Expression of mammalian proteins for diagnostics and therapeutics: a review

Nanoscale warriors against viral invaders: a comprehensive review of Nanobodies as potential antiviral therapeutics

Viral infections remain a significant global health threat, with emerging and reemerging viruses causing epidemics and pandemics. Despite advancements in antiviral therapies, the development of effective treatments is often hindered by challenges, such as viral resistance and the emergence of new strains. In this context, the development of novel therapeutic modalities is essential to combat notorious viruses. While traditional monoclonal antibodies are widely used for the treatment of several diseases, nanobodies derived from heavy chain-only antibodies have emerged as promising "nanoscale warriors" against viral infections. Nanobodies possess unique structural properties that enhance their ability to recognize diverse epitopes. Their small size also imparts properties, such as improved bioavailability, solubility, stability, and proteolytic resistance, making them an ideal class of therapeutics for viral infections. In this review, we discuss the role of nanobodies as antivirals against various viruses. Techniques used for developing nanobodies, delivery strategies are covered, and the challenges and opportunities associated with their use as antiviral therapies are discussed. We also offer insights into the future of nanobody-based antiviral research to support the development of new strategies for managing viral infections.

Novel 6xHis/HaloTag mammalian expressed autoantigens for the detection of humoral response with multiplexed electrochemical biosensors: A breakthrough in colorectal cancer and Alzheimer's disease personalized diagnostics

The integration of autoantibody detection with electrochemical biosensors allows the development of a novel strategy for managing colorectal cancer (CRC) and Alzheimer's disease (AD). This work reports the use, for the first time, of sustainable receptors, autoantigens expressed in mammalian cells, fused to 6xHis at the N-terminus and HaloTag at the C-terminus, immobilized on chloroalkane-modified magnetic beads (MBs) to selectively capture plasma autoantibodies. Detection was based on amperometric measurements using disposable multiplexed screen-printed carbon electrodes (x8 sensing surfaces), horseradish peroxidase (HRP)-conjugated secondary antibodies, and the HQ/H2O2 system. HaloTag immobilization gave rise to a great sensitivity allowing discrimination between patients and healthy individuals in comparison with HisTag or -COOH immobilization. The CRC biosensor integrated seven CRC-specific full-length autoantigens, while the AD bioplatform combined three AD-specific full-length proteins and four AD-specific peptides, which allowed a robust diagnostic performance validated by ROC analyses. These multiplexed biosensors provide minimally invasive, cost-effective, and sustainable alternatives to traditional diagnostic methods, and show ideal for discovery of new targets and for mass screening and early disease detection, supporting personalized medicine approaches.

CaClOH-Modified Silica Nanoparticles for mRNA Delivery

Messenger RNA (mRNA) technology has attracted wide attention in biomedical applications; its success relies heavily on the development of effective delivery tools. Herein, we report the synthesis of a novel CaClOH-modified silica nanoparticle (SNP-CaClOH) with a spiky surface for mRNA delivery. SNP-CaClOH is obtained by a rationally designed thermal decomposition process of hydrated CaCl2 inside the silanol-rich mesopores of preformed spiky SNPs. When used as a carrier for the cellular delivery of mRNA, the unique composition of CaClOH offers alkalinity to SNP-CaClOH that promotes endosomal escape via the proton sponge effect. Moreover, SNP-CaClOH leads to an increased intracellular Ca2+ level to activate the mammalian target of rapamycin complex 1 (mTORC1) by interacting with calmodulin (CaM) for enhanced mRNA translation. Taking further advantage of the spiky nanotopography, the superior mRNA delivery performance of SNP-CaClOH is demonstrated both in vitro and in vivo, providing useful delivery tools for mRNA technology development.

Expression and characterization of canine distemper virus hemagglutinin protein in suspension mammalian cells

Hundreds of millions of the domestic dogs worldwide are routinely inoculated with the modified live vaccines for canine distemper virus (CDV) every year. However, the corresponding serological diagnostic and detections are always lacking, thus, there is an urgent demand to establish its unique diagnostic technologies to produce high-quality antigenic biomolecules. In the present study, the ectodomain (et) of CDV hemagglutinin (H) protein was firstly expressed in a soluble and secreted forms by an Expi293F transient transfection system based on its antigenic secondary structure analysis. The yields of CDV H(et) protein was 2.6 g/L with purity over 95 % in supernatant of Expi293F cells. The CDV H(et) protein elicited comparative antibodies levels to the CDV virions in rabbit by ELISA and neutralization test. The purified polyclonal antibodies of immunized with CDV H(et) protein recognized both wild-type and vaccine CDV strains. More importantly, the purified polyclonal antibodies of CDV H(et) protein revealed significantly higher viral neutralizing activity than those from CDV-3 virions, which highlighted that the critical role of CDV H protein to elicit viral specific and protective neutralizing antibodies. Taken together, the CDV H(et) protein produced in mammalian expression systems was high-quality and good immunogenicity, and would be with great potential to serve as a serological diagnostic antigen or a novel CDV subunit vaccine in future.

Development of Complex Generics and Similar Biological Products: An Industrial Perspective of Reverse Engineering

Generic drugs are developed to be bioequivalent to innovator formulation, matching them in dosage form, safety, strength, quality and efficacy. Known as "interchangeable multi-source pharmaceutical products," generics play a crucial role in reducing therapeutic costs and enhancing patient compliance. Over the past decade, generics have accounted for more than 90% of prescriptions in the U.S., which has driven down the average price of these drugs to nearly match production costs once market competition grows. Simple generics of small-molecule drugs are often produced through trial and error based on existing data, but complex generics require advanced techniques like reverse engineering to replicate the brand drug's release profile. These complex generics include sophisticated drug delivery forms that ensure the therapeutic agent is released gradually, maximizing effectiveness. Conversely, similar biological products highly similar to approved biologics-undergo rigorous analytical and clinical evaluations due to their complexity and the nature of biologic production. The increased demand for similar biological products is driven by expiring biologic patents, economic incentives, and regulatory advancements, with the market expected to grow significantly by 2026. The Biologic Price Competition and Innovation Act (BPCIA) enable abbreviated approvals for similar biological products, promoting affordability. Despite minor differences from original biologics, similar biological products undergo extensive testing to ensure safety and efficacy, following global regulatory guidelines that emphasize strict quality standards. This framework is essential for expanding patient access to effective therapies for conditions like cancer and autoimmune diseases while supporting healthcare sustainability.

An Arrayed CRISPR Screen Identifies Knockout Combinations Improving Antibody Productivity in HEK293 Cells

Mammalian cells are used to express complex biologics, such as multispecific antibodies. While multispecifics enable promising new strategies for treating human disease, their production at high expression titer and purity can be challenging. To understand how cells respond to antibody and multispecific expression, five molecules were selected for bulk RNA sequencing (RNA-seq) early after the transfection of a human embryonic kidney 293 (HEK293) host. All five molecules shared a differential expression signature of secretory and protein folding stresses, but this signature was stronger for molecules with low titer. We then designed an arrayed CRISPR knockout screen of 206 differentially expressed target genes and 223 literature-motivated targets to identify knockouts that affect antibody productivity. Eight novel knockout targets were identified that increased expression titers by 20-80%. Notably, seven of these top eight hits were from the differentially expressed set of candidate-gene knockouts. The top knockout target, HIST2H3C, showed evidence for additivity with five other hits, including a knockout combination that increased the titer of a difficult-to-express antibody by up to 100%. Findings for both HIST2H3C and INHBE knockout targets generalized to an alternate HEK293 host expressing an additional antibody and a multispecific host with no meaningful impact on product purity. Thus, we propose HIST2H3C and INHBE disruption as a promising and novel strategy for host-cell engineering to improve antibody and multispecific productivity.

Trends and challenges in bispecific antibody production

Bispecific antibodies (bsAbs) represent a rapidly growing field of therapeutic agents. More bsAbs are being approved worldwide and are in various stages of clinical trials. However, the discovery and production of novel bsAbs presents significant challenges due to their complex structure. Thus, precise control of assembly and stability is required, given the many formats developed. This review examines recent trends in bsAb production, focusing on advancements in engineering platforms, production strategies, and challenges in large-scale manufacturing. Key developments include improvements in modular antibody design, novel expression systems, and optimization of bioprocessing techniques to enhance stability, yield, and efficacy. Additionally, the article explores the future potential of bsAbs as next-generation therapeutics, underscoring the growing impact of these innovations on expanding treatment options for patients with unmet medical needs.

Expression of UCOE and HSP27 Molecular Elements to Improve the Stable Protein Production on HEK293 Cells

Recombinant proteins represent one of the greatest achievements of modern pharmaceutical biotechnology, as they are increasingly used across nearly all branches of medicine to treat a wide range of conditions. In response to this demand, various cell engineering approaches have been developed to improve their expression. Some of these approaches involve the use of genetic elements that prevent the silencing of the gene of interest, as well as the generation of resistant cell lines to inhibit or avoid programmed cell death (PCD). This research focuses on analyzing the effects of overexpression of UCOE elements and the HSP27 protein, both individually and together, on the production of human rIFNγ in HEK293 cells. Our results show that 4-Kb UCOE elements have no effect on protein production in HEK293 cells, while overexpression of HSP27 prolongs the stationary phase during growth kinetics. The Qp of rIFNγ is 96-fold higher in clones containing the HSP27/UCOE combination compared to the clone containing only UCOE elements or to the control HEK293 cells. These results correlate with the MCP analyses, which showed that overexpression of HSP27 decreased the expression of Bax, caspase 3, cytochrome C, Beclin, and LC3II mRNA. Finally, this study suggests the potential utility of a cell engineering approach based on the overexpression of the human HSP27 protein for enhancing the production of recombinant viruses and proteins in HEK293 cells.

The Potential of Single-Chain Variable Fragment Antibody: Role in Future Therapeutic and Diagnostic Biologics

The advancement of genetic engineering has revolutionized the field of immunology by allowing the utilization of intrinsic antibody structures. One of the biologics that are being produced by recombinant antibody technology is single-chain fragments variable (scFv). Genes of variable regions, the heavy and light chains that are genetically linked into a single transcript by a short flexible linker peptide, are used to generate this fragment from cellular and synthetic libraries. The specificity and affinity of these molecules are comparable to those of parental antibodies. Fusion with marker proteins and other potent molecules improves their stability, circulation half-life, activity, and efficient purification. Besides, this review comprises construction protocols, therapeutics, and diagnostic applications of scFv, as well as related challenges. Nonetheless, there are still issues with efficacy, stability, safety, intracellular administration, and production costs that need to be addressed.

Protein-imprinted polymers: How far have "plastic antibodies" come?

Antibodies are highly selective and sensitive, making them the gold standard for recognition affinity tools. However, their production cost is high and their downstream processing is time-consuming. Molecularly imprinted polymers (MIPs) are tailor-made by incorporating specific molecular recognition sites in their structure, thus translating into receptor-like activity mode of action. The interest in molecular imprinting technology, applied to biomacromolecules, has increased in the past decade. MIPs, produced using biomolecules as templates, commonly referred to as "plastic antibodies" or "artificial receptors", have been considered as suitable cheaper and easy to produce alternatives to antibodies. Research on MIPs, designed to recognize proteins or peptides is particularly important, with potential contributions towards biomedical applications, namely biosensors and targeted drug delivery systems. This mini review will cover recent advances on (bio)molecular imprinting technology, where proteins or peptides are targeted or mimicked for sensing and therapeutic applications. Polymerization methods are reviewed elsewhere, being out of the scope of this review. Template selection and immobilization approaches, monomers and applications will be discussed, highlighting possible drawbacks and gaps in research.

Recombinant Porcine Interferon-α Decreases Pseudorabies Virus Infection

Interferon (IFN) is a cell-secreted cytokine possessing biological activities including antiviral functioning, immune regulation, and others. Interferon-alpha (IFN-α) mainly derives from plasmacytoid dendritic cells, which activate natural killer cells and regulate immune responses. IFN-α responds to the primary antiviral mechanism in the innate immune system, which can effectively cure acute infectious diseases. Pseudorabies (PR) is an acute infectious disease caused by pseudorabies virus (PRV). The clinical symptoms of PRV are as follows: reproductive dysfunction among pregnant sows and high mortality rates among piglets. These pose a severe threat to the swine industry. Related studies show that IFN-α has broad applications in preventing and treating viral diseases. Therefore, a PRV mouse model using artificial infection was established in this study to explore the pathogenic effect of IFN-α on PRV. We designed a sequence with IFN-α4 (M28623, Genbank) and cloned it on the lentiviral vector. CHO-K1 cells were infected and identified using WB and RT-PCR; a CHO-K1 cell line with a stable expression of the recombinant protein PoIFN-α was successfully constructed. H&E staining and virus titer detection were used to investigate the recombinant protein PoIFN-α's effect on PR in BALB/c mice. The results show that the PoIFN-α has a preventive and therapeutic impact on PR. In conclusion, the recombinant protein can alleviate symptoms and reduce the replication of PRV in vivo.

Molecular Farming Strategy for the Rapid Production of Protein-Based Reagents for Use in Infectious Disease Diagnostics

Recombinant proteins are a major breakthrough in biomedical research with a wide range of applications from diagnostics to therapeutics. Strategic construct design, consistent expression platforms, and suitable upstream and downstream techniques are key considerations to produce commercially viable recombinant proteins. The recombinant antigenic protein production for use either as a diagnostic reagent or subunit vaccine formulation is usually carried out in prokaryotic or eukaryotic expression platforms. Microbial and mammalian systems dominate the biopharmaceutical industry for such applications. However, there is no universal expression system that can meet all the requirements for different types of proteins. The adoptability of any expression system is likely based on the quality and quantity of the proteins that can be produced from it. The huge demand of recombinant proteins for different applications requires an inexpensive production platform for rapid development. The molecular farming scientific community has been promoting the plant system for nearly 3 decades as a cost-effective alternative to produce high-quality proteins for research, diagnostic, and therapeutic applications. Here, we discuss how plant biotechnology could offer solutions for the rapid and scalable production of protein antigens as low-cost diagnostic reagents for use in functional assays.

Application of CRISPR-Cas9 genome editing technology in various fields: A review

CRISPR-Cas9 has emerged as a revolutionary tool that enables precise and efficient modifications of the genetic material. This review provides a comprehensive overview of CRISPR-Cas9 technology and its applications in genome editing. We begin by describing the fundamental principles of CRISPR-Cas9 technology, explaining how the system utilizes a single guide RNA (sgRNA) to direct the Cas9 nuclease to specific DNA sequences in the genome, resulting in targeted double-stranded breaks. In this review, we provide in-depth explorations of CRISPR-Cas9 technology and its applications in agriculture, medicine, environmental sciences, fisheries, nanotechnology, bioinformatics, and biotechnology. We also highlight its potential, ongoing research, and the ethical considerations and controversies surrounding its use. This review might contribute to the understanding of CRISPR-Cas9 technology and its implications in various fields, paving the way for future developments and responsible applications of this transformative technology.

Recombinant vaccines in 2022: a perspective from the cell factory

The last big outbreaks of Ebola fever in Africa, the thousands of avian influenza outbreaks across Europe, Asia, North America and Africa, the emergence of monkeypox virus in Europe and specially the COVID-19 pandemics have globally stressed the need for efficient, cost-effective vaccines against infectious diseases. Ideally, they should be based on transversal technologies of wide applicability. In this context, and pushed by the above-mentioned epidemiological needs, new and highly sophisticated DNA-or RNA-based vaccination strategies have been recently developed and applied at large-scale. Being very promising and effective, they still need to be assessed regarding the level of conferred long-term protection. Despite these fast-developing approaches, subunit vaccines, based on recombinant proteins obtained by conventional genetic engineering, still show a wide spectrum of interesting potentialities and an important margin for further development. In the 80's, the first vaccination attempts with recombinant vaccines consisted in single structural proteins from viral pathogens, administered as soluble plain versions. In contrast, more complex formulations of recombinant antigens with particular geometries are progressively generated and explored in an attempt to mimic the multifaceted set of stimuli offered to the immune system by replicating pathogens. The diversity of recombinant antimicrobial vaccines and vaccine prototypes is revised here considering the cell factory types, through relevant examples of prototypes under development as well as already approved products.