RESUMEN
Background: Two-armed FabscFv-Fc is a favoured bispecific antibody (BsAb) format due to its advantages of the conventional IgG structure. Production of FabscFv-Fc requires expression of three polypeptide chains, one light chain (LC), one heavy chain (HC) and a scFv fused to the Fc (scFvFc) at optimal ratios. Methods: We designed a set of internal ribosome entry site (IRES)-mediated multi-cistronic vectors tailoring to various expression ratios of the three polypeptides to study how the chain ratios affect the FabscFv-Fc production. Results: Expression of HC and scFvFc chains at 1:1 ratio and excess LC gave the highest yield of correctly assembled product. Compared to the use of IRES and multiple promoters, using 2A peptides for co-expression of the three polypeptides gave the highest titre and correctly assembled product. Conclusion: The results obtained in this work provide insights to the impacts of hetero-chain ratios on the BsAb production.
RESUMEN
The emergence of antibiotic resistant bacteria is one of the biggest threats to human health worldwide. In 2017, World Health Organization listed the world's most dangerous antibiotic-resistant bacteria or "superbugs," such as carbapenem-resistant Pseudomonas aeruginosa and Escherichia coli, indicating the highest priority needs for new antibiotics. The possibility that such infectious diseases may soon be untreatable, due to decreased antibiotic efficacy, creates an urgent need for novel and alternative antimicrobials. Antimicrobial peptides are naturally occurring small molecules found in the innate immunity of mammals, plants and bacteria, and are potentially therapeutic candidates against drug-resistant bacteria. In this study, we examine the antimicrobial activities of the cytotoxic peptides derived from the basic region (BR) of the human hexamethylene bisacetamide-inducible protein 1 (HEXIM1). We found that, when fused with a cell penetrating peptide, the HEXIM1 BR peptide and its derivative, BR-RRR12, exhibited inhibitory activities against selected "superbugs." Negligible effects on the viability of human keratinocyte cell line were observed when the bactericidal dosages of HEXIM1 BR peptides were used. Different killing kinetics were observed between the membrane permeabilizing antimicrobial peptides and HEXIM1 BR peptides, suggesting that a different antimicrobial mechanism might be utilized by the HEXIM1 BR peptides. Using an in vitro translation system based on E. coli lysates, we found that HEXIM1 BR peptides blocked bacterial translation. Taken together, we identify the HEXIM1 BR peptide as a novel antimicrobial peptide with potent inhibitory activity against antibiotic-resistant "superbugs."
RESUMEN
X-box binding protein 1 (XBP-1) is a key regulator of the unfolded protein response (UPR), which is activated in response to endoplasmic reticulum (ER) stress. Cells contain two protein isoforms of XBP-1, the active isoform (XBP-1S) and the inactive isoform (XBP-1U). Induction of UPR leads to the generation of XBP-1S while XBP-1U is dominant in ER stress-free cells. XBP-1S is a transcriptional activator and regulates the expression of a subset of UPR genes. Importantly, recent studies have demonstrated the essential role of XBP-1S in various human diseases, such as viral infections. Many viruses have evolved to manipulate UPR/XBP-1 of the infected cells to promote viral survival and replication. In this review, we will summarize the current findings on the involvement of XBP-1 in viral infection/ replication and discuss the potential anti-viral strategies by targeting XBP-1.
