Evaluation of the allergenic risk of proteins of food origin

Abstract

Food allergy is a dangerous health issue worldwide especially in children. It is causing malnutrition problems and multiple deficiencies due to the eviction diet followed. In our study, we worked on 3 distinct axes of food allergy. First, we started with a cross-sectional, random, questionnaire based survey in the schools of the city of Guelma (Algeria). Then, allergens were extracted from different foods: ovalbumin and ovomucoid from hen’s egg, α- lactalbumin and β-lactoglobulin from cow’s milk, protein M from sardines and gliadins from wheat. A biochemical characterization was done in order to find common characteristics of allergens. Finally, leaf protein extract of lucerne was studied using a combined proteomics, in vitro and in silico approach to suggest alfalfa as a protein substitute for allergic patients. The results showed the prevalence of food allergy in schoolchildren to be 8.5% (95% CI 6.1–10.8). The top foods causing allergy were: Chocolate (1.7%), wheat (1.3%), milk (1.1%), eggs (1.1%), strawberry (1.1%), and fish (0.9%). The presence of family history influences the appearance of the allergy. On the other hand, the extracted allergens were characterized with an acidic pH. The multiple sequence alignment of the allergens didn’t reveal any sequence similarity except for the allergens from the same food. The combination of in silico and in vitro allowed the detection of proteins in alfalfa leaves sharing similar sequences or cross-reacting with plant allergens from three different allergen families such as lipid transfer protein, thaumatin-like and Bet v 1-like protein families. To conclude, the main risk factor leading to the appearance of food allergy was family history. The allergens can have some common characteristics like the acidic pH. However, no significant amino acid sequence was found to be similar between the studied allergens. The use of in silico and in vitro approach predicted the allergenicity of alfalfa. This plant can be safely introduced as a protein-rich supplement in the diet of patients allergic to animal food allergens.