Recombinant production of human interleukin 6 in Escherichia coli

The potential role of interleukins and interferons in ovarian cancer

Ovarian cancer poses significant challenges and remains a highly lethal disease with limited treatment options. In the context of ovarian cancer, interleukins (ILs) and interferons (IFNs), important cytokines that play crucial roles in regulating the immune system, have emerged as significant factors influencing its development. This article provides a comprehensive review of the involvement of various ILs, including those from the IL-1 family, IL-2 family, IL-6 family, IL-8 family, IL-10 family, and IL-17 family, in ovarian cancer. The focus is on their impact on tumor growth, metastasis, and their role in evading immune responses within the tumor microenvironment. Additionally, the article conducts an in-depth examination of the oncogenic or antitumor roles of each IL in the context of ovarian cancer pathogenesis and progression. Besides, we elucidated the enhancements in the treatment of ovarian cancer through the utilization of type-I IFN and type-II IFN. Recent research has shed light on the intricate mechanisms through which specific ILs and IFNs contribute to the advancement of the disease. By incorporating recent findings, this review also seeks to inspire further investigations into unexplored mechanisms, fostering ongoing research to develop more effective therapeutic strategies for ovarian cancer. Moreover, through an in-depth analysis of IL- and IFN-associated clinical trials, we have highlighted their promising potential of in the treatment of ovarian cancer. These clinical trials serve to reinforce the significant outlook for utilizing ILs and IFNs as therapeutic agents in combating this disease.

Current status, and the developments of hosts and expression systems for the production of recombinant human cytokines

Cytokines consist of peptides, proteins and glycoproteins, which are biological signaling molecules, and boost cell-cell communication in immune reactions to stimulate cellular movements in the place of trauma, inflammation and infection. Recombinant cytokines are designed in such a way that they have generalized immunostimulation action or stimulate specific immune cells when the body encounters immunosuppressive signals from exogenous pathogens or other tumor microenvironments. Recombinant cytokines have improved the treatment processes for numerous diseases. They are also beneficial against novel toxicities that arise due to pharmacologic immunostimulators that lead to an imbalance in the regulation of cytokine. So, the production and use of recombinant human cytokines as therapeutic proteins are significant for medical treatment purposes. For the improved production of recombinant human cytokines, the development of host cells such as bacteria, yeast, fungi, insect, mammal and transgenic plants, and the specific expression systems for individual hosts is necessary. The recent advancements in the field of genetic engineering are beneficial for easy and efficient genetic manipulations for hosts as well as expression cassettes. The use of metabolic engineering and systems biology approaches have tremendous applications in recombinant protein production by generating mathematical models, and analyzing complex biological networks and metabolic pathways via simulations to understand the interconnections between metabolites and genetic behaviors. Further, the bioprocess developments and the optimization of cell culture conditions would enhance recombinant cytokines productivity on large scales.

In vitro analysis of the interaction of tear film inflammatory markers with contemporary contact lens materials

PURPOSE

Several clinical studies have suggested that reusable silicone hydrogel contact lens materials exhibit a two-times increased rate of corneal infiltrative events compared to reusable hydrogels. One potential factor contributing to this complication relates to the differential uptake of tear film-based pro-inflammatory cytokines. The purpose of this study was to use an in vitro assay to investigate whether four pro-inflammatory cytokines differed in their uptake onto six contemporary contact lens materials.

METHODS

Conventional hydrogel (etafilcon A, omafilcon A) and silicone hydrogel (balafilcon A, comfilcon A, senofilcon A, somofilcon A) contact lens materials were soaked in solutions containing pro-inflammatory cytokines IL-1β, IL-6, IL-8 and TNF-α. Samples of the soaking solutions were collected over various time points and analyzed using the Meso Scale Discovery system, which served as a measurement of cytokine uptake onto the contact lens materials.

RESULTS

Both conventional hydrogels (etafilcon A, omafilcon A) and two of the four silicone hydrogels tested (balafilcon A, comfilcon A), exhibited some uptake of IL-1β, IL-8 or TNF-α (p < 0.05). Senofilcon A and somofilcon A did not exhibit uptake of any of these cytokines (p > 0.05). There was no uptake of IL-6 onto any of the contact lens materials investigated (p > 0.05).

CONCLUSION

The contact lens materials tested did not exhibit any uptake of IL-6 and furthermore, did not exhibit more than 10 ± 3 % to 25 ± 12 % uptake of IL-1β, IL-8 or TNF-α. Numerous factors could contribute to the reported increase in corneal infiltrative events with reusable silicone hydrogel materials, however, based on these results, it appears that uptake of these four cytokines are unlikely to contribute to this finding.

The Effects of Lactose Induction on a Plasmid-Free E. coli T7 Expression System

Recombinant production of pharmaceutical proteins like antigen binding fragments (Fabs) in the commonly-used production host Escherichia coli presents several challenges. The predominantly-used plasmid-based expression systems exhibit the drawback of either excessive plasmid amplification or plasmid loss over prolonged cultivations. To improve production, efforts are made to establish plasmid-free expression, ensuring more stable process conditions. Another strategy to stabilize production processes is lactose induction, leading to increased soluble product formation and cell fitness, as shown in several studies performed with plasmid-based expression systems. Within this study we wanted to investigate lactose induction for a strain with a genome-integrated gene of interest for the first time. We found unusually high specific lactose uptake rates, which we could attribute to the low levels of lac-repressor protein that is usually encoded not only on the genome but additionally on pET plasmids. We further show that these unusually high lactose uptake rates are toxic to the cells, leading to increased cell leakiness and lysis. Finally, we demonstrate that in contrast to plasmid-based T7 expression systems, IPTG induction is beneficial for genome-integrated T7 expression systems concerning cell fitness and productivity.

Development of nsP2 protease based cell free high throughput screening assay for evaluation of inhibitors against emerging Chikungunya virus

Chikungunya virus has emerged as one of the most important global arboviral threats over the last decade. Inspite of large scale morbidity, with long lasting polyarthralgia, so far no licensed vaccine or antiviral is available. CHIKV nsP2 protease is crucial for processing of viral nonstructural polypeptide precursor to release enzymes required for viral replication, thus making it a promising drug target. In this study, high cell density cultivation (HCDC) of Escherichia coli in batch process was carried out to produce rCHIKV nsP2pro in a cost-effective manner. The purified nsP2pro and fluorogenic peptide substrate have been adapted for fluorescence resonance energy transfer (FRET) based high throughput screening (HTS) assay with Z’ value and CV of 0.67 ± 0.054 and <10% respectively. We used this cell free HTS system to screen panel of metal ions and its conjugate which revealed zinc acetate as a potential candidate, which was further found to inhibit CHIKV in Vero cells. Scale-up process has not been previously reported for any of the arboviral nonstructural enzymes. The successful scale-up method for viral protease together with a HTS assay could lead to the development of industrial level large-scale screening platform for identification of protease inhibitors against emerging and re-emerging viruses.

Re-engineering of an Escherichia coli K-12 strain for the efficient production of recombinant human Interferon Gamma

The Escherichia coli phosphoglucose isomerase (pgi) mutant strain GALG20 was developed previously from wild-type K12 strain MG1655 for increased plasmid yield. To investigate the potential effects of the pgi deletion/higher plasmid levels on recombinant human Interferon Gamma (IFN-γ) production, a detailed network of the central metabolic pathway (100 metabolites, 114 reactions) of GALG20 and MG1655 was constructed. Elementary mode analysis (EMA) was then performed to compare the phenotypic spaces of both the strains and to check the effect of the pgi deletion on flux efficiency of each metabolic reaction. The results suggested that pgi deletion increases amino acid biosynthesis and flux efficiency towards IFN-γ synthesis by 11%. To further confirm the qualitative prediction that the pgi mutation favours recombinant human IFN-γ expression, GALG20 and MG1655 were lysogenised, transformed with a plasmid coding for IFN-γ and tested alongside with BL21(DE3) for their expression capabilities in shake flask experiments using complex media. IFN-γ gene expression was analysed by quantifying plasmid and mRNA copy number per cell and IFN-γ protein production level. Specific IFN-γ yields confirmed the in silico metabolic network predictions, with GALG20(DE3) producing 3.0-fold and 1.5-fold more IFN-γ as compared to MG1655(DE3) and BL21(DE3), respectively. Most of the total IFN-γ was expressed as inclusion bodies across the three strains: 95% in GALG20(DE3), 97% in BL21(DE3) and 72% in MG1655(DE3). The copy number of mRNA coding for IFN-γ was found to be higher in GALG20(DE3) as compared to the other two strains. Overall, these findings show that GALG20(DE3) has the potential to become an excellent protein expression strain.

Systems Metabolic Engineering of Escherichia coli

Systems metabolic engineering, which recently emerged as metabolic engineering integrated with systems biology, synthetic biology, and evolutionary engineering, allows engineering of microorganisms on a systemic level for the production of valuable chemicals far beyond its native capabilities. Here, we review the strategies for systems metabolic engineering and particularly its applications in Escherichia coli. First, we cover the various tools developed for genetic manipulation in E. coli to increase the production titers of desired chemicals. Next, we detail the strategies for systems metabolic engineering in E. coli, covering the engineering of the native metabolism, the expansion of metabolism with synthetic pathways, and the process engineering aspects undertaken to achieve higher production titers of desired chemicals. Finally, we examine a couple of notable products as case studies produced in E. coli strains developed by systems metabolic engineering. The large portfolio of chemical products successfully produced by engineered E. coli listed here demonstrates the sheer capacity of what can be envisioned and achieved with respect to microbial production of chemicals. Systems metabolic engineering is no longer in its infancy; it is now widely employed and is also positioned to further embrace next-generation interdisciplinary principles and innovation for its upgrade. Systems metabolic engineering will play increasingly important roles in developing industrial strains including E. coli that are capable of efficiently producing natural and nonnatural chemicals and materials from renewable nonfood biomass.

Anthrax lethal toxin (LeTx) neutralization by PA domain specific antisera

Anthrax associated causalities in humans and animals are implicated mainly due to the action of two exotoxins that are secreted by the bacterium Bacillus antharcis during the infection. These exotoxins comprise of three protein components namely protective antigen (PA), lethal factor (LF) and edema factor (EF). The protective antigen is the common toxin component required to form both lethal toxin (LeTx) and edema toxin (EdTx). The LeTx is formed, when PA combines with LF and EdTx is formed when PA combines with EF. Therapeutic interventions aiming to neutralize these key effectors of anthrax pathology would therefore, provide an effective means to counter the toxicity imposed by the anthrax toxins on the host. The present work describes the lethal toxin neutralization potential of polyclonal antisera developed against the individual domains of the protective antigen component of the anthrax toxin. The individual domains were produced as recombinant proteins in E. coli and validated with peptide mass fingerprinting by MALDI-TOF analysis and corresponding mice polyclonal antisera by western blotting. Each domain specific antibody titre and isotype was ascertained by ELISA. The isotyping revealed the predominance of IgG1 isotype. The toxin neutralizing potential of these domain specific antisera were evaluated by in-vitro cell viability MTT assay, employing J774.1 mouse macrophage cell line against LeTx (0.25 μg ml^-1 PA and 0.125 μg ml^-1 LF concentrations). Among the four domain specific antisera, the antiserum against PA domain IV could neutralize LeTx with high efficiency. No significant neutralization of LeTx was observed with other domain specific antibodies. Results indicate that antibodies to r-PA domain IV could be explored further as therapeutic anti toxin molecule along with appropriate antibiotic regimens against anthrax.

Enhancing recombinant interleukin-6 production yield by fermentation optimization, two-step denaturing, and one-step purification

Interleukin-6 a pleiotropic cytokine involved in a wide range of biological activities. So the large-scale production of biologically active recombinant human interleukin-6 is important for its structural and functional studies. Here, we report an optimized method for shake flask fermentation and a simplified high-yield purification procedure for the recombinant interleukin-6. This high-yield expression method not only involves the optimization of the fermentation condition but also the single step purification method as well as a two-step denaturing and one-step refolding process. This approach replaces the more conventional procedure of protein solubilization and refolding. Through applying these strategies, the final cell density and overall product yield of the recombinant human interleukin-6 were obtained as 20.4 g as cell biomass and 150 mg as purified active protein from the I-L of the culture. The purified protein was characterized by HPLC and SDS-PAGE. The results of the current work demonstrate that the described method may be used to develop the process for industrial-scale production of the biologically active recombinant interleukin-6 protein.

Efficient soluble expression of disulfide bonded proteins in the cytoplasm of Escherichia coli in fed-batch fermentations on chemically defined minimal media

BACKGROUND

The production of recombinant proteins containing disulfide bonds in Escherichia coli is challenging. In most cases the protein of interest needs to be either targeted to the oxidizing periplasm or expressed in the cytoplasm in the form of inclusion bodies, then solubilized and re-folded in vitro. Both of these approaches have limitations. Previously we showed that soluble expression of disulfide bonded proteins in the cytoplasm of E. coli is possible at shake flask scale with a system, known as CyDisCo, which is based on co-expression of a protein of interest along with a sulfhydryl oxidase and a disulfide bond isomerase. With CyDisCo it is possible to produce disulfide bonded proteins in the presence of intact reducing pathways in the cytoplasm.

RESULTS

Here we scaled up production of four disulfide bonded proteins to stirred tank bioreactors and achieved high cell densities and protein yields in glucose fed-batch fermentations, using an E. coli strain (BW25113) with the cytoplasmic reducing pathways intact. Even without process optimization production of purified human single chain IgA1 antibody fragment reached 139 mg/L and hen avidin 71 mg/L, while purified yields of human growth hormone 1 and interleukin 6 were around 1 g/L. Preliminary results show that human growth hormone 1 was also efficiently produced in fermentations of W3110 strain and when glucose was replaced with glycerol as the carbon source.

CONCLUSIONS

Our results show for the first time that efficient production of high yields of soluble disulfide bonded proteins in the cytoplasm of E. coli with the reducing pathways intact is feasible to scale-up to bioreactor cultivations on chemically defined minimal media.

Evaluation of antibody response against recombinant domain III proteins of dengue virus type 1 and 2

Dengue, a mosquito borne viral disease caused by dengue virus has emerged as a major health problem during the last few decades. The envelope domain III (DIII) protein of dengue virus is highly immunogenic and capable of inducing neutralizing antibodies against wild-type dengue virus. The envelope domain III protein is a potential subunit vaccine candidate as well as a diagnostic reagent for dengue. This report describes the high yield production and immunogenicity of recombinant DIII proteins of dengue virus type 1 and 2. The subunit DIII proteins were produced in Escherichia coli using batch and fed-batch fermentation process. Immobilized metal affinity chromatography was used to capture DIII proteins of dengue virus type 1 and 2. The purified proteins were refolded by diafiltration to achieve biologically active proteins. After fed-batch fermentation, the recombinant E. coli resulted in purified DIII proteins of about 10.06 mg and 47.70 mg per gram of dry cell weight for recombinant dengue virus type 1 and 2 respectively with more than 95% purity. Biological function of the purified DIII proteins were confirmed by their ability to generate DIII specific antibodies in mice. The DIII antigens in combination with adjuvant resulted antibody endpoint titers of 1:64,000 and 1:1,28,000 for recombinant dengue virus type 1 and 2 respectively. These findings establish that the DIII proteins in combination with adjuvant are immunogenic, which suggests that refolded and purified DIII proteins can be a potential vaccine candidates.

Trigger factor assisted soluble expression of recombinant spike protein of porcine epidemic diarrhea virus in Escherichia coli

BACKGROUND

Porcine epidemic diarrhea virus (PEDV) is a highly contagious enteric pathogen of swine. The spike glycoprotein (S) of PEDV is the major immunogenic determinant that plays a pivotal role in the induction of neutralizing antibodies against PEDV, which therefore is an ideal target for the development of subunit vaccine. In an attempt to develop a subunit vaccine for PEDV, we cloned two different fragments of S protein and expressed as glutathione S-transferase (GST)-tagged fusion proteins, namely rGST-COE and rGST-S1D, in E.coli. However, the expression of these recombinant protein antigens using a variety of expression vectors, strains, and induction conditions invariably resulted in inclusion bodies. To achieve the soluble expression of recombinant proteins, several chaperone co-expression systems were tested in this study.

RESULTS

We firstly tested various chaperone co-expression systems and found that co-expression of trigger factor (TF) with recombinant proteins at 15 °C was most useful in soluble production of rGST-COE and rGST-S1D compared to GroEL-ES and DnaK-DnaJ-GrpE/GroEL-ES systems. The soluble rGST-COE and rGST-S1D were purified using glutathione Sepharose 4B with a yield of 7.5 mg/l and 5 mg/l, respectively. Purified proteins were detected by western blot using mouse anti-GST mAb and pig anti-PEDV immune sera. In an indirect ELISA, purified proteins showed immune reactivity with pig anti-PEDV immune sera. Finally, immunization of mice with 10 μg of purified proteins elicited highly potent serum IgG and serum neutralizing antibody titers.

CONCLUSIONS

In this study, soluble production of recombinant spike protein of PEDV, rGST-COE and rGST-S1D, were achieved by using TF chaperone co-expression system. Our results suggest that soluble rGST-COE and rGST-S1D produced by co-expressing chaperones may have the potential to be used as subunit vaccine antigens.

Comparison of Three Escherichia coli Strains in Recombinant Production of Reteplase

BACKGROUND

Escherichia coli (E. coli) is the most extensively used host for the production of recombinant proteins. However, most of the eukaryotic proteins are typically obtained as insoluble, misfolded inclusion bodies that need solubilization and refolding. Reteplase as a highly disulfide-bonded recombinant protein is an example of difficult to express protein in E. coli.

METHODS

In this study, a codon optimized reteplase gene was synthetically prepared and cloned under the control of an IPTG inducible T7 promoter. The vector was simultaneously transformed and expressed in three different E. coli strains. The ability of strains for expression of this recombinant pharmaceutical was compared. Also, an attempt was made to increase the soluble production of reteplase in SHuffle T7 E. coli with alterations of expression condition like temperature, inducer concentration and oxygen supply.

RESULTS

High amounts of reteplase were expressed as inclusion bodies in all three strains. BL21 (DE3) showed the highest level of expression in inclusion bodies followed by Rosetta-gami (DE3) and Shuffle T7. Changes of expression conditions were insufficient for soluble expression of reteplase in SHuffle T7 as a genetically engineered host for production of disulfide bonded proteins.

CONCLUSION

The oxidizing cytoplasm of Rosetta-gami and Shuffle T7 in addition to alterations of cultivation parameters could not result in soluble production of reteplase, although the inclusion bodies produced in these two strains might increase the rate of refolding procedure likely due to formation of folding intermediates.

Stable Expression of Basic Fibroblast Growth Factor in Chloroplasts of Tobacco

Basic fibroblast growth factor (bFGF) is a multifunctional factor in acceleration of cell proliferation, differentiation and transference, and therefore widely used in clinical applications. In this study, expression vector pWX-Nt03 harboring a codon-optimized bFGF gene was constructed and introduced into the tobacco chloroplasts by particle bombardment. After four rounds of selection, bFGF was proved to integrate into the chloroplast genome of regenerated plants and two of four transgenic plants were confirmed to be homoplastomic by PCR and Southern hybridization. ELISA assay indicated that bFGF represented approximately 0.1% of total soluble protein in the leaves of transplastomic tobacco plants. This is the first report of bFGF expression via chloroplast transformation in model plant, providing an additional option for the production of chloroplast-produced therapeutic proteins.

An improved method for high-level soluble expression and purification of recombinant amyloid-beta peptide for in vitro studies

Amyloid-beta (Aβ) peptide mediates several neurodegenerative diseases. The 42 amino acid (Aβ1-42) is the predominant form of peptide found in the neuritic plaques and has been demonstrated to be neurotoxic in vivo and in vitro. The availability of large quantities of Aβ peptide will help in several biochemical and biophysical studies that may help in exploring the aggregation mechanism and toxicity of Aβ peptide. We report a convenient and economical method to obtain such a peptide biologically. Synthetic oligonucleotides encoding Aβ1-42 were constructed and amplified through the polymerase cycling assembly (also known as assembly PCR), followed by the amplification PCR. Aβ1-42 gene was cloned into pET41a(+) vector for expression. Interestingly, the addition of 3% (v/v) ethanol to the culture medium resulted in the production of large amounts of soluble Aβ fusion protein. The Aβ fusion protein was subjected to a Ni-NTA affinity chromatography followed by enterokinase digestion, and the Aβ peptide was purified using glutathione Sepharose affinity chromatography. The peptide yield was ∼15mg/L culture, indicating the utility of this method for high-yield production of soluble Aβ peptide. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis and immunoblotting with anti-His antibody confirmed the identity of purified Aβ fusion protein and Aβ peptide. In addition, this method provides an advantage over the chemical synthesis and other conventional methods used for large-scale production of recombinant Aβ peptide.

Recombinant glucagon: a differential biological activity

In Brazil, there is a growing demand for specialised pharmaceuticals, and the high cost of their importation results in increasing costs, reaching US$ 1.34 billion in 2012 and US$ 1.61 billion in 2013. Worldwide expenses related to drugs could reach US$ 1.3 trillion in 2018, especially due to new treatments for hepatitis C and cancer. Specialised or high-cost pharmaceutical drugs used for the treatment of viral hepatitis, multiple sclerosis, HIV and diabetes are distributed free of charge by the Brazilian government. The glucagon peptide was included in this group of high-cost biopharmaceuticals in 2008. Although its main application is the treatment of hypoglycaemia in diabetic patients, it can also be used with patients in an alcoholic coma, for those patients with biliary tract pain, and as a bronchodilator. Therefore, in order to reduce biopharmaceutical production costs, the Brazilian government passed laws focusing on the development and increase of a National Pharmaceutical Industrial Centre, including the demand for the national production of glucagon. For that reason and given the importance and high cost of recombinant glucagon, the purpose of this study was to develop methods to improve production, purification and performance of the biological activity of recombinant glucagon. Glucagon was recombined into a plasmid vector containing a Glutathione S-transferase tag, and the peptide was expressed in a heterologous Escherichia coli system. After purification procedures and molecular analyses, the biological activity of this recombinant glucagon was examined using in vivo assays and showed a highly significant (p < 0.00001) and prolonged effect on glucose levels when compared with the standard glucagon. The experimental procedure described here facilitates the high level production of recombinant glucagon with an extended biological activity.

Cloning, soluble expression, and purification of the RNA polymerase II subunit RPB5 from Saccharomyces cerevisiae

We report the molecular cloning, expression, and single-step homogeneous purification of RNA polymerase II subunit RPB5 from Saccharomyces cerevisiae. RPB5 is a 210 amino acid nuclear protein that functions as the fifth largest subunit of polymerase II and plays a central role in transcription. The gene that codes for RPB5 was generated by amplification by polymerase chain reaction. It was then inserted in the expression vector pET28a(+) under the transcriptional control of the bacteriophage T7 promoter and lac operator. BL21(DE3) Escherichia coli strain transformed with the rpb5 expression vector pET28a(+)-rpb5 accumulates large amounts of a soluble protein of about 30 kDa (25 kDa plus 5 kDa double His6-Tag at N and C-terminal). The protein was purified to homogeneity using immobilized metal affinity chromatography. RPB5 recombinant protein was further confirmed by immunoblotting with anti-His antibody. In this study, the expression and purification procedures have provided a simple and efficient method to obtain pure RPB5 in large quantities. This will provide an opportunity to study the role of S. cerevisiae RPB5 in gene expression and transcription regulation. Furthermore, it can provide additional knowledge of the interaction partners of RPB5 during various steps of transcription and gene expression.

Optimization of culture parameters and novel strategies to improve protein solubility

The production of recombinant proteins, in soluble form in a prokaryotic expression system, still remains a challenge for the biotechnologist. Innovative strategies have been developed to improve protein solubility in various protein overexpressing hosts. In this chapter, we would focus on methods currently available and amenable to "desired modifications," such as (a) the use of molecular chaperones; (b) the optimization of culture conditions; (c) the reengineering of a variety of host strains and vectors with affinity tags; and (d) optimal promoter strengths. All these parameters are evaluated with the primary objective of increasing the solubilization of recombinant protein(s) during overexpression in Escherichia coli.

Cloning, expression and evaluation of diagnostic potential of recombinant capsid protein based IgM ELISA for chikungunya virus

The resurgence of chikungunya virus in the form of unprecedented explosive epidemic with unusual clinical severity after a gap of 32 years is a point of major public health concern. Definitive diagnosis is critical in differentiating the disease, especially in dengue endemic areas. The immunoglobulin M (IgM) enzyme-linked immunosorbent assay (ELISA) is widely used for diagnosis of chikungunya infection. However IgM ELISA based on whole virus antigen is associated with biohazard risk. The present study describes the development and evaluation of recombinant capsid protein based indirect IgM antibody capture micro plate enzyme linked immunosorbent assay (ELISA) for rapid and accurate diagnosis of chikungunya infection. The gene coding for capsid protein was cloned in frame with GST tag in pET41a+ vector and expressed in E. coli followed by purification with affinity chromatography. The comparative evaluation of in-house chikungunya IgM ELISA vis-a-vis commercially available SD ELISA kit with 90 chikungunya suspected acute phase human patient serum samples revealed 97% accordance. The overall sensitivity and specificity of the reported capsid protein based IgM ELISA was 100% and 95% respectively with 96% PPV and 100% NPV. These findings clearly demonstrated the usefulness of the recombinant capsid protein based CHIKV IgM ELISA for reliable clinical diagnosis of CHIKV infection in human patient.

Comparative evaluation of recombinant protein production in different biofactories: the green perspective

In recent years, the production of recombinant pharmaceutical proteins in heterologous systems has increased significantly. Most applications involve complex proteins and glycoproteins that are difficult to produce, thus promoting the development and improvement of a wide range of production platforms. No individual system is optimal for the production of all recombinant proteins, so the diversity of platforms based on plants offers a significant advantage. Here, we discuss the production of four recombinant pharmaceutical proteins using different platforms, highlighting from these examples the unique advantages of plant-based systems over traditional fermenter-based expression platforms.

Overview of Recent Progress in Protein-Expression Technologies for Small-Molecule Screening

Production of novel soluble and membrane-localized protein targets for functional and affinity-based screening has often been limited by the inability of traditional protein-expression systems to generate recombinant proteins that have properties similar to those of their endogenous counterparts. Such targets have often been labeled as challenging. Although biological validation of these challenging targets for specific disease areas may be strong, discovery of small-molecule modulators can be greatly delayed or completely halted due to target-expression issues. In this article, the limitations of traditional protein-expression systems will be discussed along with new systems designed to overcome these challenges. Recent work in this field has focused on two major areas for both soluble and membrane targets: construct-design strategies to improve expression levels and new hosts that can carry out the posttranslational modifications necessary for proper target folding and function. Another area of active research has been on the reconstitution of solubilized membrane targets for both structural analysis and screening. Finally, the potential impact of these new systems on the output of small-molecule screening campaigns will be discussed.

Production of recombinant Chikungunya virus envelope 2 protein in Escherichia coli

Chikungunya, a mosquito-borne viral disease caused by Chikungunya virus (CHIKV), has drawn substantial attention after its reemergence causing massive outbreaks in tropical regions of Asia and Africa. The recombinant envelope 2 (rE2) protein of CHIKV is a potential diagnostic as well as vaccine candidate. Development of cost-effective cultivation media and appropriate culture conditions are generally favorable for large-scale production of recombinant proteins in Escherichia coli. The effects of medium composition and cultivation conditions on the production of recombinant Chikungunya virus E2 (rCHIKV E2) protein were investigated in shake flask culture as well as batch cultivation of Escherichia coli. Further, the fed-batch process was also carried out for high cell density cultivation of E. coli expressing rE2 protein. Expression of rCHIKV E2 protein in E. coli was induced with 1 mM isopropyl-beta-thiogalactoside (IPTG) at ~23 g dry cell weight (DCW) per liter of culture and yielded an insoluble protein aggregating to form inclusion bodies. The final DCW after fed-batch cultivation was ~35 g/l. The inclusion bodies were isolated, solubilized in 8 M urea and purified through affinity chromatography to give a final product yield of ~190 mg/l. The reactivity of purified E2 protein was confirmed by Western blotting and enzyme-linked immunosorbent assay. These results show that rE2 protein of CHIKV may be used as a diagnostic reagent or for further prophylactic studies. This approach of producing rE2 protein in E. coli with high yield may also offer a promising method for production of other viral recombinant proteins.

To fuse or not to fuse: what is your purpose?

Since the dawn of time, or at least the dawn of recombinant DNA technology (which for many of today's scientists is the same thing), investigators have been cloning and expressing heterologous proteins in a variety of different cells for a variety of different reasons. These range from cell biological studies looking at protein-protein interactions, post-translational modifications, and regulation, to laboratory-scale production in support of biochemical, biophysical, and structural studies, to large scale production of potential biotherapeutics. In parallel, fusion-tag technology has grown-up to facilitate microscale purification (pull-downs), protein visualization (epitope tags), enhanced expression and solubility (protein partners, e.g., GST, MBP, TRX, and SUMO), and generic purification (e.g., His-tags, streptag, and FLAG™-tag). Frequently, these latter two goals are combined in a single fusion partner. In this review, we examine the most commonly used fusion methodologies from the perspective of the ultimate use of the tagged protein. That is, what are the most commonly used fusion partners for pull-downs, for structural studies, for production of active proteins, or for large-scale purification? What are the advantages and limitations of each? This review is not meant to be exhaustive and the approach undoubtedly reflects the experiences and interests of the authors. For the sake of brevity, we have largely ignored epitope tags although they receive wide use in cell biology for immunopreciptation.