18 Proteomic and Immunological Characterization of Ragweed Allergens

demonstrated for all these proteins. However, the assignment of 9 distinct allergen numbers to members of the same protein family is quite unusual. Methods: Currently, the IUIS allergen database contains 12 allergen and isoallergen sequences from C. thummi thummi. The Uniprot database has demerged entry P02225, listed in the database for Chi t 7, into 7 entries, 5 from C. thummi thummi and 2 from C. thummi piger that are identical to 2 of the sequences from C. thummi thummi. Consequently, the 16 unique amino acid sequences of the mature C. thummi allergens were aligned using ClustalX2, a neighbor-joining tree was generated from the alignment and a percent sequence identity matrix was built to evaluate appropriate nomenclature. Results: Pairwise sequence alignments showed that sequences belonging to allergens Chi t 5, 6, 7 and 8 possess sequence identities to Chi t 3 of between 51 and 63%. Chi t 1, 2, 4, and 9 diverge to a greater extent from Chi t 3 (,50% identical) and from each other. Phylogenetic tree analysis suggests the clustering of Chi t 3, 6, 7, and 8, while Chi t 1, 2, 4, 5, and 9 form separate clades. Conclusions: Based on these analyses, the IUIS Allergen Nomenclature SubCommittee renames Chi t 5, 6, 7 and 8 isoallergens of Chi t 3, even though their sequence identities to Chi t 3 are below the 67% threshold previously defined for isoallergens. The remaining hemoglobins, previously designated Chi t 1, 2, 4 and 9 will retain their previous names.