Porcine streptococcus subunit vaccine and application thereof

Abstract

The invention relates to the technical field of biology, in particular to a swine streptococcus subunit vaccine and application thereof. The Fe protein is adopted to display the nanoparticle vaccine, and a large number of artificially selected and optimized specific antigens can be displayed on the surfaces of the nanoparticles, so that an organism can recognize the antigen more conveniently, immune response of the organism is stimulated more easily, and efficient recognition of the displayed antigen by the organism is promoted.

Description

Technical Field

[0001] This application relates to the field of biotechnology, and in particular to a porcine streptococcal subunit vaccine and its application. Background Technology

[0002] Streptococcal disease is a polymorphic infectious disease caused by pathogenic streptococci of the genus *Streptococcus*, affecting both animals and humans. It is one of the important bacterial infectious diseases and is primarily prevented through vaccination. *Streptococcus suis* (SS) is a Gram-positive coccus with 35 serotypes. Its main virulence factors include capsular polysaccharides, lysozyme-releasing proteins, extracellular factors, and hemolysins. Lysozyme-releasing proteins and extracellular protein factors are two important virulence factors of *Streptococcus suis*.

[0003] In recent years, streptococcal disease has become an increasingly serious threat to pig farms, making the development of streptococcal vaccines a hot research topic. Currently, the common practice in the industry is to isolate and culture *Streptococcus suis*, scale up the culture, inactivate it with an inactivating agent, and then add an adjuvant to produce a whole-cell inactivated vaccine. However, the main problems with whole-cell inactivated vaccines are: high total protein content, leading to immune stress; the introduction of excessive ineffective proteins resulting in poor immunization efficacy; and most importantly, the large number of streptococcal serotypes and weak cross-protective effects between different serotypes mean that inactivated vaccines cannot provide adequate protection. Besides inactivated vaccines, there are also reports on genetically engineered vaccines for *Streptococcus suis*, but because the antigens used are mostly expressed in inclusion body form, they are difficult to form effective biological activity or have poor biological activity, ultimately resulting in poor immunization.

[0004] For example, the existing technology CN110327460A, a bivalent subunit vaccine for streptococcal infection and Haemophilus parasuis infection, contains Haemophilus parasuis antigen proteins AfuA, OppA2, CdtB, and OppA, as well as streptococcal antigens MRP and SLY. It can elicit a strong immune response in mice and shows good cross-protection against streptococcal serotypes 2 and 9, superior to traditional inactivated vaccines. However, ① some proteins expressed by the recombinant strain constructed using this technology are inclusion body proteins, making the refolding process complex and unsuitable for large-scale production; ② the bacterial surface-displaying protein strain constructed using this technology requires preliminary quantification using Western blotting (WB), which cannot provide accurate quantification; ③ the vaccine provided by this technology only offers protection against SS2 and SS9 serotypes with a protection rate of just over 50%. Therefore, providing a streptococcal subunit vaccine with good immunogenicity and its preparation method is of significant practical importance. Summary of the Invention

[0005] In view of this, this application provides a porcine streptococcal subunit vaccine and its application, which uses Fe protein to display nanoparticle vaccines. This allows artificially selected and optimized specific antigens to be displayed on the surface of nanoparticles in large quantities, making it easier for the body to recognize them, stimulating the body's immune response more easily, and promoting the body's efficient recognition of the displayed antigens.

[0006] To achieve the above-mentioned objectives, this application provides the following technical solution:

[0007] This application provides a ferritin nanoparticle assembly, consisting of ferritin nanoparticle 1 and ferritin nanoparticle 2;

[0008] The ferritin nanoparticles 1 contain streptococcal MRP protein;

[0009] The ferritin nanoparticles 2 contain Streptococcus suis PrsA protein.

[0010] In some specific embodiments of this application, the Streptococcus suis MRP protein of the above-described ferritin nanoparticle assembly is displayed on the surface of the ferritin nanoparticle 1.

[0011] In some specific embodiments of this application, the Streptococcus suis PrsA protein of the above-described ferritin nanoparticle assembly is displayed on the surface of the ferritin nanoparticles 2.

[0012] In some specific embodiments of this application, the ferritin nanoparticles 1 of the above-mentioned ferritin nanoparticle assembly are composed of streptococcal MRP protein, linker, and ferritin linked together.

[0013] In some specific embodiments of this application, the ferritin nanoparticles 2 of the above-mentioned ferritin nanoparticle assembly are composed of streptococcal PrsA protein, linker, and ferritin linked together.

[0014] In some specific embodiments of this application, the sequence of the Streptococcus suis MRP protein in the above-described ferritin nanoparticle assembly is as follows:

[0015] (1) An amino acid sequence as shown in SEQ ID NO: 1; or

[0016] (2) An amino acid sequence obtained by substituting, deleting, or adding one or more residues as shown in (1), and whose function is the same as or similar to that of (1); or

[0017] (3) An amino acid sequence that is at least 90% homologous to the amino acid sequence shown in (1) or (2).

[0018] In some specific embodiments of this application, the sequence of the Streptococcus suis PrsA protein in the above-mentioned ferritin nanoparticle assembly is as follows:

[0019] (4) An amino acid sequence as shown in SEQ ID NO: 2; or

[0020] (5) An amino acid sequence obtained by substituting, deleting, or adding one or more residues as shown in (4), and whose function is the same as or similar to that of (4); or

[0021] (6) An amino acid sequence that is at least 90% homologous to the amino acid sequence shown in (4) or (5);

[0022] The number of items is 2 to 10.

[0023] In some specific embodiments of this application, the ferritin in the above-described ferritin nanoparticle assembly has:

[0024] (a) An amino acid sequence as shown in SEQ ID NO: 3; or

[0025] (b) An amino acid sequence obtained by substituting, deleting, or adding one or more residues to the amino acid sequence shown in (a), and whose function is the same as or similar to that of (a); or

[0026] (c) An amino acid sequence that is at least 90% homologous to the amino acid sequence shown in (a) or (b);

[0027] The number of items is 2 to 10.

[0028] In some specific embodiments of this application, the amino acid sequence of the linker in the above-mentioned ferritin nanoparticle assembly is GSGGGS (SEQ ID NO: 6).

[0029] This application also provides expression vectors, including expression vector 1 and expression vector 2;

[0030] The expression vector 1 has:

[0031] (7) A nucleotide sequence as shown in SEQ ID NO: 4; or

[0032] (8) A nucleotide sequence obtained by substitution, deletion, or addition of one or more bases to the nucleotide sequence shown in (7), and whose function is the same as or similar to that of (7); or

[0033] (9) A nucleotide sequence that is at least 90% homologous to the nucleotide sequence shown in (7) or (8);

[0034] The expression vector 2 has:

[0035] (10) A nucleotide sequence as shown in SEQ ID NO: 5; or

[0036] (11) A nucleotide sequence obtained by substituting, deleting, or adding one or more bases to the nucleotide sequence shown in (10), and whose function is the same as or similar to that of (10); or

[0037] (12) A nucleotide sequence that is at least 90% homologous to the nucleotide sequence shown in (10) or (11);

[0038] The number of items is 2 to 10.

[0039] In some specific embodiments of this application, the backbone of the expression vector is an expression vector for ferritin.

[0040] In some specific embodiments of this application, the preparation method of the above-mentioned ferritin nanoparticle combination includes: expressing the ferritin nanoparticle 1 and the ferritin nanoparticle 2 separately and mixing them to obtain the ferritin nanoparticle combination;

[0041] The ferritin nanoparticles 1 are expressed by the expression vector 1 in the above-mentioned expression vector;

[0042] The ferritin nanoparticles 2 are expressed by the expression vector 2 in the above expression vector.

[0043] In some specific embodiments of this application, the preparation method of the ferritin nanoparticles 1 in the above-mentioned ferritin nanoparticle assembly includes:

[0044] The gene for the MRP protein of Streptococcus suis was ligated into an expression vector that expresses ferritin to obtain expression vector 1;

[0045] The expression vector 1 was introduced into a host cell and expression was induced to obtain ferritin nanoparticles 1.

[0046] In some specific embodiments of this application, the preparation method of the ferritin nanoparticles 1 in the above-mentioned ferritin nanoparticle assembly includes:

[0047] The gene for the PrsA protein of Streptococcus suis was ligated into an expression vector that expresses ferritin to obtain expression vector 2;

[0048] The expression vector 2 was introduced into host cells and expression was induced to obtain ferritin nanoparticles 2.

[0049] In some specific embodiments of this application, the host cell of the above-described ferritin nanoparticle assembly can be a prokaryote or a eukaryote;

[0050] The prokaryote may be Escherichia coli;

[0051] The eukaryote can be yeast.

[0052] This application also provides the application of the above-mentioned ferritin nanoparticle combination in the preparation of biological products for the prevention or treatment of Streptococcus suis infection.

[0053] This application also provides the application of the above-mentioned ferritin nanoparticle combination in the prevention or treatment of Streptococcus suis infection.

[0054] In some specific embodiments of this application, the Streptococcus suis infection described above is an infection of at least one of Streptococcus suis type 2, Streptococcus suis type 8, and Streptococcus suis type 9.

[0055] This application also provides a vaccine comprising an adjuvant and the aforementioned combination of ferritin nanoparticles.

[0056] In some specific embodiments of this application, the adjuvant of the above-mentioned vaccine is an aluminum adjuvant.

[0057] In some specific embodiments of this application, the concentration of the ferritin nanoparticles 1 in the above-mentioned vaccine is in the range of any one or any two of 0.05 mg / mL, 0.09 mg / mL, 0.1 mg / mL, 0.11 mg / mL, and 0.15 mg / mL, and the concentration of the ferritin nanoparticles 2 is in the range of any one or any two of 0.05 mg / mL, 0.09 mg / mL, 0.1 mg / mL, 0.11 mg / mL, and 0.15 mg / mL.

[0058] In some specific embodiments of this application, the preparation method of the above-mentioned vaccine includes: mixing the adjuvant and the above-mentioned ferritin nanoparticles together, emulsifying them, and obtaining the vaccine.

[0059] This application also provides a method for preventing or treating streptococcal infection in pigs, with a dosage of 2 mL / head (pig) via intramuscular injection.

[0060] The present invention has the following beneficial effects:

[0061] 1. This invention effectively solves the problems of inactivated vaccines requiring inactivation, high total protein content, immune stress, and poor immunization efficacy due to the introduction of excessive ineffective proteins. Furthermore, the Fe protein nanoparticles constructed in this invention can be accurately quantified using the BCA protein quantification method, ensuring batch stability in scaled-up production.

[0062] 2. This invention addresses the problems of numerous streptococcal serotypes, weak cross-protection between different serotypes, and the inability of inactivated vaccines to provide adequate protection. The vaccine prepared by this invention provides over 80% protection against challenge of SS2 / 8 / 9 serotypes, with even higher cross-protection rates.

[0063] 3. This invention can solve the problem that the genetically engineered vaccines of Streptococcus suis often use antigens expressed in the form of inclusion bodies, which makes it difficult to form effective biological activity or has poor biological activity, ultimately resulting in poor immune effects. The recombinant strain constructed in this invention expresses soluble proteins at an expression level of 0.5~0.8 mg / mL, saving downstream processing costs and effectively supporting large-scale production.

[0064] 4. This invention solves the problem that genetically engineered subunit vaccines require a high protein content to achieve an immunizing effect. This invention uses Fe protein-displayed nanoparticle vaccines, which can display a large amount of artificially selected and optimized specific antigens on the surface of the nanoparticles, making it easier for the body to recognize them, more easily stimulating the body's immune response, promoting efficient recognition of the displayed antigens, and exhibiting enhanced cellular immunity. Attached Figure Description

[0065] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0066] Figure 1 SDS electrophoresis images of PrsA, MRP, Fe-MRP, and Fe-PrsA are shown.

[0067] Figure 2 Electron micrograph of Fe-MRP protein;

[0068] Figure 3 Electron micrograph of Fe-PrsA protein. Detailed Implementation

[0069] This application discloses a porcine streptococcal subunit vaccine and its application. Those skilled in the art can refer to the content of this document and appropriately modify the process parameters to achieve the vaccine. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments. Those skilled in the art can obviously make modifications or appropriate alterations and combinations to the methods and applications described herein without departing from the content, spirit, and scope of this application to realize and apply the technology of this invention.

[0070] It should be understood that the expression “one or more of…” individually includes each of the objects described after the expression, as well as various different combinations of two or more of the described objects, unless otherwise understood from the context and usage. The expression “and / or” combined with three or more described objects should be understood to have the same meaning, unless otherwise understood from the context.

[0071] The terms “including,” “having,” or “containing,” including the use of their grammatical synonyms, should generally be understood as open-ended and non-restrictive, for example, not excluding other unstated elements or steps, unless otherwise specifically stated or understood from the context.

[0072] It should be understood that the order of steps or the sequence of actions is not important as long as this application remains operational. Furthermore, two or more steps or actions can be performed simultaneously.

[0073] The use of any and all instances or exemplary language such as “e.g.” or “include” in this document is intended merely to better illustrate the application and does not constitute a limitation on the scope of the application. No language in this specification should be construed as indicating that any unclaimed element is essential to the practice of this application.

[0074] Furthermore, the numerical ranges and parameters used to define this application are approximate values, and the relevant values ​​in the specific embodiments have been presented as precisely as possible. However, any numerical value inevitably contains standard deviations due to individual test methods. Therefore, unless otherwise explicitly stated, it should be understood that all ranges, quantities, values, and percentages used in this disclosure are modified with the word "approximately." Here, "approximately" generally means that the actual value is within plus or minus 10%, 5%, 1%, or 0.5% of a specific value or range.

[0075] In this embodiment, the amino acid sequence of the MRP involved is as follows:

[0076] MPETDRPKVPYPFDPTEPDEPIDPTTPGTNGEVPNIPYVPGYTPVDPKDNTPLKPIDPNDPGKGYVPPTPENPGVDTPIPYVPVKKVVTNHVDEEGNPIAPQEEGTKPNKSIPGYEFTGKTVTDEDGNTTHIYKKTPEVKNGTVVVNYVTEDGTVIKEPVTDTPTSPEGTPYDTTDNKPKTITF KGEEYELVRVDGTENGKVVEGETVVTYVYRKVETPAKKVVTNHVDEEGNPVAPQEEGTKPNKSIPGYEFTGKTVTDEDGNTTHIYKKTPAKKVVTNHVDEEGNPIAPQEDGTTPKRQISGYEYVRTVVDEEGNTTHIYRKLSNKPTTPEKETPAKPQAGKTASGKAQLPNTGEASSVAGAL (SEQ IDNO: 1);

[0077] In the embodiments, the amino acid sequence of PrsA involved is as follows:

[0078] MKQTKKILAGAVTLFAAVTLAACSNAADKDIITMKGNTITVSEFYEKVKTNSQAQQVLLSMIISNVFEEQYGDKVTAKEVDEAYNKMAEQYGDSFATALSSAGLTQETYKEQIRTNKLVEYAVKQAAEKELTDENYKAAYDAYTPEVTARIIKLTDEAKAKEVLAAAQ AEGADFAQLAKDNSTDTATKDNGGEVKFDSTSTTVPTEVQKAVFALDAGQVGTSIVSAVDLKTYTTSYYVVKLEAKSEKSAKWEDYKDKLKEIILAQKQSDSSFVATVLKEALQKANVKVKDSAFQNLLSQYVTTEESSSSSTESSSSSTESSSSTTESSSSSGQ (SEQ ID NO: 2);

[0079] In the examples, the amino acid sequence of the ferritin involved is as follows:

[0080] DIIKLLNEQVNKETNSSHLYMSMSSWCYTHSLDGAGLFLFDHAAEEYEHAKKLIIFLNENNVPVQLTSISVPEHKFESLTQIFQKAYEHEQHISESINNIVDHAIKNKDHATNFLQWYVAEQHEEEVLFKDILDKIELIGNENHGLYLVDQYIKGIAKSRKS (SEQ ID NO: 3);

[0081] In this embodiment, the nucleotide sequence of the Fe-MRP plasmid involved is as follows:

[0082]

[0083] In this embodiment, the nucleotide sequence of the Fe-PrsA plasmid involved is as follows:

[0084]

[0085] In the examples, the AL adjuvant involved is aluminum glue adjuvant, manufacturer: SPI, product number: 120-1029-1JR2, adjuvant content: 16%.

[0086] Unless otherwise specified, the raw materials, reagents, consumables and instruments involved in this application are all commercially available products and can be purchased from the market.

[0087] The technical solution of this invention is to amplify MRP and PrsA protein sequences from streptococci isolated from a pig farm and send them for sequencing. Through genetic engineering technology, the MRP and PrsA protein sequences are fused with Fe protein plasmids to construct Fe-MRP, Fe-PrsA, MRP, and PrsA plasmids, respectively. The target proteins are expressed and purified using an E. coli expression system. Effective data are obtained by comparing the protection rates of different forms of vaccines against mouse immune challenge.

[0088] The present invention will be further illustrated below with reference to the embodiments.

[0089] Example 1: Protein Expression

[0090] I. Construction of Expression Carrier

[0091] 1. After genomic DNA was extracted from diseased pig samples, positive results were identified by PCR using specific primers, and then the samples were sent for sequencing to obtain the sequences.

[0092] 2. Extract bacterial genome using a bacterial genome extraction kit according to the instructions. Store the extracted genome at -20°C for later use. After obtaining the complete genome sequence of Streptococcus suis, design primers and perform PCR using the complete genome as a template to amplify the target genes MRP and PrsA, respectively. After obtaining the target genes, construct them on pET-28a and Fe protein plasmids using homologous recombination to obtain correctly sequenced Fe-MRP, Fe-PrsA, pET-MRP, and pET-PrsA plasmids.

[0093] II. Induction of Expression and Purification Validation

[0094] 1. Plasmid transformation of Escherichia coli BL21

[0095] Add 2 μL of plasmid to 50 μL of BL21 competent cells, incubate on ice for 30 min, heat shock at 42℃ for 90 s, incubate on ice for 2 min, add 500 μL of antibiotic-free LB medium in a clean bench, and shake at 37℃ and 180 rpm for 45 min. Spread 100 μL of the bacterial culture onto the corresponding antibiotic-containing LB agar plate and incubate overnight at 37℃.

[0096] 2. Protein induction, expression, purification, and quantification

[0097] Picking bacteria: Pick a single colony and inoculate it into 5 mL of LB liquid medium containing the corresponding resistance, and incubate overnight at 37°C.

[0098] Transfer and induction: 1% of the culture was inoculated into 500 mL of LB liquid medium containing the corresponding antibiotic and cultured at 37°C until the OD reached 0.6-0.8. Then, 0.5 mM of isopropyl thiogalactoside (IPTG) was added and the culture was induced at 18°C ​​for 16 h.

[0099] Bacterial cell collection: Collect bacteria by centrifugation at 8000 rpm for 10 min and store at -20℃.

[0100] Sample preparation and purification: Bacterial cells were reconstituted at a wet weight to lysis buffer ratio of 1:20 (lysis buffer: 20 mM PB + 0.1% Triton X-100, pH=7.4). The cells were homogenized four times at 900 bar, centrifuged at 12000 rpm for 30 min, and the supernatant was filtered through a 0.45 μm filter for nickel column purification. The cells were washed with 100 mM imidazole + 20 mM PB (pH=7.4) and eluted with 500 mM imidazole + 20 mM PB (pH=7.4). During purification, the reconstituted bacterial cells were collected, and after disruption, the supernatant and precipitate were centrifuged. The eluted and washed samples from the nickel column chromatography were collected. The collected protein solution was desalted and centrifuged at 12000 rpm for 15 min at 4℃. The supernatant was collected, transferred to a biosafety cabinet, and filtered through a 0.22 μm filter. The PES needle filter was used for filtration, and the samples were stored at -80°C. Samples were then taken for BCA protein concentration quantification and SDS-polyacrylamide gel electrophoresis analysis.

[0101] like Figure 1 As shown in the gel image, the four target proteins Fe-MRP, Fe-PrsA, MRP, and PrsA were all soluble and expressed, with a soluble content of >50% in the supernatant. The purity of the purified proteins was higher than 95%, and the protein expression yield could reach more than 0.5 mg / mL without optimizing the fermentation culture. Figure 2 , Figure 3 Electron micrographs of Fe-MRP and Fe-PrsA are shown respectively.

[0102] Example 2: Animal Experiment

[0103] I. Vaccine Preparation

[0104] 1. Vaccine 1: Surface-display protein vaccine

[0105] The purified Fe-MRP and Fe-PrsA proteins were mixed, and the resulting protein solution was mixed with AL adjuvant at a certain volume (adjuvant content 16%) so that the concentration of Fe-MRP and Fe-PrsA proteins in the emulsified vaccine was 0.1 mg / mL.

[0106] 2. Vaccine 2: Purified protein vaccine

[0107] The purified MRP and PrsA proteins were mixed, and the resulting protein solution was mixed with AL adjuvant at a certain volume (adjuvant content 16%) so that the concentration of MRP and PrsA proteins in the emulsified vaccine was 0.1 mg / mL.

[0108] 3. Vaccine 3: Inactivated vaccine

[0109] Streptococcus suis serotypes 2, 8, and 9 were streaked onto TSB (containing 10% horse serum) solid medium and incubated overnight at 37°C. The next day, single colonies were picked and inoculated into TSB (containing 10% horse serum) liquid medium. After incubation at 37°C and 200 rpm for 12 h, each colony was sequentially transferred to 500 mL of the corresponding medium at a 1:100 ratio and incubated at 37°C and 200 rpm for 4 h. 100 μL of each of the three bacterial cultures were serially diluted and plated onto their respective plates for colony counting. The bacteria were aseptically harvested, washed three times with PBS, resuspended in PBS, and inactivated with 1.5‰ formaldehyde. After 48 h, the bacteria were plated to check for complete inactivation. Finally, the four bacterial cultures were mixed with AL adjuvant at specific volumes to emulsify them, resulting in concentrations of 1.5 × 10⁻⁶ for each of the three bacterial strains. 9 CFU / mL.

[0110] II. Mouse Immunization Experiment

[0111] One hundred and twenty 6-week-old Balb / C mice were randomly divided into four groups of 30 mice each. Each mouse was immunized intraperitoneally with 0.2 mL of serum. A second immunization was administered 14 days after the first immunization, using the same dosage and route as the first immunization. Fourteen days after the second immunization, blood was collected from the tails of all mice, and the serum was separated, aliquoted, and cryopreserved for later use. Simultaneously, intraperitoneal challenge was performed using Streptococcus suis type 2 / 8 / 9 isolates at doses of 1.2 × 10⁻⁶, respectively. 9 CFU / each, 1×10 9 CFU / each, 8×10 8 CFU / mouse, and the survival status of mice was observed and recorded over one week. Tables 1-3 show the results of the immune challenge experiment.

[0112] Table 1

[0113]

[0114] Table 2

[0115]

[0116] Table 3

[0117]

[0118] Data show that vaccines displaying the surface of Fe protein nanoparticles provide 100%, 80%, and 100% protection against Streptococcus suis 2 / 8 / 9 challenges, respectively. Pure protein vaccines provide 80%, 50%, and 70% protection against Streptococcus suis 2 / 8 / 9 challenges, respectively. Inactivated vaccines provide 70%, 70%, and 80% protection against Streptococcus suis 2 / 8 / 9 challenges, respectively.

[0119] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A ferritin nanoparticle assembly, characterized in that, It is composed of ferritin nanoparticles 1 and ferritin nanoparticles 2; The ferritin nanoparticles 1 contain streptococcal MRP protein; The ferritin nanoparticles 2 contain Streptococcus suis PrsA protein.

2. The ferritin nanoparticle combination of claim 1, wherein, The sequence of the Streptococcus suis MRP protein is as follows: (1) An amino acid sequence as shown in SEQ ID NO: 1; or (2) An amino acid sequence obtained by substituting, deleting, or adding one or more residues as shown in (1), and whose function is the same as or similar to that of (1); or (3) An amino acid sequence that is at least 90% homologous to the amino acid sequence shown in (1) or (2).

3. The ferritin nanoparticle combination of claim 1 or 2, wherein, The sequence of the Streptococcus suis PrsA protein is as follows: (4) An amino acid sequence as shown in SEQ ID NO: 2; or (5) An amino acid sequence obtained by substituting, deleting, or adding one or more residues as shown in (4), and whose function is the same as or similar to that of (4); or (6) An amino acid sequence that is at least 90% homologous to the amino acid sequence shown in (4) or (5); The number of items is 2 to 10.

4. Expression vector for the preparation of the ferritin nanoparticle assembly according to any one of claims 1 to 3, characterized in that, Including expression vector 1 and expression vector 2; The expression vector 1 has: (7) A nucleotide sequence as shown in SEQ ID NO: 4; or (8) A nucleotide sequence obtained by substitution, deletion, or addition of one or more bases to the nucleotide sequence shown in (7), and whose function is the same as or similar to that of (7); or (9) A nucleotide sequence that is at least 90% homologous to the nucleotide sequence shown in (7) or (8); The expression vector 2 has: (10) A nucleotide sequence as shown in SEQ ID NO: 5; or (11) A nucleotide sequence obtained by substituting, deleting, or adding one or more bases to the nucleotide sequence shown in (10), and whose function is the same as or similar to that of (10); or (12) A nucleotide sequence that is at least 90% homologous to the nucleotide sequence shown in (10) or (11); The number of items is 2 to 10.

5. The ferritin nanoparticle combination of claim 1, wherein, The preparation method includes: expressing the ferritin nanoparticles 1 and ferritin nanoparticles 2 separately and mixing them to obtain the ferritin nanoparticle combination; The ferritin nanoparticles 1 are expressed by the expression vector 1 in the expression vector of claim 4; The ferritin nanoparticles 2 are expressed by the expression vector 2 in the expression vector of claim 4.

6. The use of the ferritin nanoparticle combination as described in any one of claims 1, 2, 3, and 5 in the preparation of biological products for the prevention or treatment of Streptococcus suis infection.

7. Use according to claim 6, wherein The Streptococcus suis infection is an infection of at least one of Streptococcus suis type 2, Streptococcus suis type 8, and Streptococcus suis type 9.

8. Vaccine, characterized in that, Combining an adjuvant and ferritin nanoparticles according to any one of claims 1, 2, 3, and 5.

9. The vaccine of claim 8, wherein the antigen is a protein or a polypeptide. The adjuvant is an aluminum adjuvant.

10. The vaccine as described in claim 8 or 9, characterized in that, The concentration of ferritin nanoparticle 1 is 0.1 mg / mL, and the concentration of ferritin nanoparticle 2 is 0.1 mg / mL.

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