Identification of a protective B-cell epitope of the Staphylococcus aureus GapC protein by screening a phage-displayed random peptide library

Abstract

The impact of epidemic Staphylococcus aureus (S. aureus) on public health is increasing. Because of the abuse of antibiotics, the antibiotic resistance of S. aureus is increasing. Thus, there is an urgent need to develop new immunotherapies and immunoprophylaxes. Previous studies showed that the GapC protein of S. aureus, which is a surface protein with high glyceraldehyde 3-phosphate dehydrogenase activity, transferrin binding activity, and other biological activities, is highly conserved. GapC induces an effective humoral immune response in vivo. However, the B-cell epitopes of S. aureus GapC have not been well identified. Here we used the bioinformatics tools to analyze the sequence of GapC, and we generated protective anti-GapC monoclonal antibodies (mAbs). A protective mAb (1F4) showed strong specificity to GapC and the ability to induce macrophages to phagocytose S. aureus. We screened the motif 272GYTEDEIVSSD282, which was recognized by mAb 1F4, using a phage display system. Then, we used site-directed mutagenesis to identify key amino acids in the motif. Residues G272 D276 E277 I278 and V279 formed the core of the 272GYTEDEIVSSD282 motif. In addition, we showed that this epitope peptide induced a protective humoral immune response against S. aureus infection in immunized mice. Our results will be useful for the further study of epitope-based vaccines against S. aureus infection.

Phage display for the detection, analysis, disinfection, and prevention of Staphylococcus aureus

“…[41][42][43][44]47 Another application of phage display is to help develop strategies to ameliorate the pathogenic tendencies of S. aureus through the mapping of different cell sites. [52][53][54][55][56][57][58][59] This application may serve several functions, including the identification of novel drug targets, 52,53 development of novel drug candidates, 54,55 or the display of specific antigens to work as a vaccine that elicits a strong immunological response 48,[60][61][62][63][64][65][66][67] (Figure 2). Furthermore, because phage display proteins have the capacity to bind strongly to their target receptors with high specificity, the platform can be used for the development of site-specific drug carriers, potentially enhancing the therapeutic effect of a given compound.…”

“…In addition, antigenic epitopes of adhesion molecules, surface proteins, and peptides have also been explored to understand molecular interactions between S. aureus and host cells (Table 2). [56][57][58][59] While this platform will enable the rapid identification of vaccine candidates, it does not alleviate the broader challenges associated with vaccine development. 78 Doubtless, these combined findings suggest clinical translatability in using phage display to develop human vaccine candidates that protect against S. aureus infections.…”

“…� Surface proteins � Glyceraldehyde-3-phosphate dehydrogenase C (GapC) 57 � Fibronectin-binding protein A 58 � Extracellular fibrinogen-binding protein (Efb) 59 with killed S. aureus and IgY from their spleen and blood was obtained. The RNA was obtained from the blood and spleen and subsequently reverse transcribed into cDNA.…”

“…F I G U R E 3 Summary of diverse applications of phage display on the detection, 41-51 analysis,[52][53][54][55][56][57][58][59] disinfection,48,[60][61][62][63][64][65][66][67]81,[87][88][89]95,96 and prevention51,97 of Staphylococcus aureus.4 of 16 -TIAN ET AL.…”

Filamentous bacteriophages, natural nanoparticles, for viral vaccine strategies

“…36 Precise determination of conformational epitopes of neutralizing antibodies represents a crucial step in the rational design of novel vaccines. 37 The screening of random peptide libraries displayed on phages and of gene or genome fragment phage libraries provides a powerful, cheap, and quick technique for epitope mapping. In addition, a phage random peptide library is used to find peptide candidates that bind to the target of interest.…”