Bio-engineered flagellin-derived scaffold backbone and uses thereof

Abstract

A bio-engineered scaffold backbone 18 is provided comprising a first protein-fragment arm 12a, a linker 14a connected to the first protein-fragment arm 12a, and a second protein-fragment arm 12b connected directly or indirectly to the linker 14a. The first and second protein-fragment arms 12a, 12b bond or interact with one another which can thus make the scaffold backbone 10 suitable in a wide variety of contexts, wherein the first and second protein-fragment arms 12a, 12b are bioengineered amino acid sequences derived from flagellin protein fragments derived from non-pathogenic extremophiles. In particular, the backbone 18 can combine to form a scaffold 10 with a polypeptide region 16 for use in diagnostic testing.

Description

[0001]Bio-Engineered Polypeptide Scaffold Backbone and Uses Thereof FIELD OF THE INVENTION The present invention relates to the discovery of biological scaffolds and the use of heterologous polypeptides embedded within a scaffold. The scaffolds are selected, and extensively bio- engineered, to facilitate the expression, correct folding and stability of embedded peptides. The bio-engineered scaffolds are intrinsically suited to accepting, expressing and displaying a single peptide, a polypeptide or multiplexed composite polypeptides. Moreover, the bio-engineered scaffolds enable high efficiency cloning, high yield expression, and increased stability of the heterologous peptide(s) or protein(s). The scaffolds bioproducts (i.e., scaffold plus embedded polypeptide) can be used for serodiagnosis, peptide mapping, antigen testing, environmental and security monitoring, synthetic biology and research. The invention further relates to a method of generating antibodies using a multi-peptide-based scaffold as immunogen. The invention further relates to a peptide-based vaccine utilising such polypeptide scaffolds’ complex, to a pharmaceutical composition comprising the polypeptide scaffolds, and to a recombinant nucleotide sequence encoding the bio-engineered polypeptide scaffold. By virtue of their intrinsic stability which were further enhanced by selective evolutionary mutations, the scaffolds of the present invention can be used to prolong the stability and activity of embedded peptides, polypeptides or proteins sequences during in vitro and potentially in vivo processes. The scaffolds complexes in the present invention can be expressed in prokaryotic, virus, eukaryotic, archaebacteria, microalgae expression systems or in vitro using an in vitro transcription / translation system. BACKGROUND The use of so-called protein scaffolds is gaining attention in biochemistry as a potential route to generating novel ligand binding proteins for use in research and medicine. Historically, biologic scaffolds were composed of allogeneic or xenogeneic extracellular matrix and commonly used for the repair and functional reconstruction of injured and missing tissues. Scaffolds were also used to enhance the stability of peptides / proteins towards proteolytic proteases (Szewczuk et al.,1992), enhance binding affinity for cognate binding proteins (Rizo and Gierasch, 1992), for in vivo screening for effector proteins, the identification of interacting proteins, and potential use as a therapeutic in physiological conditions. Several scaffolds capable of presenting a protein of interest are described in the literature and include minibody structures, loops on beta-sheet turns, coiled- coil stem structures, zinc-finger domains, cystine linked structures, helical barrels, leucine Zipper motifs and neuropeptide head activator. Prior art scaffolds also include inactivated staphylococcal nuclease, green fluorescent protein (GFP) and thioredoxin A (TrxA), the fibronectin type III domain (`Fn3`), lipocalin family proteins, bilin binding protein (BBP), as well as isolated protein folds such as the Z domain of Staphylococcal protein A, "affibodies", anticafins, and ankyrin repeats, and others. In this invention, the focus is on a specific type of scaffold that facilitates the expression, solubility and stability of one or more heterologous polypeptide sequences in their native conformation. Chemical synthesis of high-quality peptides is an option but has a significant limitation, especially for >20 amino acids long peptides which are required in many situations. Moreover, some peptides will have low yields due to insolubility issues. The synthetic process will generate toxic by-products due to the use of strong solvents and hazardous reagents. Also, high quality long peptides are expensive to produce by chemical synthesis due to high costs for purification, that are often contaminated with by-products and trifluoroacetic acid (TFA), which is usually used to cleave the polypeptides from solid-phase resins. Some peptides tend to form β-sheet or α-helical structures within the molecule and therefore they have high aggregation / low solubility potential and are difficult to synthesise. Finally, the use of chemical synthesis is implausible for the multiplexing of several peptides into one chimeric entity. The term `protein scaffold` in the present invention describes a type of protein structure that supports the expression and stability of heterologous peptide sequences observed in differing contexts and with distinct biochemical and biological functions. Likewise, recombinant production of peptides in expression systems such as prokaryotic systems (e.g., Escherichia coli (E. coli)) or eukaryotic systems (e.g., Saccharomyces cerevisiae, Pichia pastoris) also have limitations. It is well known in the art that the expression yield, solubility and folding of a peptide / protein is greatly impacted in expression system such as E. coli by codon bias, the starting and ending residues of the target peptide (Klock et al.2008), by certain contiguous hydrophobic residues, low complexity regions, and regions of biased sequence composition (i.e., homopolymeric runs, short-period repeats, and overrepresentations of one or a few residues) (DePristo et al., 2006). Also, the presence of disulfide bonds (cystine residues) in a peptide / protein of interest (e.g., growth factors and antibody FAB fragments) negatively correlates with soluble expression in E. coli and other expression systems (Stewart et al., 1998). Moreover, short peptides (100 or fewer amino acids) are rapidly degraded by the proteolytic machinery and often their expression in E. coli and other expression systems will be of low yield and quality. Another potential problem with biological expression systems is that expressed heterologous peptides may not conform to their native structure and therefore lose their bioactivity. An additional technical challenge for the existing biological expression systems is that the expression of multiple peptides at once via linkers to produce a multi-peptide chimeric complex is an exigent and costly task. Often prokaryotic or eukaryotic systems produce unstable structures due to degradation, and aggregation as well as poorly folded products when the multiplexing (i.e., the combining of multiple peptides via linkers) of peptides has been attempted. It is known in the art that given the unique structure of flagellin molecules; they are intrinsic scaffold proteins. The helical N- and C-termini of a flagellin are responsible for flagellin's ability to polymerize into a stable structure. The middle portion which is wildly variable and can be absent in some flagellin proteins, protrudes outward. The flagellins’ natural structure dictates it is possible to remove the variable-middle portion of flagellins partially or entirely and replace with a heterologous peptide / protein without impacting the stable structure formed between the N- and C- termini. Also, it is known in the art to be possible to fuse a heterologous peptide / protein of interest to the N- and / or C-terminus of a full or partial flagellin. The use of flagellin-based scaffolds has been reported previously for expressing heterologous peptides (Patent No: US2023 / 285532 A1). Moreover, the use of flagellin-based scaffolds has been reported previously for vaccine development to Clostridium difficile and enteropathogenic E. coli (for example, disclosed inUS2016 / 166671 A1, US2016 / 074493 A1). Despite the relevant success in utilising flagellin derived scaffolds to express heterologous peptides and proteins; there persist significant drawbacks. The flagellin-based scaffolds proteins described above had originated from Clostridium difficile and E. coli pathogenic species and hence will have a strong immunoreactivity to bodily fluids, hindering their use in serology testing, antigen testing and peptide immunogenicity mapping. Additional challenges include size limitation of heterologous peptide embedded within the flagellin- derived scaffolds, and a lack of capacity to combine multiple peptides via linkers. By and large, prior art scaffolds, including those flagellin derived scaffolds, are not readily amenable to supporting the expression and the correct folding of peptide(s) of choice with high efficiency. More significant challenge for prior art scaffolds is the capacity to support the expression and folding of multiple peptides at once, especially of varying amino acid lengths and compositions. Moreover, prior art scaffolds systems produce products in low yield and low stability which deem them economically an unviable option to be pursued. Also, and importantly, prior art scaffolds, specifically flagellin derived scaffolds, are often immunoreactive with bodily fluids (i.e., antibodies in serum, saliva, urine) which hinders their use in serodiagnosis, antigen testing and peptide immunogenicity mapping. This is because interaction between antibodies in samples with the scaffold will lead to false positives. There is an unmet demand (especially in the field of serodiagnosis, peptide mapping and antigen testing, peptides-based vaccines and peptides-based immunogen) for a stable consistent scaffold to facilitate the economic expression of difficult-to-express peptides, polypeptides, multiple-peptide complex, multiple domains, and full proteins and ultimately provide the flexibility for the heterologous sequences to fold into their native structures. Given the millions of potential flagellin scaffolds, there are none so far that can express heterologous peptides / proteins to satisfy the different applications discussed above. The scaffolds described herein were derived from flagellin proteins that correspond to novel non- pathogenic extremophiles. The scaffolds were selected because they are readily expressed in biological expression systems (i.e., E.coli) and following purification and refolding, they formed the rigid stable structure seen in flagellins. The high conformational stability of the scaffolds of the present invention ensured the embedded heterologous peptides / polypeptides / proteins are readily expressed, soluble and folded into their native structures. Importantly, the selected scaffolds were not immunoreactive with bodily fluids (i.e., antibodies in serum or saliva didn’t react with the scaffolds), opening up the ideal opportunity for their use in serology testing, antigen testing, peptide immunogenicity mapping, peptide / antibody discovery and screening. The immunoreactivity point is a difficult criterion to satisfy since mammals’ sera / saliva will often display an immunoreactivity towards flagellins. Because the scaffolds of the present invention can stably support the expression of multiple peptides with varied sizes and amino acid composition opens up the opportunity to use in developing peptide-based vaccines or antibodies. The scaffolds of the invention can also function as a protein tag for purification and detection. Therefore, the new entity of the scaffold and heterologous peptide(s), can potentially provide the means to study / quantify the interaction between antigen / antibody, ligand / receptor and create novel biologicals. The unique nucleotide sequences of the scaffolds of the present invention made them amenable to further bioengineering alterations (i.e. deletion, addition and substitution of original amino acid sequences) which was carried out in order to improve certain physiochemical characteristics and properties which includes and not limited to; (i) increasing the size of the nucleotide sequence that can be embedded / cloned into the scaffold, maintaining a stable expression of the heterologous peptide(s) in an expression system of choice, (ii) increasing the number of heterologous peptides sequences that can be embedded into the scaffolds of the present invention, producing a stable multi-peptide scaffold complex as one entity in a biological expression of choice, (iii) improving the cloning efficiency of the expressed peptides of interest (s), (iv) increasing the expression yield of the heterologous peptide(s), (v) improving stability and reducing degradation of the heterologous peptide(s), and (vi) reducing immunoreactivity of the scaffolds of the present inventions to bodily fluids to ensure the scaffolds are almost inert and unlikely to interfere with assays or tests developed. It is an object of the present invention to resolve the challenges described above of expressing a single peptide / multiple peptides of varying sized and composition in a stable native conformation using biological expression system of choice which include; (i) the lack of a biological expression system that can efficiently express short peptides (<100 amino acids), (ii) the lack of an expression platform to stably express multiple heterologous peptides in one complex, (iii) overcome issues associated with recombinant production such as the low cloning efficiency, low protein yield and low stability encountered when attempting to recombinantly express, short peptides, multiplexed peptides, or difficult-to-express peptides / proteins and (iv) the lack of non-immunoreactive scaffolds to antibodies present in clinical samples such as serum and saliva. Specifically, it is an object of the present invention to transform the diagnostic landscape and improve accuracy by developing peptide based tests, and thus develop a system capable of producing peptides economically and in their native conformation. SUMMARY OF THE INVENTION According to a first aspect of the invention, there is provided a bio-engineered scaffold backbone comprising: a first protein-fragment arm; a linker connected to the first protein-fragment arm; and a second protein-fragment arm connected directly or indirectly to the linker; wherein the first and second protein-fragment arms bond or interact with one another to form a scaffold structure, wherein the first and second protein-fragment arms are bioengineered sequences derived from flagellin protein fragments derived from non-pathogenic extremophiles In one example, the first and second protein-fragment arms may be protein fragments derived from non-pathogenic extremophiles of the species Thermotoga, Thermithiobacillus, Aquifex, Geobacillus, Acidithiobacillus, Alkalispirochaeta, Desulfosporosinus, Bermanella, and / or Azospirillum. The scaffold-based chimeric peptide(s) / protein(s) additionally includes polypeptide tags fused to isolate the chimeric protein. The tag may be a known tag such as a FLAG-tag, a HIS- tag, or the like. Multiple tags can be fused to the scaffold simultaneously and can be fused in the middle of the scaffold structure, N- or C-termini. The scaffold-based chimeric peptide(s) / protein(s) may instead, or additionally, include a cleavage site adjacent to the heterologous peptide(s) / protein(s). Directed evolutionary modifications to specific nucleotides of the scaffold’s arms in the present invention were carried out through substitution / deletion / addition to improve certain characteristics and included but are not limited to; ^ To readily accept heterologous peptide(s) of diverse composition, corresponding to a single peptide, multiple peptides, domain(s), and full protein(s) without impacting expression efficiency, solubility and stability. As discussed above, there are many factors that will impact expression efficiency, yield, solubility and stability of recombinant products. Regardless of the amino acid composition of the heterologous peptide, the expression efficiency of the present invention is as high as 99% which is a significant invention given the difficulties encountered in expressing short peptides, hydrophobic residues, low complexity regions, cysteine rich sequences, and regions of biased sequence composition. ^ Flexibility in size of the expressed heterologous peptides (i.e., the number of nucleotides) that can be potentially embedded in the scaffold. It is well established in the art that biological expression systems are greatly affected by the size of the heterologous peptide / protein to be expressed, as is the yield, solubility and stability. Comparative studies have shown that the probability of soluble expression in E. coli decreases with small recombinant peptides (>100 aa) and with increasing molecular weight (>60 kD) (Canaves et al., 2004, Goh et al., 2004, Graslund et al., 2008). The present invention facilitates the expression of heterologous peptides that can range in size from 5 amino acids to 1000 amino acids with up to 99% efficiency, high yield and stability. This capacity is a marked innovation of the present invention compared to the currently available scaffolds. ^ Flexibility in the number of heterologous peptides connected via appropriate linkers that can be embedded into the scaffold and expressed efficiently to a soluble stable recombinant product. It is well established in the art that the expressing of multiple peptides recombinantly is a major challenge which will dramatically impact the expression efficiency, expression yield, solubility and stability of recombinant product. The challenges include contiguous hydrophobic residues, low complexity regions, cystine rich peptides, regions of biased sequence composition (i.e., homopolymeric runs, short-period repeats, overrepresentations of one or a few residues). Several of the aforementioned challenges are often present at once when expressing multiple heterologous peptides, making the expression of multi-peptides a daunting and uneconomical undertaking. This difficulty explains the lack of scaffolds suitable for expressing multiple peptides into one chimeric recombinant product. The present invention has overcome the aforementioned challenges which is a significant advancement to currently available scaffolds. The present invention has the capacity to express up to 15 peptides connected via linkers to produce a chimeric multi-peptide recombinant product. Expressing multiple peptides as one entity opens up the opportunity to transform serology testing, antigen testing, peptide-based vaccine development, and peptide-based antibody development. ^ The scaffolds were modified to ensure preferential binding to testing surfaces (i.e., gold nanoparticles, ELISA plates) which will lead to improved orientation and presentation of the heterologous peptide(s) embedded withing the scaffold. Correct orientation and presentation will positively impact immunoassay sensitivity and reproducibility. ^ Another novel property of the present invention is the low immunoreactivity to bodily fluids such as serum and saliva. This property is a prerequisite if a scaffold is to be suitable for use in serology testing, antigen testing and peptide immunogenicity mapping. It is well- established in the art that it remains difficult to identify scaffolds with low immunoreactivity, hence there are no scaffolds available for use in serodiagnosis, antigen testing and peptide mapping. For flagellin derived scaffolds, it is considered an even bigger challenge to find a protein of low immunoreactivity which explains why there hasn’t been a single flagellin- based scaffold used in serology and antigen testing. This is due to the documented evidence that flagellin proteins derived from common micro-organisms or pathogenic micro-organisms are invariably immunoreactive to bodily fluids. Flagellins originating from microorganisms such as E. coli, Clostridium difficile, Salmonella enterica, Campylobacter jejuni, Burkholderia cenocepacia, and Pseudomonas aeruginosa are highly immunoreactive. The scaffold flagellin arms in the present invention were derived from non-pathogenic extremophiles and selected deliberately to be non-immunoreactive with human or animal sera. Moreover, further targeted bio-engineering in the flagellin arm sequences were carried out in order to reduce the scaffolds immunoreactivity. It is crucial for diagnostic purposes that the scaffold structure cannot be reactive to the biological matrices using in testing, such as human sera. The immunoreactivity will create false positives and low specificity and performance of such a test. The scaffold-peptide(s) recombinant products can be highly purified under denaturing conditions and easily re-folded, allowing high throughput purification of peptides or peptide libraries in a cost- effective manner. The polypeptide(s) region retains its native conformation or bioactivity. Additionally, the scaffolds of the present invention are capable of displaying single chain variable fragments of antibodies and single-domain antibody fragments. Purified recombinant proteins are used in products ranging from biological soap powders, diagnostic devices to therapeutics. The rate at which these proteins degrade is critical to their function and utility. Technologies / platforms that address the rate of degradation and enable novel applications can transform the value of a protein. The present invention provides a rigid and stable framework to address protein instability especially in the context of proteolytic degradation and increase the half-life of peptide(s) / proteins for use in research, therapy and diagnosis. This provides stability without needing to modify the polypeptide region, thereby maintaining its function. An additional advantage of the scaffold of the present invention is that it facilitates high expression yields of heterologous peptide(s), ranging from 200mg / L to 1g / L. The scaffolds of the present invention can be expressed in prokaryotic, virus, eukaryotic, archaebacteria, microalgae expression systems or in vitro using an in vitro transcription / translation system. Optionally, the scaffold backbone formed by the first and second protein-fragment arms may have a helical structure. The robust helical stem-like structure may act as a framework structure anchoring and displaying the peptide(s) in the correct orientation. Some of the scaffolds’ first and second protein-fragment arms were flagellin sequences derived from non-pathogenic thermophiles which infer that their proteins naturally exhibit high thermal stability, a highly desired property for optimization of biopharmaceutical and biotechnological processes. The amino acid sequence of the first protein-fragment arm may be derived from a sequence selected from any of SEQ ID NOs: 1 to 10. The amino acid sequence of the second protein-fragment arm may be derived from a sequence selected from any of SEQ ID NOs: 11 to 20. The amino acid sequence of the first or second protein-fragment arm may be a sequence defined by any of SEQ ID NOs: 51 to 62. The difficulty in identifying a suitable flagellin-based scaffold derived from pathogenic or non- pathogenic microorganisms, including extremophiles, is complicated by the vast numbers of sequences available. The vast possibilities of flagellins must be tested empirically to provide evidence for their suitability which is an expensive and daunting task. As such, the present invention has isolated many viable sequences which have a specific species selection, flagellin sequence, bio-engineered so as to be suitable for use in many different contexts, including but not limited to serology testing, antigen testing, peptide immunogenicity mapping, antibody library screening and peptide evolutionary screening. The amino acid sequence of the left linker may be defined by SEQ ID NO: 21. The amino acid sequence of the right linker may be defined by SEQ ID NO: 22. The amino acid sequence of a middle linker associated between adjacent peptides in the polypeptide region may be defined by SEQ ID NO: 23. The amino acid sequence of a purification tag associated with the first or second protein-fragment arm may be defined by SEQ ID NOs: 24 to 25. Ideally, a functional variant has at least 90% amino acid sequence identity with SEQ ID NO: 1 to 20, and no more than two amino acids change with the linkers defined by SEQ ID NO: 21, SEQ ID NO: 22, and SEQ ID NO.23. Optionally, the amino acid sequence of the first protein-fragment arm may be longer than the amino acid sequence of the second protein-fragment arm. According to a second aspect of the invention, there is provided a bio-engineered scaffold comprising a bio-engineered scaffold backbone in accordance with the first aspect of the invention, wherein the second protein-fragment arm is connected directly to the linker. The bio-engineered scaffold may further comprise an immunostimulant; an inhibitor or immunosuppressant; or an adjuvant The backbone may have various uses in isolation, particularly in the field of immunostimulation or immunosuppression, or as a vaccine adjuvant. According to a third aspect of the invention, there is provided a bio-engineered scaffold comprising a bio-engineered scaffold backbone in accordance with the first aspect of the invention, further comprising a second linker connected directly to the second protein-fragment arm, and a peptide region having at least one peptide connected to the first said linker and the second linker. Optionally, the peptide region is a polypeptide region comprising a plurality of peptides. In the preferred embodiment of the invention, the backbone acts as a support for one or more peptides, this peptide having a wide range of expressible characteristics which have, in particular, diagnostic and therapeutic capabilities. Preferably, the heterologous peptide region may comprise up to 15 peptides. The peptide(s) may have a length between 5 and 1000 amino acids. Each peptide may comprise a short peptide, a long peptide, a complete structural or functional domain of a protein, or a whole protein. The polypeptide region may comprise any of: an antigen; an antigen carrier; an antigen competitor; a screening agent for B-cell and T-cell epitopes; an immunostimulant; an inhibitor or immunosuppressant; an immunogenicity test peptide or protein; a therapeutic peptide which may be selected from an antimicrobial / antiviral / immunogenic peptide; a ligand-receptor binding site; an antibody binding site; an antigen binding site; or a combination thereof. More preferably, the polypeptide region may comprise a library of any of: an antigen, particularly in serology testing or in testing of vaccine efficacy and quality control; an antigen carrier, particularly in serology testing; an antigen competitor; a screening agent for B-cell and T-cell epitopes; an immunostimulant; an inhibitor or immunosuppressant; an immunogenicity test peptide or protein; an immunogen peptide, that is, for use in immunisation of animals for antibody production or immunised B cells for library construction or monoclonal antibody development; a ligand-receptor binding site; an antibody binding site; an antigen binding site; or a combination thereof. The polypeptide region can be applied to find high affinity interactions between antibodies and antigens, which play a critical role in viral pathogenesis, vaccines, and other treatments. Screening the scaffold peptide libraries as an effective means of identifying peptides that can bind target molecules and regulate their function. The peptide(s) libraries of second and third aspects of the present invention can be used for (i) B-cell and T-cell epitope mapping, (ii) selection of bioactive peptides bound to receptors / proteins / enzymes / chemicals, disease-specific antigen mimics, peptides bound to non-protein targets, cell-specific peptides, or organ-specific peptides, (iii) development of peptide-mediated drug delivery systems and other applications, (iv) peptide directed evolution to identify peptides with certain physiochemical and binding properties. According to a fourth aspect of the invention, there is provided a diagnostic serology or antigen kit comprising a bio-engineered scaffold in accordance with the third aspect of the invention. Optionally, the heterologous polypeptide region may be provided as an antigen, an antibody carrier, or an antigen competitor. In the context of serodiagnosis, antigen testing and peptide immunogenicity profiling, the scaffolds of the present invention are ideally suitable because of their low immunoreactive with bodily fluids especially testing material such as serum, saliva and urine samples. The present invention also exhibits a compact stable structure that is able to accept and present one or more peptides(s) of varying sequence origin and length, and maintain their native confirmation. In addition, the protein scaffolds of the present invention facilitate high yield, stability, and efficiency as well as a standardised purification protocol making the product economically viable. The present invention may also be used as a probe to home in on a binding partner, e.g., in cells or tissues by immunohistochemistry, using the invention as a tag. Furthermore, the present invention can be used as bait to isolate a binging partner, for instance, in an affinity pull-down assay or co-immunoprecipitation assay using peptide(s) scaffold complex as a tag. There may also be provided an assay for determining the presence of an antigen, the assay comprising steps of displaying a detection antibody using the agent as described above and reacting the detection antibody with sample to detect the presence of the antigen. Preferably, the antigen is detected by any immunoassay based on antigen / antibody interaction, for example, Western Blot, Enzyme-Linked Immunoassays, lateral flow, Surface Plasmon Resonance, Radioimmunoassay, Chemiluminescence immunoassay, Fluoroimmunoassay, Enzyme Immunoassays, cloned enzyme donor immunoassay, Memory Lymphocyte Immunostimulation Assay, Immunoscreening, dot blot, Nephelometry, Magnetic immunoassay, Surround Optical Fiber Immunoassay, CD / DVD based immunoassay, immunohistochemistry, affinity pull-down assay or co-immunoprecipitation assay, Agglutination-PCR, and a protein-based array. According to a fifth aspect of the invention, there is provided a method of ex vivo diagnosis of a condition performed using a diagnostic kit in accordance with the fourth aspect of the invention. Optionally, the condition is SARS-CoV-2 or Lyme disease. According to a sixth aspect of the invention, there is provided a method of generating antibodies and peptide mapping using a bio-engineered scaffold in accordance with the third aspect of the invention, wherein the polypeptide region embedded within the scaffold comprises one or a library of immunogenic peptide(s) for one or more desired targets. According to a seventh aspect of the invention, there is provided a vaccine comprising a bio- engineered scaffold backbone in accordance with the first aspect of the invention. In a preferred embodiment, the polypeptide region one or more immunodominant peptides. The vaccine may further comprise an adjuvant. Additionally, or alternatively, and in according with the first aspect of the invention, the scaffold may itself be a vaccine adjuvant. The scaffold alone, or the peptide(s)-scaffold complex can be used as an immunostimulant or vaccine adjuvant alone or as a hybrid. The route of administration can be oral, via intraperitoneal injection, or other techniques known in the art. According to an eighth aspect of the invention, there is provided a pharmaceutical composition comprising the bio-engineered scaffold in accordance with the third aspect of the invention and a pharmaceutically acceptable carrier. The resulting products from the peptide(s)-scaffold can be used as; (1) an antigen / antibody in an immunoassay, an immunogen or a vaccine, (2) a binder in an assay, e.g. function as a competitor, (3) a bioactive molecule, e.g. as an immune stimulatory / inhibitory molecule, (4) (the scaffold itself can function as) a tag for purification and / or a general detection tag for the peptide displayed, (5) a stable structure to express proteins with short-half life for use in research, therapy and diagnosis, (6) a therapeutic peptide, e.g. an antimicrobial peptide, an antiviral peptide and an immunogenic peptide. According to a ninth aspect of the invention, there is provided a recombinant nucleotide sequence encoding the bio-engineered scaffold backbone in accordance with the first aspect of the invention or the bio-engineered scaffold in accordance with the second or third aspects of the invention. An optimised nucleotide sequence encoding the isolated polypeptide, wherein the optimised nucleotide sequence comprises (or consists of) a combination of at least one of SEQ ID NO: 26, SEQ ID NO: 27, SEQ ID NO: 28, SEQ ID NO: 29, SEQ ID NO: 30, SEQ ID NO: 31, SEQ ID NO: 32, SEQ ID NO: 33, SEQ ID NO: 34, or SEQ ID NO: 35, or a functional variant thereof or functional fragment thereof; and at least one of SEQ ID NO: 36, SEQ ID NO: 37, SEQ ID NO: 38, SEQ ID NO: 39, SEQ ID NO: 40, SEQ ID NO: 41, SEQ ID NO: 42, SEQ ID NO: 43, SEQ ID NO: 44, or SEQ ID NO: 45, or a functional variant or functional fragment thereof; and both of SEQ ID NO: 46, SEQ ID NO: 47, or all of SEQ ID NO: 46, SEQ ID NO: 47 and SEQ ID NO: 48, or a functional variant or functional fragment thereof. The functional variant of nucleotide sequence can differ substantially and be codon-optimised for a specific species providing that it encodes for the same peptide sequence or functional variant or functional fragment thereof. Preferably, the purification tags may be defined by SEQ ID NO: 49 and SEQ ID NO: 50. According to a tenth aspect of the invention, there is provided an agent comprising a recombinant construct in accordance with the ninth aspect of the invention having at least one peptide flanked either side by an arm and connected either side by a linker. According to an eleventh aspect of the invention, there is provided a recombinant construct comprising (or consisting of) an isolated polypeptide having a left arm selected from SEQ ID NO: 1, SEQ ID NO: 2, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 5, SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO: 9, or SEQ ID NO: 10 or a functional variant or functional fragment thereof; a right arm selected from SEQ ID NO: 11, SEQ ID NO: 12, SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 15, SEQ ID NO: 16, SEQ ID NO: 17, SEQ ID NO: 18, SEQ ID NO: 19, or SEQ ID NO: 20, or a functional variant or functional fragment thereof; and a linker selected from SEQ ID NO: 21, SEQ ID NO: 22, and SEQ ID NO.23, or a functional variant or functional fragment thereof. The linker defined by SEQ ID NO: 23 is used to provide a flexible linker between multiple peptides as needed to separate and prevent interference between adjacent peptides. Preferably, the functional variant has at least 80% amino acid sequence identity with SEQ ID NO.1 to 23. Preferably, the functional variant has at least 81% amino acid sequence identity with SEQ ID NO: 1 to 23. Preferably, the functional variant has at least 82% amino acid sequence identity with SEQ ID NO: 1 to 23. Preferably, the functional variant has at least 83% amino acid sequence identity with SEQ ID NO: 1 to 23. Preferably, the functional variant has at least 84% amino acid sequence identity with SEQ ID NO: 1 to 23. Preferably, the functional variant has at least 85% amino acid sequence identity with SEQ ID NO: 1 to 23. Preferably, the functional variant has at least 86% amino acid sequence identity with SEQ ID NO: 1 to 23. Preferably, the functional variant has at least 87% amino acid sequence identity with SEQ ID NO: 1 to 23. Preferably, the functional variant has at least 88% amino acid sequence identity with SEQ ID NO: 1 to 23. Preferably, the functional variant has at least 89% amino acid sequence identity with SEQ ID NO: 1 to 23. Preferably, the functional variant has at least 90% amino acid sequence identity with SEQ ID NO: 1 to 23. Preferably, the functional variant has at least 91% amino acid sequence identity with SEQ ID NO: 1 to 23. Preferably, the functional variant has at least 92% amino acid sequence identity with SEQ ID NO: 1 to 23. V Preferably, the functional variant has at least 93% amino acid sequence identity with SEQ ID NO: 1 to 23. Preferably, the functional variant has at least 94% amino acid sequence identity with SEQ ID NO: 1 to 23. Preferably, the functional variant has at least 95% amino acid sequence identity with SEQ ID NO: 1 to 23. Preferably, the functional variant has at least 96% amino acid sequence identity with SEQ ID NO: 1 to 23. Preferably, the functional variant has at least 97% amino acid sequence identity with SEQ ID NO: 1 to 23. Preferably, the functional variant has at least 98% amino acid sequence identity with SEQ ID NO: 1 to 23. Preferably, the functional variant has 99% amino acid sequence identity with SEQ ID NO: 1 to 23. According to a twelfth aspect of the invention, there is provided a method of preparing a bio- engineered scaffold, the method comprising the steps of: a] selecting a protein fragment selected from sequences derived from flagellin protein fragments derived from non-pathogenic extremophiles, according to at least one of stability, expression yield, and immunoreactivity with human sera; b] bioengineering the protein fragment to reduce immunoreactivity thereof; c] further bioengineering the protein fragment to increase surface binding and / or improve orientations to form a protein-fragment arm; and d] using a linker connecting the protein-fragment arm to a peptide region along with a complementary protein-fragment arm, the first and second said protein- fragment arms bonding or interacting with one another to form a scaffold structure. DEFINITIONS In the specification, the term “scaffold protein” should be understood to mean a nucleic acid sequence onto which heterologous nucleotide sequences are cloned, and the resulting construct is expressed in an expression system of choice. The expressed composite-structure ((scaffold plus peptide(s)) is then purified natively or denatured and refolded to bring together the complex (i.e., scaffold plus polypeptide(s)) in a relatively stable configuration. The scaffolds of the present invention facilitate the high expression yield of the heterologous peptides, act as a purification tag, and also acts as a framework structure with its inherently stable stem-like structure displaying the peptides outward in their native conformation and providing structural stability. In the specification, the term “expression platform or expression system” should be understood to mean the genetic machinery required to transfer the transgene into a cell, and generally comprises an organism, for example a bacterium, capable of mediating cellular transformation and containing a recombinant construct of the invention. Examples of transformation platforms include E. coli, A. tumefaciens, E. adhaerens, and certain “transbacter” strains of bacteria, yeast and eukaryotic cells. Other examples include biolistic transformation and floral dipping. Alternatively, the term “expression platform or expression system” can be any cell free in vitro transcription / translation platforms that are commercially available, for example, the TnT® Quick Coupled Transcription / Translation System from Promega. Cell-free expression enables high throughput production of small amounts of protein for testing and screening purposes. In the specification, the term “plasmid” should be understood to mean a small, often circular DNA molecule found in bacteria and other cells. Plasmids are separate from the bacterial chromosome and replicate independently of it. They generally carry only a small number of genes, notably some associated with antibiotic resistance. Plasmids may be passed between different bacterial cells. The plasmid may comprise regulatory machinery, for example promoters, terminators, and / or enhancers. The nucleotide sequence of the scaffold and its polypeptide(s) of interest may be under the control of a promotor region. It will be appreciated that any suitable cell specific promotor known in the art may be used. The promotor may be such that multiple copies of the scaffolds- polypeptide(s) are produced. Plasmids used in the experiments carried out herein are set out in the Materials and Methods section below. In the specification, the term “chemical synthesis” should be understood to mean artificial synthesis of polypeptides without the use of genetic machinery. In the specification, the term “antibody” should be understood to mean immunoglobulin molecules and immunologically active determinants of immunoglobulin molecules, e.g., molecules that contain an antigen binding site which binds, e.g., specifically binds, (immunoreacts with) a protein to be activated or inhibited. The term “antibody” encompasses whole antibodies, single chain variable fragments of antibodies, or single domain antibodies (such as VhH fragments found in camelids) derived from mammals, birds, bony or cartilaginous fishes, e.g., of any isotype (IgG, IgA, IgM, IgE, IgD, IgY (birds), IgT (Teleost / Holostean bony fish), IgNAR (sharks). In this specification, the term “administering” should be taken to include any form of delivery that can deliver a pharmaceutical composition (for example, a vaccine, probiotic bacteria, a bioactive polypeptide, and the like) parenterally, orally, nasally, rectally, topically, or buccally. Such routes include local delivery, intravenous delivery, oral delivery, intranasal delivery, intramuscular delivery, intraperitoneal injection, intrathecal delivery, transdermal delivery, inhaled delivery, and topical delivery. Methods for achieving these means of delivery will be well known to those skilled in the art of drug delivery. In this specification, the term “pharmaceutical composition” should be taken to mean compositions comprising a therapeutically effective amount of the scaffold protein, and a pharmaceutically acceptable carrier or diluent. In a specific embodiment, the term "pharmaceutically acceptable" means approved by a regulatory agency of the Federal or a state government or listed in the U.S. Pharmacopeia or other generally recognized pharmacopeia for use in animals, and more particularly in humans. The term "carrier" refers to a diluent, adjuvant, excipient, or vehicle with which the composition is administered. Such (pharmaceutical) carriers can be sterile liquids, such as water and oils, including those of petroleum, animal, vegetable or synthetic origin, such as peanut oil, soybean oil, mineral oil, sesame oil and the like. Water is a preferred carrier when the pharmaceutical composition is administered intravenously. Saline solutions and aqueous dextrose and glycerol solutions can also be employed as liquid carriers, particularly for injectable solutions. Suitable excipients include starch, glucose, lactose, sucrose, gelatin, malt, rice, flour, chalk, silica gel, sodium stearate, glycerol monostearate, talc, sodium chloride, dried skim milk, glycerol, propylene glycol, water, ethanol and the like. In this specification, the term “vaccine therapy” should be understood to mean the administration of an immunogenic peptide or protein to an animal with a view to eliciting a response by the host immune system that results in the peptide or protein being recognised and subsequently destroyed by the host immune system. In this specification, the term “immune response” should be understood to mean induced humoral or cellular response in the host. In this specification, the term “vaccine” should be understood to mean a composition comprising at least an immunogenic peptide or protein and optionally a suitable adjuvant and / or carrier. The preparation of vaccines comprising peptides or proteins as active agent is well described in the literature, for example US4599230 and US4601903, the complete contents of which are incorporated herein by reference. The term “DNA vaccine” should be understood to mean a composition that comprises a nucleic acid construct capable of being delivered to a patient / subject and expressing in the subject the antigen of interest and may also include other immune promotion components such as an immune modulatory cytokine. The antigens may be expressed as separate protein / peptides or in the form of a fusion protein. The vaccine may also include a suitable adjuvant, a pharmaceutically acceptable carrier, or both. The nucleic acid construct is preferably in the form of an expression vector, the detail of which will be known to those skilled in the art, for example a plasmid or a virus such as a lentivirus. DNA vaccines are discussed in detail in Kutzler et al. (Nat Rev Genet.2008 Oct;9(10):776-88). The term “RNA vaccine” should be understood to mean a composition comprising a messenger ribonucleic acid (mRNA) comprising an open reading frame encoding heterologous peptides of interest and the scaffold backbone capable of being delivered to a patient / subject and expressing in the subject the antigen of interest and may also include other immune promotion components such as an immune modulatory cytokine. The antigens may be expressed as separate protein / peptides or in the form of a fusion protein. The vaccine may also include a suitable adjuvant, a pharmaceutically acceptable carrier, or both. RNA vaccines are discussed in detail (Gote et al. 2023). In this specification, the term “adjuvant” should be understood to mean an agent that enhances the recipient’s immune response to an immunogenic peptide or protein. Details of suitable adjuvant compositions are well known to those skilled in the art. An adjuvant is a substance used to increase the immunogenicity to improve antigen presentation in lymphoid tissues by inducing the expression of major histocompatibility molecules and co-stimulatory molecules, modulate antigen-specific immune response toward a Th1-type or Th2-type response, and decrease the dose of antigen and frequency of administration necessary to achieve vaccine efficacy. An overview of adjuvants is discussed in detail (Facciola et al.2022). The adjuvant can consist of the scaffold, the scaffold derivative and a heterologous peptide- scaffold complex, or can be an entity with adjuvant properties expressed as part of the -scaffold complex. In vivo trials may last up to 12 weeks during which, a veterinary species of interest, is disease challenged with pathogen(s) following administration of adjuvant. The initial evaluation of the adjuvant function of the invention will be carried out on the European seabass (Dicentrarchus labrax) and Nile tilapia, (Oreochromis niloticus). In this specification, the term “immunogenic” refers to a composition comprising the scaffold protein as set out in the claims, or an immunogenic portion of either, that is capable of inducing an immune response in an individual which will enhance robustness to combat infection by viral, bacterial and parasitic pathogens, e.g., fish infectious spleen and kidney necrosis virus, Tilapia Lake Virus. Proteins and peptides (including variants and fragments thereof) of and for use in the invention may be generated by expression in vivo or by transcription / translation in vitro from nucleic acid sequence. In this specification, the term “therapeutic peptide” refers to peptides selected from the group consisting of an antimicrobial peptide and antiviral peptide. In the specification, the term “sample” should be understood to include a biopsy, a tumour sample, a biofluid sample, blood, serum, plasma, urine, sperm, mucus, tissue biopsy, organ biopsy, bronchial secretions, bile fluid, cerebrospinal fluid (CSF), synovial fluid, pleural fluid (pleural lavage), pericardial fluid, peritoneal fluid, amniotic fluid, saliva, sweat, nasal fluid, optic fluid, gastric fluid, mucosal secretion, effusion, breast milk, as well as cell culture supernatants. If the sample is a blood sample, this is typically drawn using capillary-based or venous withdrawal. The term also includes a mixture of the above-mentioned samples. The term “test sample” also includes untreated or pretreated (or pre-processed) biological samples. In some embodiments of any of the aspects, a test sample can comprise cells from a subject. As used herein the term “variant thereof” should be understood to mean a sequence which is substantially identical to a given amino acid sequence, but which is altered in respect of one or more amino acid residues or nucleotide residues compared to the given sequence, in such a way so as not to significantly alter the claimed function. The nucleotide sequence encoding for the same protein can be different due to codon redundancy. Typically, the variant is a (nucleotide or amino acid) sequence having from about 30% to about 99% sequence identity with a given sequence. Generally, the variant is a (nucleotide or amino acid) sequence having from about 70% to about 99% sequence identity, preferably 70, 75, 80, 85, 86, 88, 87, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98 or 99%, sequence identity with a given sequence and which is typically capable of eliciting an immune response in an individual, or bind a target molecule, i.e., variant is a functional variant. Such alterations include, insertion, addition, deletion and / or substitution of an amino acid residue(s), or a nucleotide residue(s). There may be 1, 2, 3, 4, or 5 alterations. It will be appreciated that such variants may be naturally occurring variants or may be a non-natural variant. The term variant also includes a fragment of a sequence. In relation to a variant of a peptide, the insertion, addition, and substitution with natural and modified amino acids are envisaged. The variant may have conservative amino acid changes, wherein the amino acid being introduced is similar structurally, chemically, or functionally to that being substituted. The term “functional variant” when used herein is taken to mean a variant of SEQ ID NO: 1 to 50 which is capable of, for example, eliciting an immune response in an individual, or bind a target molecule. Critically, the functional variant should be able to adapt to native conformations and retain the bioactive properties of the polypeptide of interest encoded by the scaffold protein. The term “fragment” means a segment of a given sequence. Typically, the fragment has from about 10 to 1000 contiguous amino acids, preferably about 50, 100, 200, 300, 400, 500, 600, 700, 800, or 900 amino acids. Typically, the fragment has from 30 to 3000 contiguous nucleotides preferably about 100, 250, 500, 750, 1000, 1250, 1500, 1750, 2000, 2250, 2500 or 2750 nucleotides. The fragment is a functional fragment, i.e., it is a segment of SEQ ID NO: 1 to 10 which can adapt to native conformations and retain the bioactive properties of the polypeptide of interest encoded by the scaffold protein. Functional fragments of functional variants of the invention are also provided. In terms of “sequence homology”, the term should be understood to mean that a variant (or homolog) which shares a defined percent similarity or identity with a reference sequence when the percentage of aligned residues of the variant (or homolog) are either identical to, or conservative substitutions of, the corresponding residues in the reference sequence and where the variant (or homolog) shares the same function as the reference sequence. In this specification, “homology”, “identity” or “similarity” refers to the relationship between two polypeptides or two nucleotide sequences based on an alignment of the sequences. The term “identity” when used herein means the percentage of identical, or conservative substitutions of, amino acid or nucleotide residues at corresponding positions in two sequences when the sequences are aligned and is across the entire length of the sequence, i.e. a variant (or homolog) that shares 70% sequence identity with a reference sequence is one in which any 70% of aligned residues of the variant (or homolog) are identical to, or conservative substitutions of, the corresponding residues in the reference sequence across the entire length of the sequence. For sequence comparison, one sequence acts as a reference sequence, to which test sequences are compared. This alignment and the percent homology, similarity or sequence identity can be determined using software programs known in the art, for example, BLAST, EMBOSS Needle, Clustal Omega, or MatGAT using default parameters. Details of these programs can be found at the following Internet address: http: / / www.ncbi.nlm.nih.gov. The scaffold proteins described above can be in the free form or in the form of salt, if applicable. A salt, for example, can be formed between an anion and a positively charged group (e.g., amino) on a protein-polymer scaffold protein of this invention. Suitable anions include chloride, bromide, iodide, sulfate, nitrate, phosphate, citrate, methanesulfonate, trifluoroacetate, and acetate. Likewise, a salt can also be formed between a cation and a negatively charged group (e.g., carboxylate) on a conjugate of this invention. Suitable cations include sodium ion, potassium ion, magnesium ion, calcium ion, and an ammonium cation such as tetramethylammonium ion. In addition, the scaffold proteins may have one or more double bonds, or one or more asymmetric centres. Such a conjugate can occur as racemates, racemic mixtures, single enantiomers, individual diastereomers, diastereomeric mixtures, and cis- or trans- or E- or Z- double bond isomeric forms. The term “peptide and polypeptide” used herein refers to a polymer composed of up to 1000 amino acid monomers via peptide bond linkage. Both terms “polypeptide” and “peptide” used herein refer to a polymer composed of a chain of amino acid monomers via peptide bonds. Both of the terms “peptide” and “polypeptide” used herein are interchangeable. Peptides or polypeptides can be prepared by conventional methods, i.e., chemical synthesis or recombinantly (in vivo expression / purification, or in vitro transcription / translation / purification). When necessary, any of the cytotoxic peptides employed in the conjugate of the invention can be chemically modified to increase their stability. A chemically modified peptide or a peptide analog includes any functional chemical equivalent of the peptide characterized by its increased stability and / or efficacy in vivo or in vitro in respect of the practice of the invention. The term peptide analog also refers to any amino acid derivative of a peptide as described herein. A peptide analog can be produced by procedures that include, but are not limited to, modifications to side chains, incorporation of unnatural amino acids and / or their derivatives during peptide synthesis and the use of cross-linkers and other methods that impose conformational constraint on the peptides or their analogs. Examples of side chain modifications include modification of amino groups, such as by reductive alkylation by reaction with an aldehyde followed by reduction with NaBH4; amidation with methylacetimidate; acetylation with acetic anhydride; carbamylation of amino groups with cyanate; trinitrobenzylation of amino groups with 2, 4, 6, trinitrobenzene sulfonic acid (TNBS); alkylation of amino groups with succinic anhydride and tetrahydrophthalic anhydride; and pyridoxylation of lysine with pyridoxa-5'- phosphate followed by reduction with NABH4. The guanidino group of arginine residues may be modified by the formation of heterocyclic condensation products with reagents such as 2,3- butanedione, phenylglyoxal and glyoxal. The carboxyl group may be modified by carbodiimide activation via o-acylisourea formation followed by subsequent derivatization, for example, to a corresponding amide. Sulfhydryl groups may be modified by methods, such as carboxymethylation with iodoacetic acid or iodoacetamide; performic acid oxidation to cysteic acid; formation of mixed disulphides with other thiol compounds; reaction with maleimide; maleic anhydride or other substituted maleimide; formation of mercurial derivatives using 4-chloromercuribenzoate, 4- chloromercuriphenylsulfonic acid, phenylmercury chloride, 2-chloromercuric-4-nitrophenol and other mercurials; carbamylation with cyanate at alkaline pH. Tryptophan residues may be modified by, for example, oxidation with N-bromosuccinimide or alkylation of the indole ring with 2-hydroxy- 5-nitrobenzyl bromide or sulphonyl halides. Tryosine residues may be altered by nitration with tetranitromethane to form a 3-nitrotyrosine derivative. Modification of the imidazole ring of a histidine residue may be accomplished by alkylation with iodoacetic acid derivatives or N- carbethoxylation with diethylpyrocarbonate. Examples of incorporating unnatural amino acids and derivatives during peptide synthesis include, but are not limited to, use of norleucine, 4-amino butyric acid, 4-amino-3-hydroxy-5-phenylpentanoic acid, 6-aminohexanoic acid, t-butylglycine, norvaline, phenylglycine, ornithine, sarcosine, 4-amino-3-hydroxy-6-methylheptanoic acid, 2- thienyl alanine and / or D-isomers of amino acids. In the specification, diagnostic or screening methods or tools can be selected from quantitative, semi-quantitative, or qualitative ELISA; enzyme immunoassay (EIA); radioimmunoassay (RIA); fluoroimmunoassay (FIA); chemiluminescent immunoassay (CLIA) and counting immunoassay (CIA); Lateral flow tests (LFTs); Surface Plasmon Resonance, Western Blot; peptide array immunoassay; immunohistochemistry, affinity pull-down assay or co-immunoprecipitation assay, and Immuno-Polymerase Chain Reaction. For example, overlapping peptides covering a target of interest are cloned onto the present invention and used as antigens to screen clinical samples using, for example, the ELISA platform or any high throughput alternative. In the specification, the term “immunostimulant” should be understood to mean an agent that activates the immune system of a subject and promotes the release of endogenous immune mediators. The use of immunostimulants in veterinary medicine is promoted to fight against opportunistic and pathogenic organisms. Work of this nature can be divided into two parts: 1) in vitro evaluation of immunostimulatory capacity of scaffold / scaffold-derivative / chimeric scaffold in relevant primary cell culture / cell lines; and 2) in vivo trials of the immunostimulatory role of the present invention in relevant species. In vivo trials may last up to 12 weeks during which, a veterinary species of interest, is disease challenged with pathogen(s) following administration of immunostimulant. The initial evaluation of the immunostimulatory function of the invention will be carried out on commercial fish species and shrimp (Penaeus monodon). In the specification, the term “immunosuppressant” should be understood to mean an agent used in immunosuppressive therapy, which can be important in the treatment of auto-immune disorders as well as in organ transplantation. Peptide-based therapy is gathering momentum due to less cytotoxicity, high efficacy as well as high specificity by the virtue of their inherent molecular targeted action. Peptides have been studied for various therapeutic properties such as antimicrobial, antifungal, antibacterial, antimycobacterial, cell penetrating, cancer-biomarker, etc. Similarly, many peptides have been studied for their ability to suppress the immune system and have emerged as promising immunosuppressive therapeutic agents. Most of the immunosuppressive peptides are naturally occurring in organisms such as fungi, bacteria, venom toxin as well as in plants. Immunosuppressant properties of scaffold / scaffold-derivative / chimeric peptide(s)-scaffolds will be elucidated in vitro using relevant primary cell culture / cell lines. In vivo clinical trials to verify the immunosuppressant role of the present invention will be carried out in relevant species. BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a pictorial representation of a scaffold backbone in accordance with the first aspect of the invention; Figure 2 shows a pictorial representation of a heterologous peptide scaffold in accordance with the third aspect of the invention; Figure 3 shows a pictorial representation of several heterologous peptide(s) scaffold in accordance with the third aspect of the invention; Figure 4 shows a pictorial representation of a method for bioengineering a proposed scaffold backbone in accordance with the first aspect of the invention; Figure 5 is a table indicating exemplary protein candidates tested for suitability for use as a scaffold backbone in accordance with the first aspect of the invention; Figure 6 is a table indicating selected protein candidates identified in Figure 5 as being suitable for further bioengineering to reduce their relevant immunoreactivity ;Figure 7 shows a bar chart comparing the percentage of IgG and IgM immunoreactivity of original BHS scaffold and bioengineered BHS both loaded with 15 borrelia burgdorferi peptides and screened across 192 Lyme positive serum samples using standard ELISA; Figure 8 shows a bar chart comparing the percentage of IgG and IgM cross-reactivity of original BHS scaffold and a bioengineered BHS both loaded with 15 borrelia burgdorferi peptides and screened across 198 Lyme negative serum samples using standard ELISA Figure 9 shows a representation of overlapping peptides in relation to the SARS-CoV-2 nucleocapsid viral protein; Figure 10 shows an electrophoresis gel (SDS PAGE) depicting the purified overlapping peptides of Figure 9, created by expressing individual peptides on the scaffold of the present invention for peptide mapping purposes in accordance with the first aspect of the invention; Figure 11 shows two graphs of seroreactivity percentages of the overlapping peptides against COVID-19 human serum samples; Figure 12 shows the peptide location of five immunodominant peptides (P1-P5) corresponding to the SARS-CoV-2 nucleocapsid viral antigen identified in Figure 11; Figure 13 shows an electrophoresis gel (SDS PAGE) depicting the purified immunodominant peptides P1-P5 of Figure 8 and a composite containing all five peptides linked by four flexible glycine-serine (GS) linkers (P6) and a mutant variant of P6 (P6m) in which the reference sequences were replaced with the prevalent mutations published on the GISAID website Figure 14 shows the evaluation of IgG seroreactivity percentage of the individual polypeptides (P1-P5) and the multiplexed polypeptide (P6) when used against COVID-19 human serum samples; Figure 15 shows the evaluation of IgG seroreactivity percentage of the multiplexed peptide (P6), the mutant multiplexed peptide (P6m), and the combined peptides (P6 + P6m) when used against COVID-19 human serum samples; Figure 16 shows a graphical evaluation of the impact of SARS-CoV-2 mutations on the antibody response; Figures 17 and 18 show two series of samples collected at different time points post COVID-19 from two patients which were tested using two pairs of mutant peptides RG203KR and D3G; and Figure 19 shows how a heterologous peptide scaffold in accordance with the third aspect of the invention can be utilised to increase the stability of proteins. DETAILED DESCRIPTION OF THE DRAWINGS Referring to Figure 1, there is indicated a pictorial representation of heterologous peptides scaffold complex, referenced globally at 10. The peptide scaffold 10 comprises a first protein-fragment arm 12a, a left linker 14a connected to the first protein-fragment arm 12a, a polypeptide region 16 comprising at least one peptide POI, the peptide region 16 being connected to the first linker 14a, a right linker 14b connected to the polypeptide region 16, and a second protein-fragment arm 12b connected to the right linker 14b. The first and second protein-fragment arms 12a, 12b bond or interact with one another to form a scaffold backbone 18, examples of which are shown in Figures 2 and 3 having one peptide POI in Figure 2, and multiple peptides POI1, POI2, POIn in Figure 3, where n is representative of an ‘n’ length chain of polypeptides POI. However, it may be that the scaffold backbone 18 could be provided as a unit it its own right, for example, being combined with a non-peptide immunosuppressant or immunostimulant, to have useful properties in isolation. It could also be used as part of a vaccine adjuvant. The first protein-fragment arm 12a is here shown as a bioengineered N-terminal segment of flagellin, with the second protein-fragment arm 12b being shown as a bioengineered C-terminal segment of flagellin. One or more optional purification or detection tags 20 may be present. One purification tag 20 is shown at the C-terminal of the second protein-fragment arm 12b, though purification tags 20 could be present at the N-terminal, the C-terminal, middle, or both termini. The tags 20 are used for purification and detection purposes. The polypeptide region 16 comprises at least one peptide POI. The polypeptide region 16 may comprise any peptides POI of the B-cell and T-cell immunodominant nature corresponding to antigens from a pathogen or pathogens, autoantibody marker, or autoantibodies markers, to be used in serology-based diagnosis. The size and the number of peptides POI will be empirically determined to develop a serology test with appropriate accuracy. The polypeptide region 16 may comprise any peptide or peptides, or one or more subunits thereof corresponding to antigens from a pathogen or pathogens or a pathogenic strain or strains to be used for vaccine discovery (i.e., identify immunodominant peptides / antigens). The polypeptide region 16 may comprise any peptide or peptides, or one or more subunits thereof having an immunodominant nature corresponding to antigens from a pathogen or pathogens or a pathogenic strain or strains to be used for vaccine development. The size and the number of peptides POI will be empirically determined to produce effective polyvalent and multivalent peptide- based vaccines and administered as a recombinant protein, a DNA or RNA vaccine. The polypeptide region 16 may comprise any peptide or peptides, or one or more subunits thereof, or a protein or proteins with an immunostimulatory nature (immunostimulant). On some occasions, the scaffold backbone 18 only, having no polypeptide region, may be suitable for stimulatory uses in some species. The immunostimulant can be administered as a recombinant protein, a DNA or RNA vaccine. The polypeptide region 16 may comprise any peptide or peptides, or one or more subunits thereof, or a protein or proteins with an inhibitory nature. The inhibitor can be administered as a recombinant protein, a DNA or RNA vaccine. The polypeptide region 16 may comprise any peptide or peptides, or one or more subunits thereof, or a protein or proteins designed for adjuvant uses. On some occasion and relevant in some species, scaffold backbone 18 only may have adjuvant properties and be used as a protein adjuvant with commercial vaccines. The adjuvant can be administered as a recombinant protein, a DNA or RNA vaccine. Scaffold with adjuvant properties can be embedded with heterologous peptides of interest composed of an immunogenic peptide or peptides corresponding to antigens from a pathogen or pathogens or a pathogenic strain or strains and can be combined to create a peptide-based vaccine-adjuvant combination and administered as a recombinant protein, a DNA or RNA vaccine. The polypeptide region 16 may comprise one or more peptides POI comprising an antibody or antibody fragment to be used in antigen-based diagnosis testing. The polypeptide region 16 may comprise one or more peptides POI comprising a receptor binding domain to screen for ligands or vice versa. A polypeptide region 16 having only a single peptide may be used to construct a library for screening purposes, which includes T-cell and B-cell epitopes as well as ligand-receptor screening. The nucleotide sequence, either DNA or gene, of the peptide POI can be generated using DNA synthesis, polymerase chain reaction (PCR), or similar techniques, and incorporated into the peptide-scaffold 10 via any routine molecular cloning technique, including but not limited to T4 DNA ligase mediated ligation or gene assembly. A plasmid construct is used to transform E. coli cells so that they transcribe and translate the desired chimeric protein, that is, the scaffold backbone 18 plus the polypeptide region 16. The scaffold backbone 18 facilitates the expression of peptides POI otherwise not readily expressed. The cells are then lysed to extract the expressed polypeptide POI fusion protein for subsequent purification. The peptide POI fusion can be purified under native condition, or alternatively under denaturing condition and refolded subsequently. In the refolding buffer, the first and second protein-fragment arms 12a, 12b interact with each other to form a stable helical structure. The left and right linkers 14a, 14b provide the flexibility to incorporate peptides POI of the polypeptide region 16. A flexible glycine-serine (GS) linker 22 may be used between adjacent peptides POI in the polypeptide region 16. The flexibility ensures that the peptides POI of the polypeptide region 16 are able to be expressed despite the rigidity of the scaffold backbone 18. The fusion of the peptides POI in the middle of the scaffold 10 ensures peptide POI integrity of the full-length final product. The peptide-scaffold 10 is amenable to expressing a single peptide, a polypeptide and multiplexed polypeptides. The scaffolds 10 folds into compact and stable structures subsequently providing a stable framework onto which peptides can be displayed without which such structures will be difficult to be expressed in an expression system. The peptide-scaffold 10 are preferably modified flagellins selected from a group of non-pathogenic extremophiles including species from Thermotoga, Thermithiobacillus, Aquifex, Geobacillus, Acidithiobacillus, Alkalispirochaeta, Desulfosporosinus, Bermanella, and Azospirillum. The monomeric flagellin molecule is characterized by a highly conserved N- and C-terminal domains, the first and second protein- fragment arms 12a, 12b respectively, with an intervening hypervariable region. The N- and C- termini of flagellin form the stable helical core of the flagellin protein through hydrophobic interactions, ionic interactions, hydrogen bonds, electrostatic forces and Van der Waals forces. The middle domain of flagellin protrudes outward and can ultimately be removed, modified or replaced without impacting the structural integrity of the monomeric flagellin. This property has been utilised whereby the middle domain of a group of selected flagellins were removed and subsequently replaced with one or more peptides POI. Furthermore, the first and second protein- fragment arms 12a, 12b have been further bio-engineered through amino acid substitution, deletion and addition to improve certain characteristics. The use of flagellins as scaffold proteins displaying one or more peptides POI has not been previously described in the context of this application, and is the focus of this invention. There has not been described before the use of the present invention in serology-based diagnosis (i.e., antibody-based assays). The backbone scaffold 18 is able to accommodate the polypeptide region 16 having one or more peptides POI that can be readily expressed in a suitable expression system, whereby these peptides POI are expressed as fusion proteins located between the first and second protein-fragment arms 12a, 12b. The polypeptide region 16 is connected to the first and second protein-fragment arms 12a, 12b via the left and right linkers 14a, 14b. The left and right linkers 14a, 14b together are pH neutral, small, free to rotate and are divergent enough to design nucleotide sequences for directional cloning. The left and right linkers 14a, 14b are compatible with genetic manipulation so that the peptides POI can be readily cloned into the scaffold backbone 18 directionally and efficiently using any recombination gene assembly reagents, and with amino acid sequences neutral and flexible to rotate. Following transformation of the recombinant construct into a suitable expression system, then purification and folding of the recombinant peptide scaffolds 10, the first and second protein-fragment arms 12a, 12b inherently interact with each other and create the stable helical structure described earlier and provide the structure to support the polypeptide expression and presentation, whilst the left and right linkers 14a, 14b provide the freedom for the expressed polypeptides POI to rotate. Thus, the expressed peptides POI are free to adopt their native conformations and retain their bioactive properties. There has not been described before the use of the present invention in antigen testing. The backbone scaffold 18 is able to accommodate the polypeptide region 16 having one or more single chain variable fragments and single-domain antibody fragments that can be readily expressed in a suitable expression system, whereby these nanobodies POI are expressed as fusion proteins located between the first and second protein-fragment arms 12a, 12b. The polypeptide region 16 is connected to the first and second protein-fragment arms 12a, 12b via the left and right linkers 14a, 14b. The left and right linkers 14a, 14b together are pH neutral, small, free to rotate and are divergent enough to design nucleotide sequences for directional cloning. The left and right linkers 14a, 14b are compatible with genetic manipulation so that the peptides POI can be readily cloned into the scaffold backbone 18 directionally and efficiently using any recombination gene assembly reagents, and with amino acid sequences neutral and flexible to rotate. Following transformation of the recombinant construct into a suitable expression system, then purification and folding of the recombinant peptide scaffolds 10, the first and second protein-fragment arms 12a, 12b inherently interact with each other and create the stable helical structure described earlier and provide the structure to support the nanobody expression and presentation, whilst the left and right linkers 14a, 14b provide the freedom for the expressed polypeptides POI to rotate. Thus, the expressed nanobodies POI are free to adopt their native conformations and retain their bioactive properties. Expressing single chain variable fragments and single-domain antibody fragments can be useful to increase half-life of antibody fragments for therapeutic purposes, provide a framework structure to increase size of nanobodies for Point-Of-Care testing, increased yield, and biosensor applications. There has not been described before the use of the present invention in peptide immunogenicity mapping. The backbone scaffold 18 is able to accommodate the polypeptide region 16 having one or more peptides POI that can be readily expressed in a suitable expression system, whereby these peptides POI are expressed as fusion proteins located between the first and second protein- fragment arms 12a, 12b. The polypeptide region 16 is connected to the first and second protein- fragment arms 12a, 12b via the left and right linkers 14a, 14b. The left and right linkers 14a, 14b together are pH neutral, small, free to rotate and are divergent enough to design nucleotide sequences for directional cloning. The left and right linkers 14a, 14b are compatible with genetic manipulation so that the peptides POI can be readily cloned into the scaffold backbone 18 directionally and efficiently using any recombination gene assembly reagents, and with amino acid sequences neutral and flexible to rotate. Following transformation of the recombinant construct into a suitable expression system, then purification and folding of the recombinant peptide scaffolds 10, the first and second protein-fragment arms 12a, 12b inherently interact with each other and create the stable helical structure described earlier and provide the structure to support the polypeptide expression and presentation, whilst the left and right linkers 14a, 14b provide the freedom for the expressed polypeptides POI to rotate. Thus, the expressed peptides POI are free to adopt their native conformations and retain their bioactive properties to be utilised for peptide mapping. The scaffold of the first and second protein-fragment arms 12a, 12b are selected and manipulated for high expression yields (200mg / l to 1g / L) in different expression platforms, high solubility and high stability. The second protein-fragment arm 12b has a His tag at its C-terminal for easy purification using IMAC based techniques. The first protein-fragment arms 12a can have a second tag (e.g., SEQ: NPVIRYKRRS) at its N-terminal or C-terminal to which a monoclonal antibody has been developed to be used for further purifications and detection assays including ELISA, lateral flow and Surface Plasmon Resonance (SRP)-based devices. Because the first and second protein- fragment arms 12a, 12b naturally fold into relatively stable structures which have been further stabilised by the use of directed evolutionary manipulation methods, they act as stabilisers to facilitate the expression of unstable antigens including peptide(s). These properties means that the entity of peptide(s) scaffold complex can be easily expressed in an expression system of choice, easily purified under denaturing conditions and readily refolded. Thus, a simple standardised protocol can be applied for the production and purification of the different polypeptides in a high throughput manner making the process economically favourable. The scaffold proteins of the first and second protein-fragment arms 12a, 12b have overcome the poor expression, size limitation and stability issues of expressing individual polypeptides in prokaryotic and eukaryotic systems. Importantly, the first and second protein-fragment arms 12a, 12b are amenable to expressing multiple polypeptides in one chimeric entity. The resulting products (i.e., peptide(s)-scaffold 10) are compatible with an enzyme-linked immunosorbent assay (ELISA), lateral flow tests (LFTs), Radioimmunoassay (RIA), Chemiluminescence immunoassay (CLIA), Fluoroimmunoassay (FIA), Enzyme Immunoassay (EIA), Surface Plasmon Resonance, Western Blot (WB), cloned enzyme donor immunoassay (CEDIA), Immuno-screening, dot blot, Memory Lymphocyte Immunostimulation Assay (MELISA), Nephelometry, Magnetic immunoassay, Surround Optical Fiber Immunoassay (SOFIA), CD / DVD based immunoassay, immunohistochemistry, an affinity pull-down assay or co-immunoprecipitation assay, Agglutination-PCR, and protein arrays. The scaffold backbone 18 provides the supporting and stabilising structure for the expression and display of a peptide or multiplexed peptides in the polypeptide region 16. The displaying of a peptide POI on the scaffold 10 does not reduce its conformational freedom, nor create constrained structural frameworks, subsequently conferring high ligand / receptor or antigen / antibody binding affinity, specificity, and enhanced stability. IDENTIFICATION OF CANDIDATE SCAFFOLDS To identify suitable scaffolds 10, initially 79 potential candidate scaffolds were produced recombinantly, based on their capacity to readily express one or more peptides, have high yields, and high stability. Scaffolds showing good capacity to express peptides were taken forward to test their immunoreactivity across a panel of human sera samples (n=156). Most tested candidates demonstrated unacceptable levels of immunoreactivities to human sera which meant they were excluded. The four least reactive scaffolds were (P41, P45, P47, P0) – see Table 1 below. In order to use for serology testing, the immunoreactivity of P41, P45, P47, P0 ought to be reduced to <1%. Extensive modifications to the candidates to the four scaffolds in order to reduce immunoreactivities was performed. The modifications included deletions of reactive “hot-spots” and substitutions of certain amino acids of antigenic regions. Then the modified scaffolds were recombinantly produced and re-tested using a human sera panel (n=800). Overall, immunoreactivity of the four scaffolds were reduced. Following two further rounds of modification and re-testing, the immunoreactivity of the scaffolds was reduced to ~1%. A stepwise diagram of scaffold discovery steps is reproduced in Figure 4, with the method being referenced globally at M100. There is a first step, of initial selection, step M101, which utilises bioinformatics, prediction and testing for accepting peptides, which, in a first experiment, yielded a total of 79 initial proteins for consideration. A table of results for the 79 initial proteins is provided in Table 1, illustrated in Figure 5, plus additional information on yield, capacity to express peptides, stability and immunoreactivity. From the initial proteins, individual protein candidates suitable for use as scaffold backbones based on stability and / or expression yield, step M102, and a further selection step is made, step M103, based on immunoreactivity with human sera. Once a selection of protein candidates has been made, the candidates are bioengineered to reduce immunoreactivity, by removal of and / or substitution of antigenic regions thereof, at step M104. This yields a final list of proteins suitable for use as scaffold candidates. A further bioengineering step can then be performed, at step M105, which is bioengineering to increase the surface binding and improve the orientations thereof, for instance, by the addition of hydrophobic sequences. Examples of candidate proteins that have been bioengineered in accordance with steps M104 and M105 are provided in Figure 6, represented by Table 2. Example Scaffold Candidate P47 The following disclosure represents exemplary steps taken to bioengineer a suitably identified extremophile flagellin protein for use in the present invention. Candidate P47 showed modest immunoreactivity to biological samples and a capacity to accept peptides into its structure. P47 (Acidithiobacillus thiooxidans) original sequence MAISGIINTNTSALSTLNALNGTQGSLNTYLQQLSTGKSINGPADNPAGYAIAQRFQTQINGMNQ AISNGNQGVSLVQTATGAIQNQTSLLQQIRTTAVQAANASNTTSDRQALQGVVSQLLAQVQTIAT QTQFNGQNLLDGTFAGAAFQVGANSNQIINVAVGDTTTSSMGNYSTTVSGGAYTSSGSFQMG GYAAGGSFTISTSSGAGNFLSGSALNIQGSVGNASVSVNSSTESAANLAAAVNGVSAQTGVSA QAYTSVAFKATAGTYTFTLSNGSSGAPTNAVNISADVTQGSNGQANISSLVTAINNQAAVTGVSA GTQTVNGTTELVLTNANGNNINISAGVTNGGALSGAGLASGSTGSLQAVSGTGVSLVGTAITSG SANALIQGAVQFNSASSYAIGNGGSIGFSTQATSLSGSAVSNINVTTAAGAQQAIGIVDQAINYLN QQNGSLGAIQNRIQASVSNDQTTATNLQSAQSVVQDANIAQATSQLTKYQILQQAGISTLAQENS LQQSYLKLLP The first bioengineering step created a modified scaffold as follows: P86 (MODIFIED SCAFFOLD GENERATION 1) MLSTLNALNGTQGSLNTYLQQLSTGKSINGPADNPAGYAIAQRFQTQINGMNQAISNGNQGVSL VQTATGAIQNQTSLLQQIRTTAVQAANASNTTSDRQALQGVVSQLLAQVQTIATQTQFNGQNLL DNINVTTAAGAQQAIGIVDQAINYLNQQNGSLGAIQNRIQASVSNDQTTATNLQSAQSVVQDANI AQATSQLTKYQIL Comparison of the sequences can be outlined as follows: Multiple sequence alignment of P47 (original scaffold) vs P86 (modified scaffold GENERATION 1) P47 MAISGIINTNTSALSTLNALNGTQGSLNTYLQQLSTGKSINGPADNPAGYAIAQRFQTQI 60 P86 ------------MLSTLNALNGTQGSLNTYLQQLSTGKSINGPADNPAGYAIAQRFQTQI 48 *********************************************** P47 NGMNQAISNGNQGVSLVQTATGAIQNQTSLLQQIRTTAVQAANASNTTSDRQALQGVVSQ 120 P86 NGMNQAISNGNQGVSLVQTATGAIQNQTSLLQQIRTTAVQAANASNTTSDRQALQGVVSQ 108 ************************************************************ P47 LLAQVQTIATQTQFNGQNLLDGTFAGAAFQVGANSNQIINVAVGDTTTSSMGNYSTTVSG 180 P86 LLAQVQTIATQTQFNGQNLLDNINV----------------------------------- 133 *********************. . P47 GAYTSSGSFQMGGYAAGGSFTISTSSGAGNFLSGSALNIQGSVGNASVSVNSSTESAANL 240 P86 ------------------------------------------------------------ 133 P47 AAAVNGVSAQTGVSAQAYTSVAFKATAGTYTFTLSNGSSGAPTNAVNISADVTQGSNGQA 300 P86 ------------------------------------------------------------ 133 P47 NISSLVTAINNQAAVTGVSAGTQTVNGTTELVLTNANGNNINISAGVTNGGALSGAGLAS 360 P86 ------------------------------------------------------------ 133 P47 GSTGSLQAVSGTGVSLVGTAITSGSANALIQGAVQFNSASSYAIGNGGSIGFSTQATSLS 420 P86 ------------------------------------------------------------ 133 P47 GSAVSNINVTTAAGAQQAIGIVDQAINYLNQQNGSLGAIQNRIQASVSNDQTTATNLQSA 480 P86 ---------TTAAGAQQAIGIVDQAINYLNQQNGSLGAIQNRIQASVSNDQTTATNLQSA 184 *************************************************** P47 QSVVQDANIAQATSQLTKYQILQQAGISTLAQENSLQQSYLKLLP 525 P86 206 ********************** The second bioengineering step yielded a modified scaffold as follows: D (MODIFIED SCAFFOLD GENERATION 2) MPADNPAGYAIAQDFQTQINGMNQAISNGNQGVSLVQTATGAIENQTSLLQQIRTTAVQAAYAS NTTSDDQALQGVVSQLLAQVQTIATQTQFNGQNLLDNINVTTAAGAQQAIGIVDQAINYLNQKNG SLGAIQNRIQASVSNRQTTATNLQSAQSVVQEANIAQATSQLTKYQIL Comparison of the sequences can be outlined as follows: Multiple sequence alignment of P47 (original scaffold) vs D (modified scaffold GENERATION 2) P47 D -MPADNPAGYAIAQDFQTQI ************ ***** P47 NGMNQAISNGNQGVSLVQTATGAIQNQTSLLQQIRTTAVQAANASNTTSDRQALQGVVSQ 120 D NGMNQAISNGNQGVSLVQTATGAIENQTSLLQQIRTTAVQAAYASNTTSDDQALQGVVSQ ************************:***************** ******* ********* P47 LLAQVQTIATQTQFNGQNLLDGTFAGAAFQVGANSNQIINVAVGDTTTSSMGNYSTTVSG 180 D LLAQVQTIATQTQFNGQNLLDNINV----------------------------------- 104 *********************. . P47 GAYTSSGSFQMGGYAAGGSFTISTSSGAGNFLSGSALNIQGSVGNASVSVNSSTESAANL 240 A further bioengineering step yielded a modified scaffold as follows: DHS (MODIFIED SCAFFOLD GENERATION 3) MAIAWDFQTAINGVNAAISNGNQGVSLVQTATGAIENQTSLLQQIRTTAVQAAYASNTTSDDQAL QGVPSQLLAQVQTIAAQTVFNGQILLDLINVTTAAGAQQAIGIVDQAINYLNQKNGSLGAIQNRIQ ASVSNRQTTATNLQSAQSVVQLAIIAVATSLLTIYQIL Comparison of the sequences can be outlined as follows: Multiple sequence alignment of P47 (original scaffold) vs DHS (latest scaffold GENERATION 3) P47 MAISGIINTNTSALSTLNALNGTQGSLNTYLQQLSTGKSINGPADNPAGYAIAQRFQTQI 60 DHS -------------------------------------------------MAIAWDFQTAI 11 *** *** * P47 NGMNQAISNGNQGVSLVQTATGAIQNQTSLLQQIRTTAVQAANASNTTSDRQALQGVVSQ 120 DHS NGVNAAISNGNQGVSLVQTATGAIENQTSLLQQIRTTAVQAAYASNTTSDDQALQGVPSQ 71 **:* *******************:***************** ******* ****** ** P47 LLAQVQTIATQTQFNGQNLLDGTFAGAAFQVGANSNQIINVAVGDTTTSSMGNYSTTVSG 180 DHS LLAQVQTIAAQTVFNGQILLDLINVTT--------------------------------- 98 *********:** **** *** . : P47 GAYTSSGSFQMGGYAAGGSFTISTSSGAGNFLSGSALNIQGSVGNASVSVNSSTESAANL 240 DHS ------------------------------------------------------------ 98 P47 AAAVNGVSAQTGVSAQAYTSVAFKATAGTYTFTLSNGSSGAPTNAVNISADVTQGSNGQA 300 DHS ------------------------------------------------------------ 98 P47 NISSLVTAINNQAAVTGVSAGTQTVNGTTELVLTNANGNNINISAGVTNGGALSGAGLAS 360 DHS ------------------------------------------------------------ 98 P47 GSTGSLQAVSGTGVSLVGTAITSGSANALIQGAVQFNSASSYAIGNGGSIGFSTQATSLS 420 DHS ------------------------------------------------------------ P47 GSAVSNINVTTAAGAQQAIGIVDQAINYLNQQNGSLGAIQNRIQASVSNDQTTATNLQSA 480 DHS -----------AAGAQQAIGIVDQAINYLNQKNGSLGAIQNRIQASVSNRQTTATNLQSA 147 ********************:***************** ********** P47 QSVVQDANIAQATSQLTKYQILQQAGISTLAQENSLQQSYLKLLP 525 DHS QSVVQLAIIAVATSLLTIYQIL----------------------- 169 ***** * ** *** ** **** Following bio-engineering, the total number of residues and more importantly the immunoreactivity with human sera decreases at each stage, as indicated below for P47, P41, P45 and P0: Acidithiobacillus Original Generation 1 Generation Generation 3 thiooxidans scaffold scaffold 2 scaffold scaffold (P47) (P86) (D) (DHS) Hydrophobic residues 37.71% 37.68% 39.55% 46.15% Acidic residues 2.10% 2.91% 4.52% 3.55% Basic residues 1.52% 2.91% 2.82% 2.37% Neutral residues 58.70% 56.31% 53.11% 47.93% Size (aa) 525 206 177 169 Immunoreactivity 21.6% 14.3% 6.3% 0.8% (false positive) Aquifex pyrophilus Original Generation 1 Generation Generation 3 sequence scaffold (P85) 2 scaffold scaffold (P41) (B11) (BHS) Hydrophobic residues 40.72% 43.00% 42.94% 47.10% Acidic residues 11.18% 11.59% 12.88% 10.32% Basic residues 8.98% 11.11% 10.43% 9.68% Neutral residues 39.12% 34.30% 33.74 32.90% Size (aa) 501 207 165 155 Immunoreactivity (false positive) 21.20% 16.40% 4.50% 0.30% Thermithiobacillus Original Generation 1 Generation Generation 3 tepidarius sequence scaffold 2 scaffold scaffold (P45) (P45-1) (P45H) (CHS) Hydrophobic residues 41.15% 40.78% 41.24% 47.53% Acidic residues 6.58% 9.22% 10.37% 6.79% Basic residues 5.56% 6.80% 6.78% 6.17% Neutral residues 46.71% 43.20% 41.24 39.51% Size (aa) 486 206 177 162 Immunoreactivity (false positive) 19.90% 14.20% 5.08% 0.78% Azospirillum Original Generation 1 Generation Generation 3 baldaniorum sequence scaffold 2 scaffold scaffold (P0) (P91) (P0H) (FHS) Hydrophobic residues 42.34% 40.91% 42.70% 46.41% Acidic residues 11.68% 13.13% 14.04% 9.15% Basic residues 6.57% 8.59% 8.43% 7.84% Neutral residues 39.42% 37.37% 34.83% 36.60% Size (aa) 274 198 178 153 Immunoreactivity (false positive) 19.90% 15.30% 5.40% 0.50% What can be seen, however, is that the percentage of hydrophobic residues in the final bioengineered scaffold exceeds that of the unmodified protein, with the proportion of neutral residues decreasing. Figures 7 and 8 show bar chart comparing the percentage of IgG and IgM immunoreactivity of original BHS scaffold and bioengineered BHS both loaded with 15 borrelia burgdorferi peptides. The bioengineered BHS was mutated to preferentially bind to the ELISA plate surface. Figure 7, tested on 192 Lyme positive serum samples, demonstrates that IgG and IgM sensitivity improved by 5.73% and 2.61%, respectively, whereas Figure 8, tested on 198 Lyme negative samples demonstrates that IgG and IgM specificity improved by 4.04% and 6.56%, respectively. METHODS AND MATERIALS The present invention has been used to display a single peptide or multiple peptides, protein domains, and whole proteins. A large polypeptide (protein domains or whole proteins) will provide additional conformational epitopes in addition to the linear epitopes it carries. The maximum number of polypeptides tried so far in one complex is, and not limited to, 15 but this can be increased to 16, 17, 18, 19, 20 or more. A polypeptide with up to 1000 amino acids has been successfully expressed, displayed by the scaffold 10, and purified from E. coli. Vectors and cloning The scaffold expression vectors (plasmids) for the expression of epitopes have been constructed by commercial gene synthesis and assembled into a T7-based expression plasmid using NEBuilder® HiFi DNA Assembly Cloning Kit (NEB). All the plasmids have been sequence- confirmed using a commercial sequencing service. Linear vectors were prepared by PCR using high-fidelity Q5 DNA polymerase (NEB) and purified. The nucleotide sequences for the expression of polypeptides of interest were PCR amplified or codon optimised and synthesised commercially. The codons were optimised for the expression host (i.e., E. coli) when the genes were synthesised. The polypeptides of interest were inserted using NEBuilder(RTM) HiFi DNA Assembly Cloning Kit (NEB), plasmid purified, and sequence confirmed. Protein expression and purification The expression of the target protein from the construct, purification and refolding of the purified protein are performed using standard methods (i.e., Wang et al., J Immunol.2011; 186: 708-21; and Wang et al., Interleukin (IL)-2 Is a Key Regulator of T Helper 1 and T Helper 2 Cytokine Expression in Fish: Functional Characterization of Two Divergent IL2 Paralogs in Salmonids. Front Immunol.2018; 9: 1683). The protein concentration was quantified on SDS-PAGE gel using BSA (bovine serum albumin) as a standard control. ELISA detection of antibody in COVID patients 1. ELISA plates (Microplate, 96 well, PS, F-bottom / chimney well, MICROLON® 600, high binding, clear) High-bind, were coated with epitopes produced as above at 100 ng / well in 100 μl overnight at 4°C. 2. The plates were washed three times with wash buffer (PBS-T, PBS containing 0.05% Tween®-20 (polyethylene glycol sorbitan monolaurate, having a molecular weight of ~1228 Da). 3. Dilute plasma or serum samples in diluent buffer and apply to wells. 4. Incubate for 1h at room temperature (RT). 5. Remove samples. 6. Wash plate three times with PBS-T, 300 μl / well three times using a plate washer. 7. Prepare second antibody solution and apply to each well for 0.5-1h at RT. 8. Wash plate three times with PBS-T, 300 μl / well three times using a plate washer. 9. Apply 3,3',5,5'-Tetramethylbenzidine (TMB) substrate to each well for 5-10 min. 10. Add a stop solution to each well. 11. Read Optical Density (OD) at 450nm (OD450). Production of scaffold with a single polypeptide / epitope A single peptide can be displayed by the scaffold 10 in the present invention as disclosed herein. The DNA encoding for a single peptide or polypeptide was prepared by polymerase chain reaction (PCR) from known DNA sequences, or codon-optimised and synthesised commercially. The DNA fragment was cloned into the scaffold construct using a NEBuilder® HiFi DNA Assembly Cloning Kit (NEB). The protein was produced, purified, and quantitated as above. Production of scaffold with multiple peptides / polypeptides Multiple peptides (at least between 2-15 or 2-20) can be displayed by the scaffold 10. Multiple peptides were connected by a flexible GS linker with a sequence of GGGSGGG (SEQ ID NO: 23). The linker separates adjacent peptides, preventing interference from each other and provides freedom of individual epitopes to rotate and form a stable conformation. The DNA sequence encoding the multiple peptides or polypeptides (i.e., multiplexed) was codon-optimised and synthesised commercially. The cloning, protein production, purification and quantitation was as described above. Production of scaffold with large polypeptide / protein domain / whole protein A large polypeptide or a protein domain or a whole protein up to 1000 amino acids long has been produced by the invention. The DNA sequence encoding the polypeptide was codon-optimised and synthesised commercially or PCR amplified from an existing DNA construct. The cloning, protein production, purification and quantitation was as described above. Monitor the impact of mutations on antibody response When an amino acid mutation (a substitution, deletion, or insertion) occurs in a protein or a peptide of concern, its effects on antibody response can be assessed. Both the wild-type peptides’ sequences and its corresponding mutant peptides can be individually expressed and displayed on the scaffold 10 to function as antigens. Samples from patients affected by the mutation and control cohorts are then used to assess the antibody response by any antigen or antibody assay of choice, e.g., ELISA. The impact of 50 SARS-CoV-2 mutations using serum samples from COVID-19 patients and pre-COVID controls has been examined. The same principal can be used to assess antigen impact of mutations on diagnostic antibodies, therapeutic antibodies, ligand-receptor binding, and vaccine efficacy to mutant pathogen. Western blotting The construct structure (polypeptides or peptides) of the scaffold 10 can be directly used as antigens for serology testing e.g., ELISA, Western-blot. Recombinant proteins used for Western blotting analysis were prepared as described above.500 ng recombinant proteins were mixed with Invitrogen NuPAGE LDS loading buffer (Fisher Scientific, UK) containing 5% β-mercaptoethanol (β-ME, Merck) and incubated at 70°C for 10 min before loading on a 4-12% Bis-tris SDS-PAGE gel (Invitrogen). The gel electrophoresis was run at 130V for 1 h. Then the separated proteins were transferred onto a PVDF membrane (Millipore) using an Xcell SureLock™ Electrophoresis Cell system (Invitrogen). Membrane was stained with Ponceau S solution (Merck, UK) according to the manufacturer's instructions. The membrane was then blocked with 5% non-fat milk prepared in PBST for 1 h at RT, and washed with PBST for 5 min. Serum samples were heated at 56°C for 30 min before use and diluted at 1:500 in PBST. Each membrane was then incubated with prepared serum samples overnight at 4°C. Next day, membrane was washed five times with PBST for 15 min at RT. Membrane was then incubated with a Goat-anti-human IgG (γ) gamma chain HRP conjugated secondary antibody (Roche, UK) prepared at 1:3000 dilution in PBST for 1h at RT. Membrane was washed with PBST for 15 min repeated four times at RT again. The peroxidase activity was detected using a SuperSignal™ West Pico PLUS Chemiluminescent Substrate (Fisher Scientific, UK) according to the manufacturer's instructions. Images were captured with a Vilber- fusion Chemiluminescence-imaging camera (Fusion Spectra Software Fx, UK). of B-cell and T-cell T-cell and B-cell epitopes can be predicted by publicly available and / or commercial software with a wide range of success rate and need further experimental verification. In other cases, a library of overlapping peptides from a target of interest must be screened to identify the immune-dominant peptides for the purpose of establishing sensitive detection methods or development of protein or peptide-based vaccines. A single peptide or a library of peptides can be displayed by the invention for high quality, high throughput production. DNA nucleotides encoding the peptide or a library of peptides of interest are synthesised chemically or by PCR, and cloned into the scaffold 10 as described above. Proteins or peptides are prepared as above or by high throughput cell-free in vitro transcription / translation platforms. Each peptide can be assessed for its ability to stimulate an antibody response, or TCR-binding. The displayed peptide libraries are used for the screening of serum samples from immunised or infected subjects to identify immune-dominant B-cell peptides using a method of choice, e.g., ELISA. Similarly, T-cell peptides can be assessed using a T-cell in vitro response. Further uses The expressed and displayed peptide(s) can be directly used as antigens for immunisations and / or vaccinations, efficacy testing and quality control for vaccine production; can be directly used as bioactive molecules (i.e., immunostimulants, inhibitors); can be mixed with commercial vaccines to act as vaccine adjuvants by, for example, embedding a bioactive protein (for example, a stimulatory cytokine) into the scaffold, or one can fuse an antigen with a protein adjuvant. The scaffold alone in some species may have immunostimulatory and adjuvant properties hence it can be used as an immunostimulant or adjuvant. Identification and verification of immune-dominant regions or targets is the first step in the development of a peptide / subunit -based vaccine. The polypeptide region 16 is embedded on the scaffold 10 as an antigen. The antigenicity index can be assessed, in the case of an infectious disease caused by bacterial, viral, and parasitic agents by a serology test of choice using serum samples from infected subjects. The immunogenicity or antigenicity can also be assessed by immunisation using the scaffold 10 as a displayed target or other form of the target. The scaffold 10 as a displayed target or peptide can be used as an antigen to evaluate the immune response, e.g., antibody titres. Peptides or subunits of an immunodominant nature can be assembled on the scaffold backbone 8 to create a composite antigen, expressed in an appropriate system to be used directly as a vaccine. Proof of concept data of the potential use of the peptide(s)-scaffold 10 antigen as a vaccine. This will be evaluated in fish whereby healthy fish are divided randomly into several groups including control groups. The vaccination trial will be carried out as follows: briefly, the peptide-scaffold 10 construct or recombinant is administered to fish at least twice over an 8- to 12-week period and then disease-challenged with a live pathogen. Mortality is monitored over a period of 14 days after the challenge. Serum samples of fish in each group are collected for the detection of immune related indexes at appropriate intervals. The scaffold of the present invention can be used to increase the half-life of active agents that will ultimately be used for therapeutic and diagnostic purposes. Displaying a single antibody or a library of antibodies The scaffold 10 complex can be used for the detection of an antigen, or for screening or selecting for the best ligand / receptor binding partners, for example, a cytokine and its cognate receptor(s). An antibody library construct can be generated by cloning antibody fragments, from either a vaccinated animal / infected animal or synthetically, to the scaffold 10 and expressed. A ligand or receptor library construct can be generated by cloning a synthesised combination of DNA fragments to the scaffold 10 and expressed. The scaffold 10 can also function as a detection tag. For library screening, the scaffold 10 is displayed on a cell surface using a surface display technology known to the skilled person, such as, a recombinant technology that expresses target proteins on cell membranes of Gram-negative and Gram-positive bacteria, eukaryotic yeast cells and mammalian cells. EXPERIMENTAL DATA Example 1 Figures 9 to 11 show the use of the invention in peptide immunogenicity mapping. Figure 9 shows overlapping peptides corresponding to the SARS-CoV-2 nucleocapsid viral protein which were utilised for peptide mapping of the viral capsid N protein (16 overlapping polypeptides of 50 amino acid long (50-mer) and 17 separated peptides of 25 amino acids (25-mer)). The nucleotide sequence of the peptides POI was generated by PCR, then ligated into the scaffold backbone 18 using gene assembly and individually transformed E. coli cells. The peptide scaffolds 10 were then expressed and purified individually. Figure 10 shows an SDS PAGE gel of the purified peptide-scaffolds 10 recombinant protein demonstrating that the polypeptides POI are highly expressed and purified readily with high quality using the present invention. Figure 11 shows a bar chart evaluating the immunogenicity of the peptides POI using the present invention. Indirect-ELISA was used to qualitatively detect Immunoglobin G (IgG) in commercial human serum samples infected by SARS-CoV-2 (COVID-19), or by the other common cold coronaviruses (Common cold). Common cold is the major source of non-specific signal of any COVID-19 serology tests and reactivity to Common cold should be identified early in the assay development. The microwells were pre-coated with the purified individual peptide scaffold 10antigen.20 COVID-19 positive serum samples 20 Common cold serum samples were incubated with the peptide scaffold-10 antigen. Any specific antibody interactions in the sera will bind to the immobilized peptide POI fusion. Peroxidase conjugated goat anti-human IgG was added to the wells which will react with the IgG antibody immobilized on the solid phase. Then the microwells were incubated with peroxidase Substrate Solution. Hydrolysis of the Substrate by peroxidase produces a colour change. After a period of time, the reaction is stopped and the colour intensity of the solution is measured photometrically. The colour intensity of the solution depends upon the reactive antibody concentration in the original test sample. A signal to noise ratio above 3 was considered positive. X-axis represents individual peptides presented on the peptide scaffold 10, and y-axis represents number of samples of the 20 COVID-19 and 20 Common cold patients that reacted to the individual epitope. The epitopes strongly reacted with COVID-19 samples with minimum non-specific response (i.e., reaction to Common cold samples in this case) can be chosen for further development of Serology tests. Example 2 Figure 12 shows the suitability of the present invention to express a single peptide POI or composite peptides POI to develop a serology test for SARS-CoV-2. The location of five peptides (P1-P5) corresponding to SARS-CoV-2 nucleocapsid viral protein that were identified as immunodominant were prepared to have their sero-reactivity evaluated against COVID-19 patients’ sera. DNA strands encoding the five individual polypeptides (P1-P5), the composite polypeptide (P6) linked by four flexible GS linkers, and its corresponding mutant variant (P6m) were synthesised and cloned into the bio-engineered construct to be expressed and purified in E. coli cells. Figure 13 shows an SDS PAGE image of the purified scaffold-polypeptides P1, P2, P3, P4, P5, P6 and P6m, illustrating that the proteins are highly expressed with high quality of individual peptides or multiplexed peptides (i.e., P6 and P6m). Figure 14 shows a bar chart comparing the percentage of seropositive polypeptides (P1-P5) and the composite epitope (P6). The peptide scaffold 10 of the invention P1, P2, P3, P4, P5 and P6 were used to assess immunoreactivity percentage (presence of antibodies recognising peptides POI of interest) in 110 COVID-19 patients sera samples. The peptide scaffolds 10 produced were used as antigen to coat 96-well ELISA plates. Their antigenicity was assessed using standard ELISA methodology and serum samples from COVID-19 patients. A signal to noise ratio above 3 was considered positive. X-axis represents P1, P2, P3, P4, P5, P6 presented on the scaffolds 10, and Y-axis represents percentage of samples from 110 COVID-19 patients with COVID-19 antibodies recognising the peptide POI. Figure 15 shows a bar chart illustrating the percentage of seropositive COVID-19 patients using the composite peptide (P6) and the mutant composite peptide (P6m) and combined P6 and P6m. The scaffolds 10 produced according to the invention which expressed P6, P6m and P6+P6m were used to assess immunoreactivity percentage against 110 COVID-19 patients sera samples. The scaffolds 10 were used as antigen to coat 96-well ELISA plates. Their antigenicity was assessed using standard ELISA methodology and serum samples from COVID-19 patients. A signal to noise ratio above 3 was considered positive. X-axis represents P6, P6m (P6+P6m) presented on the scaffold, and Y-axis represents percentage of samples from 110 COVID-19 patients with COVID- 19 antibodies recognising the polypeptide POI. Figure 16 shows the use of the scaffolds 10 of the present invention to evaluate SARS-CoV-2 mutations on the IgG antibody response in COVID-19 patients using reference / mutant peptide pairs. The two pairs of mutant peptides shown in Figure 16 corresponds to the spike protein Y144del (the reference peptide with amino acid sequences LGVYYHKNNKSWMES, and the mutant peptide with amino acid sequence LGVYHKNNKSWMES), spike protein P681H (the reference peptide with amino acid sequences YQTQTNSPRRARSVA, and mutant peptide with amino acid sequence YQTQTNSHRRARSVA). The reference and mutant peptides pairs were expressed and produced using the present system. The peptide specific IgG antibody response in COVID-19 patients’ samples were determined by ELISA. The microwell plates were coated with the reference peptide and mutant peptide (100 ng / well). A serum sample was considered positive when a signal to background noise ratio is ≥ 3 (Y-axis). In selected patients, antibody response can only be detected by the reference peptide or the mutant peptide. The results indicate that the scaffolds of the present invention provide a convenient approach to recombinantly produce peptide antigens to evaluate the effects of mutations on antibody responses, whereby a single mutation in SARS-CoV-2 spike and nucleocapsid proteins can abolish the antibody reactivity. Figures 17 and 18 show two series of samples collected at different time points post COVID-19 from two patients which were tested using two pairs of mutant peptides RG203KR and D3G. The RG203KR pair corresponds to the capsid reference peptide with amino acid sequences NSTPGSSRGTSPARM, and the mutant peptide with amino acid sequence NSTPGSSKRTSPARM. The D3G pair corresponds to the membrane protein reference peptide with amino acid sequence MADSNGTITVEELKK, and the mutant peptide with amino acid sequence MAGSNGTITVEELKK. No antibody response was detected towards the mutant SARS- CoV-2, indicating that the mutant SARS-CoV-2 strain will escape antibody neutralisation and the antibody produced towards the reference strain will be inefficient for protection against the infection by the mutant virus when this antibody response is essential. Figure 19 shows the use of the scaffold backbone 18 to aid in the expression and stabilisation of unstable candidates. The N-terminal pro b-type natriuretic peptide (NT-proBNP) has a half-life between 60-120 h. DNA strands encoding the NT-proBNP antigen were synthesised and cloned into the bio-engineered polypeptide scaffolds to be expressed and purified in E. coli cells. An SDS PAGE image is shown of the purified scaffold-NT-proBNP complex stored at -70°C, 4 °C (fridge), room temperature, and 37 °C for three days. No obvious degradation was seen even at 37 °C, suggesting high stability during accelerated stability testing. USES Scaffold Platform The scaffolds backbone 18 of the present invention can be used in general terms, as a scaffold platform for peptide expression. Over 2000 peptides have been expressed and purified successfully using the present system. The peptides include single peptide of 5 to 1000 amino acids, composite peptides of up to 15 peptides connected by the GS linker with a combined size of 1000 amino acids. Examples include libraries of overlapping peptides for immune-dominant peptide mapping in the development of SARS-CoV-2 (viral disease) and bacterial Lyme disease serology tests; sub-domain and full-length proteins of SARS CoV-2 nucleocapsid and spike proteins, and outer surface protein C (OspC) and VlsE antigens from Lyme disease causing agents, i.e. Borrelia species such as Borellia burgdorferi; domain antibody, e.g., VHH fragments; unstable polypeptide, e.g., NT-proBNP; polypeptides from other virus, e.g. TiLV and SKNVV; and extracellular domains or loops of receptors, e.g. follicle-stimulating hormone receptor. The success rate of production of a single peptide is over 99%. Serodiagnosis The suitability of the scaffold backbone 18 to be used in serodiagnosis is determined by the following properties; (a) its immunoreactivity to biological testing material. Immunoreactivity will equate to false positives in serology tests. The scaffold proteins of the present invention are derived from non-pathogenic extremophiles, i.e., species from Thermotoga, Thermithiobacillus, Aquifex, Geobacillus, Acidithiobacillus, Alkalispirochaeta, Desulfosporosinus, Bermanella, and Azospirillum. They live in extreme environment and are rarely encountered by humans to initiate an immune response. Additional directed manipulation to the scaffold arms were designed to reduce the immunoreactivity further. The scaffolds backbone 18 of the present invention were tested for immunoreactivity towards human serum samples using gold standard ELISA method with a signal to noise ratio >3 scoring positive. Testing of 800 human serum samples, the reactivities are less than 1% in most of the scaffold proteins without extra amino acid sequences in the middle. (b) the second key aspect of the present invention is the capacity to express up to 15 multiple peptides at once and produce a stable peptide-scaffold 10. The multiplexing of immunodominant peptides is a useful property in serology testing because it increases the assay sensitivity and overall accuracy. (c) the high cloning efficiency, high yield, ease of purification of heterologous peptides, and high solubility and stability makes the platform economically viable for serodiagnosis. Development of SARS-CoV-2 peptide-based serology tests Peptide mapping Peptide -based serology test has the potential for high specificity and sensitivity. A critical first step is the identification of immune-dominant peptides. For this purpose, a library of overlapping peptides of 25 and 50 amino acids across the whole nucleocapsid, membrane, envelop and spike SARS-CoV-2 viral proteins has been produced, that is used for the screening of COVID-19 and non-COVID-19 serum samples to identify immunodominant peptides for an antibody response, as shown in Figures 9 to 11. Peptides with cross reactivity to non-COVID samples have also been identified that are excluded in the final serology tests for increased specificity. Multiplexing The second critical step is how to put multiple immuno-dominant peptides into the same test to increase sensitivity. Mixing individual peptides into the same test has limitations such as the need to chemically synthesize or recombinantly express individual peptides, the need for a carrier to display the peptides in correct conformation, the need for multiple buffers including folding buffers and storage buffers to solubilise the peptides and reduce precipitation, which will lead to high costs. Combining multiple peptides into the same entity, then utilising a stable scaffold to recombinantly express the multi-peptide complex will increase the sensitivity but decrease the production cost and assay complexity. Multiple COVID-19 specific peptides selected above were used to produce composite antigens in which each antigen contains up to nine peptides linked by a flexible GS linker. The composite antigen construct has a combined reactivity of individual peptides and enhances the antibody assay sensitivity. This is shown in Figures 12 to 14. Reduction of non-specific binding using epitopes Several immune-dominant peptides have been shown to react with pre-COVID samples albeit at low reaction rate and low signal. This is due to infections by other homologous non-COVID coronavirus. Several small peptides that bind non-specifically in pre-COVID serum samples have been identified from non-COVID coronaviruses. These non-COVID peptides preferentially binding to antibodies in non-COVID samples result in the reduction of the binding to COVID antigens when added into the sample diluent. Several non-COVID peptides have been added into the diluent of the serology (antibody) assay, leading to the increase of specificity from 98.5% to 100% in the Universal COVID-19 IgG ELISA assay as independently verified by the National Institute for Biological Standards and Control (NIBSC) and World Health Organisation (WHO). The invention has also aided the production of large peptide-containing structure / domains of SARS-CoV-2 nucleocapsid and spike viral proteins. These large peptides give additional reactivity by providing linear epitopes and as well as conformational epitopes to further increase sensitivity. The peptide constructs produced have been used to establish multiple serology tests of COVID- 19 with superior specificity and sensitivity. A similar protocol was applied in the development of serology tests of Lyme disease caused by Borrelia species bacteria. Evaluate mutations on immune response The pathogen of a pandemic will undergo mutations that may have major influence on pathogenesis and a risk factor of change of disease severity and reduction of vaccine efficacy. Evaluation of the effects of mutation on antibody response can be facilitated using the scaffold system of the invention. Thirteen pairs of peptides of 50 amino acids have been produced using the scaffold backbone 18 from the reference and mutant variant of COVID-19 strains. These peptide pairs have been used to evaluate the effect of single mutation on antibody responses. As shown in Figure 14 antibody response can only be detected by the reference / wild type epitope or the mutant epitope in selected COVID-19 patients, suggesting that a single mutation in SARS- CoV-2 spike and nucleocapsid proteins can abolish antibody reactivity. The results indicate that the scaffold of the present invention provides a convenient approach to produce peptide antigens to evaluate the effects of mutations on antibody responses. The antibody responses can also be detected by Western-blot using the peptide / polypeptide displayed on the invention. Essentially, the scaffold functions as a carrier of the detecting antigen / peptide. The antibody responses shown in Figure 16 can also be detected by Western- blot using the corresponding epitope antigen produced by the present invention. Peptide Mapping Peptide mapping described above in COVID-19 serology test development was also applied in mapping immune-dominant peptides for Lyme disease serology tests. A library of overlapping peptides of 40 amino acids long across 40 antigens of the Borrelia species, such as Borellia burgdoferi, was used for the screening of Lyme and non-Lyme serum samples to identify immunodominant and Borrelia-specific epitopes. Multiple Borrelia species, such as Borellia burgdoferi, specific peptides have been selected to make composite antigens in which each antigen contains up to 15 peptides linked by a GS linker. The composite antigen construct has a combined sensitivity and specificity of 94.3% and 95.5% respectively. This data shows that the present invention can be applied for the serodiagnosis of a wide spectrum of diseases. Another example of peptide -mapping is the mapping of a linear peptide of the fusion protein of Respiratory syncytial virus, or RSV to monoclonal antibodies. Again, overlapping epitopes of 40 amino acids were produced using the scaffold system and their binding to monoclonal antibodies was evaluated using ELISA. A single epitope was identified that binds to antibody clone 11-3-A3. Increasing stability of unstable peptides Some peptides / proteins are inherently unstable and cannot preserve their native conformation or function alone as seen with canine natriuretic peptide. The N-terminal pro b-type natriuretic peptide (NT-proBNP) levels are elevated in dogs with mitral valve disease and dilated cardiomyopathy. The NT-proBNP concentration in blood correlates with the severity of the disease and reflects the risk of subsequent complications. NT-proBNP measurement helps to distinguish congestive heart failure from primary respiratory tract disease as an underlying cause of respiratory signs in dogs (Boswood et al 2008, J Small Anim Pract.49, 26-32.). An increasing number of studies have shown that NT-proBNP can be successfully used for the diagnosis of cardiac disease in dogs, assessing the severity of the disease in dogs with cardiac disease and prognosis in dogs with heart disease. One of the main challenges with canine NT-proBNP measurements is the low stability of the analyte (half-life is between 60-120 h), hence a stable NT-proBNP calibrant is not available to be used to develop point-of-care testing and home testing in blood samples. The bio-engineered polypeptide scaffold was used to improve the stability of NT-proBNP. The NT-proBNP was displayed on the invention and purified. The protein was stored at -70°C, 4 °C, room temperature, and 37 °C for three days and analysed by SDS-PAGE. The NT-proBNP stored at the four conditions showed no difference in stability, as shown in Figure 19. Peptide-based vaccine development There are multiple approaches for vaccine design. One promising method is peptide-based vaccines. The basic idea behind this strategy was to identify the immunodominant epitopes that elicit an immune response. This strategy offers several advantages, including (i) elimination of undesirable immune responses by designing specific constructs; (ii) generation of prolonged immunity with required responses; and (iii) cost- and time-effectiveness (Rock et al., 2016). The first peptide-based vaccine against infectious diseases caused by Vibrio cholerae and Escherichia coli was developed in 1985 (Jacob et al., 1985). The low immunogenicity of single-peptide has led to the idea of designing constructs with multiple peptides. Vaccine constructs with several polypeptides tend to improve both the antigenicity and immunogenicity of the vaccines. A key step in epitope-based vaccine design is the engineering of the immunogenic peptides construct and the expression of a stable chimeric antigen for evaluation of the vaccine efficiency. The scaffold 18 backbone is used to multiplex polypeptides of the immunodominant peptides corresponding to Tilapia Lake Virus (TiLV) and Infectious Spleen and Kidney Necrosis Virus (ISKNV) to create a multivalent peptide-based vaccine to be used for vaccine development and efficacy evaluation. Innovation is urgently required for production of viral vaccines for Tilapia, as GMP production of classic live attenuated or inactivated vaccines produced in cell cultures faces two major bottlenecks: (1) the lack of appropriate cell lines for culturing the virus and (2) associated high production costs coupled with adjuvant costs that make this vaccine technology ineffective and expensive for global acceptance and uptake. The vaccines for tilapia need to be affordable, because it is a low value species. The peptide scaffold 10 can be used to solve the multiplexing challenge to create stable chimeric multiplexed polypeptides suitable for vaccine development. Peptide-based immunogens for antibody development According to several recent studies, an unexpectedly high number of antibodies used for research, diagnostic, food analytical, environmental, and other purposes were not reproducible (Weller et al., 2016). One reason for the poor performance stems from poor antibody development strategy. Moreover, developing antibodies to proteins associated with membrane lipid-bilayer of the cell such as GPCRs, and proteins belonging to highly conserved families such as zinc finger (ZNF) proteins and cytochrome P450s is challenging (Ayoub et al., 2017). The present invention offers a significant improvement to the art of antibody development as unique peptides of interest corresponding to antigenic regions and specific to the target of choice can be selected for the antibody development stage. The present system was utilised to multiplex the three extracellular loops of follicle-stimulating hormone receptor (NP 001119702.1) into a stable chimeric antigen which was then used for immunisation and development of antibodies. Displaying single-chain and domain antibodies Antibodies are most commonly used in ELISA tests due to their high sensitivity, specificity, established manufacturing processes and safety. Antibodies have also found use in point-of-care diagnostic devices (also known as lateral flow immunoassays (LFIs)), due to their low cost and ease of use. Nanobodies (also known as the VHHs) are the variable antigen-binding region that arise in single-domain antibodies (sdAbs) derived from a single heavy chain antibody variant found in camelids. Nanobodies have revolutionized structural biology, and have entered clinical trials as therapies and tools (Salvador et al., 2019). Despite their usefulness, nanobodies haven’t found use in ELISA and LF diagnostic devises. The limitations of nanobodies in ELISA and LFs relates to factors, such as poor adhesion to the plate and gold nanoparticles via passive adsorption and obstruction of the binding motif due to their small size. To increase the size, nanobodies are conjugated with IgG Fc fragment. Although this method overcomes the limitations of nanobodies, it increases the cost of production dramatically because the addition of the IgG FC means the need to use eucaryotic, preferably mammalian, expression systems instead of a prokaryotic system. The bio-engineered polypeptide scaffold was used to express and display nanobodies in a stable manner using E. coli expression system. SEQUENCES The following sequences are disclosed, and provided in the accompanying sequence listing. The left arm may be bioengineered from the precursor sequence (SEQ ID NO: 1): Azospirillum MRYLNINSENQSSSVSKIASGSRITKASDDAAGLAVGTSLTSHITVLKQAATNASHGSSILRAADG GMSRVSDIVQRMRSLATQSLSGAVTDTERGFLDAEFQQLIEEIRGIASGTRFNDDPLLD The left arm may be bioengineered from the precursor sequence (SEQ ID NO: 2): Aquifex pyrophilus MAVTYTTLKQNERLMNKSLLRLSTGLRILSAADDASGLFIARQLSLVSTGLQQGNRNIQFAGSAL QIAEGGVAQIYKKLKTMYQKAVSAANDINDPNAGAALQRDIENLRDAIQKIAQDTEYNGIRLLD The left arm may be bioengineered from the precursor sequence (SEQ ID NO: 3): Thermotoga petrophila MAWRNIDQTQYSMSKTLERLSSGLRINRAGDDAAGLAISEKMRGQIRGLNMAIKNAQDAISLIQT AEGTLTEVHSILQRMRELAVQAASDTNTNVDRNQIQKEIEQLREEIDRIARTTEFNTKKLLD The left arm may be bioengineered from the precursor sequence (SEQ ID NO: 4): Thermotoga caldifontis MAWRSMSETQYSMSKTLEKLSSGLRINRAGDDAAGLAISEKMYGQIRGLNMAVKNAQDAISLIN TAEGALTEVHSILQRMKELAVQAASDTNTDVDRYQIQADLDQLREEIDRIARTTEFNTMKLLD The left arm may be bioengineered from the precursor sequence (SEQ ID NO:5): Geobacillus stearothermophilus MAYRNLAASQSNISKNLERLSSGLRINRAADDAAGLAISEKMRSEIRGLQMAERNALDAISLIQTA EGALNEVHSILQHMRELAVQAANGTNQDTDREALESEFQQLKQEIDRIGTDTQFNTMNILA The left arm may be bioengineered from the precursor sequence (SEQ ID NO: 6): Thermithiobacillus tepidarius MLFTQNALNGTSSALNQALQRLSTGLKINSPGDDPAGYAVAQRFTTGINGTNQAISNAQQATAL VQSATGGIQDSTDLLQQIRKIAVQAANGSQSDSDRAALQNVVAALKDQISTIAKQTQFNGKSLLD The left arm may be bioengineered from the precursor sequence (SEQ ID NO: 7): Acidithiobacillus thiooxidans MLSTLNALNGTQGSLNTYLQQLSTGKSINGPADNPAGYAIAQDFQTQINGMNQAISNGNQGVSL VQTATGAIENQTSLLQQIRTTAVQAAYASNTTSDDQALQGVVSQLLAQVQTIATQTQFNGQNLL D The left arm may be bioengineered from the precursor sequence (SEQ ID NO: 8): Alkalispirochaeta americana MRRQGITTQDVQGNIEKLSSGLRINRAGDDASGLAVSEKMRSQIGGLNQASRNAADGISLIQTTE GELQSSQDVLQKLRELAVQSANGIYTAEDRYQIQVEVSQLIDEIDRVASHAQFNGMNLLT The left arm may be bioengineered from the precursor sequence (SEQ ID NO: 9): Bermanella marisrubri MRNLDKSQSANQTALQRLSSGLRINSAKDDAAGLAISTRFNSDIRGLNVAQKNAGDGISLAQTAE GALGSMNDNLQRIGELAVQSANATNSDVEREALQAEVSQLVSEISRTADETAFNGRKLLD The left arm may be bioengineered from the precursor sequence (SEQ ID NO: 10): Desulfosporosinus youngiae MIYNKLATNTANSAKSLEKLSSGLRINKAGDDAAGLAISEKMKAQIRGLNQASRNAQVGISLIQTA EGALSNTQSILQRMRELATQASNKTNTDSDRGEIQKEVNQLTSEINRIGNTSEFNAIKLLK The right arm may be bioengineered from the precursor sequence (SEQ ID NO: 11): Thermithiobacillus tepidarius DIDVSTVDGANKALQIADFALDFLNAEGGRLGAQNERIKATLATLQTASLNLTAGYSAVQDANLA EETSELTKNQIL The right arm may be bioengineered from the precursor sequence (SEQ ID NO:12): Azospirillum fermentarium DVGTSATASAALTALDTAVETLSSADADVGALISRFEFRGQVLGTSIENTEAAQSAIMDVDVAAE QAELASTK The right arm may be bioengineered from the precursor sequence (SEQ ID NO: 13): Bermanella marisrubri EIDISTFEGATAALTAIDNAIGAIASQDADLGAIQNRIESTYSNLAVTSENLTAANSKIADADFAAET AELSRTQVLQQAGISIL The right arm may be bioengineered from the precursor sequence (SEQ ID NO: 14): Aquifex pyrophilus AIDVTTNEGAELAMDILTIAAQKVEEIRSQIGSTIINLQAIYDAKAVAKDNTKNAENIIRNVDFALEMT EFTKYQIRM The right arm may be bioengineered from the precursor sequence (SEQ ID NO: 15): Acidithiobacillus NINVTTAAGAQQAIGIVDQAINYLNQKNGSLGAIQNRIQASVSNRQTTATNLQSAQSVVQEANIA QATSQLTKYQIL The right arm may be bioengineered from the precursor sequence (SEQ ID NO: 16): Thermotoga petrophila SLKVTTQDAAERAIMVVDAAIHRVSTADAALGAIQNRLEHTISNLGFAAENLTAAESRIRDADMAK ELMEFTKQQILLQSSMAML The right arm may be bioengineered from the precursor sequence (SEQ ID NO: 17): Alkalispirochaeta americana MMSLSSPDSANASIGLLDTALRSVSKQDADLGAYQNRLEMAVQGIDIAAENLQAASSRIRDVDM ASEVVDFTVNQILAQSSTAML The right arm may be bioengineered from the precursor sequence (SEQ ID NO: 18): Thermotoga caldifontis SLKVTDQDSAERTIMVIDAAIHKVSSARAHLGAVQNRLEHTISNLGYAAENLTAAESRIQDADMA KEMMEFTKQQILMQSSMAML The right arm may be bioengineered from the precursor sequence (SEQ ID NO: 19): Desulfosporosinus youngiae FALDVSSFESATAAISVLNDAIAAVSSEFSKLGAFQNRLEHTIAELSTTSENMTGAESRIKDVDMA KEMMEFQKNNILAQAATAML The right arm may be bioengineered from the precursor sequence (SEQ ID NO: 20): Geobacillus stearothermophilus SLDIKQVANAQAAIAKLDEAIISVSRTRSKMGAYQNDLEHTINNLTTANENLTAAESRIMDTDMAM EMAEFTKNNILTQAAQAML Both the left and right arm sequences can be changed substantially if the changes have no effects on its structure, expression, and stability. The left linker has the sequence (SEQ ID NO: 21): GGDDAGG The right linker has the sequence (SEQ ID NO: 22): GGAKKGG The middle linker has the sequence (SEQ ID NO: 23) GGGSGGG that provides a flexible linker to join multiple peptides. The purification tags have the sequence (SEQ ID NO: 24): GSGHHHHHHHHHH The purification tags could also have the sequence (SEQ ID NO: 25): NPVIRYKRRS The nucleotide sequences codon optimised for expression in E. coli, and which encode the protein sequences provided above, are: The left arm may be bioengineered from the precursor sequence (SEQ ID NO: 26): ATG CGC TAT CTC AAT ATC AAC AGC GAG AAT CAG TCG AGT AGT GTC TCC AAA ATT GCC AGC GGG TCC CGC ATT ACG AAG GCT TCG GAT GAC GCC GCT GGG TTG GCG GTA GGT ACA TCG CTT ACC TCT CAC ATT ACT GTG TTA AAA CAA GCC GCA ACC AAC GCC AGT CAT GGT AGC TCC ATT CTG CGT GCA GCA GAT GGC GGT ATG TCT CGT GTT TCA GAT ATC GTG CAA CGA ATG CGG TCA CTG GCG ACT CAG AGC CTA TCT GGC GCG GTT ACC GAT ACG GAG CGC GGC TTT CTG GAC GCG GAA TTC CAG CAG CTG ATC GAA GAA ATA CGC GGA ATC GCG AGC GGC ACC CGT TTT AAC GAC GAT CCG CTG CTG GAT The left arm may be bioengineered from the precursor sequence (SEQ ID NO: 27): ATG GCG GTT ACG TAC ACT ACC TTA AAG CAG AAC GAA CGG TTG ATG AAT AAA TCG TTA TTG CGT CTT TCT ACA GGC CTT CGT ATA CTA TCG GCG GCC GAC GAC GCT TCC GGC CTG TTT ATT GCG CGT CAA CTC AGT CTG GTA TCA ACG GGA CTC CAA CAG GGG AAC CGA AAT ATC CAA TTC GCG GGC AGC GCT CTG CAA ATC GCG GAA GGC GGT GTC GCC CAG ATC TAC AAG AAA CTG AAA ACC ATG TAT CAG AAA GCT GTG AGC GCA GCA AAT GAT ATT AAC GAC CCG AAT GCG GGT GCC GCA CTG CAG CGC GAT ATT GAG AAC CTG CGC GAT GCC ATC CAG AAA ATT GCA CAG GAT ACC GAA TAT AAC GGT ATT CGC CTG CTG GAT The left arm may be bioengineered from the precursor sequence (SEQ ID NO: 28): ATG GCG TGG CGA AAC ATC GAC CAG ACC CAA TAT TCC ATG AGC AAG ACG TTA GAG CGG CTT TCC AGT GGA TTG AGA ATA AAT CGT GCG GGA GAC GAT GCG GCC GGT TTA GCG ATC TCG GAG AAA ATG CGT GGC CAG ATC CGT GGG CTC AAC ATG GCC ATA AAG AAT GCA CAA GAC GCA ATC AGT CTG ATT CAG ACT GCA GAA GGG ACG CTA ACC GAG GTG CAT TCG ATC CTG CAA CGC ATG CGT GAA CTG GCT GTC CAG GCG GCT AGC GAT ACT AAC ACA AAT GTT GAC CGC AAC CAG ATT CAG AAA GAA ATT GAA CAG CTG CGA GAA GAA ATT GAT CGC ATT GCC CGC ACC ACG GAA TTT AAT ACC AAG AAA CTG TTA GAT The left arm may be bioengineered from the precursor sequence (SEQ ID NO: 29): ATG GCT TGG CGT AGT ATG TCA GAG ACC CAA TAC AGC ATG AGC AAA ACT TTG GAG AAA CTA AGT TCG GGA CTT CGC ATT AAC CGT GCC GGT GAC GAT GCT GCC GGC TTG GCC ATT AGT GAG AAA ATG TAT GGG CAG ATA CGG GGA CTC AAC ATG GCG GTG AAG AAT GCT CAG GAC GCT ATA TCC TTG ATC AAT ACG GCA GAG GGC GCT TTG ACA GAA GTC CAT AGC ATC TTA CAA CGT ATG AAA GAA TTA GCG GTA CAA GCA GCT TCT GAC ACA AAT ACG GAT GTC GAC CGA TAT CAA ATT CAG GCG GAT CTG GAT CAG CTG CGC GAA GAG ATT GAT CGC ATC GCG CGT ACG ACT GAA TTT AAT ACC ATG AAG CTG CTG GAC The left arm may be bioengineered from the precursor sequence (SEQ ID NO:30): ATG GCT TAT CGT AAC TTA GCA GCG TCT CAG AGC AAC ATA AGC AAG AAC CTT GAA CGC CTA TCC TCA GGA TTG CGG ATT AAT CGA GCA GCT GAT GAC GCA GCG GGC CTG GCC ATT TCG GAG AAA ATG CGT AGT GAA ATT CGC GGG CTC CAG ATG GCA GAG CGC AAC GCG CTG GAC GCT ATT AGC CTG ATC CAG ACA GCC GAA GGC GCG TTG AAC GAA GTG CAC TCG ATC TTA CAA CAT ATG CGT GAA CTG GCC GTT CAA GCG GCC AAC GGT ACT AAT CAA GAC ACC GAT CGC GAG GCG CTG GAA AGT GAA TTC CAG CAG CTG AAA CAG GAA ATT GAT CGT ATC GGT ACC GAT ACG CAG TTT AAT ACC ATG AAT ATC CTG GCC The left arm may be bioengineered from the precursor sequence (SEQ ID NO: 31): ATG CTT TTC ACT CAA AAT GCA CTG AAC GGC ACC TCC AGT GCG CTC AAC CAG GCG CTG CAG CGG TTG AGT ACC GGT CTG AAA ATT AAC TCC CCG GGT GAC GAC CCA GCC GGG TAT GCT GTC GCT CAA CGT TTT ACC ACA GGG ATC AAT GGT ACC AAT CAA GCA ATC TCT AAT GCG CAG CAG GCA ACC GCT CTG GTA CAA TCT GCG ACG GGC GGA ATA CAA GAT TCG ACG GAT TTG CTA CAG CAA ATC CGC AAA ATT GCA GTT CAG GCG GCG AAC GGC AGC CAG TCG GAT AGC GAC CGC GCC GCC TTA CAG AAC GTG GTG GCG GCC TTA AAA GAT CAG ATT TCA ACT ATT GCC AAA CAG ACG CAG TTT AAC GGC AAG AGC CTG CTG GAT The left arm may be bioengineered from the precursor sequence (SEQ ID NO: 32): ATG CTG TCC ACA CTG AAT GCC CTG AAT GGA ACT CAA GGC AGT CTC AAT ACC TAC TTG CAA CAA CTG TCA ACC GGC AAA TCG ATT AAT GGC CCG GCA GAC AAT CCA GCC GGC TAT GCG ATC GCG CAG GAT TTT CAA ACG CAG ATT AAC GGT ATG AAC CAG GCG ATC TCT AAT GGT AAC CAG GGT GTG AGC TTA GTT CAA ACA GCC ACC GGT GCC ATT GAA AAC CAA ACC AGT TTG CTG CAG CAG ATT CGC ACG ACT GCT GTT CAG GCA GCT TAT GCT TCG AAC ACC ACC AGC GAT GAT CAG GCG CTT CAG GGA GTC GTG AGC CAA TTA CTG GCA CAG GTT CAG ACC ATC GCG ACG CAA ACG CAG TTC AAC GGG CAA AAC CTG CTA GAC The left arm may be bioengineered from the precursor sequence (SEQ ID NO: 33): ATG CGT CGG CAG GGG ATC ACC ACT CAG GAC GTA CAA GGC AAC ATC GAG AAA CTG TCA TCG GGG TTA CGT ATA AAC CGT GCG GGT GAC GAC GCC AGT GGT CTG GCG GTC AGC GAA AAG ATG CGA TCC CAA ATC GGT GGA CTA AAT CAA GCT TCC CGC AAC GCC GCC GAC GGC ATC TCC CTC ATT CAG ACC ACA GAA GGT GAG CTT CAA TCG AGT CAG GAT GTC CTG CAA AAG CTG CGC GAA TTG GCT GTG CAG AGC GCG AAT GGC ATT TAC ACG GCA GAA GAT CGC TAT CAG ATT CAG GTG GAA GTG TCT CAG TTA ATT GAT GAA ATT GAT CGC GTT GCA AGT CAT GCG CAG TTT AAT GGG ATG AAC CTG CTG ACC The left arm may be bioengineered from the precursor sequence (SEQ ID NO: 34): ATG CGC AAC TTA GAC AAA TCG CAA AGT GCA AAC CAG ACC GCG TTG CAA CGT TTG TCA TCT GGA CTC CGG ATT AAT TCC GCC AAA GAT GAT GCT GCT GGT TTA GCT ATC TCG ACA CGC TTT AAT AGC GAC ATT CGT GGG CTG AAC GTG GCC CAG AAG AAC GCA GGC GAT GGT ATC TCT CTA GCG CAA ACC GCC GAA GGC GCG CTT GGC AGT ATG AAC GAC AAT CTG CAG CGA ATT GGT GAG CTG GCA GTC CAG TCC GCC AAC GCC ACG AAT TCA GAT GTT GAG CGC GAA GCG CTG CAG GCG GAA GTA AGC CAG CTG GTG AGC GAA ATC AGC CGC ACC GCA GAT GAA ACT GCG TTC AAT GGC CGT AAA CTG CTG GAT The left arm may be bioengineered from the precursor sequence (SEQ ID NO: 35): ATG ATC TAT AAC AAA CTA GCG ACC AAT ACG GCT AAT AGC GCC AAG TCG CTT GAG AAA CTC AGT TCT GGC TTG CGG ATT AAC AAG GCT GGG GAC GAT GCT GCA GGC CTG GCA ATA TCA GAG AAA ATG AAA GCA CAA ATC CGT GGA CTG AAC CAA GCC TCG CGC AAC GCC CAA GTT GGT ATC TCC TTA ATC CAG ACC GCG GAA GGT GCT CTC AGC AAT ACC CAG AGC ATT TTG CAG CGC ATG CGT GAA CTG GCT ACC CAG GCG TCC AAT AAA ACT AAT ACG GAT TCT GAT CGC GGT GAA ATC CAG AAA GAA GTG AAT CAG TTA ACA AGT GAA ATT AAT CGT ATT GGC AAC ACT AGC GAA TTT AAC GCC ATT AAA CTC CTG AAA The right arm may be bioengineered from the precursor sequence (SEQ ID NO: 36): GAC ATC GAT GTA TCC ACC GTT GAC GGC GCA AAC AAA GCT CTT CAG ATT GCG GAT TTC GCA CTA GAT TTT CTG AAT GCT GAA GGA GGC CGT TTG GGT GCA CAG AAC GAA CGC ATC AAA GCG ACC TTG GCA ACT CTG CAA ACG GCG TCA CTG AAT CTG ACT GCC GGT TAT AGC GCC GTG CAG GAT GCC AAC CTG GCA GAA GAG ACG AGT GAA CTG ACG AAG AAT CAA ATT CTG The right arm may be bioengineered from the precursor sequence (SEQ ID NO:37): GAT GTA GGC ACT AGC GCT ACC GCT TCA GCG GCC CTG ACG GCA CTG GAT ACC GCG GTT GAA ACG CTC TCC AGT GCA GAT GCG GAT GTC GGC GCC CTG ATT TCT CGC TTC GAA TTT CGT GGG CAA GTT TTA GGT ACC AGC ATT GAG AAC ACA GAA GCG GCT CAG TCG GCC ATC ATG GAC GTG GAC GTG GCG GCC GAA CAG GCA GAG TTG GCG TCG ACC AAA The right arm may be bioengineered from the precursor sequence (SEQ ID NO: 38): GAA ATC GAT ATC AGT ACA TTT GAA GGG GCA ACT GCC GCC CTC ACG GCG ATT GAC AAT GCG ATC GGT GCG ATT GCT TCG CAG GAT GCC GAC TTG GGC GCA ATA CAG AAT CGT ATC GAG TCC ACT TAT TCA AAC CTG GCG GTT ACG TCG GAA AAC CTG ACC GCC GCG AAC TCT AAA ATT GCT GAT GCG GAC TTC GCG GCG GAA ACC GCA GAG CTT AGC CGC ACC CAG GTG TTA CAA CAA GCA GGC ATC AGC ATA CTG The right arm may be bioengineered from the precursor sequence (SEQ ID NO: 39): GCG ATT GAC GTA ACT ACA AAT GAG GGC GCA GAG TTG GCA ATG GAC ATT TTA ACA ATC GCT GCC CAG AAG GTG GAA GAG ATC CGG AGC CAG ATT GGT AGT ACG ATT ATT AAT CTG CAG GCC ATA TAT GAT GCC AAA GCA GTT GCG AAA GAT AAT ACG AAG AAC GCG GAA AAC ATC ATC CGT AAC GTC GAT TTT GCG CTG GAA ATG ACC GAA TTC ACC AAG TAC CAG ATT CGA ATG The right arm may be bioengineered from the precursor sequence (SEQ ID NO: 40): AAT ATC AAT GTA ACC ACT GCA GCT GGT GCC CAG CAG GCT ATT GGG ATA GTG GAT CAG GCA ATT AAT TAT CTC AAT CAA AAG AAC GGC AGC CTC GGC GCG ATT CAA AAC CGT ATA CAA GCC TCT GTC TCC AAC CGC CAA ACC ACA GCC ACC AAC CTG CAG TCG GCA CAG AGT GTC GTA CAG GAA GCG AAC ATC GCG CAG GCG ACG TCA CAG CTG ACG AAG TAC CAA ATC TTA The right arm may be bioengineered from the precursor sequence (SEQ ID NO: 41): AGT CTC AAG GTA ACG ACC CAG GAC GCG GCT GAG CGT GCG ATC ATG GTT GTC GAT GCA GCC ATC CAC CGC GTG TCG ACA GCC GAT GCT GCC TTA GGC GCG ATT CAG AAT CGT CTG GAA CAT ACC ATT TCC AAC CTG GGT TTC GCA GCA GAA AAC CTG ACC GCG GCG GAA TCT CGG ATT CGC GAT GCC GAC ATG GCT AAA GAG TTG ATG GAA TTT ACT AAA CAA CAA ATC CTT CTG CAG AGC TCA ATG GCG ATG CTG The right arm may be bioengineered from the precursor sequence (SEQ ID NO: 42): ATG ATG AGT CTG TCC AGC CCG GAT TCG GCT AAT GCT TCC ATT GGT CTG TTG GAT ACC GCG TTA CGG TCT GTG AGT AAA CAA GAC GCG GAC CTC GGC GCC TAT CAG AAC CGC CTT GAA ATG GCA GTT CAG GGG ATC GAC ATC GCA GCG GAG AAC CTG CAA GCC GCA AGC TCA CGC ATT CGT GAT GTG GAT ATG GCC TCT GAA GTC GTT GAT TTT ACT GTA AAT CAG ATT CTG GCG CAG TCG AGC ACG GCG ATG CTG The right arm may be bioengineered from the precursor sequence (SEQ ID NO: 43): AGT TTA AAG GTC ACG GAC CAG GAT TCA GCG GAA CGC ACA ATC ATG GTG ATT GAT GCC GCG ATT CAT AAA GTT AGC AGC GCT CGT GCC CAT CTT GGT GCC GTA CAG AAT CGG TTG GAA CAC ACC ATC TCT AAC CTC GGC TAT GCG GCA GAA AAC CTG ACC GCT GCA GAG TCG CGC ATT CAG GAC GCA GAT ATG GCG AAA GAA ATG ATG GAG TTT ACT AAA CAG CAA ATC CTG ATG CAA TCG TCC ATG GCG ATG CTG The right arm may be bioengineered from the precursor sequence (SEQ ID NO: 44): TTT GCC CTG GAT GTC TCC AGC TTC GAG TCT GCC ACT GCA GCT ATC TCG GTT CTG AAC GAC GCA ATC GCA GCC GTA TCG AGC GAA TTC AGC AAA TTG GGT GCC TTT CAG AAT CGT TTA GAG CAT ACG ATT GCG GAA CTG AGT ACA ACC AGT GAA AAT ATG ACC GGC GCG GAA TCA CGC ATT AAA GAT GTG GAT ATG GCT AAA GAA ATG ATG GAA TTT CAG AAG AAC AAC ATT CTT GCG CAA GCG GCG ACC GCT ATG CTC The right arm may be bioengineered from the precursor sequence (SEQ ID NO: 45): TCT TTG GAT ATT AAA CAG GTA GCG AAT GCC CAG GCT GCC ATC GCA AAG TTA GAT GAA GCT ATC ATT AGT GTT AGC CGC ACG AGG AGC AAA ATG GGC GCC TAT CAA AAT GAC CTC GAG CAT ACT ATT AAC AAC CTT ACG ACA GCG AAC GAA AAT CTG ACC GCC GCT GAA TCC CGG ATT ATG GAT ACC GAC ATG GCA ATG GAG ATG GCT GAA TTT ACC AAG AAC AAT ATC CTG ACC CAA GCG GCC CAG GCG ATG CTG The left linker has the sequence (SEQ ID NO: 46): GGA GGT GAT GAC GCA GGC GGT The right linker has the sequence (SEQ ID NO: 47): GGT GGA GCG AAG AAA GGA GGC The middle linker has the sequence (SEQ ID NO: 48) GGC GGA GGG TCT GGT GGA GGG The purification tag has the sequence (SEQ ID NO: 49): GGA AGT GGG CAT CAT CAT CAC CAC CAT CAT CAC CAT CAC The purification tag could also have the sequence (SEQ ID NO: 50): AAC CCG GTG ATT CGC TAT AAA CGC CGC AGC The left arm or right arm may have the latest bioengineered sequence generation (SEQ ID NO: 51): Azospirillum (FHS) MAAGLAVGTSLTSHITVLKQAATNASHGSSILRAADGGMSRVSDIVQRMRSLATQSLSGAVTDT ERGFLDAEFQQLIEEIRGIASGTRFNVIPLLD The left arm or right arm could also have the latest bioengineered sequence generation (SEQ ID NO: 52): Aquifex pyrophilus (BHS) MQGNRNIQFAGSALQIAEGGVAQIYIALKTMYQKAVSAANDINDPNAGAALQRAIENLRDAIQKIA QDTVYNGIRLLD The left arm or right arm could also have the latest bioengineered sequence generation (SEQ ID NO: 53): Thermithiobacillus tepidarius (CHS) MTGINGTNQAISNAIQATALVQSATGGIQDSTDLLQQIRKIAVQAANGSQSDSDRAALQNVVAAL KDQISTIAKQTQFNGKSLLW The left arm or right arm could also have the latest bioengineered sequence generation (SEQ ID NO: 54): Acidithiobacillus thiooxidans (DHS) MAIAWDFQTAINGVNAAISNGNQGVSLVQTATGAIENQTSLLQQIRTTAVQAAYASNTTSDDQAL QGVPSQLLAQVQTIAAQTVFNGQILLD The left arm has the latest generation sequence (SEQ ID NO: 55): ATGGCGGCAGGGCTAGCTGTAGGAACATCATTGACCAGCCATATCACCGTTCTGAAACAGG CAGCTACCAATGCGAGCCACGGCTCTAGCATCCTGAGAGCGGCGGATGGCGGTATGAGCC GTGTGTCGGATATTGTTCAACGTATGCGTTCCTTAGCTACGCAAAGCTTGTCTGGTGCCGTC ACCGACACCGAGCGCGGCTTCCTCGACGCGGAGTTCCAGCAGCTGATTGAAGAAATCCGC GGTATTGCATCCGGTACTCGTTTTAACGTGATCCCGCTGCTGGAC The left arm could also have the latest generation sequence (SEQ ID NO: 56): ATGCAGGGAAACAGGAATATACAATTTGCTGGCTCCGCGTTGCAAATTGCGGAAGGTGGTG TGGCCCAGATCTACATTGCGCTGAAAACGATGTACCAGAAGGCTGTCAGCGCTGCTAATGA CATCAACGACCCGAATGCGGGCGCAGCGTTGCAACGCGCAATCGAGAACCTGCGTGATGC GATTCAGAAGATCGCCCAAGATACCGTTTATAACGGTATTCGTCTGCTGGAC The left arm could also have the latest generation sequence (SEQ ID NO: 57): ATGACTGGAATAAACGGGACAAATCAAGCTATCTCCAACGCGATTCAAGCGACTGCGTTGG TTCAGTCTGCAACCGGTGGTATTCAGGATAGCACGGACCTGCTGCAACAAATCCGCAAGAT CGCCGTTCAAGCGGCTAATGGCAGCCAGTCCGACAGCGATCGTGCAGCGTTGCAAAACGT GGTGGCCGCTCTCAAGGACCAGATCTCGACCATTGCGAAACAGACCCAGTTCAACGGCAAA AGCCTGCTGTGG The left arm could also have the latest generation sequence (SEQ ID NO: 58): ATG GCA ATA GCG TGG GAT TTT CAA ACA GCT ATC AAC GGC GTC AAC GCA GCC ATC AGC AAT GGT AAT CAG GGC GTG TCC CTG GTG CAA ACG GCT ACC GGT GCG ATT GAG AAC CAG ACC TCG TTG TTG CAA CAA ATT CGT ACC ACC GCA GTT CAA GCG GCG TAC GCC AGC AAC ACC ACG TCT GAC GAC CAG GCG CTG CAA GGT GTG CCG AGC CAG CTG CTG GCT CAG GTT CAA ACC ATT GCG GCG CAG ACT GTT TTC AAC GGC CAG ATC CTG TTA GAT The right arm has the latest generation sequence (SEQ ID NO: 59): GCG ATA GAT GTA TCA ACA GTT GCA GGA GCT AAC AAG GCG CTG CAA ATC GCC GAT TTC GCC CTC GAC TTC CTG AAT GCA GAA GGC GGT CGC CTG GGC GCA CAG AAC TTT CGT ATT AAA GCT GTT CTG GCT ACC CTT ATC ACC GCG AGC CTG AAC TTG ACG GCG GGT TAC TCC GCG GTG CAG GAC GCG AAC TTG GCG GTG GCG ACC AGC GAG CTG ACT GCT AAT GTT ATT CTG The right arm could also have the latest generation sequence (SEQ ID NO: 60): GCT GTA GGA ACT TCA GCG ACA GCA AGT GCT GCG TTG ACC GCG CTG GAT ACG GCT GTG GAG ACT CTG TCT AGC GCG GAC GCT GAC GTG GGT GCA TTA ATC AGC CGT TTT GAA TTC CGC GGT CAG GTT CTG GGC ACC TCC ATC GCC AAC ACC GTT GCG GCA CAA AGC GCG ATT The right arm could also have the latest generation sequence (SEQ ID NO: 61: GCTATAGATGTAACTACAAATGAAGGAGCAGAGTTGGCTATGGATATTCTGACGATCGCCG CACAGAAAGTTATTGAGATCCGCTCCCAAATTGGTAGCACCATCATCAACCTGCAAGCGATT TATGATGCAAAGGCGGTCGCGAAGGACAACACCAAGAACGCGGAAAATATTATCCGTAATG TGGACTTCGCCCTGGCTATGACTGCGTTTACCAAATACCAGATCCGT The right arm could also have the latest generation sequence (SEQ ID NO: 62): CTAATAAATGTAACTACAGCGGCAGGAGCTCAACAAGCCATCGGCATCGTGGACCAGGCGA TCAACTATTTGAATCAGAAGAACGGTAGCCTGGGTGCTATCCAAAACCGCATTCAAGCTTCG GTGTCCAATCGTCAGACCACCGCAACGAACCTCCAATCTGCGCAGAGCGTTGTTCAGCTGG CAATCATTGCGGTCGCGACTAGCTTGCTGACCATTTACCAGATTCTG All the nucleotide sequences encoding for scaffold and target protein can be changed substantially due to genetic code redundancy. It is therefore possible to provide a stable structure for free expression of one or more peptides using scaffold backbone 18, preferably formed based on a scaffold protein derived from non- pathogenic extremophiles. The system provides a novel approach to efficiently express and display a single peptide, a polypeptide or multiplexed polypeptides of different lengths. The composite comprising the scaffold protein embedded with one or more peptides can be produced in a bacterium or eukaryotic system and purified using denaturing or native conditions. The inserted embedded peptides retain their native or bioactive conformation. The words ‘comprises / comprising’ and the words ‘having / including’ when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components, but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination. The embodiments described above are provided by way of examples only, and various other modifications will be apparent to persons skilled in the field without departing from the scope of the invention as defined herein.

Claims

CLAIMS 1. A bio-engineered scaffold backbone comprising: a first protein-fragment arm; a linker connected to the first protein-fragment arm; a second protein-fragment arm connected directly or indirectly to the linker; wherein the first and second protein-fragment arms bond or interact with one another to form a scaffold structure, wherein the first and second protein-fragment arms are selected from sequences derived from flagellin protein fragments derived from non-pathogenic extremophiles and bioengineered to reduce immunoreactivity by removing and / or substituting antigenic regions thereof.

2. A bio-engineered scaffold backbone as claimed in claim 1, wherein the first and second protein-fragment arms interact with each other and form a stable helical structure.

3. A bio-engineered scaffold backbone as claimed in claim 1 or claim 2, wherein the first and second protein-fragment arms are protein fragments derived from non-pathogenic extremophiles of the species Thermotoga, Thermithiobacillus, Aquifex, Geobacillus, Acidithiobacillus, Alkalispirochaeta, Desulfosporosinus, Bermanella, and / or Azospirillum.

4. A bio-engineered scaffold backbone as claimed in any one of the preceding claims, wherein the amino acid sequence of the first protein-fragment arm is derived from a sequence defined by any of SEQ ID NOs: 1 to 10.

5. A bio-engineered scaffold backbone as claimed in any one of the preceding claims, wherein the amino acid sequence of the second protein-fragment arm is derived from a sequence defined by any of SEQ ID NOs: 11 to 20.

6. A bio-engineered scaffold backbone as claimed in any one of the preceding claims, wherein the amino acid sequence of the first or second protein-fragment arm is a sequence defined by any of SEQ ID NOs: 51 to 62 7. A bio-engineered scaffold backbone as claimed in any one of the preceding claims, wherein the amino acid sequence of the first protein-fragment arm is longer than the amino acid sequence of the second protein-fragment arm.

8. A bio-engineered scaffold comprising a bio-engineered scaffold backbone as claimed in any one of the preceding claims, wherein the second protein-fragment arm is connected directly to the linker.

9. A bio-engineered scaffold as claimed in claim 8, further comprising: an immunostimulant; an inhibitor or immunosuppressant; or an adjuvant.

10. A bio-engineered scaffold comprising a bio-engineered scaffold backbone as claimed in any one of claims 1 to 7, further comprising a second linker connected directly to the second protein-fragment arm, and a peptide region having at least one peptide connected to the first said linker and the second linker.

11. A bio-engineered scaffold as claimed in claim 10, wherein the peptide region is a polypeptide region comprising a plurality of peptides.

12. A bio-engineered scaffold as claimed in claim 10, wherein the polypeptide region comprises up to 15 peptides.

13. A bio-engineered scaffold as claimed in any one of claims 10 to 12, wherein the polypeptide region of the bio-engineered scaffold comprises any of: an antigen; an antigen carrier; an antigen competitor; a screening agent for B-cell and T-cell epitopes; an immunostimulant; an inhibitor or immunosuppressant; an immunogenicity test peptide or protein; a therapeutic peptide; a ligand- receptor binding site; an antibody binding site; an antigen binding site; or a combination thereof.

14. A bio-engineered scaffold as claimed in claim 10, wherein the polypeptide region of the bio-engineered scaffold comprises a library of any of: an antigen; an antigen carrier; an antigen competitor; a screening agent for B-cell and T-cell epitopes; an immunostimulant; an inhibitor or immunosuppressant; an immunogenicity test peptide or protein; a therapeutic peptide; a ligand- receptor binding site; an antibody binding site; an antigen binding site; or a combination thereof.

15. A diagnostic kit comprising a bio-engineered scaffold as claimed in any one of claims 10 to 14.

16. A diagnostic kit as claimed in claim 15, wherein the polypeptide region of the bio- engineered scaffold is provided as an antigen, an antibody carrier, or an antigen competitor.

17. A diagnostic kit as claimed in claim 16, in the form of a serological test kit.

18. A method of ex vivo diagnosis of a condition performed using a diagnostic kit as claimed in any one of claims 15 to 17.

19. A method as claimed in claim 18, wherein the condition is SARS-CoV-2 or Lyme disease.

20. A method of generating antibodies using a bio-engineered scaffold as claimed in any one of claims 10 to 14, wherein the polypeptide region of the bio-engineered scaffold comprises one or a library of immunogenic epitopes for one or more desired antibodies.

21. A vaccine comprising a bio-engineered scaffold as claimed in any one of claims 10 to 14 and a pharmaceutically acceptable carrier.

22. A vaccine as claimed in claim 2`, further comprising an adjuvant.

23. A pharmaceutical composition comprising a bio-engineered scaffold as claimed in any one of claims 10 to 14 and a pharmaceutically acceptable carrier.

24. A recombinant nucleotide sequence encoding the bio-engineered scaffold backbone as claimed in any one of claims 1 to 7 or a bio-engineered scaffold as claimed in any one of claims 8 to 14.

25. A method of preparing a bio-engineered scaffold, the method comprising the steps of: a] selecting a protein fragment selected from sequences derived from flagellin protein fragments derived from non-pathogenic extremophiles, according to at least one of stability, expression yield, and immunoreactivity with human sera; b] bioengineering the protein fragment to reduce immunoreactivity thereof; c] further bioengineering the protein fragment to increase surface binding and / or improve orientations to form a protein-fragment arm; and d] using a linker connecting the protein-fragment arm to a peptide region along with a complementary protein-fragment arm, the first and second said protein-fragment arms bonding or interacting with one another to form a scaffold structure.

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