Identification and Physicochemical Characterization of a New Allergen from <i>Ascaris lumbricoides</i>

• Main Authors: Velky Ahumada, María Manotas, Josefina Zakzuk, Lorenz Aglas, Sandra Coronado, Peter Briza, Peter Lackner, Ronald Regino, Galber Araujo, Fatima Ferreira, Luis Caraballo
• Format: Article
• Language: English
• Published: MDPI AG 2020-12-01
• Series: International Journal of Molecular Sciences
• Subjects: <i>Ascaris</i>; allergen; IgE; Asc l 5; cDNA-library
• Online Access: https://www.mdpi.com/1422-0067/21/24/9761
• ISSN: 1661-6596; 1422-0067

To analyze the impact of <i>Ascaris lumbricoides</i> infection on the pathogenesis and diagnosis of allergic diseases, new allergens should be identified. We report the identification of a new <i>Ascaris lumbricoides</i> allergen, Asc l 5. The aim of this study was to evaluate the physicochemical and immunological features of the Asc l 5 allergen. We constructed an <i>A. lumbricoides</i> cDNA library and Asc l 5 was identified by immunoscreening. After purification, rAsc l 5 was physicochemically characterized. Evaluation of its allergenic activity included determination of Immunoglobulin E (IgE) binding frequency (in two populations: 254 children and 298 all-age subjects), CD203c based-basophil activation tests (BAT) and a passive cutaneous anaphylaxis (PCA) mouse model. We found by amino acid sequence analysis that Asc l 5 belongs to the SXP/RAL-2 protein family of nematodes. rAsc l 5 is a monomeric protein with an alpha-helical folding. IgE sensitization to rAsc l 5 was around 52% in general population; positive BAT rate was 60%. rAsc l 5 induced specific IgE production in mice and a positive PCA reaction. These results show that Asc l 5 has structural and immunological characteristics to be considered as a new allergen from <i>A. lumbricoides</i>.