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Research Project: Defining, Measuring, and Mitigating Attributes that Adversely Impact the Quality and Marketability of Foods

Location: Healthy Processed Foods Research

Title: Almond (prunus dulcis) allergen pru du 8, the first member of a new family of food allergens

item CHE, HULIAN - China Agricultural University
item Zhang, Yuzhu
item JIANG, SONGSONG - China Agricultural University
item JIN, TENGCHUAN - University Of Science And Technology Of China
item LYU, SHU-CHEN - Stanford University
item NADEAU, KARI - Stanford University
item McHugh, Tara

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/9/2019
Publication Date: 7/9/2019
Citation: Che, H., Zhang, Y., Jiang, S., Jin, T., Lyu, S., Nadeau, K.C., McHugh, T.H. 2019. Almond (prunus dulcis) allergen pru du 8, the first member of a new family of food allergens. Journal of Agricultural and Food Chemistry. 67(31):8626-8631.

Interpretive Summary: Characterization of allergens is needed for a better understanding of the allergenicity of food allergens and their cross-reactivities. FDA considers almond as a tree nut which is one of the eight major food groups that cause most of the allergies in the U.S. To date, information about almond allergens is limited and sometimes confusing. A previously reported almond allergen was debated to be the 2S albumin or the 7S vicilin. This study report the identification of a new almond allergen. It contains the tow peptides for the almond allergen above. This novel allergen has antimicrobial activity and defines a new class of allergenic food proteins. The reported result and the recombinant allergen generated may be used to understand the allergenicity of almond proteins.

Technical Abstract: families. Four almond allergens are designated by WHO/IUIS. Another almond allergen with two known short peptide sequences was reported as the 2S albumin but later suspected as vicilin. Whether this almond allergen in question was the albumin, vicilin, or another uncovered protein remains to be investigated. Methods: Total RNA of the Nonpareil almond was isolated. A cDNA library was constructed by reverse transcription using a poly-T primer. The two short peptide sequences of the debated almond allergen were used to mine the database and predict its likely identity. A forward primer was designed based on its likely ortholog in Prunus mume and used, in combination with a poly-T oligo, to determine the mRNA sequence of the suspect allergen. The deduced protein was produced recombinantly, and 18 almond allergic sera were used to test whether it was an allergen. Results: Five out of 18 sera contained IgE antibodies that reacted with the recombinant protein. It is an antimicrobial protein that contains the two sequences of the above almond allergen. Vicilins of some species contained an extended N-terminal region that has homology to this antimicrobial protein, while many other species have vicilins without the extended N-terminal. Conclusions: A new almond allergen was identified. It contains the two peptides determined for a previously reported almond allergen with debated identity. This new allergen belongs to a novel class of allergenic food proteins.