D3.485 - Prevalence of Ambrosia artemisiifolia in Italy: Bioinformatics and Botanical Aerobiology Analysis

Ambrosia artemisiifolia is a plant native to northern Europe whose recent spread, favored by climate change, represents a growing issue in allergology. Eleven allergens (Amb a 1–Amb a 11) have been identified, with Amb a 1 being the major allergen, recognized by more than 90% of sensitized patients. Skin prick tests are the reference method for diagnosis. Particular attention is given to Amb a 1 and Amb a 4, the latter showing homology with Art v 1 from Artemisia vulgaris.

Comparative bioinformatic analyses were performed between Amb a 1, Amb a 4, and various allergens (trees, grasses, mites, fruits, animals). These included sequence comparison, calculation of similarity and identity, Levenshtein distance, 3D modeling, and epitope prediction. For these allergens, an analysis was carried out using online prediction tools (PyMOL), aimed at identifying potential epitope regions of the proteins, as well as investigating possible correspondence between the predicted epitope regions of different allergens and those of Amb a 1 or Amb a 4 proteins, with which they had shown significant values in the initial study.

No significant homology was observed between Amb a 1 and most of the allergens studied, with the exception of Cup a 1 and Cry j 1 (tree allergens), which showed high Similarity and Identity values. Amb a 4 shows notable homology with Cup a 1 (Identity 40.8% + Similarity 53.8%), but no significant relationship with grasses or trees. Despite some structural similarities, epitope predictions do not clearly demonstrate immunological cross-reactivity.

These results highlight the specificity of Amb a 1 and confirm the diagnostic value of ragweed extracts. The similarity observed with certain tree allergens is not sufficient to predict IgE cross-reactivity. A notable exception concerns the tree allergens Cup a 1 and Cry j 1, which show high Similarity and Identity values with Amb a 1. The limitations of in silico approaches justify the need for additional experimental studies to confirm the clinical relevance of these observations.