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Evaluation of cross-reactivity between casein components using inhibition assay and in silico analysis
  • +3
  • Michihiro Naito,
  • Teruaki Matsui,
  • Chikako Yamada,
  • Kazunori Tagami,
  • Komei Ito,
  • Hidehiko Izumi
Michihiro Naito
Nagoya University of Arts and Sciences
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Teruaki Matsui
Aichi Children’s Health and Medical Center
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Chikako Yamada
Nagoya University of Arts and Sciences
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Kazunori Tagami
Aichi Children’s Health and Medical Center
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Komei Ito
Aichi Children’s Health and Medical Center
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Hidehiko Izumi
Nagoya University of Arts and Sciences
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Abstract

Background: We previously reported that the specific IgE levels to αs1-casein (CN) and β-CN in patients with cow’s milk allergy decreased with similar dynamics during oral immunotherapy. Therefore, we hypothesized that αs1- and β-CN have strong cross-reactivity among CN components, despite the low similarity in the full-length amino acid sequences. Methods: The αs1-, β-, and κ-CN were purified from commercial cow’s milk. We recruited 39 patients with cow’s milk allergy and the serum IgE levels for each CN component were measured by enzyme-linked immunosorbent assay (ELISA). Cross-reactivity between CN components was investigated by competitive ELISA against αs1-CN. Sequence homology between CN components at the peptide level was calculated using in silico analysis and quantified by the Property Distance (PD) value. Results: The αs1-CN-specific IgE levels exhibited a strong positive correlation with the β-CN-specific IgE (r = 0.945, P < 0.001). Complete competition was observed by β-CN against αs1-CN, suggesting the presence of common epitopes between them. In silico analysis detected 24 peptide sets with PD values lower than 10 between αs1- and β-CN, and 14 sets between αs1- and κ-CN. The amino acid sequences of αs1- (E61-E70) and β-CN (I12-E21) that showed the lowest PD value (5.30) were present in the characteristic sequence known as casein phosphopeptide (CPP). Conclusion: We detected strong cross-reactivity between CN components. Furthermore, we found highly homologous sequences in the CPP region, which contains a core sequence of “SSSEE” with phosphorylated serine residues.

Peer review status:UNDER REVIEW

23 Jun 2020Submitted to Pediatric Allergy and Immunology
28 Jun 2020Reviewer(s) Assigned
15 Jul 2020Review(s) Completed, Editorial Evaluation Pending
24 Jul 2020Editorial Decision: Revise Major
17 Sep 20201st Revision Received
21 Sep 2020Review(s) Completed, Editorial Evaluation Pending
25 Sep 2020Reviewer(s) Assigned