Proteome Profiling of Strawberry and Characterization of a Bet v 1-Homologous Allergen

Strawberry (Fragaria ananassa) is an economically important crop, and recognised as an important source of antioxidants and bioactive compounds with health promoting effects. Yet increased incidence of allergy puts a limit to the choice of food for an increasing percentage of the population.

As part of this thesis a strawberry allergen termed Fra a 1 was identified, which is related to a major birch pollen allergen. Allergy against strawberry is thus one of many allergies against fruits, berries and vegetables that are caused by a cross-reaction to the major birch pollen allergen, Bet v 1. The Fra a 1 gene was sequenced and found to have very little variability in amino acid sequence among different strawberry varieties.

In the search for a strawberry variety with low allergenic impact, differential expression analysis using two-dimensional electrophoresis was performed to assess the biological variation. White strawberry varieties, assumed to be tolerated by individuals affected by allergy, were found to be virtually free from the strawberry allergen. A small clinical study including a double-blind placebo-controlled food challenge indicated that the low amount of Fra a 1 in white strawberries is probably clinically relevant.

The allergen content varied between the different red strawberry varieties examined, and also within one single variety, from different producers at different growth sites, showing that searching for low-allergen strawberries must include an assessment of allergen content under several different conditions for each variety.

This thesis work has also contributed to the development of tools for proteomic data analysis, an open source project to facilitate the storage and analysis in proteomic experiments (http://www.proteios.org/) and SPECLUST, a tool for identifying protein isoforms which is available as a web-based application (http://bioinfo.thep.lu.se/speclust.html).