Preparation and characterization of monoclonal antibody against digoxin

Bacteriophages: an overview of the control strategies against multiple bacterial infections in different fields

Bacteriophages (phages/viruses) need host bacteria to replicate and propagate. Primarily, a bacteriophage contains a head/capsid to encapsidate the genetic material. Some phages contain tails. Phages encode endolysins to hydrolyze bacterial cell wall. The two main classes of phages are lytic or virulent and lysogenic or temperate. In comparison with antibiotics, to deal with bacterial infections, phage therapy is thought to be more effective. In 1921, the use of phages against bacterial infections was first demonstrated. Later on, in humans, phage therapy was used to treat skin infections caused by Pseudomonas species. Furthermore, phages were successfully employed against infections in animals - calves, lambs, and pigs infected with Escherichia coli. In agriculture, for instance, phages have successfully been used e.g., Apple blossom infection, caused by Erwinia amylovora, was effectively catered with the use of bacteriophages. Bacteriophages were also used to control E. coli, Salmonella, Listeria, and Campylobacter contamination in food. Comparatively, phage display is a recently discovered technology, whereby, bacteriophages play a significant role. This review is an effort to collect almost recent and relevant information regarding applications and complications associated with the use of bacteriophages.

Preparation and Characterization of a Monoclonal Antibody Against Morphine

A monoclonal antibody (MAb) was produced by immunization of a BALB/c mouse with a conjugated morphine C6-hemisuccinated derivative (MHS) to cationized bovine serum albumin (cBSA). The hybridoma clones were screened by indirect ELISA using MHS-BSA. The best hybridoma clone was subcloned thrice by limiting dilution. This hybridoma was found to be of IgG2b class and subclass and contained lambda light chain. The affinity of the MAb to morphine was obtained 2.8×10(9) M(-1). The titer of the cell culture supernatant was at least 1:800. The MAb was cross-reacted with codeine (100%) and apomorphine (16.5%), but not with heroin, naloxone, naltrexone, or papaverine. Morphine was conjugated to HRP using a mixed anhydride method and a direct competitive ELISA was designed using anti-morphine MAb. The assay was sensitive over the 50 ng/mL to 5 μg/mL concentration range. In conclusion, this MAb is useful for the development of immunoassays to measure morphine in urine.

Advances in phage display technology for drug discovery

INTRODUCTION

Over the past decade, several library-based methods have been developed to discover ligands with strong binding affinities for their targets. These methods mimic the natural evolution for screening and identifying ligand-target interactions with specific functional properties. Phage display technology is a well-established method that has been applied to many technological challenges including novel drug discovery.

AREAS COVERED

This review describes the recent advances in the use of phage display technology for discovering novel bioactive compounds. Furthermore, it discusses the application of this technology to produce proteins and peptides as well as minimize the use of antibodies, such as antigen-binding fragment, single-chain fragment variable or single-domain antibody fragments like VHHs.

EXPERT OPINION

Advances in screening, manufacturing and humanization technologies demonstrate that phage display derived products can play a significant role in the diagnosis and treatment of disease. The effects of this technology are inevitable in the development pipeline for bringing therapeutics into the market, and this number is expected to rise significantly in the future as new advances continue to take place in display methods. Furthermore, a widespread application of this methodology is predicted in different medical technological areas, including biosensing, monitoring, molecular imaging, gene therapy, vaccine development and nanotechnology.

Immunodot blot assay to detect Helicobacter pylori using monoclonal antibodies against the 26 kDa protein

Development of a specific immunoassay to detect Helicobacter pylori infection in stool samples requires monoclonal antibody against the specific antigen. The aims of this study were to establish monoclonal antibodies against the 26 kDa protein of H. pylori and develop an immunodot blot for their application to recognize H. pylori infection using stool samples. Mice were immunized intraperitoneally with homogenized gel containing the 26 kDa band of cell surface proteins of H. pylori in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The monoclonal antibodies were produced using the hybridoma technique. Reactivity of monoclonal antibodies was tested with the purified 26 kDa antigen and cell surface proteins from cultured H. pylori by ELISA. Furthermore reactivity of monoclonal antibodies was tested on negative and positive stool samples for H. pylori and suspensions of several major bacteria in stool by immunodot blot assay. Five stable hybridoma monoclones were obtained. The concordant reactivity of the monoclonal antibodies with H. pylori present in the stool samples, which had been tested previously using an ACON ELISA kit for H. pylori stool antigen testing, and unreactivity with several different major fecal bacteria in immunodot blotting indicates high specificity of the immunodot blot based on the reaction of produced monoclonal antibodies with the H. pylori antigen in stools. The findings indicate that the novel immunodot blot developed based on new monoclonal antibodies for stool antigens would be useful as a noninvasive method of diagnosing H. pylori infection.

New analytical applications of gold nanoparticles as label in antibody based sensors

Gold nanoparticles (AuNPs) with optical and electrochemical distinctiveness as well as biocompatibility characteristics have proven to be powerful tools in nanomedicinal application. This review article discusses recent advances in the application of AuNPs as label in bioanalytical devices, especially electrochemical immunosensors, rapid and point-of-care (PoC) tests. A crucial assessment regarding implementation of different formats of antibodies allowing rapid and sensitive analysis of a range of analytes is also provided in this study. In addition to this, different approaches to minimize antibodies into Fab, scFv or even single-domain antibody fragments like VHHs will be reviewed. Given the high level of target specificity and affinity, such biomolecules are considered to be excellent elements for on-site or PoC analysis.

Effect of osmolytes on the conformational stability of mouse monoclonal antidigoxin antibody in long-term storage

The natural selection of small organic molecules (osmolytes) that protect cellular proteins against denaturing stresses is characteristic of plants and animals that have adapted to environmental extremes. In this study the role of osmolytes on the structural stability of antibody in long-term storage was investigated. Native antibody preparations isolated from cell culture supernatant were formulated with different additives for storage stabilization. The additives studied were arginine, proline, and sorbitol. Structural stability of antibody investigated and effect of these osmolytes on retaining the native structure in long-term storage were established. CD spectra of native IgG showed the characteristics expected for beta-proteins. After the passing of given time, the beta-sheet structure of IgG was reduced but the addition of the osmolyte to antibody solution prevented loosing the ordered structures. These results can be effective for stabilization of proteins in commercial and industrial processes.

Production and Characterization of Monoclonal Antibody Against Human Serum Albumin

Hybridomas secreting monoclonal antibodies (MAbs) producing stable, specific and high affinity against human serum albumin (HSA) have been established. The aim of the present study was the production of MAbs that will be potentially used in designing immunoassay methods especially immunochromatography assay kit for screening of microalbuminuria (MAU) in the early detection of diabetic and nondiabetic nephropathy. The hybridomas were obtained by fusion of spleen cells from immunized mice with mouse myeloma cell line (SP2). After limiting dilutions three clones producing antibodies were designed as EMRC1-3, which displayed different pattern of fine specificity for HSA and low cross reaction with other proteins as elucidated by inhibition enzyme-linked immunosorbent assay (ELISA). These clones were found to be of immunoglobulin G (IgG) class with k light chain. Subclass determination showed that all three MAbs secreted IgG1 type of antibody. The results of affinity purification for the two selected clones (EMRC1 and EMRC3) displayed high affinity with no cross reactivity with any of the related protein molecules. The stable hybridomas secreting anti-HSA were expanded in 50-mL flasks for large-scale production of the required antibodies. The standard curves were constructed with a sensitivity of 10 pg per well covering up to 100 ng per well. The high binding activity to HSA antigen and having no cross reactivity with other related molecules illustrated the potential application of these antibodies as an immunodiagnostic reagent in designing an immunochromatography assay kit for screening of MAU in diabetic and nondiabetic patients.

Epitope Mapping of PR81 anti-MUC1 Monoclonal Antibody Following PEPSCAN and Phage Display Techniques

PR81 is an anti-MUC1 monoclonal antibody (MAb) which was generated against human MUC1 mucin that reacted with breast cancerous tissue, MUC1 positive cell line (MCF-7, BT-20, and T-4 7 D), and synthetic peptide, including the tandem repeat sequence of MUC1. Here we characterized the binding properties of PR81 against the tandem repeat of MUC1 by two different epitope mapping techniques, namely, PEPSCAN and phage display. Epitope mapping of PR81 MAb by PEPSCAN revealed a minimal consensus binding sequence, PDTRP, which is found on MUC1 peptide as the most important epitope. Using the phage display peptide library, we identified the motif PD(T/S/G)RP as an epitope and the motif AVGLSPDGSRGV as a mimotope recognized by PR81. Results of these two methods showed that the two residues, arginine and aspartic acid, have important roles in antibody binding and threonine can be substituted by either glycine or serine. These results may be of importance in tailor making antigens used in immunoassay.