Cloning and immunobiochemical analyses on recombinant chymopapain allergen Cari p 2 showing pollen-fruit cross-reaction

• Published in: Molecular immunology 2021-09, Vol.137, p.42-51
• Main Authors: Bhowmik, Moumita, Biswas Sarkar, Moumita, Kanti Sarkar, Rajat, Dasgupta, Angira, Saha, Sudipto, Jana, Kuladip, Sircar, Gaurab, Gupta Bhattacharya, Swati
• Format: Article
• Language: English
• Subjects: Cari p 2; Chymopapain; Cross-reactivity; Papaya allergy; Recombinant allergen
• ISSN: 0161-5890; 1872-9142
• DOI: 10.1016/j.molimm.2021.06.010

•Respiratory symptoms frequently occur in patients with papaya fruit allergy.•An IgE-reactive chymopapain (Cari p 2) is expressed in papaya pollen and fruit.•Cari p 2 is monomeric and shows basophil degranulation.•Cari p 2 is resistant to pepsin digestion and cross-reacts with homologous cysteine proteases from pineapple and kiwi. Papaya is reported to trigger food and respiratory allergy. Here, we identified chymopapain Cari p 2 as an allergen that can sensitize atopic individuals through fruit consumption followed by respiratory hazards through pollen exposure. Recombinant Cari p 2 displayed IgE-reactivity with 78% of papaya allergic sera. rCari p 2 also displayed allergenic activity through basophil degranulation. rCari p 2 is correctly folded and showed irreversible denaturation in the melting curve. rCari p 2 displayed IgE-cross-reactivity with homologous cysteine proteases from kiwi and pineapple. Cari p 2 transcript was also detected in papaya pulps. rCari p 2 was resistant to pepsin digestion and retained IgE-reactivity after 60 minutes of pepsin digestion. In mouse model, rCari p 2 was found to elicit inflammatory responses in the lung and gastrointestinal epithelium. Hence, Cari p 2 is a newly characterized allergen with diagnostic and immunotherapeutic potential for managing allergic disorders in papaya sensitized individuals.