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Antigenic epitopes on the outer membrane protein A of Escherichia coli identified with single-chain variable fragment

Pharaoh Fellow Mwale1,2, Chi-Hsin Lee1,2, Sy-Jye Leu3,4

  • 1Ph.D. Program in Medical Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan.

Applied Microbiology and Biotechnology
|April 28, 2019
PubMed

Insights

Researchers developed specific antibodies targeting Outer Membrane Protein A (OmpA) from Escherichia coli K1, a key cause of neonatal meningitis. These diagnostic antibodies show promise for detecting E. coli K1 meningitis.

Area of Science:

  • Microbiology
  • Immunology
  • Molecular Biology

Background:

  • Bacterial meningitis is a severe, often fatal, disease, with *Escherichia coli* (E. coli) K1 being a primary cause in neonates.
  • The E. coli K1 outer membrane protein A (OmpA) is crucial for bacterial adhesion and invasion of endothelial cells, making it a potential diagnostic and therapeutic target.

Purpose of the Study:

  • To develop specific antibodies against the OmpA protein of *E. coli* K1 for potential use as diagnostic agents.
  • To characterize the binding epitopes of these antibodies on the OmpA protein.

Main Methods:

  • Recombinant OmpA proteins (full-length and truncated) were expressed and purified.
  • Antibody libraries were constructed using phage display technology to select single-chain variable fragment (scFv) antibodies against OmpA.
  • Antibody specificity and binding epitopes were confirmed using ELISA, immunofluorescent staining, and immunoblotting.

Main Results:

  • Twelve monoclonal antibodies were identified that react with OmpA fragments.
  • Seven scFvs recognized fragments including residues 1-346, 1-287, 1-167, and 60-192.
  • Three distinct antigenic epitopes on OmpA were mapped: 60-160 aa, 161-167 aa, and 193-245 aa.

Conclusions:

  • The developed scFv antibodies exhibit strong reactivity against *E. coli* K1 OmpA.
  • These antibodies represent promising diagnostic tools for the detection of *E. coli* K1 meningitis.
Keywords:
Antigenic epitopesBacterial meningitisEscherichia coli strain K1Outer membrane protein A (OmpA)Phage display technologySingle-chain variable fragment (scFv) antibody

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