Tuning plasmid DNA amounts for cost-effective transfections of mammalian cells: when less is more

Transient gene expression (TGE) in mammalian cells is a well-known approach to the fast expression of recombinant proteins. The human cell line HEK (human embryonic kidney) 293F is widely used in this field, due to its adaptability to grow in suspension to high cell densities in serum-free media, amenability to transfection, and production of recombinant proteins in satisfactory quantities for functional and structural analysis. Amounts of plasmid DNA (pDNA) required in transfections for TGE remain high (usually 1 µg pDNA/mL, or even higher), representing a noticeable proportion of the overall cost. Thus, there is an economic need to reduce amounts of coding pDNA in TGE processes. In this work, amounts of both pDNA and transfecting agent used for TGE in HEK 293F cells have been explored in order to reduce them without compromising (or even improving) the productivity of the process in terms of protein yield. In our hands, minimal polyethyleneimine (PEI) cytotoxicity and optimum protein yields were obtained when transfecting at 0.5 µg pDNA/mL (equal to 0.5 µg pDNA/million cells) and a DNA-to-PEI ratio of 1:3, a trend confirmed for several unrelated recombinant proteins. Thus, carefully tuning pDNA and transfecting agent amounts not only reduces the economic costs but also results in higher recombinant protein yields. These results surely have a direct application and interest for the biopharmaceutical industry, always concerned in increasing productivity while decreasing economic costs. KEY POINTS: • Mammalian cells are widely used to produce recombinant proteins in short times. • Tuning DNA and transfecting agent are of great interest to optimize economic costs. • Reducing DNA and transfecting agent amounts result in higher protein yields.

Construction of a highly efficient adsorbent for one-step purification of recombinant proteins: Functionalized cellulose-based monolith fabricated via phase separation method

Currently, purification step in the recombinant protein manufacture is still a great challenge and its cost far outweighs those of the upstream process. In this study, a functionalized cellulose-based monolith was constructed as an efficient affinity adsorbent for one-step purification of recombinant proteins. Firstly, the fundamental cellulose monolith (CE monolith) was fabricated based on thermally induced phase separation, followed by being modified with nitrilotriacetic acid anhydride through esterification to give NCE monolith. After chelating with Ni2+, the affinity adsorbent NCE-Ni2+ monolith was obtained, which was demonstrated to possess a hierarchically porous morphology with a relatively high surface area, porosity and compressive strength. The adsorption behavior of NCE-Ni2+ monolith towards β2-microglobulin with 6 N-terminus His-tag (His-β2M) was evaluated through batch and fixed-bed column experiments. The results revealed that NCE-Ni2+ monolith exhibited a relatively fast His-β2M adsorption rate with a maximum adsorption capacity of 329.2 mg/g. The fixed-bed column adsorption implied that NCE-Ni2+ monolith showed high efficiency for His-β2M adsorption. Finally, NCE-Ni2+ monolith was demonstrated to have an excellent His-β2M purification ability from E. coli lysate with exceptional reusability. Therefore, the resultant NCE-Ni2+ monolith had large potential to be used as an efficient adsorbent for recombinant protein purification in practical applications.

The immunogenicity of p24 protein from HIV-1 virus is strongly supported and modulated by coupling with liposomes and mannan

Anti-viral and anti-tumor vaccines aim to induce cytotoxic CD8+ T cells (CTL) and antibodies. Conserved protein antigens, such as p24 from human immunodeficiency virus, represent promising component for elicitation CTLs, nevertheless with suboptimal immunogenicity, if formulated as recombinant protein. To enhance immunogenicity and CTL response, recombinant proteins may be targeted to dendritic cells (DC) for cross presentation on MHCI, where mannose receptor and/or other lectin receptors could play an important role. Here, we constructed liposomal carrier-based vaccine composed of recombinant p24 antigen bound by metallochelating linkage onto surface of nanoliposomes with surface mannans coupled by aminooxy ligation. Generated mannosylated proteonanoliposomes were analyzed by dynamic light scattering, isothermal titration, and electron microscopy. Using murine DC line MutuDC and murine bone marrow derived DC (BMDC) we evaluated their immunogenicity and immunomodulatory activity. We show that p24 mannosylated proteonanoliposomes activate DC for enhanced MHCI, MHCII and CD40, CD80, and CD86 surface expression both on MutuDC and BMDC. p24 mannosylated liposomes were internalized by MutuDC with p24 intracellular localization within 1 to 3 h. The combination of metallochelating and aminooxy ligation could be used simultaneously to generate nanoliposomal adjuvanted recombinant protein-based vaccines versatile for combination of recombinant antigens relevant for antibody and CTL elicitation.

Novel melanin-derived stationary phase for immobilized metal ion affinity chromatography in recombinant His-tagged protein purification

The matrix of the stationary phase is a crucial element in affinity chromatography for protein purification. Various materials, including polymer or magnetic materials, have been employed as the matrix in the purification of His-tagged protein. Here, for the first time, we utilized a combination of melanin and alginate, both natural polymer materials, to synthesize Ni-melanin/alginate (Ni-M/A) beads for His-tagged protein purification. We investigated the binding of His-tagged Mpro on the Ni-M/A beads, referred to as Ni-M/A-Mpro, and assessed the elution efficiency of Mpro from the beads. Our examination involved FTIR, EDS, XRD, SDS-PAGE, and Western blotting methods. FTIR spectra revealed notable changes in the stretching patterns and intensities of hydroxyl, amine, carbonyl, imine and amide chemical groups, when Mpro protein was present in the Ni-M/A sample. XRD spectra demonstrated the occurrence of two Nickel peaks at 35-40 deg and 40-45 deg in Ni-M/A, but only one nickel peak at 35-40 deg in Ni-M/A-Mpro, indicating the binding of Mpro on the Nickel ions. EDS analysis reported a decrease in the concentration of Nickel on the surface of Ni-M/A from 16% to 7% when Mpro protein was loaded into the stationary phase. Importantly, our data indicated that the purity of the His-tagged protein Mpro after purification reached 97% after just one-step purification using the Ni-M/A stationary phase. Moreover, the binding capacity of Ni-M/A for Mpro was approximately 5.2 mg/g with recovery efficiency of 40%. Our results suggested Ni-M/A as a highly potential solid phase for affinity chromatography in the purification of His-tagged protein.

Novel method for production and purification of untagged pneumococcal surface protein A from clade 1

Streptococcus pneumoniae can cause diseases with high mortality and morbidity. The licensed vaccines are based on capsular polysaccharides and induce antibodies with low cross reactivity, leading to restricted coverage of serotypes. For surpassing this limitation, new pneumococcal vaccines are needed for induction of broader protection. One important candidate is the pneumococcal surface protein A (PspA), which can be classified in 6 clades and 3 families. We have reported an efficient process for production and purification of untagged recombinant PspA from clade 4 (PspA4Pro). We now aim to obtain a highly pure recombinant PspA from clade 1 (PspA1) to be included, together with PspA4Pro, in a vaccine formulation to broaden response against pneumococci. The vector pET28a-pspA1 was constructed and used to transform Escherichia coli BL21(DE3) strain. One clone with high production of PspA1 was selected and adapted to high-density fermentation (HDF) medium. After biomass production in 6 L HDF using a bioreactor, the purification was defined after testing 3 protocols. During the batch bioreactor cultivation, plasmid stability remained above 90% and acetate formation was not detected. The final protein purification process included treatment with a cationic detergent after lysis, anion exchange chromatography, cryoprecipitation, cation exchange chromatography, and multimodal chromatography. The final purification process showed PspA1 purity of 93% with low endotoxin content and an overall recovery above 20%. The novel established process can be easily scaled-up and proved to be efficient to obtain a highly pure untagged PspA1 for inclusion in vaccine formulations. KEY POINTS: • Purification strategy for recombinant PspA1 from Streptococcus pneumoniae • Downstream processing for untagged protein antigens, the case of PspA1 • Purification strategy for PspA variants relies on buried amino acids in their sequences.

Sustainable Bombyx mori's silk fibroin for biomedical applications as a molecular biotechnology challenge: A review

Silk is a natural engineering material with a unique set of properties. The major constituent of silk is fibroin, a protein widely used in the biomedical field because of its mechanical strength, toughness and elasticity, as well as its biocompatibility and biodegradability. The domestication of silkworms allows large amounts of fibroin to be extracted inexpensively from silk cocoons. However, the industrial extraction process has drawbacks in terms of sustainability and the quality of the final medical product. The heterologous production of fibroin using recombinant DNA technology is a promising approach to address these issues, but the production of such recombinant proteins is challenging and further optimization is required due to the large size and repetitive structure of fibroin's DNA and amino acid sequence. In this review, we describe the structure-function relationship of fibroin, the current extraction process, and some insights into the sustainability of silk production for biomedical applications. We focus on recent advances in molecular biotechnology underpinning the production of recombinant fibroin, working toward a standardized, successful and sustainable process.

Modifications of the 5' region of the CASPONTM tag's mRNA further enhance soluble recombinant protein production in Escherichia coli

BACKGROUND

Escherichia coli is one of the most commonly used host organisms for the production of biopharmaceuticals, as it allows for cost-efficient and fast recombinant protein expression. However, challenging proteins are often produced with low titres or as inclusion bodies, and the manufacturing process needs to be developed individually for each protein. Recently, we developed the CASPONTM technology, a generic fusion tag-based platform process for high-titer soluble expression including a standardized downstream processing and highly specific enzymatic cleavage of the fusion tag. To assess potential strategies for further improvement of the N-terminally fused CASPONTM tag, we modified the 5'UTR and 5' region of the tag-coding mRNA to optimize the ribosome-mRNA interactions.

RESULTS

In the present work, we found that by modifying the 5'UTR sequence of a pET30acer plasmid-based system, expression of the fusion protein CASPONTM-tumour necrosis factor α was altered in laboratory-scale carbon-limited fed-batch cultivations, but no significant increase in expression titre was achieved. Translation efficiency was highest for a construct carrying an expression enhancer element and additionally possessing a very favourable interaction energy between ribosome and mRNA (∆Gtotal). However, a construct with comparatively low transcriptional efficiency, which lacked the expression enhancer sequence and carried the most favourable ∆Gtotal tested, led to the highest recombinant protein formation alongside the reference pET30a construct. Furthermore, we found, that by introducing synonymous mutations within the nucleotide sequence of the T7AC element of the CASPONTM tag, utilizing a combination of rare and non-rare codons, the free folding energy of the nucleotides at the 5' end (-4 to + 37) of the transcript encoding the CASPONTM tag increased by 6 kcal/mol. Surprisingly, this new T7ACrare variant led to improved recombinant protein titres by 1.3-fold up to 5.3-fold, shown with three industry-relevant proteins in lab-scale carbon limited fed-batch fermentations under industrially relevant conditions.

CONCLUSIONS

This study reveals some of the complex interdependencies between the ribosome and mRNA that govern recombinant protein expression. By modifying the 5'UTR to obtain an optimized interaction energy between the mRNA and the ribosome (ΔGtotal), transcript levels were changed, highlighting the different translation efficiencies of individual transcripts. It was shown that the highest recombinant titre was not obtained by the construct with the most efficient translation but by a construct with a generally high transcript amount coupled with a favourable ΔGtotal. Furthermore, an unexpectedly high potential to enhance expression by introducing silent mutations including multiple rare codons into the 5'end of the CAPONTM tag's mRNA was identified. Although the titres of the fusion proteins were dramatically increased, no formation of inclusion bodies or negative impact on cell growth was observed. We hypothesize that the drastic increase in titre is most likely caused by better ribosomal binding site accessibility. Our study, which demonstrates the influence of changes in ribosome-mRNA interactions on protein expression under industrially relevant production conditions, opens the door to the applicability of the new T7ACrare tag in biopharmaceutical industry using the CASPONTM platform process.

Chimeric proteins of Mycoplasma hyopneumoniae as vaccine and preclinical model for immunological evaluation

Mycoplasma hyopneumoniae (M. hyopneumoniae) is a primary agent of porcine enzootic pneumonia, a disease that causes significant economic losses to pig farming worldwide. Commercial vaccines induce partial protection, evidencing the need for a new vaccine against M. hyopneumoniae. In our work, three chimeric proteins were constructed, composed of potentially immunogenic domains from M. hyopneumoniae proteins. We designed three chimeric proteins (Q1, Q2, and Q3) based on bioinformatics analysis that identified five potential proteins with immunogenic potential (MHP418, MHP372, MHP199, P97, and MHP0461). The chimeric proteins were inoculated in the murine model to evaluate the immune response. The mice vaccinated with the chimeras presented IgG and IgG1 against proteins of M. hyopneumoniae. There was induction of IgG in mice immunized with Q3 starting from 30 days post-vaccination, and groups Q1 and Q2 showed induction at 45 days. Mice of the group immunized with Q3 showed the production of IgA. In addition, the mice inoculated with chimeric proteins showed a proinflammatory cytokine response; Q1 demonstrated higher levels of TNF, IL-6, IL2, and IL-17. In contrast, animals immunized with Q2 showed an increase in the concentrations of TNF, IL-6, and IL-4, whereas those immunized with Q3 exhibited an increase in the concentrations of TNF, IL-6, IL-10, and IL-4. The results of the present study indicate that these three chimeric proteins can be used in future vaccine trials with swine because of the promising antigenicity.

Development of in-house ELISA based on recombinant gag proteins of small ruminant lentiviruses isolated from goats in Thailand

Small ruminant lentiviruses (SRLVs), are grouped in Retroviridae family, remain a significant loss in the small ruminant husbandry. As a result of unavailability of vaccine and effective treatment, the diagnosis plays a crucial role for the control of SRLV infection. However, the major challenge of diagnosis of SRLV infection is the genetic and antigenic variability of the viruses that can lead to a failure in serological detection. This study investigated the circulating strains of the viruses in goats in Thailand and an in-house ELISA was developed. The coding sequences for gag protein were optimized, synthesized, and expressed in Escherichia coli for increasing the sensitivity of ELISA test. A total of 365 serum samples were examined against the recombinant protein in an in-house ELISA. The results showed that the recombinant gag achieves 96.67% sensitivity and 93.18% specificity as compared with the commercially available ELISA test kit.

New anticoagulant protein from medicinal leech

The saliva of the medicinal leech contains various anticoagulants. Some of them, such as hirudin, are well known. However, it is reasonable to believe that not all anticoagulant proteins from medicinal leech saliva have been identified. We previously performed a comprehensive study of the transcriptome, genome, and proteome of leech salivary gland cells, which led to the discovery of several previously unknown hypothetical proteins that may have anticoagulant properties. Subsequently, we obtained a series of recombinant proteins and investigated their impact on coagulation in in vitro assays. We identified a previously undescribed protein that exhibited a high ability to suppress coagulation. The His-tagged recombinant protein was expressed in Escherichia coli and purified using metal chelate chromatography. To determine its activity, commonly used coagulation methods were used: activated partial thromboplastin time, prothrombin time, and thrombin inhibition clotting assay. Clotting and chromogenic assays for factor Xa inhibition were performed to evaluate anti-Xa activity. We used recombinant hirudin as a control anticoagulant protein in all experiments. The new protein showed significantly greater inhibition of coagulation than hirudin at the same molar concentrations in the activated partial thrombin time assay. However, hirudin demonstrated better results in the direct thrombin inhibition test, although the tested protein also exhibited the ability to inhibit thrombin. The chromogenic analysis of factor Xa inhibition revealed no activity, whereas the clotting test for factor Xa showed the opposite result. Thus, a new powerful anticoagulant protein has been discovered in the medicinal leech. This protein is homologous to antistatin, with 28 % identical amino acid residues. The recombinant protein was expressed in E. coli. This protein is capable of directly inhibiting thrombin, and based on indirect evidence, other proteases of the blood coagulation cascade have been identified.

Removal of plant endogenous proteins from tobacco leaf extract by freeze-thaw treatment for purification of recombinant proteins

Plants are useful as a low-cost source for producing biopharmaceutical proteins. A significant hurdle in the production of recombinant proteins in plants, however, is the complicated process of removing plant-derived components. Removing endogenous plant proteins, including ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), a major photosynthetic plant enzyme that catalyzes photosynthesis through carboxylation and oxygenation, is important for the purification of recombinant plant proteins. In particular, RuBisCO accounts for 50% of the soluble leaf protein; thus, the removal of RuBisCO is critical for the purification of recombinant proteins from plant materials. An effective conventional method, known as freeze-thaw treatment, was developed for the removal of RuBisCO from Nicotiana benthamiana, which expresses recombinant green fluorescent protein (GFP). Crude extracts or supernatants were frozen at - 30 °C. Upon thawing, most of the RuBisCO was precipitated by centrifugation without significant inactivation and/or yield reduction of GFP. Based on the proteomics analysis, using this method, RuBisCO large and small subunits were reduced to approximately 10% and 20% of those of the unfrozen supernatant solutions, respectively, without the need for specific reagents or equipment. The proteomic analysis also revealed that many ribosomal proteins were removed from the extracts. This method improves the purification process of recombinant proteins from plant materials. Prolonged freezing damaged recombinant β-glucuronidase (GUS), suggesting that the applicability of this treatment should be carefully considered for each recombinant protein.

Use of recombinant malate dehydrogenase (MDH) and superoxide dismutase (SOD) [CuZn] as antigens in indirect ELISA for diagnosis of bovine brucellosis

The objective of this study was to validate an indirect enzyme-linked immunoassay (iELISA) using the recombinant proteins, malate dehydrogenase (MDH) and superoxide dismutase (SOD) [CuZn], as antigens and to evaluate its ability to discriminate antibodies produced by vaccination from those induced by infection in the diagnosis of bovine brucellosis. Sera from six groups were evaluated: G1 - culture-positive animals (52 serum samples) (naturally infected); G2 - non-vaccinated animals (28 serum samples) positive in RBT (Rose Bengal test) and 2ME (2-mercaptoethanol test) selected from brucellosis-positive herds; G3 - animals from a brucellosis-free area (32 serum samples); G4 - S19 vaccinated heifers (114 serum samples); G5 - RB51 vaccinated heifers (60 serum samples); G6 - animals inoculated with inactivated Yersinia enterocolitica O:9 (42 serum samples). Diagnostic sensitivity (DSe) and diagnostic specificity (DSp) were estimated using the frequentist approach and the confidence interval (CI) (95%) calculated by the Clopper-Pearson (exact) method. The DSe for iELISA_MDH in the G1 group was 71.7% (CI 95%: 57.6-83.2%) and for the G2 100.0% (CI 95%: 87.7-100.0%), whereas the DSp was 84.4% in the G3 (CI 95%: 67.2-94.7%). For the iELISA_SOD the DSe was estimated 67.3% for the G1 (CI 95%: 52.9-79.7%) and 71.4% for G2 (CI 95%: 51.3-86.8%), while the DSp for G3 was 87.5% (CI 95%: 71.0-96.5%). iELISA_MDH and iELISA_SOD showed potential to be used in the diagnosis of infected animals, increasing the range of serological tests available for the diagnosis of bovine brucellosis, with the advantage of being S-LPS-free. However, none of the tests could differentiate between infection and vaccination.

Secretory production of the Hericium erinaceus laccase from Saccharomyces cerevisiae

Mushroom laccases play a crucial role in lignin depolymerization, one of the most critical challenges in lignin utilization. Importantly, laccases can utilize a wide range of substrates, such as toxicants and antibiotics. This study isolated a novel laccase, named HeLac4c, from endophytic white-rot fungi Hericium erinaceus mushrooms. The cDNAs for this enzyme were 1569 bp in length and encoded a protein of 523 amino acids, including a 20 amino-acid signal peptide. Active extracellular production of glycosylated laccases from Saccharomyces cerevisiae was successfully achieved by selecting an optimal translational fusion partner. We observed that 5 and 10 mM Ca2+, Zn2+, and K+ increased laccase activity, whereas 5 mM Fe2+ and Al3+ inhibited laccase activity. The laccase activity was inhibited by the addition of low concentrations of sodium azide and L-cysteine. The optimal pH for the 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt was 4.4. Guaiacylglycerol-β-guaiacyl ether, a lignin model compound, was polymerized by the HeLac4c enzyme. These results indicated that HeLac4c is a novel oxidase biocatalyst for the bioconversion of lignin into value-added products for environmental biotechnological applications. .

Production of a Bacteriocin Like Protein PEG 446 from Clostridium tyrobutyricum NRRL B-67062

Clostridium tyrobutyricum strain NRRL B-67062 was previously isolated from an ethanol production facility and shown to produce high yields of butyric acid. In addition, the cell-free supernatant of the fermentation broth from NRRL B-67062 contained antibacterial activity against certain Gram-positive bacteria. To determine the source of this antibacterial activity, we report the genome and genome mining of this strain. The complete genome of NRRL B-67062 showed one circular chromosome of 3,242,608 nucleotides, 3114 predicted coding sequences, 79 RNA genes, and a G+C content of 31.0%. Analyses of the genome data for genes potentially associated with antimicrobial features were sought after by using BAGEL-4 and anti-SMASH databases. Among the leads, a polypeptide of 66 amino acids (PEG 446) contains the DUF4177 domain, which is an uncharacterized highly conserved domain (pfam13783). The cloning and expression of the peg446 gene in Escherichia coli and Bacillus subtilis confirmed the antibacterial property against Lactococcus lactis LM 0230, Limosilactobacillus fermentum 0315-25, and Listeria innocua NRRL B-33088 by gel overlay and well diffusion assays. Molecular modeling suggested that PEG 446 contains one alpha-helix and three anti-parallel short beta-sheets. These results will aid further functional studies and facilitate simultaneously fermentative production of both butyric acid and a putative bacteriocin from agricultural waste and lignocellulosic biomass materials.

Magnetic Janus micromotors for fluorescence biosensing of tacrolimus in oral fluids

Tacrolimus (FK506) is a macrolide lactone immunosuppressive drug that is commonly used in transplanted patients to avoid organ rejection. FK506 exhibits high inter- and intra-patient pharmacokinetic variability, making monitoring necessary for organ graft survival. This work describes the development of a novel bioassay for monitoring FK506. The bioassay is based on using polycaprolactone-based (PCL) magnetic Janus micromotors and a recombinant chimera receptor that incorporates the immunophilin tacrolimus binding protein 1A (FKBP1A) tagged with Emerald Green Fluorescent Protein (EmGFP). The approach relies on a fluorescence competitive bioassay between the drug and the micromotors decorated with a carboxylated FK506 toward the specific site of the fluorescent immunophilin. The proposed homogeneous assay could be performed in a single step without washing steps to separate the unbound receptor. The proposed approach fits the therapeutic requirements, showing a limit of detection of 0.8 ng/mL and a wide dynamic range of up to 90 ng/mL. Assay selectivity was evaluated by measuring the competitive inhibition curves with other immunosuppressive drugs usually co-administered with FK506. The magnetic propulsion mechanism allows for efficient operation in raw samples without damaging the biological binding receptor (FKBP1A-EmGFP). The enhanced target recognition and micromixing strategies hold considerable potential for FK506 monitoring in practical clinical use.

Recombinant proteins production in Escherichia coli BL21 for vaccine applications: a cost estimation of potential industrial-scale production scenarios

Recent SARS-CoV-2 pandemic elevated research interest in microorganism-related diseases, and protective health application importance such as vaccination and immune promoter agents emerged. Among the production methods for proteins, recombinant technology is an efficient alternative and frequently preferred method. However, since the production and purification processes vary due to the protein nature, the effect of these differences on the cost remains ambiguous. In this study, brucellosis and its two important vaccine candidate proteins (rOmp25 and rEipB) with different properties were selected as models, and industrial-scale production processes were compared with the SuperPro Designer® for estimating the unit production cost. Simulation study showed raw material cost by roughly 60% was one of the barriers to lower-cost production and 52.5 and 559.8 $/g were estimated for rEipB and rOmp25, respectively.

Production of recombinant HPV11/16 E6/E7-MBP-His6 fusion proteins and their potential to induce cytokine secretion by immune cells in peripheral blood

Human papillomavirus (HPV) infection poses a significant threat to public health worldwide. Targeting the function of HPV E6 and E7 proteins and activating the host immune response against these proteins represent promising therapeutic strategies for combating HPV-related diseases. Consequently, the efficient production of soluble, high-purity E6 and E7 proteins is crucial for function and host immune response studies. In this context, we selected the pMCSG19 protein expression vector for Escherichia coli to produce soluble MBP-His6 tagged HPV11/16 E6/E7 proteins, achieving relatively high purity and yield. Notably, these proteins exhibited low toxicity to peripheral blood mononuclear cells (PBMCs) and did not compromise their viability. Additionally, the recombinant proteins were capable of inducing the secretion of multiple cytokines by immune cells in peripheral blood, indicating their potential to elicit immune responses. In conclusion, our study offers a novel approach for the production of HPV11/16 E6/E7 fusion proteins with relatively high purity and yield. The fusing HPV11/16 E6/E7 proteins to MBP-His6 tag may serve as a valuable method for large-scale protein production in future research endeavors.

Gene Stacking and Stoichiometric Expression of ER-Targeted Constructs Using "2A" Self-Cleaving Peptides

Simultaneous stoichiometric expression of multiple genes plays a major part in modern research and biotechnology. Traditional methods for incorporating multiple transgenes (or "gene stacking") have drawbacks such as long time frames, uneven gene expression, gene silencing, and segregation derived from the use of multiple promoters. 2A self-cleaving peptides have emerged over the last two decades as a functional gene stacking method and have been used in plants for the co-expression of multiple genes under a single promoter. Here we describe design features of multicistronic polyproteins using 2A peptides for co-expression in plant cells and targeting to the endoplasmic reticulum (ER). We designed up to quad-cistronic vectors that could target proteins in tandem to the ER. We also exemplify the incorporation of self-excising intein domains within 2A polypeptides, to remove residue additions. These features could aid in the design of stoichiometric protein co-expression strategies in plants in combination with targeting to different subcellular compartments.

Molecular and functional characterization of ribosome protein S24 in ovarian development of Macrobrachium nipponense

Ribosomal proteins (RPs) have mang extraribosomal functions including regulation of ovarian development in some organisms. In order to solve the problem of rapid ovarian maturation in Macrobrachium nipponense aquaculture, this study identified a RPS24 (MnRPS24) gene from M. nipponense, which encodes a protein of ββαβαααα folding structure type. MnRPS24 exhibited the greatest expressions in the female adult stage among the six growth stages, in the ovary among the nine tissues, and in the stage I ovary among the six ovarian development stages. The MnRPS24 protein located in the cytoplasm of oogonia, previtellogenic and early-vitellogenic oocytes, and the follicular cells surrounding the oocytes. The expression of the vitellogenin (MnVg), vitellogenin receptor (MnVgr), cell cycle protein B (MnCyclin B) and cell division cyclin 2 (MnCdc2) genes were increased by recombinant MnRPS24 protein incubation. Conversely, the expression of the Wee1 kinase (MnWee1) gene was decreased. MnRPS24 gene silencing downregulated the expression for MnVg, MnVgr, MnCyclin B and MnCdc2 and upregulated the expression for MnWee1. Furthermore, MnRPS24 gene silencing delayed the vitellogenesis of oocytes, halting the progression of ovarian development. The findings of this research demonstrate that MnRPS24 could potentially function as a stimulator in promoting the development of ovaries in M. nipponense.

Establishment and characterization of a novel indirect ELISA method based on ASFV antigenic epitope-associated recombinant protein

African Swine Fever (ASF) is an acute and highly lethal disease in pigs caused by African Swine Fever Virus (ASFV). Viral proteins have been commonly used as antigenic targets for the development of ASF diagnostic methods. However, the prokaryotic expression of viral proteins has deficiencies such as instability, insolubility, and high cost in eukaryotic situations. This study screened and verified ASFV-encoded p72, p54, and p30 protein antigenic epitopes. Subsequently, a novel antigenic epitope-associated recombinant protein was designed based on an ideal structural protein and expressed in Escherichia coli (E. coli). Western blot analysis indicated that the recombinant protein could specifically react with the monoclonal antibody (mAb) of p72 and polyclonal antibodies of p54 and p30, respectively. Next, an ASF indirect ELISA (iELISA) method was established based on the recombinant protein, which has no specific reaction with sera of other important pig viral diseases. Meanwhile, it shows a sensitivity to detecting dilutions of ASF-positive reference serum up to 1:6400. The clinical sample detection results showed a high coincidence rate of 98 % with a commercial competition ELISA kit. In conclusion, we established a novel specific, and sensitive ASF serologic detection method that opens new avenues for ASF serodiagnostic method development.

Production, expression, and function of dual-specific monoclonal antibodies in a single plant

MAIN CONCLUSION

LSC CO17-1AK and anti-HER2 VHH-FcK can be produced in a single plant and exhibit anti-tumor activities comparable to those of their respective parent antibodies. Recombinant monoclonal antibodies (mAbs) which can be applied to treat various cancers, are primarily produced using mammalian, insect, and bacteria cell culture systems. Plant expression systems have also been developed to produce antibodies. Plant expression systems present several advantages, including a lack of human pathogenic agents, efficient production costs, and easy large-scale production. In this study, we generated a transgenic plant expressing anti-colorectal cancer large single chain (LSC) CO17-1AK and anti-human epidermal growth factor receptor 2 (HER2) VHH-FcK mAbs by cross-pollinating plants expressing LSC CO17-1AK and anti-HER2 VHH-FcK, respectively. F1 siblings expressing both LSC CO17-1AK and anti-HER2 VHH-FcK were screened using polymerase chain reaction and Western-blot analyses. The cell enzyme-linked immunosorbent assay (Cell ELISA) confirmed the binding of LSC CO17-1AK and anti-HER2 VHH-FcK to target proteins in the SW620 human colorectal cancer and the SKBR-3 human breast cancer cell lines, respectively. The wound healing assay confirmed the inhibitory activity of both antibodies against SW620 and SKBR-3 cell migration, respectively. In conclusion, both LSC CO17-1AK mAb and anti-HER2 VHH-FcK can be produced in a single plant, achieve binding activities to SW620 and SKBR-3 cancer cells, and inhibitory activity against SW620 and SKBR-3 cell migration similar to their parental antibodies, respectively.

Current achievements, strategies, obstacles, and overcoming the challenges of the protein engineering in Pichia pastoris expression system

Yeasts serve as exceptional hosts in the manufacturing of functional protein engineering and possess industrial or medical utilities. Considerable focus has been directed towards yeast owing to its inherent benefits and recent advancements in this particular cellular host. The Pichia pastoris expression system is widely recognized as a prominent and widely accepted instrument in molecular biology for the purpose of generating recombinant proteins. The advantages of utilizing the P. pastoris system for protein production encompass the proper folding process occurring within the endoplasmic reticulum (ER), as well as the subsequent secretion mediated by Kex2 as a signal peptidase, ultimately leading to the release of recombinant proteins into the extracellular environment of the cell. In addition, within the P. pastoris expression system, the ease of purifying recombinant protein arises from its restricted synthesis of endogenous secretory proteins. Despite its achievements, scientists often encounter persistent challenges when attempting to utilize yeast for the production of recombinant proteins. This review is dedicated to discussing the current achievements in the usage of P. pastoris as an expression host. Furthermore, it sheds light on the strategies employed in the expression system and the optimization and development of the fermentative process of this yeast. Finally, the impediments (such as identifying high expression strains, improving secretion efficiency, and decreasing hyperglycosylation) and successful resolution of certain difficulties are put forth and deliberated upon in order to assist and promote the expression of complex proteins in this prevalent recombinant host.

Safety and immunogenicity of a booster dose of S-268019-b: Interim findings of a Phase 3, open-label clinical study in Japan

Despite the initial success of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines in prevention of symptomatic and severe diseases, booster vaccination has become increasingly important with the advent of variants with immune-escaping capacity. Herein, we report the safety and immunogenicity of S-268019-b, comprising SARS-CoV-2 spike protein and a squalene-based adjuvant, as a booster dose. We performed an interim analysis of an open-label, Phase 3 study data until Day 29 following S-268019-b booster in Japanese adults (aged 20-64 years) who had completed primary vaccination with mRNA-1273 and in Japanese elderly (aged ≥ 65 years) who had completed primary vaccination with mRNA-1273 or BNT162b2. Reactogenicity was mild in most participants; no serious treatment-related adverse events were noted. S-268019-b enhanced SARS-CoV-2 neutralizing antibodies, immunoglobulin G antibodies, and predominant T-helper 1-mediated immune reaction in all cohorts, regardless of age, in Japanese participants with prior vaccination with mRNA vaccines.

Production of Bioactive Human PAX4 Protein from E. coli

Paired box 4 (PAX4) is a pivotal transcription factor involved in pancreatogenesis during embryogenesis, and in adults, it is key for β-cell proliferation and survival. Additionally, PAX4 also functions as a tumor suppressor protein in human melanomas. The present study demonstrates the production of bioactive recombinant human PAX4 transcription factor. At first, the inserts (PAX4 protein-coding sequence having tags at either ends) were cloned in an expression vector to give rise to pET28a(+)-HTN-PAX4 and pET28a(+)-PAX4-NTH genetic constructs, and these were then transformed into Escherichia coli (E. coli) for their expression. The HTN-PAX4 and PAX4-NTH fusion proteins produced were purified with a yield of ~ 3.15 mg and ~ 0.83 mg, respectively, from 1.2 L E. coli culture. Further, the secondary structure retention of the PAX4 fusion proteins and their potential to internalize the mammalian cell and its nucleus was demonstrated. The bioactivity of these fusion proteins was investigated using various assays (cell migration, cell proliferation and cell cycle assays), demonstrating it to function as a tumor suppressor protein. Thus, this macromolecule can prospectively help understand the function of human PAX4 in cellular processes, disease-specific investigations and direct cellular reprogramming.

Interim results from a phase I randomized, placebo-controlled trial of novel SARS-CoV-2 beta variant receptor-binding domain recombinant protein and mRNA vaccines as a 4th dose booster

BACKGROUND

SARS-CoV-2 booster vaccination should ideally enhance protection against variants and minimise immune imprinting. This Phase I trial evaluated two vaccines targeting SARS-CoV-2 beta-variant receptor-binding domain (RBD): a recombinant dimeric RBD-human IgG1 Fc-fusion protein, and an mRNA encoding a membrane-anchored RBD.

METHODS

76 healthy adults aged 18-64 y, previously triple vaccinated with licensed SARS-CoV-2 vaccines, were randomised to receive a 4th dose of either an adjuvanted (MF59®, CSL Seqirus) protein vaccine (5, 15 or 45 μg, N = 32), mRNA vaccine (10, 20, or 50 μg, N = 32), or placebo (saline, N = 12) at least 90 days after a 3rd boost vaccination or SARS-CoV-2 infection. Bleeds occurred on days 1 (prior to vaccination), 8, and 29.

CLINICALTRIALS

govNCT05272605.

FINDINGS

No vaccine-related serious or medically-attended adverse events occurred. The protein vaccine reactogenicity was mild, whereas the mRNA vaccine was moderately reactogenic at higher dose levels. Best anti-RBD antibody responses resulted from the higher doses of each vaccine. A similar pattern was seen with live virus neutralisation and surrogate, and pseudovirus neutralisation assays. Breadth of immune response was demonstrated against BA.5 and more recent omicron subvariants (XBB, XBB.1.5 and BQ.1.1). Binding antibody titres for both vaccines were comparable to those of a licensed bivalent mRNA vaccine. Both vaccines enhanced CD4+ and CD8+ T cell activation.

INTERPRETATION

There were no safety concerns and the reactogenicity profile was mild and similar to licensed SARS-CoV-2 vaccines. Both vaccines showed strong immune boosting against beta, ancestral and omicron strains.

FUNDING

Australian Government Medical Research Future Fund, and philanthropies Jack Ma Foundation and IFM investors.

Cloning, expression and purification of Eimeria maxima gametocyte antigen-EmGam56 for control of poultry coccidiosis

Poultry coccidiosis is an important devitalizing enteric protozoan disease caused by a group of obligatory intracellular apicomplexan parasites of the Genus Eimeria contributing to major economic loss in commercial poultry worldwide. As the current method of chemotherapeutic control using ionophores in feed had led to development of drug resistant isolates, the need for development of prophylactic vaccines is the most viable alternate and eco-friendly control strategy as on date. Of the several candidate vaccines, the EmGam 56 is one of the most promising candidates which protect the birds against E. maxima, E. tenella and E. acervulina, the three most pathogenic coccidian species infecting commercial chicken. EmGam56 is a major wall forming component of macrogametocyte of E. maxima and a candidate with high immunogenicity and low virulence. The present study was planned and carried out for the generation of E.coli expressed recombinant gametocyte antigen-EmGam56 using pET 28(a+) as cloning vector and BL21 DE3 (pLysS) as prokaryotic expression system in a Bio-fermentor (New Brunswick™ Scientific BioFlo 310). The recombinant protein was purified by conventional (Ammonium sulphate precipitation) and by automatic purification system (AKTA prime) in Ni-NTA column for a planned immunization trial with experimental chickens.

Development of recombinant subunit vaccine targeting InvH protein of Salmonella Typhimurium and evaluation of its immunoprotective efficacy against salmonellosis

Salmonella Typhimurium is the most prevalent non-host specific Salmonella serovars and a major concern for both human and animal health systems worldwide contributing to significant economic loss. Type 3 secretion system (T3SS) of Salmonella plays an important role in bacterial adherence and entry into the host epithelial cells. The product of invH gene of Salmonella is an important component of the needle complex of the type 3 secretion system. Hence, the present study was undertaken to clone and express the 15 kDa InvH surface protein of Salmonella Typhimurium in an E. coli host and to evaluate its immune potency in mice. The purified recombinant InvH (r-InvH) protein provoked a significant (p < 0.01) rise in IgG in the inoculated mice. The immunized mice were completely (100%) protected against the challenge dose of 107.5 LD50, while protection against challenge with the same dose of heterologous serovars was 90%. The bacterin-vaccinated group showed homologous protection of 60% against all three serovars. Findings in this study suggest the potential of the r-InvH protein of S. Typhimurium as an effective vaccine candidate against Salmonella infections.

Production and characterization of egg yolk antibodies against the ZIKV NS2B expressed in Nicotiana benthamiana

The emergence of Zika virus (ZIKV) and its associated neonatal and congenital complications pose a threat to global health, particularly in tropical and subtropical regions with co-circulation of related flaviviruses and intense vector proliferation. Diagnosis of ZIKV by RT-PCR is limited to the viraemic phase and is not always accessible in low-income tropical settings, while serological tests often show cross-reactivity with other flaviviruses. Given the similarity of ZIKV symptoms to those of other arboviruses, but the different prognosis and risks, it is important to develop specific and accessible diagnostic tools. Egg yolk antibodies (IgY) were obtained from Leghorn laying hens immunized with recombinant ZIKV NS2B protein produced in agroinfiltrated Nicotiana benthamiana. After three immunizations, total IgY was recovered from the eggs by the 20% ammonium sulfate precipitation method. After characterisation by SDS-PAGE, dot blotting and ELISA, the IgY was adsorbed to dengue virus (DENV) from cell culture supernatants and tested for its ability to specifically detect ZIKV-positive sera samples. High yield and purity were observed on SDS-PAGE for polyclonal IgY, which reacted with NS2B at high titres in ELISA and detected both NS2B and ZIKV in dot blotting. However, a cross-reaction with DENV was observed and the anti-NS2B IgY was unable to discriminate ZIKV from DENV positive sera samples, even after adsorption with DENV. This is probably due to the phylogenetic relationship of the viruses and the shared identity of their proteins.

Modulation of Kex2p Cleavage Site for In Vitro Processing of Recombinant Proteins Produced by Saccharomyces cerevisiae

Kex2 protease (Kex2p) is a membrane-bound serine protease responsible for the proteolytic maturation of various secretory proteins by cleaving after dibasic residues in the late Golgi network. In this study, we present an application of Kex2p as an alternative endoprotease for the in vitro processing of recombinant fusion proteins produced by the yeast Saccharomyces cerevisiae. The proteins were expressed with a fusion partner connected by a Kex2p cleavage sequence for enhanced expression and easy purification. To avoid in vivo processing of fusion proteins by Kex2p during secretion and to guarantee efficient removal of the fusion partners by in vitro Kex2p processing, P1', P2', P4, and P3 sites of Kex2p cleavage sites were elaborately manipulated. The general use of Kex2p in recombinant protein production was confirmed using several recombinant proteins.

Anti-CD19/CD8 bispecific T cell engager for the potential treatment of B cell malignancies

The administration of blinatumomab was accompanied by several adverse effects, including activation of regulatory T-cells and cytokine storm. The objective of this study was to produce and evaluate a novel αCD8/CD19 BiTE (αCD8/CD19) with the potency to directly target CD8+T-cells. In-silico studies were utilized for determining proper folding, receptor binding, and structural stability of αCD8/CD19 protein. Western blotting and indirect surface staining were used to evaluate the size accuracy and binding potency of the purified protein. Functionality was assessed for granzyme B production, cytotoxicity, and proliferation. TheαCD8/CD19recombinant protein was produced in the CHO-K1 cell line with a final concentration of 1.94 mg/l. The αCD8/CD19 bound to CD8+and CD19+cell lines and induced significant granzyme B production, cytotoxic activity and proliferation potential in the presence of IL-2 and tumor target cells. The maximum CD8+T-cell biological activity was observed on the 10th day with 10:1 effector-to-target ratio.

Expression and Biological Evaluation of an Engineered Recombinant L-asparaginase Designed by In Silico Method Based on Sequence of the Enzyme from Escherichia coli

Purpose

Medical usage of L-asparaginase (ASNase), the first-line of acute lymphoblastic leukemia treatment, is linked to allergic responses and toxicities, which necessitates the development of new bio-better ASNases. The aim of the current study was in silico design of a novel ASNase with predicted improved enzymatic properties using strategies encompassing sequence-function analysis of known ASNase mutants. Additionally, current study aimed to show that the new enzyme is active.

Methods

Based on 21 experimentally reported mutations for ASNase, a virtual library of mutated enzymes with all 7546 possible combinations of up to 4 mutations was generated. Three-dimensional models of proposed mutant enzymes were built and their in silico stabilities were calculated. The most promising mutant was selected for preparing a genetic construct suitable for expression of the designed ASNase in bacterial cells.

Results

Computational study predicted that Y176F/S241C double mutation of Escherichia coli ASNase may increase its folding stability. The designed ASNase was expressed in two different E. coli strains (Origami B(DE3) and BL21(DE3)pLysS) and then the soluble fractions prepared from the cell lysates of the host cells were used in enzyme activity assay. Results showed that enzyme activity of soluble fraction from Origami (95.4 ± 7.5 IU/0.1 mL) was four times higher than that of soluble fraction from pLysS (25.8 ± 2.5 IU/0.1 mL).

Conclusion

A novel functional double mutant ASNase with predicted improved enzymatic properties was designed and produced in E. coli. The results of the current study suggest a great commercial potential for the identified enzyme in pharmaceutical and industrial applications.

Recombinant protein embedded liposome on gold nanoparticle based on LSPR method to detect Corona virus

Antibody sensor to detect viruses has been widely used but has problems such as the difficulty of right direction control of the receptor site on solid substrate, and long time and high cost for design and production of antibodies to new emerging viruses. The virus detection sensor with a recombinant protein embedded liposome (R/Li) was newly developed to solve the above problems, in which R/Li was assembled on AuNPs (Au@R/Li) to increase the sensitivity using localized surface plasmon resonance (LSPR) method. Recombinant angiotensin-converting enzyme-2 (ACE2) was used as host receptors of SARS-CoV and SARS-CoV-2, and the direction of enzyme active site for virus attachment could be controlled by the integration with liposome. The recombinant protein embedded liposomes were assembled on AuNPs, and LSPR method was used for detection. With the sensor platform S1 protein of both viruses was detected with detection limit of 10 pg/ml and SARS-CoV-2 in clinical samples was detected with 10 ~ 35 Ct values. In the selectivity test, MERS-CoV did not show a signal due to no binding with Au@R/Li. The proposed sensor platform can be used as promising detection method with high sensitivity and selectivity for the early and simple diagnosis of new emerging viruses.

Synthesis of Ni2+-functionalized polydopamine magnetic beads for facilitated purification of histidine-tagged proteins

Facilitated purification of proteins, at a low cost and a short time, is one of the key steps in the industrial production of recombinant proteins. In the current study, polydopamine nanoparticles (PDA-NPs) are considered in the synthesis of magnetic beads for purifying recombinant proteins due to advantages such as biocompatibility/ biodegradability, easy synthesis, as well as the ability to directly chelate metal ions. They were synthesized in Tris buffer (pH: 8:5), then chelated with Fe3+(20 mg) and Ni2+ ions at concentrations of 2, 3, 5, and 7 mg/ml. Prepared nanoparticles were characterized through scanning electron microscopy (SEM), ultraviolet-visible spectroscopy (UV-vis), dynamic light scattering (DLS), Inductively Coupled Plasma (ICP), and vibrating sample magnetometer (VSM). The size distribution of the particles was reported in the narrow range of 120-140 nm and 200 to 220 nm by the SEM image and DLS analysis, respectively. The chelation of ions on the surface of the nanoparticle was confirmed by the ICP technique with a magnetization of 35.42 emu/g. The highest adsorption rate of Ni2+ ions to polydopamine was obtained at a ratio of 1.4. The SDS-PAGE and western blot analysis confirmed the purification of eGFP and Hsp40 by PDA/Fe3+/Ni2+ at 26 and 40 kDa compared to the commercial nickel column. Moreover, the concentration of purified eGFP by PDA/Fe3+/Ni2+ was reported 138.83 µg/ml by the fluorescent signals, which is almost equal to or more than the protein purified by commercial Ni-NTA column (108.28 µg/ ml). The stability of PDA/Fe3+/Ni2+ has also been evaluated by ICP-OES for 10 days, and the result suggested that PDA magnetic beads were stable. Therefore, it can be concluded that PDA/Fe3+/Ni2+ have the ability to purify recombinant proteins in one less step and shorter time.

Recombinant protein based on domain III and capsid regions of zika virus induces humoral and cellular immune response in immunocompetent BALB/c mice

Zika virus infection continues to be a global concern for human health due to the high-risk association of the disease with neurological disorders and microcephaly in newborn. Nowadays, no vaccine or specific antiviral treatment is available, and the development of safe and effective vaccines is yet a challenge. In this study, we obtained a novel subunit vaccine that combines two regions of zika genome, domain III of the envelope and the capsid, in a chimeric protein in E. coli bacteria. The recombinant protein was characterized with polyclonal anti-ZIKV and anti-DENV antibodies that corroborate the specificity of the molecule. In addition, the PBMC from zika-immune donors stimulated with the ZEC recombinant antigen showed the capacity to recall the memory T cell response previously generated by the natural infection. The chimeric protein ZEC was able to self-assemble after combination with an immunomodulatory specific oligonucleotide to form aggregates. The inoculation of BALB/c mice with ZEC aggregated and not aggregated form of the protein showed a similar humoral immune response, although the aggregated variant induced more cell-mediated immunity evaluated by in vitro IFNγ secretion. In this study, we propose a novel vaccine candidate against the zika disease based on a recombinant protein that can stimulate both arms of the immune system.

High-throughput process development from gene cloning to protein production

In the post-genomic era, the demand for faster and more efficient protein production has increased, both in public laboratories and industry. In addition, with the expansion of protein sequences in databases, the range of possible enzymes of interest for a given application is also increasing. Faced with peer competition, budgetary, and time constraints, companies and laboratories must find ways to develop a robust manufacturing process for recombinant protein production. In this review, we explore high-throughput technologies for recombinant protein expression and present a holistic high-throughput process development strategy that spans from genes to proteins. We discuss the challenges that come with this task, the limitations of previous studies, and future research directions.

An in vitro Assay to Probe the Formation of Biomolecular Condensates

Biomolecular condensates are membrane-less assemblies of proteins and nucleic acids formed through liquid-liquid phase separation (LLPS). These assemblies are known to temporally and spatially regulate numerous biological activities and cellular processes in plants and animals. In vitro phase separation assay using recombinant proteins represents one of the standard ways to examine the properties of proteins undergoing LLPS. Here, we present a detailed protocol to investigate in vitro LLPS using in vitro expressed and purified recombinant proteins.

Production of recombinant proteins including the B-cell epitopes of autolysin A of Staphylococcus aureus isolated from clinical sheep mastitis and their potential for vaccine development

Staphylococcus aureus is the most common clinical mastitis-associated pathogen in sheep which contributes to reduced welfare of affected animals and, therefore, compromises the quality and quantity of milk production. To prevent mastitis and its spread, it is essential to guarantee adequate breeding conditions and animal health, through the adoption of good farm management practices and the application of suitable biosecurity measures. Vaccination can play a strategic role in prevention, control, and eradication of diseases. The identification of secreted and cellular antigens of the predominant sheep-CC130/ST700/t1773 lineage would assist in the design of effective vaccine against mammary infections caused by S. aureus. In the current study, we carried out a 3D structural prediction analysis with the identification of the best B cell epitopes of the whole and secreted portion of S. aureus AtlA. Fragments of atlA, containing the main predicted epitopes, were amplified, cloned, and expressed in Escherichia coli for recombinant protein production. Two selected clones produced recombinant proteins (rAtl4 and rAtl8) showing strong reactivity with a hyperimmune serum against the native AtlA and with blood sera collected from sheep with clinical S. aureus mastitis. These may represent potential candidate protein-based vaccines able to elicit a protective immune response to be evaluated by vaccination and subsequent challenge of the vaccinated sheep.

Identification, expression pattern and functional characterization of IFN-γ involved in activating JAK-STAT pathway in Sebastes schlegeli

IFN-γ (interferon gamma) is a critical cytokine in the immune system involved both directly and indirectly in antiviral activity, stimulation of bactericidal activity, antigen presentation and activation of macrophages via the Janus kinase/signal transducer and activator of transcription (JAK-STAT) pathway. The IFN-γ function is best described in cell defense against intracellular pathogens in mammals, but IFN-γ cytokine-induced metabolic change and its role in anti-infection remain unknown in teleost fish. In this study, a novel IFN-γ (SsIFN-γ) was identified from black rockfish (Sebastes schlegeli) by rapid amplification of cDNA ends (RACE). The open reading frame (ORF) of SsIFN-γ encoded a putative protein of 215 amino acids and shares 60.2%-93.5% overall sequence identities with other teleost IFN-γ. SsIFN-γ was distributed ubiquitously in all the detected tissues and immune cells, which was highly expressed in the spleen, gills, head kidney by quantitative real-time PCR. The mRNA expression of SsIFN-γ was significantly upregulated in the spleen, head kidney, head kidney (HK) macrophages and peripheral blood lymphocytes (PBLs) during pathogen infection. Meanwhile, the recombinant protein (rSsIFN-γ) exhibited an immunomodulatory function to enhance respiratory burst activity and nitric oxide response of HK macrophages. Furthermore, rSsIFN-γ could effectively upregulate the expression of macrophage proinflammatory cytokine, the expression of JAK-STAT signaling pathway related genes and interferon-related downstream genes in the head kidney and spleen. Luciferase assays showed ISRE and GAS activity were obviously enhanced after rSsIFN-γ treatment. These results indicated that SsIFN-γ possessed apparent immunoregulatory properties and played a role in fighting pathogen infection which will be helpful to further understanding of the immunologic mechanism of teleosts IFN-γ in innate immunity.

Novel recombinant proteins and peptides from Clonorchis sinensis and Opisthorchis viverrini for liver fluke exposure ELISA

Human serum samples from individuals living in Vietnam and Taiwan suspected of past Clonorchis sinensis or Opisthorchis viverrini infection were screened using several novel peptides and recombinant liver fluke proteins to determine if any consistent patterns could be discerned and used as the basis for future liver fluke ELISA development. Absorbance values at 405 nm were compared to those of pooled unexposed normal human serum and analyzed for statistical significance. The data exhibited some interesting patterns consistent with egg antigen sequestration in the gut possibly leading to lower serum antibody levels and potential regional exposure differences between Vietnamese and Taiwanese subjects. In particular, antibodies against Cathepsin B and B2 peptides, as well as a partial Cahedrin Domain peptide may be elevated in some Taiwanese serum samples while antibodies against recombinant Clonorchis egg protein and Hepatocellular Carcinoma Peptide Antigen 59 may be elevated in some samples from both Taiwan and Vietnam. The data appear to suggest that some of the novel recombinant protein and peptide antigens selected and tested herein warrant further study with larger sample sizes as possible targets for detecting anti-liver fluke antibodies by ELISA from humans suspected of liver fluke infections.

PLGA nanoparticles containing Intimin-Flagellin fusion protein for E. coli O157:H7 nano-vaccine

Escherichia coli O157:H7 is a foodborne pathogen that can lead to severe gastrointestinal diseases in humans. Vaccination is a promising strategy for preventing E. coli O157:H7 infections, which offers socio-economic benefits and provides the possibility of stimulating both humoral and cellular immune responses at systemic and mucosal sites. In this study, we developed a needle-free vaccine candidate against E. coli O157:H7 using poly(lactic-co-glycolic acid) (PLGA) nanoparticles entrapping a chimeric Intimin-Flagellin (IF) protein. The IF protein was expressed and verified using SDS-PAGE and western blot analysis, with a yield of 1/7 mg/L and a molecular weight of approximately 70 kDa. The prepared nanoparticles showed uniformly shaped spherical particles in the 200-nm range, as confirmed by SEM and DLS analysis. Three different routes of vaccine administration were used, including intranasal, oral, and subcutaneous, and the groups vaccinated with NPs protein had a higher antibody response compared to those receiving free protein. Subcutaneous administration of IF-NPs resulted in the highest level of IgG antibody titer, while oral administration of IF-NPs produced the highest amount of IgA antibody titer. Finally, all mice in the nanoparticle- intranasal and oral administered groups challenged with 100LD50 survived, while all control mice died before day 5. Based on these findings, we conclude that the PLGA-encapsulated IF protein has the potential to serve as a promising needle-free vaccine candidate against E. coli O157:H7.

Comparison of Anti-Trop2 Extracellular Domain Antibodies Generated Against Peptide and Protein Immunogens for Targeting Trop2-Positive Tumour Cells

Trophoblast antigen 2 (Trop2) is a transmembrane glycoprotein upregulated in multiple solid tumours. Trop2-based passive immunotherapies are in clinical trials, while Trop2 targeting CAR-T cell-based therapies are also reported. Information about its T- and B-cell epitopes is needed for it to be pursued as an active immunotherapeutic target. This study focused on identification of immunodominant epitopes in the Trop2 extracellular domain (ECD) that can mount an efficient anti-Trop2 antibody response. In silico analysis using various B-cell epitope prediction tools was carried out to identify linear and conformational B-cell epitopes in the ECD of Trop2. Three linear peptide immunogens were shortlisted and synthesized. Along with linear peptides, truncated Trop2 ECD that possesses combination of linear and conformational epitopes was also selected. Recombinant protein immunogen was produced in 293-F suspension culture system and affinity purified. Antisera against different immunogens were characterized by ELISA and Western blotting. Two anti-peptide antisera detected recombinant and ectopically expressed Trop2 protein; however, they were unable to recognize the endogenous Trop2 protein expressed by cancer cells. Antibodies against truncated Trop2 ECD could bind to the endogenous Trop2 expressed on the surface of cancer cells. In addition to their high avidity, these polyclonal anti-sera against truncated Trop2 protein also mediated antibody-dependent cell-mediated cytotoxicity (ADCC). In summary, our comparative analysis demonstrated the utility of truncated Trop2 ECD as a promising candidate to be pursued as an active immunotherapeutic molecule against Trop2-positive cancer cells.

Cloning, expression of porcine GSDME and identification of its site cleaved by caspase-3

As a member of the gasdermin family, gasdermin E (GSDME) is specifically cleaved by caspase-3, resulting in pyroptosis. To date, the biological characteristics and functions of human and mouse GSDME have been extensively studied; however, little is known of porcine GSDME (pGSDME). In this study, the full-length pGSDME-FL was cloned, which encodes 495 amino acids (aa) that have closely evolutionary relationships to the homolog of camelus, aquatic mammals, cattle and goat. Moreover, pGSDME was detected at different levels of expression in 21 tissues and 5 pig-derived cell lines tested by qRT-PCR, with the highest expression levels in mesenteric lymph nodes and PK-15 cell lines. Anti-pGSDME polyclonal antibody (pAb) with good specificity was generated by expressing the truncated recombinant protein pGSDME-1-208 and immunizing the rabbits. By western blot analysis using highly specific anti-pGSDME polyclonal antibody (pAb) prepared as primary antibody, it was not only confirmed that paclitaxel and cisplatin were positive stimuli to pGSDME cleavage and caspase-3 activation, but also identified the aspartate (D268) at position 268th of pGSDME as a cleavage site of caspase-3, and the overexpressed pGSDME-1-268 possesses cytotoxicity to HEK-293T cells, indicating that pGSDME-1-268 may contain active domains and involve pGSDME-mediated pyroptosis. These results lay a foundation for further investigating the function of pGSDME, especially its role in pyroptosis and its interaction with pathogens.

Protective efficacy of recombinant proteins AMA1 and IMP1 in rabbits infected with Eimeria intestinalis

Eimeria intestinalis is one of the most pathogenic rabbit coccidia species causing severe intestinal damage and increased risk of secondary infection from opportunistic pathogens, which results in huge economic losses to the rabbit industry. Anticoccidial drugs are currently the main method to control coccidiosis; however, increasing resistance and drug residues have fueled research on anticoccidial vaccines. Apical membrane antigen 1 (AMA1) and immune mapped protein 1 (IMP1), as surface proteins, are associated with host invasion and might have the potential as candidate vaccine antigens. In the present study, recombinant IMP1 (rEiIMP1) and AMA1 (rEiAMA1) from E. intestinalis were expressed using Escherichia coli BL21. The immunoreactivity and immunoprotective effects of rEiIMP1 and rEiAMA1 were then analyzed. Fifty rabbits were grouped randomly (n = 10 per group): The unimmunized-unchallenged control group (sterilized phosphate-buffered saline (PBS)), the unimmunized-challenged control group (sterilized PBS), the vector protein-challenged control group (100 μg of pET-32a vector protein per rabbit), the rEiIMP1 immunized group (100 μg of rEiIMP1 per rabbit), and the rEiAMA1 immunized group (100 μg of rEiAMA1 per rabbit). After two immunizations, the rabbits were challenged with homologous oocysts (except for the unimmunized-unchallenged group). Serum specific antibody levels were assessed weekly throughout the experimental period; and the levels of different cytokines in the serum before the challenge were detected. The clinical symptoms, oocysts output, weight gain, feed conversion ratio (FCR), and lesion scores were recorded after experimental infection, and the anticoccidial indexes (ACIs) were calculated. The results showed that both rEiIMP1 and rEiAMA1 had good immunoreactivity. Rabbits immunized with rEiIMP1 and rEiAMA1 displayed 66.74 % and 63.14 % oocyst reduction, respective land 81.79 % and 78.87 % body weight gain, respectively. The rEiIMP1 and rEiAMA1 groups had lower FCRs (3.77:1 and 4.06:1, respectively) and lesion scores (P = 0.00). The rEiIMP1 and rEiAMA1 showed moderate effects, with an ACI of 152.09 and 147.17, respectively. Immunization induced high levels of anti-rEiIMP1 and -rEiAMA1 antibodies. Rabbits immunized with rEiIMP1 and rEiAMA1 displayed significantly increased interleukin (IL)- 2 (P = 0.00), interferon gamma (IFN)- γ (P = 0.00), and IL- 4 (P = 0.00) levels. Therefore, this study provided potential candidate vaccine antigens for E. intestinalis.

Enhanced soluble expression of active recombinant human interleukin-29 using champion pET SUMO system

Current research focuses on the soluble and high-level expression of biologically active recombinant human IL-29 protein in Escherichia coli. The codon-optimized IL-29 gene was cloned into the Champion™ pET SUMO expression system downstream of the SUMO tag under the influence of the T7 lac promoter. The expression of SUMO-fused IL-29 protein was compared in E. coli Rosetta 2(DE3), Rosetta 2(DE3) pLysS, and Rosetta-gami 2(DE3). The release of the SUMO fusion partner resulted in approximately 98 mg of native rhIL-29 protein with a purity of 99% from 1 l of fermentation culture. Purified rhIL-29 was found to be biologically active, as evaluated by its anti-proliferation assay. It was found that Champion™ pET SUMO expression system can be used to obtained high yield of biologically active soluble recombinant human protein compared to other expression vector.

Effects of codon optimization on expression in Escherichia coli of protein-coding DNA sequences from the protozoan Eimeria

The objective of this study was to compare the levels of recombinant protein from three Eimeria genes before and after optimization of codons for expression in Escherichia coli. Protein coding sequences from Eimeria maxima (EmaxSO7, EmaxIMP1) and Eimeria acervulina (EAH00033530) were cloned with or without prior codon optimization and expressed as polyHis fusion proteins. All three outcomes: higher, lower, or no change in the yield of amount of recombinant protein were observed suggesting that codon optimization alone for expression in E. coli does not inevitably lead to higher expression levels. Analysis of codon usage for each gene sequence revealed that, similar to other organisms, Eimeria intersperses rare and frequently used codons in protein-coding sequences. However, no relationship was observed between the predicted protein structure and the location of major and minor codons, suggesting that codon selection in this apicomplexan parasite is influenced by factors other than regional secondary protein structure.

Trends and prospects in dairy protein replacement in yogurt and cheese

There is a growing demand for nutritional, functional, and eco-friendly dairy products, which has increased the need for research regarding alternative and sustainable protein sources. Plant-based, single-cell (SCP), and recombinant proteins are being explored as alternatives to dairy proteins. Plant-Based Proteins (PBPs) are commonly used to replace total dairy protein. However, PBPs are generally mixed with dairy proteins to improve their functional properties, which makes them dependent on animal protein sources. In contrast, single-Cell Proteins (SCPs) and recombinant dairy proteins are promising alternatives for dairy protein replacement since they provide nutritional components, essential amino acids, and high protein yield and can use industrial and agricultural waste as carbon sources. Although alternative protein sources offer numerous advantages over conventional dairy proteins, several technical and sensory challenges must be addressed to fully incorporate them into cheese and yogurt products. Future research can focus on improving the functional and sensory properties of alternative protein sources and developing new processing technologies to optimize their use in dairy products. This review highlights the current status of alternative dairy proteins in cheese and yogurt, their functional properties, and the challenges of their use in these products.

17β-Hydroxysteroid dehydrogenases types 1 and 2: Enzymatic assays based on radiometric and mass-spectrometric detection

The 17β-hydroxysteroid dehydrogenase type 1 (HSD17B1) has a key role in estrogen biosynthesis as it catalyzes the reduction of estrone to the most potent estrogen, estradiol. Estradiol has a high affinity for estrogen receptors and thus stimulates their transactivation, which leads to cell proliferation and numerous other effects. HSD17B2 catalyzes the oxidation of estradiol to the less potent estrone, thereby decreasing estrogen receptor activation, which results in reduction of estrogen-associated effects. HSD17B1 and HSD17B2 overexpressing E.coli homogenates or recombinant enzymes can be used for screening and development of drugs against various pathologies such as cancer, endometriosis or osteoporosis. Here we describe the preparation of HSD17B1 and HSD17B2 bacterial homogenates and purified recombinant HSD17B1 protein as enzyme sources as well as enzymatic assays based on radiometric and mass-spectrometric detection for enzyme characterization.

Overexpression of genes by stress-responsive promoters increases protein secretion in Saccharomyces cerevisiae

Recombinant proteins produced by cell factories are now widely used in various fields. Many efforts have been made to improve the secretion capacity of cell factories to meet the increasing demand for recombinant proteins. Recombinant protein production usually causes cell stress in the endoplasmic reticulum (ER). The overexpression of key genes possibly removes limitations in protein secretion. However, inappropriate gene expression may have negative effects. There is a need for dynamic control of genes adapted to cellular status. In this study, we constructed and characterized synthetic promoters that were inducible under ER stress conditions in Saccharomyces cerevisiae. The unfolded protein response element UPRE2, responding to stress with a wide dynamic range, was assembled with various promoter core regions, resulting in UPR-responsive promoters. Synthetic responsive promoters regulated gene expression by responding to stress level, which reflected the cellular status. The engineered strain using synthetic responsive promoters P_{4UPRE2 - TDH3} and P_{4UPRE2 - TEF1} for co-expression of ERO1 and SLY1 had 95% higher α-amylase production compared with the strain using the native promoters P_TDH3 and P_TEF1. This work showed that UPR-responsive promoters were useful in the metabolic engineering of yeast strains for tuning genes to support efficient protein production.

Inducer-free recombinant protein production in Trichoderma reesei: secretory production of endogenous enzymes and heterologous nanobodies using glucose as the sole carbon source

BACKGROUND

The filamentous fungus Trichoderma reesei has been used as a host organism for the production of lignocellulosic biomass-degrading enzymes. Although this microorganism has high potential for protein production, it has not yet been widely used for heterologous recombinant protein production. Transcriptional induction of the cellulase genes is essential for high-level protein production in T. reesei; however, glucose represses this transcriptional induction. Therefore, cellulose is commonly used as a carbon source for providing its degraded sugars such as cellobiose, which act as inducers to activate the strong promoters of the major cellulase (cellobiohydrolase 1 and 2 (cbh1 and cbh2) genes. However, replacement of cbh1 and/or cbh2 with a gene encoding the protein of interest (POI) for high productivity and occupancy of recombinant proteins remarkably impairs the ability to release soluble inducers from cellulose, consequently reducing the production of POI. To overcome this challenge, we first used an inducer-free biomass-degrading enzyme expression system, previously developed to produce cellulases and hemicellulases using glucose as the sole carbon source, for recombinant protein production using T. reesei.

RESULTS

We chose endogenous secretory enzymes and heterologous camelid small antibodies (nanobody) as model proteins. By using the inducer-free strain as a parent, replacement of cbh1 with genes encoding two intrinsic enzymes (aspartic protease and glucoamylase) and three different nanobodies (1ZVH, caplacizumab, and ozoralizumab) resulted in their high secretory productions using glucose medium without inducers such as cellulose. Based on signal sequences (carrier polypeptides) and protease inhibitors, additional replacement of cbh2 with the nanobody gene increased the percentage of POI to about 20% of total secreted proteins in T. reesei. This allowed the production of caplacizumab, a bivalent nanobody, to be increased to 9.49-fold (508 mg/L) compared to the initial inducer-free strain.

CONCLUSIONS

In general, whereas the replacement of major cellulase genes leads to extreme decrease in the degradation capacity of cellulose, our inducer-free system enabled it and achieved high secretory production of POI with increased occupancy in glucose medium. This system would be a novel platform for heterologous recombinant protein production in T. reesei.

Enhanced Biomass Production of Recombinant Pfu DNA Polymerase Producer Escherichia coli BL21(DE3) by Optimization of Induction Variables Using Response Surface Methodology

Pfu DNA polymerase is one of the most preferred molecular enzymes that is isolated from the hyperthermophilic Pyrococcus furiosus and used for high-throughput DNA synthesis by the polymerase chain reaction. Therefore, an efficient Pfu DNA polymerase production method is necessary for molecular techniques. In the present study, Pfu DNA polymerase was expressed in recombinant Escherichia coli BL21(DE3) and significant parameters for the biomass production were optimized using the central composite design which is the most popular method of response surface methodology. Induction conditions including cell density prior induction (OD_600nm), post-induction temperature, IPTG concentration, and post-induction time and their interactions on biomass production were investigated. The maximum biomass production (14.1 g/L) in shake flasks was achieved using the following predicted optimal conditions: OD_600nm before induction of 0.4 and the induction at 32 °C for 7.7 h, with 0.6 mM IPTG. Optimized culture conditions were implemented to scale up experiments. 22% and 70% increase in biomass production was achieved in 3 L and 10 L bioreactors, respectively as compared to initial biomass production observed in unoptimized conditions. Similary, a 30% increase of Pfu DNA polymerase production was obtained after the optimization. The polymerase activity of the purifed Pfu DNA polymerase was assessed by PCR amplification and determined as 2.9 U/μl by comparison with commercial Pfu DNA polymerase. The findings of this study indicated that the proposed fermentation conditions will contribute to further scale‑up studies to enhance the biomass for the production of other recombinant proteins.