Identification of an immunodominant IgE epitope of Der p 39, a novel allergen of Dermatophagoides pteronyssinus

Wei-Yong Li; Ze-Lang Cai; Bo-Ping Zhang; Jia-Jie Chen; Kunmei Ji

doi:10.1016/j.waojou.2022.100651

Identification of an immunodominant IgE epitope of Der p 39, a novel allergen of Dermatophagoides pteronyssinus

World Allergy Organ J. 2022 May 6;15(5):100651. doi: 10.1016/j.waojou.2022.100651. eCollection 2022 May.

Authors

Wei-Yong Li¹, Ze-Lang Cai¹, Bo-Ping Zhang¹, Jia-Jie Chen¹, Kunmei Ji¹

Affiliation

¹ Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Health Science Center, Shenzhen University, No. 1066 Xueyuan Road, Nanshan District, Shenzhen 518060, China.

Abstract

Background: House dust mites (HDMs) are the main source of indoor inhalatory allergens that cause IgE-mediated allergic diseases. The discovery and identification of HDM allergens are important for the diagnosis and treatment of allergic diseases.

Objective: We sought to identify a Group 39 Dermatophagoides pteronyssinus (Der p) allergen, namely Der p 39, and explore its immunodominant IgE epitopes.

Methods: Homology analysis of amino acid (aa) sequences in HDM and human troponin C (TnC)-like protein was performed. Total RNA of Der p was extracted and used to amplify Der p 39 cDNA with specific primers. Recombinant Der p 39 protein was expressed with a pET-His prokaryotic expression system and purified with Ni-NTA resins. IgE binding was evaluated with western blot, dot blot, and enzyme-linked immunosorbent assay (ELISA) experiments. The IgE binding epitopes of Der p 39 were identified by observing HDM-allergic sera interactions with truncated and hybrid proteins formed from Der p 39 and human TnC-like proteins.

Results: The Der p 39 open reading frame (ORF) cDNA was found to be 462 base pairs and registered in the NCBI library (GenBank no. MZ336019.1). Der p 39, which encoded 153 aa, was found to have 35.63% and 99.35% homology with human TnC and Dermatophagoides farina (Der f) 39, respectively. IgE-ELISA showed IgE binding with expressed and purified recombinant Der p 39 (18 kDa) in 5/87 (5.75%) HDM-allergic sera samples. Analyses of IgE binding with Der p 39-based truncated and hybrid proteins indicated that IgE binding epitopes are likely located in the C-terminal region and dependent on conformational structure. The data from this study were submitted to the World Health Organization and International Union of Immunological Societies (WHO/IUIS) Allergen Nomenclature database.

Conclusion: Der p 39 was identified as a minor HDM allergen with a conformational IgE binding epitope. These findings could have important theoretical implications in the development of HDM allergy diagnostics and therapeutics.

Keywords: Der p 39; HDM; IgE-binding; Immunodominant IgE epitope.