCUGGACCUGAAAAACUACAUCGAUAAGGAGCUGCUGCCCAAACUGAACAAUCACGACUGUCGGAUCCCCAAUAUUGAGACUGUGAUUGAGUUCCAGCAGAAGAACAAUCGCCUGCUGGAGAUCGCCCGGGAGUUCAGCGUGAACGCAGGCAUUACCACACCACUGUCCACCUACAUGCUGACAAAUAGUGAGCUGCUGUCACUGAUUAACGACAUGCCCAUCACCAAUGAUCAGAAGAAACUGAUGAGUUCAAACGUGCAGAUCGUCAGGCAGCAGAGCUAUUCCAUUAUGUGCAUCGUCAAGGAGGAAGUGAUCGCCUACGUGGUCCAGCUGCCUAUCUACGGCGUGAUCGAUACACCAUGCUGGAAGCUGCAUACUUCACCCCUGUGUACUACCGACAACAAAGAGGGGAGCAAUAUCUGCCUGACAAGAACUGACAGGGGAUGGUACUGUGAUAACGCUGGCUCUGUGAGUUUCUUUCCUCAGGCAGAAACCUGCAAGGUGCAGUCUAACCGCGUCUUCUGUGAUACAAUGAAUAGUCUGACCCUGCCAACAGACGUGAACCUGUGCAAUACAAACAUCUUUAAUACCAAGUACGACUGUAAGAUUAUGACUUCCAAGACCGACAUCAGCUCCUCUGUGAUCACUUCUAUUGGGGCCAUCGUCAGUUGCUACGGAAAGACAAAAUGUACUGCUAGCAACAAGAAUCGGGGCAUCAUCAAGACAUUCAGUAACGGGUGUGAUUAUGUGUCAAAUAAGGGCGUGGACACUGUGAGCGUCGGGAACACCCUGUACUAUGUGAAUAAGGUGGAGGGAAAAGCUCUGUACAUCAAGGGCGAACCUAUCAUUAACUACUAUGAUCCACUGGUGUUCCCCUCAGACGAGUUUGAUGCAAGCAUUGCCCAGGUGAACGCCAAAAUCAAUCAGUCUCUGGCUUUUAUUAGGCGCAGCGACGAGCUGCUGAGCGCAAUUGGAGGUUACAUCCCUGAAGCCCCUAGAGAUGGCCAGGCAUAUGUGAGGAAGGAUGGCGAAUGGGUGCUGCUGAGCACCUUUCUGGGAGGUCUGGUGCCUAGAGGAUCUUGAUAGGGUACCGAUAUCUGAUAAUAGGCUGGAGCCUCGGUGGCCAUGCUUCUUGCCCCUUGGGCCUCCCCCCAGCCCCUCCUCCCCUUCCUGCACCCGUACCCCCGUGGUCUUUGAAUAAAGUCUGAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA（SEQ ID NO.22）；

the RNA sequence of the complete EGFP mRNA is transcribed in vitro:

GAAAUAAGAGAGAAAAGAAGAGUAAGAAGAAAUAUAAGAGCCACCGCUAGCCUCGAGGCCACCAUGGACGCCAUGAAGAGGGGGCUGUGCUGCGUGCUGCUGCUGUGCGGAGCCGUGUUCGUGAGCGCCUCCAUGGUGAGCAAGGGCGAGGAGCUGUUCACCGGGGUGGUGCCCAUCCUGGUCGAGCUGGACGGCGACGUAAACGGCCACAAGUUCAGCGUGUCCGGCGAGGGCGAGGGCGAUGCCACCUACGGCAAGCUGACCCUGAAGUUCAUCUGCACCACCGGCAAGCUGCCCGUGCCCUGGCCCACCCUCGUGACCACCCUGACCUACGGCGUGCAGUGCUUCAGCCGCUACCCCGACCACAUGAAGCAGCACGACUUCUUCAAGUCCGCCAUGCCCGAAGGCUACGUCCAGGAGCGCACCAUCUUCUUCAAGGACGACGGCAACUACAAGACCCGCGCCGAGGUGAAGUUCGAGGGCGACACCCUGGUGAACCGCAUCGAGCUGAAGGGCAUCGACUUCAAGGAGGACGGCAACAUCCUGGGGCACAAGCUGGAGUACAACUACAACAGCCACAACGUCUAUAUCAUGGCCGACAAGCAGAAGAACGGCAUCAAGGUGAACUUCAAGAUCCGCCACAACAUCGAGGACGGCAGCGUGCAGCUCGCCGACCACUACCAGCAGAACACCCCCAUCGGCGACGGCCCCGUGCUGCUGCCCGACAACCACUACCUGAGCACCCAGUCCGCCCUGAGCAAAGACCCCAACGAGAAGCGCGAUCACAUGGUCCUGCUGGAGUUCGUGACCGCCGCCGGGAUCACUCUCGGCAUGGACGAGCUGUACAAGUAGGGUACCGAUAUCUGAUAAUAGGCUGGAGCCUCGGUGGCCAUGCUUCUUGCCCCUUGGGCCUCCCCCCAGCCCCUCCUCCCCUUCCUGCACCCGUACCCCCGUGGUCUUUGAAUAAAGUCUGAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA（SEQ ID NO.23）

2. LNP package

The plasmid pCAGGS-probactatin-F obtained in example 1 was usedBsaI restriction endonuclease is digested to allowLinearizing the plasmid. Next, the linearized DNA was purified by adding 1/10 volume of 3M sodium acetate (pH=5.2) and 3 volume of absolute ethanol, 1/20 volume of 0.5M EDTA, followed by treatment of the DNA fragment with porin K, purification of the DNA with an equal volume of phenol/chloroform, resuspension of the DNA with DNase-free water, and determination of the DNA concentration.

T7 High Yield RNA Transcription Kit (N) ¹ -Me-pseudoUTP) product, and obtaining N by in vitro transcription reaction ¹ -Me-pseudoutp modified mRNA of interest to reduce the natural immune response of the host. The "Cap 1" structure-mRNA was constructed from transcribed RNA by the Cap 1 supporting System product of offshore company. RNA was purified by phenol chloroform and concentration was measured and then packaged with Lipid Nanoparticles (LNP).

The specific method comprises the following steps: lipid was expressed as cationic lipid (SM 102): distearoyl phosphatidylcholine (DSPC) : cholesterol: DMG-2000 (available from sainobond corporation) =50:10:38.5:1.5 (mass ratio) was dissolved in absolute ethanol as an alcohol phase; mRNA was dissolved in 50 mM of citric acid buffer (pH 4.0) as an aqueous phase; and then coating the alcohol phase and the water phase with mRNA according to the volume ratio of 1:3 by using a microfluidic device, diluting with PBS buffer solution without RNase after obtaining the preparation, concentrating and replacing the solution by using a 30 kDa ultrafiltration tube, regulating the mRNA concentration to 120 mug/mL, adding PBS solution with 20% of sucrose concentration in an equal volume to ensure that the mRNA concentration is 60 mug/mL and the sucrose concentration is 10%, filtering with a 0.22 mu m filter membrane, and storing at the temperature of minus 20 ℃ for standby.

The prepared BRSV-preF mRNA vaccine particles are verified to be uniform by an electron microscope detection result (figure 6). FIG. 7 shows that the particle size of the BRSV-preF mRNA vaccine is 172.1nm, the concentration is 5.9×10 ¹¹ And each mL.

Example 4 mouse immune evaluation experiment

The prepared BRSV-preF mRNA vaccine is used for immunizing BALB/c mice to evaluate the immune effect. 10 8 week old SPF BALB/c mice purchased from Liaoning long biotechnology Co., ltd were randomly divided into 2 groups, 5 mice/group. The first group was immunized with 20ug each of BRSV-preF mRNA vaccine, and the second group was immunized with an equal volume of PBS each. After 3 weeks of immunization, booster immunization was performed with the same dose volume of vaccine as the first immunization, after which mice were collected blood every two weeks and serum was isolated for antibody detection.

(1) Detection of specific anti-F protein IgG antibodies

The immune serum was assayed for specific anti-F IgG antibody titers by an indirect ELISA method based on F protein. Coating ELISA plates with purified F protein (0.6 mug/mL), performing multiple dilution on serum separated at different time points after boosting, adding the serum into the corresponding ELISA plates, sequentially adding HRP-anti-mouse IgG secondary antibody and TMB, detecting OD value by A450 after color development is stopped, and determining antibody titer. The results are shown in fig. 9, which shows that the titers of the mouse serum F protein-specific IgG antibodies are highest two weeks after the mRNA vaccine was double-immunized (fig. 9, table 1).

(2) Detection of specific neutralizing antibodies

Neutralizing antibody titers in immune sera were analyzed by neutralization assay. Neutralizing equal volumes of BRSV virus and equal volumes of mouse serum with different dilutions at 37 ℃ for 1h, adding the equal volumes of BRSV virus and the equal volumes of mouse serum into Vero cells, and observing BRSV pathological changes after infection for 4-5 days. Neutralizing antibody titers were defined as neutralizing 200 TCID ₅₀ Highest serum dilution fold of BRSV. The results are shown in FIG. 10 and Table 1, and the anti-BRSV nAb titer of the mice is highest four weeks after the mRNA vaccine is subjected to secondary immunization, and the mRNA vaccine can induce high-efficiency humoral immunity.

The results in FIG. 11 show that the mRNA vaccine immunized group still has high levels of specific IgG and neutralizing antibodies 19 weeks after the second immunization, and that the IgG antibodies and neutralizing antibodies 8 weeks after the second immunization have no statistically significant difference, indicating that the prepared BRSV-preF mRNA vaccine can maintain humoral immunity for a longer period of time.

TABLE 1 mRNA vaccine immunization mice expressing Pre-fusion F protein induced antibody titres

(3) Cellular immunoassay

Detection of antigen-specific T cells by cytokine staining (ICCS) experiments to assess cellular immunity, BRSV-preF was taken

mRNA vaccine immunized murine lymphocytes were inoculated into culture plates and stimulated with BRSV-F protein. Cells were CO-stimulated with anti-CD 28 antibodies at 37 ℃ and 5% CO 2. DMSO was used as negative control. PMA/ionomycin was used as positive control. Subsequently, the following cytokine antibodies were used: anti-IFN-gamma, anti-TNF-alpha, anti-IL-2 and anti-IL-4 act on lymphocytes and finally cytokine specific lymphocyte numbers are analyzed by flow cytometry. Several weeks after booster vaccination, experimental results showed that BRSV-preF mRNA vaccine induced antigen-specific, multifunctional CD8 expressing IFN-gamma, IL-2 and TNF-a ⁺ T cells. The BRSV-preF mRNA candidate vaccine induces effective cellular immune protection.

EXAMPLE 5 bovine immune assessment experiment

Immunization was performed on 2 month old calves. 10 calves, 5 calves each, one group of muscles inoculated with mRNA vaccine at a dose of 200 mug/head; another group was injected with equal volumes of PBS as a control. The same dose and route was followed for the second inoculation 3 weeks after the first inoculation.

(1) Detection of specific anti-F protein IgG antibodies

The immune serum was assayed for specific anti-F IgG antibody titers by an indirect ELISA method based on F protein. Coating ELISA plate with purified F protein (0.6 μg/mL), performing multiple dilution on serum separated at different time points after boosting, adding into corresponding ELISA plate, sequentially adding HRP-anti-bovine IgG secondary antibody and TMB, and after color development is terminated, A ₄₅₀ OD values were measured and antibody titers were determined. The result shows that the BRSV-preF mRNA vaccine can generate high and durable specific anti-F protein IgG antibodies in calves.

(2) Detection of specific neutralizing antibodies

Neutralizing antibody titers in immune sera were analyzed by neutralization assay. Neutralizing equal volumes of BRSV virus and equal volumes of bovine serum with different dilutions at 37 ℃ for 1h, adding the obtained product into Vero cells, and observing BRSV pathological changes after infection for 4-5 days. Neutralizing antibody titers were defined as neutralizing 200 TCID ₅₀ Highest serum dilution of BRSVMultiple. The result shows that the BRSV-preF mRNA vaccine can induce higher specific neutralizing antibodies when the calf is immunized.

Example 6 safety experiment

Immunization was performed on 2 month old calves. 10 calves, 5 calves each, one group of muscles inoculated with high dose mRNA vaccine, 600 μg/head; another group was injected with PBS as a control. The same dose and route was followed for the second inoculation 3 weeks after the first inoculation. And (5) observing the body health condition of the calves. All cattle in the PBS group and the mRNA vaccine group calf have good health status and normal body temperature, which indicates that the vaccine has good safety.

Example 7 method for preparing antibodies by mRNA vaccine

And immunizing BALB/c mice with the prepared BRSV-preF mRNA vaccine to prepare the monoclonal antibody. 5 Liaoning long biotechnology Co., ltd were ordered with 8 week old SPF BALB/c mice. The BRSV-preF mRNA vaccine was immunized, 20 ug/hr. 3 weeks after immunization, booster immunization was performed with the same dose volume of vaccine as the first immunization. Mouse serum is isolated after booster immunization to determine serum antibody titer, and when the antibody titer is more than 20000, the immunized mouse spleen cells are fused with SP2/0 cells. Positive cell clones are identified by ELISA method, indirect immunofluorescence and other detection methods, hybridoma cell strains which stably secrete specific monoclonal antibodies are obtained, and the prepared monoclonal antibodies can be used for establishing a diagnosis method for detecting BRSV pathogens and antibodies.

Claims

1. Cattle respiratory syncytial virusBovine respiratory syncytial virus) The mRNA vaccine of (2) is characterized in that the mRNA vaccine codes for an F protein mutant of respiratory syncytial virus, and the amino acid sequence of the F protein mutant of the respiratory syncytial virus is shown as SEQ ID NO.13.

2. The mRNA vaccine of claim 1, wherein the mRNA vaccine consists of: the coding RNA gene of the F protein mutant of the respiratory syncytial virus, the 3' untranslated region and the poly-A.

3. The mRNA vaccine of claim 2, wherein the DNA sequence of the 5 'untranslated region is shown in SEQ ID No.2, the DNA sequence of the 3' untranslated region is shown in SEQ ID No.3, the DNA sequence of the signal peptide is shown in SEQ ID No.5, and the sequence of the RNA gene encoding the F protein mutant of the respiratory syncytial virus is shown in SEQ ID No. 21.

4. The application of the F protein mutant of the bovine respiratory syncytial virus in preparing an mRNA vaccine for preventing or treating the bovine respiratory disease syndrome is characterized in that the amino acid sequence of the F protein mutant of the bovine respiratory syncytial virus is shown as SEQ ID NO.13.

5. Use of a recombinant plasmid comprising a DNA molecule encoding the mRNA vaccine of claim 1 for the preparation of an mRNA vaccine for the prevention of bovine respiratory disease syndrome.

6. Use of a recombinant microbial cell comprising the mRNA vaccine of claim 1 for the preparation of an mRNA vaccine for the prevention of bovine respiratory disease syndrome.

7. Use of lipid nanoparticles comprising the mRNA vaccine of claim 1 for the preparation of an mRNA vaccine for the prevention of bovine respiratory disease syndrome.

8. The use according to any one of claims 5 to 7, wherein the virus that causes the bovine respiratory disease syndrome is bovine respiratory syncytial virus.

9. Use of an mRNA vaccine according to any one of claims 1 to 4 for the preparation of antibodies to bovine respiratory syncytial virus.

10. An F protein mutant of bovine respiratory syncytial virus, which is characterized in that the mutant is characterized in that S of 155 th and 290 th amino acids of an amino acid sequence coded by a nucleotide sequence shown in SEQ ID NO.8 is mutated into C, S of 190 th is mutated into F, V of 207 th is mutated into L, S of 215 th is mutated into P and I of 144 th is mutated into S; replacing the amino acid sequence of a transmembrane region by the amino acid sequence of a trimer domain of T4-phage fibrin, wherein the gene sequence of the transmembrane region is shown as SEQ ID NO. 9; the amino acid sequence of the trimer structural domain of the T4-phage fibrin is shown as SEQ ID NO. 14; the amino acid sequence at positions 104-142 is deleted.