The Staphylococcus aureus protein A (SpA) can be obtained through the culture of wild-type S. aureus and also as a recombinant protein in safe bacterial hosts. Several methods have been used to purify SpA among which ion-exchange chromatography, affinity chromatography, gel filtration, and per aqueous liquid chromatography (PALC) are common. SpA has a wide range of biochemical, biotechnological, and medical applications and is most commonly used in test methods such as immunoprecipitation, enzyme-linked immunosorbent assay, and Western blotting. SpA has also been widely utilized in pharmaceutical applications to bind to immune complexes and serum immunoglobulins. SpA also directly binds to the B-cells preventing initiation of infectious diseases as well as having a role in the development of various autoimmune diseases. This review considers different applications of SpA in biotechnology and its novel clinical application for effective treatment of autoimmune diseases. It also discusses various strategies for expression and purification of the SpA including types of column chromatography that are commonly used in protein purification and developing SpA surface display technologies. Finally, this review highlights the potential and novel applications of SpA immobilization, SpA typing, protein engineering for further development of immunological and biochemical research, and also application of SpA as a diagnostic biosensor.
Protein A from Staphylococcus aureus (SpA) is a 40-60 kDa cell-wall component, composed of five homologous immunoglobulin (Ig)-binding domains folded into a three-helix bundle. Each of these five domains is able to bind Igs from many different mammalian species. Recombinant SpA is widely used as a component of diagnostic kits for the detection and purification of IgGs from serum or other biological fluids. In this study, purified SpA was adsorbed and covalently linked to Bacillus subtilis spores. Spores are extremely stable cell forms and are considered as an attractive platform to display heterologous proteins. A sample containing about 36 μg of SpA was covalently immobilized on the surface of 4 × 10(10) spores. Spore-bound SpA retained its IgG-binding activity, even after seven consecutive binding and washing steps, suggesting that it can be recycled and utilized several times. FACS analysis revealed that spores with covalently attached SpA had significantly improved fluorescence intensities when compared to those of spores with adsorbed SpA, suggesting that the covalent approach is more efficient than sole adsorption regarding protein attachment to the spore surface.
High-affinity ligands, such as protein A, can be used to develop biocompatible matrices for antibody purification. In this paper, two methods were used for immobilization of protein A on the chitosan. In the first approach, amino groups of chitosan beads were functionalized with tris(2-aminoethyl)amine to produce amine double-branched moieties, which were subsequently activated with glutaraldehyde. In the second approach, chitosan beads were directly modified by glutaraldehyde to produce aldehyde groups. Structural characterization and successful modification of the functional groups on the supports were confirmed by scanning electron microscopy, FTIR spectroscopy and elemental analysis. Covalent immobilization of protein A was then performed on the surface of both supports. The immobilization yield was determined by using fluorescence spectroscopy, showing almost 15% increased capacity for the double-branched derivatized chitosan. The Immunoglobulin G (IgG) purification ability of the double-branched support was also almost 1.7-fold higher than the monoaldehyde derivative at the same condition.
Aim: The presence of microbial species in reproductive tubes plays an essential protective role against the proliferation of harmful organisms and is an important factor in reproductive health. High-throughput culture-independent technologies allow the study of the vaginal microbiome on a large scale. This study aimed to compare the vaginal microbiota between pregnant and nonpregnant women of different ages and races using the meta-analysis method. Materials & methods: Seven articles with 16S rRNA gene sequences were studied and analyzed using CLC Genomics Workbench 20.1.1. Results & conclusion: This study revealed new insights into the effects of age and ethnicity on the pregnant and nonpregnant vaginal microbiome and found that the microbiome of Chinese women is more distinct than that of other ethnicities.
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