Recombinant Cell Culture Research Articles

Dialysis rolled scaffold bioreactor allows extended production of monoclonal antibody with reduced media use.

Rapidly expanding biopharmaceutical market demands more cost-effective platforms to produce protein therapeutics. To this end, novel approaches, such as perfusion culture or concentrated fed-batch, have been explored for higher yields and lower manufacturing costs. Although these new approaches produced promising results, but their wide-spread use in the industry is still limited. In this study, a dialysis rolled scaffold bioreactor was presented for long-term production of monoclonal antibodies with reduced media consumption. Media dialysis can selectively remove cellular bio-wastes without losing cells or produced recombinant proteins. The dialysis process was streamlined to significantly improve its efficiency. Then, extended culture of recombinant CHO cells for 41 days was successfully demonstrated with consistent production rate and minimal media consumption. The unique configuration of the developed bioreactor allows efficient dialysis for media management, as well as rapid media exchange to harvest produced recombinant proteins before they degrade. Taken together, it was envisioned that the developed bioreactor will enable cost-effective and long-term large-scale culture of various cells for biopharmaceutical production.

Biomanufacturing for a Sustainable Future: Unleashing the Potential of Biotechnology in Pharmaceutical Raw Material Production

The pharmaceutical industry relies heavily on raw materials for drug development, with Active Pharmaceutical Ingredients (APIs) and excipients forming the fundamental components of pharmaceutical formulations. Traditional methods of pharmaceutical raw material production are plagued by inefficiencies, environmental concerns, and limitations in producing complex molecules. In contrast, biotechnology offers a promising alternative with its capacity for efficient, sustainable, and precise synthesis of pharmaceutical raw materials. This article explores the potential of biotechnology in pharmaceutical raw material production, focusing on techniques such as recombinant DNA technology, microbial fermentation, biocatalysis, and cell culture technology. These methods enable the production of complex molecules with high specificity, purity, and scalability, addressing the shortcomings of traditional approaches. Furthermore, biotechnology facilitates the development of novel drugs, personalized medicine strategies, and innovative treatments, offering hope for previously untreatable conditions. Despite the transformative potential of biotechnology, challenges such as high initial investment, regulatory considerations, and safety concerns need to be addressed for its widespread adoption. In conclusion, embracing biotechnology represents a paradigm shift in pharmaceutical production, promising a more sustainable, personalized, and effective healthcare future. Collaboration between stakeholders is essential to navigate challenges and ensure the responsible advancement of biotechnological applications in healthcare, ultimately improving the quality of life for millions worldwide

De novo synthesis of 2'-fucosyllactose in engineered Bacillus subtilis ATCC 6051a

Microbial synthesis of 2'-fucosyllactose (2'-FL) has received much attention in recent years. In this study, Bacillus subtilis ATCC 6051a, a nonpathogenic GRAS (generally recognized as safe) organism, was engineered to produce 2'-FL. After a synthetic pathway comprising six genes was incorporated into the host cell genome, only a low level of 2'-FL (120 mg/L) was initially detected in recombinant cell culture. Comparison of heterologous lactose transporters confirmed the superior role of LacY from Escherichia coli for efficient production of 2'-FL in B. subtilis. There are two β-galactosidases, GanA and YesZ, in B. subtilis. Deletion of ganA and yesZ caused by insertion of the lacY cassette led to 2'-FL accumulation in shaking-flask culture at concentrations of 3.13 g/L and 5.56 g/L, respectively, which increased to 6.13 g/L in the double-deletion strain 164FL-GY. In addition, enhanced xylose metabolism in 164FL-GY further increased the concentration of 2'-FL to 7.14 g/L. In fed-batch fermentation, the highest productivity of 0.56 g/L·h was achieved in glycerol and xylose containing medium using engineered B. subtilis, and the accumulated 2'-FL reached 31.2 g/L. This is the first report of recombinant B. subtilis for high-level production of 2'-FL via a de novo synthesis pathway.

In vivo Evidence for Brain Region-Specific Molecular Interactions Between Cannabinoid and Orexin Receptors.

The endocannabinoid and orexin neuromodulatory systems serve key roles in many of the same biological functions such as sleep, appetite, pain processing, and emotional behaviors related to reward. The type 1 cannabinoid receptor (CB1R) and both subtypes of the orexin receptor, orexin receptor type 1 (OX1R) and orexin receptor type 2 (OX2R) are not only expressed in the same brain regions modulating these functions, but physically interact as heterodimers in recombinant and neuronal cell cultures. In the current study, male and female C57BL/6 mice were co-treated with the cannabinoid receptor agonist CP55,940 and either the OX2R antagonist TCS-OX2-29 or the dual orexin receptor antagonist (DORA) TCS-1102. Mice were then evaluated for catalepsy, body temperature, thermal anti-nociception, and locomotion, after which their brains were collected for receptor colocalization analysis. Combined treatment with the DORA TCS-1102 and CP55,940 potentiated catalepsy more than CP55,940 alone, but this effect was not observed for changes in body temperature, nociception, locomotion, or via selective OX2R antagonism. Co-treatment with CP55,940 and TCS-1102 also led to increased CB1R-OX1R colocalization in the ventral striatum. This was not seen following co-treatment with TCS-OX2-29, nor in CB1R-OX2R colocalization. The magnitude of effects following co-treatment with CP55,940 and either the DORA or OX2R-selective antagonist was greater in males than females. These data show that CB1R-OX1R colocalization in the ventral striatum underlies cataleptic additivity between CP55,940 and the DORA TCS-1102. Moreover, cannabinoid-orexin receptor interactions are sex-specific with regards to brain region and functionality. Physical or molecular interactions between these two systems may provide valuable insight into drug-drug interactions between cannabinoid and orexin drugs for the treatment of insomnia, pain, and other disorders.

Recombinant Human Erythropoietin Production in Chinese Hamster Ovary Cells Is Enhanced by Supplementation of α-Helix Domain of 30Kc19 Protein

The enhancement of recombinant therapeutic protein production in mammalian cell culture has been regarded as an important issue in the biopharmaceutical industry. Previous studies have reported that the addition of the recombinant 30Kc19 protein, a silkworm-derived plasma protein with simultaneous cell-penetrating and mitochondrial enzyme-stabilizing properties, can enhance the recombinant protein expression in Chinese hamster ovary (CHO) cell culture. Here, we produced an α-helix N-terminal domain of 30Kc19, called (30Kc19α), and investigated its effects on the production of human erythropoietin (EPO), a widely used therapeutic protein for the treatment of anemia, in recombinant CHO cell culture. Similar to the full-length 30Kc19, 30Kc19α was able to be mass-produced in a form of recombinant protein through an Escherichia coli expression system and delivered into EPO-producing CHO (EPO–CHO) cells. Supplementing the medium of EPO–CHO cell culture with 30Kc19α increased the intracellular NADPH/NADP+ ratio related to the flux of metabolic reducing power for protein biosynthesis, subsequently enhancing EPO production in serum-free culture. 30Kc19α is considered to have certain advantages in the downstream purification process of therapeutic protein production when it is used as a medium supplement due to its small size and low isoelectric point compared to the full-length 30Kc19. These results suggest that 30Kc19α has potential use for manufacturing biopharmaceutical proteins.

Continuous Feeding Reduces the Generation of Metabolic Byproducts and Increases Antibodies Expression in Chinese Hamster Ovary-K1 Cells.

Chinese hamster ovary (CHO) cells are the most important host system used for monoclonal antibody (mAb) expression. Moreover, the fed-batch culture mode is the most widely used method to increase mAb expression in CHO cells by increasing the amount of feed. However, a high amount of culture feed results in the production of metabolic byproducts. In this work, we used a continuous feeding strategy to reduce metabolic byproducts and improve mouse–human chimeric anti-epidermal growth factor receptor vIII (EGFRvIII) antibody C12 expression in Chinese hamster ovary-K1 cells. Moreover, the effects of the feeding strategy on the cell culture and monoclonal antibody production were evaluated in chemically defined suspension cultures of recombinant CHO-K1 cells. Compared with bolus feeding methods, the continuous feeding method did not have any advantages when the feeding amount was low, but with a high feeding amount, the continuous feeding method significantly reduced the concentrations of lactate and NH4+ in the later culture stage. At the end of the culture stage, compared with bolus feeding methods, the lactate and NH4+ concentrations under the continuous feeding mode were reduced by approximately 45% and 80%, respectively. In addition, the antibody C12 expression level was also increased by almost 10%. Compared to the bolus feeding method, the antibody C12 produced by the continuous feeding method had a lower content of high-mannose glycoforms. Further analysis found that the osmolality of the continuous feeding method was lower than that of the typical fed-batch bolus feeding method. Conclusively, these results indicate that the continuous feeding method is very useful for reducing metabolic byproducts and achieving higher levels of mAb production.

Chimeric VLPs Bearing VP60 from Two Serotypes of Rabbit Haemorrhagic Disease Virus Are Protective against Both Viruses.

The VP60 capsid protein from rabbit haemorrhagic disease virus (RHDV), the causative agent of one of the most economically important disease in rabbits worldwide, forms virus-like particles (VLPs) when expressed using heterologous protein expression systems such as recombinant baculovirus, yeasts, plants or mammalian cell cultures. To prevent RHDV dissemination, it would be beneficial to develop a bivalent vaccine including both RHDV GI.1- and RHDV GI.2-derived VLPs to achieve robust immunisation against both serotypes. In the present work, we developed a strategy of production of a dual-serving RHDV vaccine co-expressing the VP60 proteins from the two RHDV predominant serotypes using CrisBio technology, which uses Tricholusia ni insect pupae as natural bioreactors, which are programmed by recombinant baculovirus vectors. Co-infecting the insect pupae with two baculovirus vectors expressing the RHDV GI.1- and RHDV GI.2-derived VP60 proteins, we obtained chimeric VLPs incorporating both proteins as determined by using serotype-specific monoclonal antibodies. The resulting VLPs showed the typical size and shape of this calicivirus as determined by electron microscopy. Rabbits immunised with the chimeric VLPs were fully protected against a lethal challenge infection with the two RHDV serotypes. This study demonstrates that it is possible to generate a dual cost-effective vaccine against this virus using a single production and purification process, greatly simplifying vaccine manufacturing.

Enhancement of Cell-Based Vaccine Manufacturing through Process Intensification.

There are many drivers to intensify the manufacturing of vaccines. The emergence of SARS-CoV-2 has only added to them. Since the pandemic began, we have been seeing an acceleration of vaccine development and approval, including application of novel prophylactic vaccine modalities. We have also seen an increase in the appreciation and general understanding of what had been a somewhat obscure discipline. Concurrently, there has been great interest in the application of new understandings and technology to the intensification of biopharmaceutical processes in general. The marriage of these developments defines the field of vaccine manufacturing process intensification Difficulties in its implementation include the many disparate vaccine types-from conjugate to hybrid to nucleic acid based. Then, there are the respective and developing manufacturing methods, modes, and platforms-from fermentation of transformed bacteria to the bioreactor culture of recombinant animal cells to production of virus-like particles in transgenic plants. Advances are occurring throughout the biomanufacturing arena, from process development (PD) techniques to manufacturing platforms, materials, equipment, and facilities. Bioprocess intensification refers to systems for producing more product per cell, time, volume, footprint, or cost. The need for vaccine manufacturing process intensification is being driven by desires for cost control, process efficiency, and the heightened pressures of pandemic response. We are seeing great interest in the power of such disciplines as synthetic biology, process simplification, continuous bioprocessing, and digital techniques in the optimization of vaccine PD and manufacturing. Other powerful disciplines here include process automation, improved monitoring, optimized culture materials, and facility design. The intent of this short commentary is to provide a brief review and a few examples of the exciting advances in the equipment, technology, and processes supporting this activity.

Effect of encephalomyocarditis virus 3'Untranslated region on GFP transient expression: implications in recombinant protein production

The enrichment of therapeutic protein production yield in mammalian cell cultures by modulating mRNA stability is a fairly new strategy in biotechnological applications. Here, we describe the application of 3′-untranslated region (3′UTR) from RNA viral genome to modulate mRNA stability. The data obtained showed that the use of the 3 'UTR sequence of the encephalomyocarditis virus (EMCV 3'UTR) downstream of the target gene was not able to significantly modulate the free energy density indicators of the RNA. However, the sequence influenced the stability of the mRNA (and, therefore, the amount of protein production) in a cell type and time-dependent manner, indicating a central role of mRNA-stabilizing binding sites/cellular factors in this process. Our data might be of interest for the biotechnology community to improve recombinant protein production in mammalian cell cultures and RNA-based therapy/vaccination approaches.

Development of rolled scaffold for high-density adherent cell culture.

Bioreactors for large-scale culture of mammalian cells are playing vital roles in biotechnology and bioengineering. Various bioreactors have been developed, but their capacity and efficiency are often limited by insufficient mass transfer rate and high shear stress. A rolled scaffold (RS) is a fully defined scaffold for high-density adherent culture of mammalian cells. The RS is a polymer film with spacers, that is rolled into a cylinder with a pre-determined gap between each turn. Cells are cultured on its inner surfaces, while media flows through the gap. The RS exhibits high surface-area-to-volume ratio over 100cm2/mL and can transport nutrients and gases with significantly reduced shear stress via convection in a unidirectional laminar flow, rather than diffusion and random turbulent flow as in stirred-tank bioreactors. In this paper, we expanded Chinese Hamster Ovary cells with RS bioreactors and demonstrated cell culture density over 60 million cells/mL with a growth rate higher than conventional suspension culture. Besides, murine embryonic stem cells were successfully expanded without losing their pluripotency. The RS will provide an affordable, scalable, and reliable platform for large-scale culture of recombinant cells in biopharmaceutical industries and shear-sensitive stem cells for tissue engineering.

Enhanced transient expression of an anti-CD52 monoclonal antibody in CHO cells through utilization of miRNA sponge technology.

Chinese hamster ovary (CHO) cells are the dominant mammalian host system for the production of recombinant therapeutic proteins. Improving the viable cell density during culture of recombinant CHO cells can greatly affect the production yield. MicroRNAs (miRs) -15a and 16-1 are known as negative regulators of multiple genes involved in cell cycle progression and apoptotic inhibition. miR sponges, which act as decoy targets, are transcripts which contain complementary binding sites to the seed region of related miRs. Stably expressed miR sponges are known as efficient tools for miR loss of function studies. In this study, stable CHO cell pools and clones expressing miRs-15a and 16-1 specific decoy transcript downstream of an enhanced green fluorescent protein reporter gene was developed. Analysis of cell growth during 12 days of batch culture indicated improved maximum viable cell density of CHO cells and clones expressing the decoy transcript. In addition, transient expression of a recombinant anti-CD52 monoclonal antibody was significantly improved in a decoy harboring CHO cell clone, representing a 3.37-fold increase in yield after 4 days of culture. Our results indicated that miR sponge technology can be successfully applied for the improvement of cell viability and transient monoclonal antibody expression in CHO host cells.

Biotechnological technique for improvement of ornamental crops

Plant biotechnology plays an important role in mass production of improved crop varieties as well as their genetic improvement. It develops business processes and products, using recombinant DNA, gene transfer, embryo manipulation, plant regeneration, cell culture, monoclonal antibodies and bio-processed engineering, and biologically active substances such as food additives, dyes, pharmaceuticals, Helps in the production of bio-. Pesticides for the benefit of man and society. The development of techniques of molecular classification through RAPD and RFLP in genomic analysis and classification has opened up new options for germplasm characterization of ornamental plants such as roses, haptiolas, orchids, ornamental pods, anthurium, gerbera, gulgenvia and cut-offs. genetic engineering. Flowers (pink to white chrysanthemum) become easier. Transgenic plants are now available in haptiolus, petunia, rose, carnation, orchids, gerberas, etc. Bioreactor technology is the need of the hour which can cut the cost of production of plants. It is clear to develop new varieties produced by cross-hybridization, mutation breeding and reverse mutation or in combination through genetic mutations. Secondary metabolites from cell culture have been established for the synthesis of codine (Papaversomniferum), quinine (Cinchona liturgiana), pyrethrin (Crescentheim urn cineraphyrium), taxol (Taxisbactata), rutculin (Rata spans..) and bain and papain. Somatic embryogenesis is a powerful tool for the improvement of jewelery, not only in relation to the spread of clots, but also for other biotechnological applications. It has been successfully used in crop improvement, such as Enthurium, Alstroemeria, Hadiolus, Iris, Lilium etc. Artificial (encapsulated) seeds contain somatic embryos, which are covered with a protected gel, also known as somatic embryogenesis. Ovule culture is now applied in Freesia for the production of embryonic culture and interspecific hybrids in Alstroemeria, in Alstroemeria and Cyclamen. Thus, it is clear that the application of various strategies to biotechnological approaches offers immense opportunities for improvement in ornamental plants.

DoE to improve supercoiled p53-pDNA purification by O-phospho-l-tyrosine chromatography

P53 is implicated in various cellular functions and several studies have shown that transfection of cancer cells with wild-type p53-expressing plasmids could directly drive cells into growth arrest and/or apoptosis. In the present work, the 6.07 kbp pcDNA3-FLAG-p53 plasmid, which encodes the p53 tumor suppressor, was produced and recovered from a recombinant cell culture of Escherichia coli DH5α. Following plasmid biosynthesis, the O-phospho-l-tyrosine chromatographic matrix was explored to purify the supercoiled p53-encoding plasmid. In order to quickly determine the optimal chromatographic performance and to obtain the required purity degree, maximizing the recovery yield of the supercoiled plasmid DNA, the Composite Central Face design was applied. The model revealed to be statistically significant (p-value < 0.05), with coefficient of determination of 0.9434 for the recovery yield and 0.9581 for purity and the central point was successfully validated. After the chromatographic process optimization by using the design of experiments tool, 49.7% of the supercoiled p53-encoding plasmid was recovered with 98.2% of purity, when a decreasing ammonium sulphate gradient was applied. The dynamic binding capacity of the O-phospho-l-tyrosine agarose column was 0.35 ± 0.02 mg pDNA/mL matrix at 50% of the breakthrough. Finally, the purified sample was analysed to assess the content of endotoxins, proteins and genomic DNA, showing that all these impurity levels were below the recommendations of the regulatory agencies.

The Expression Pattern of the Phosphoproteome Is Significantly Changed During the Growth Phases of Recombinant CHO Cell Culture.

Post-translational modification of proteins by reversible phosphorylation plays a pivotal role in regulating key cellular processes including transcription, translation, cell proliferation, differentiation, apoptosis, and signal transduction. Despite the importance of the phosphorylation level of regulation, little work has been carried out on the phosphoproteomic characterization of Chinese hamster ovary (CHO) cells in bioprocess-relevant conditions. Growth control strategies are often used to prolong culture duration and increase specific productivity; however, the cellular mechanisms and regulatory pathways underlying growth strategies are poorly understood in CHO cells. Phosphorylation changes are dynamic and will respond to changes in culture conditions; this may reflect the status of the cells with respect to growth and viability of the culture. Herein, this study uses a phosphopeptide enrichment strategy in conjunction with LC-MS/MS to carry out a large-scale differential phosphoproteomic analysis of IgG producing CHO DP12 cells at various phases of growth in serum-free suspension batch culture to characterize dynamic changes to the phosphoproteome with changing culture conditions. In total over the various growth phases, 3777 differentially expressed unique phosphopeptides are identified from 1415 differentially expressed unique phosphoproteins. Analysis of the whole cell lysate without phosphopeptide enrichment over the various growth phases revealed the differential expression of 834 unique proteins, with an overlap of 188 proteins between the proteomic and phosphoproteomic analyses. The inclusion of phosphoproteomic data significantly improves proteome coverage but also gives insights into the post-translational level of regulation during cellular growth of recombinant CHO cells.

Multiplexed Digital mRNA Expression Analysis Profiles System-Wide Changes in mRNA Abundance and Responsiveness of UPR-Specific Gene Expression Changes During Batch Culture of Recombinant Chinese Hamster Ovary Cells.

The unfolded protein response (UPR) signaling pathway is viewed as critical for setting the effectiveness of recombinant protein expression in CHO cells. In this study, Nanostring nCounter technology is used to study expression of a group of genes associated with cellular processes linked to UPR activation under ER stress and the changing environment of a batch culture. Time course induction of ER stress, using tunicamycin (TM), shows a group of genes such as Chop, Trb3, Sqstm1, Grp78, and Herpud1 respond rapidly to TM inhibition of N-glycosylation, while others such as Atf5, Odz4, and Birc5 exhibits a delayed response. In batch culture, expression of "classical" UPR markers only increases when cells enter decline phase. In addition to providing a detailed analysis of the expression of process-relevant UPR markers during batch culture and in response to imposed chemical stress, we also highlighted six genes (Herpud1, Odz4, Sqstm1, Trb3, Syvn1, and Birc5) associated with the perception of ER stress responses in recombinant CHO cells. Herpud1 (involved in ER-associated degradation) exhibits a rapid (primary) response to stress and its relationship (and that of the other five genes) to the overall cellular UPR may identify novel targets to modulate recombinant protein production in CHO cells.

12PD - MemoMAB, a novel technology for the banking and screening of cognate human immunoreceptor repertoires

Aim/Background: Providing a platform for the comprehensive analysis of the repertoires of human T and B cells in recombinant form while preserving the original heavy and light chain pairing of immunoreceptors (cognate, non-combinatorial libraries). Discovery of antibodies and TCRs generated in response to immune-stimulation such as administration of checkpoint inhibitors in cancer immunotherapy. Methods: A high throughput microfluidics-based single-cell molecular cloning and recombinant expression platform was developed that enables the generation of cognate human immunoreceptor repertoire libraries from human B and T cells (MemoMAB platform). Screening of this library can be performed by high-throughput single-cell-based mammalian display methods such as cell surface expression followed by cytometric sorting or encapsulation and culture of single recombinant cells in nanoliter reactors followed by functional screenings. Results: Using the MemoMAB platform technology, we have generated and screened antibody repertoire libraries from more than 100’000 human memory B cells from several human donors. Initial proof of concept of the platform has been performed in rabbits where monoclonal antibodies to several targets have been identified using cell surface expression or single cell encapsulation in nanoliter reactors. Conclusions: The generation of human cognate antibody repertoire analysis comprising 100’000 and more human memory B cells is feasible. Screening of these libraries is a straightforward process directly leading to the identification of clonal cell lines producing the immunoreceptor of interest in recombinant form. This tool can be expected to aid in the discovery of novel antibodies and their targets as candidate agents for cancer immuno-therapy. A particular area of interest for the application of the MemoMAB technology would be the analysis of antibody and T cell repertoires of patients undergoing immune-checkpoint-inhibitor therapy with the goal to identify novel immunogenic determinants for cancer immunotherapy. Legal entity responsible for the study: Klonale Analyse von menschlichen Antikörperrepertoires (2016-01260) Kantonale Ethikkommission Zürich Funding: Memo Therapeutics AG Disclosure: C. Esslinger: Shareholder and employee of Memo Therapeutics. S. Schmitt, M. Weber, A. Guimaraes: Employee of Memo Therapeutics.

Comparison of three transposons for the generation of highly productive recombinant CHO cell pools and cell lines

Several naturally occurring vertebrate transposable elements have been genetically modified to enable the transposition of recombinant genes in mammalian cells. We compared three transposons-piggyBac, Tol2, and Sleeping Beauty-for their ability to generate cell pools (polyclonal cultures of recombinant cells) and clonal cell lines for the large-scale production of recombinant proteins using Chinese hamster ovary cells (CHO-DG44) as the host. Transfection with each of the dual-vector transposon systems resulted in cell pools with volumetric yields of tumor necrosis factor receptor-Fc fusion protein (TNFR:Fc) that were about ninefold higher than those from cell pools generated by conventional plasmid transfection. On average, the cell pools had 10-12 integrated copies of the transgene per cell. In the absence of selection, the volumetric productivity of the cell pools decreased by 50% over a 2-month cultivation period and then remained constant. The average volumetric TNFR:Fc productivity of clonal cell lines recovered from cell pools was about 25 times higher than that of cell lines generated by conventional transfection. In 14-day fed-batch cultures, TNFR:Fc levels up to 900 mg/L were obtained from polyclonal cell pools and up to 1.5 g/L from clonal cell lines using any of the three transposons. Biotechnol. Bioeng. 2016;113: 1234-1243. © 2015 Wiley Periodicals, Inc.

High zinc ion supplementation of more than 30 μM can increase monoclonal antibody production in recombinant Chinese hamster ovary DG44 cell culture.

Effects of high ZnSO4·7H2O supplementation on cell growth and monoclonal antibody (mAb) production in chemically defined suspension cultures of recombinant Chinese hamster ovary (rCHO) DG44 cells were examined. The supplementation of ZnSO4·7H2O up to 120 μM gradually increased specific mAb production rate of rCHO DG44 cells in the early growth phase (0-4 days of culture). The ZnSO4·7H2O concentration for enhancing mAb production without any cytotoxic effects on cell growth was 30-60 μM. In addition of 60 μM ZnSO4·7H2O to in-house protein-free medium and in-house chemically defined medium, mAb production was increased 2.0-fold and 6.5-fold, respectively. Moreover, addition of ZnSO4·7H2O to three kinds of commercial chemically defined media yielded a greater than 1.2-fold enhancement of mAb production. These data indicate that simple supplementation of a relatively high zinc ion concentration to cell culture media without significant changes of rCHO DG44 cell culture process can be useful for achieving high production of mAb.

Antibodies Targeting Novel Neutralizing Epitopes of Hepatitis C Virus Glycoprotein Preclude Genotype 2 Virus Infection.

Currently, there is no effective vaccine to prevent hepatitis C virus (HCV) infection, partly due to our insufficient understanding of the virus glycoprotein immunology. Most neutralizing antibodies (nAbs) were identified using glycoprotein immunogens, such as recombinant E1E2, HCV pseudoparticles or cell culture derived HCV. However, the fact that in the HCV acute infection phase, only a small proportion of patients are self-resolved accompanied with the emergence of nAbs, indicates the limited immunogenicity of glycoprotein itself to induce effective antibodies against a highly evolved virus. Secondly, in previous reports, the immunogen sequence was mostly the genotype of the 1a H77 strain. Rarely, other genotypes/subtypes have been studied, although theoretically one genotype/subtype immunogen is able to induce cross-genotype neutralizing antibodies. To overcome these drawbacks and find potential novel neutralizing epitopes, 57 overlapping peptides encompassing the full-length glycoprotein E1E2 of subtype 1b were synthesized to immunize BALB/c mice, and the neutralizing reactive of the induced antisera against HCVpp genotypes 1–6 was determined. We defined a domain comprising amino acids (aa) 192–221, 232–251, 262–281 and 292–331 of E1, and 421–543, 564–583, 594–618 and 634–673 of E2, as the neutralizing regions of HCV glycoprotein. Peptides PUHI26 (aa 444–463) and PUHI45 (aa 604–618)-induced antisera displayed the most potent broad neutralizing reactive. Two monoclonal antibodies recognizing the PUHI26 and PUHI45 epitopes efficiently precluded genotype 2 viral (HCVcc JFH and J6 strains) infection, but they did not neutralize other genotypes. Our study mapped a neutralizing epitope region of HCV glycoprotein using a novel immunization strategy, and identified two monoclonal antibodies effective in preventing genotype 2 virus infection.

The overproduction of Synechocystis sp. PCC 6803 heat-shock protein (Sll0170) protects Escherichia coli against high-temperature stress

The most important role of molecular chaperones, especially under extreme temperature, is in handling with the impact of such stress on proteins and avoiding loss of their native conformation. Molecular chaperones play roles in the folding, transport, synthesis and quality control of other proteins under extreme temperature. The genome of the cyanobacterium Synechocystis PCC 6803 includes three dnaK genes (encoding heat-shock protein 70, Hsp70). The role of the second Hsp70 protein (Sll0170; DnaK2) in the acquisition of thermotolerance in Escherichia coli cells was investigated. Escherichia coli strain BL21 (DE3) was transformed with an expression vector (pTYB21) carrying the coding sequence of the Sll0170 gene under the control of the lac promoter. The recombinant cells which showed inducible expression of DnaK2 were observed to have improved viability compared to the wild-type strain upon transfer from 37 °C to 52 °C for up to 2, 4 and 6 min. Moreover, the growth of the wild-type cell culture decreased to 64% of that of the recombinant cell culture, following a transient (15 min) heat shock at 45 °C after which the culture was subsequently transferred back to 37 °C. Interestingly, the recombinant E. coli cells showed significantly faster culture growth than the wild-type cells at 37 °C.