Recombinant production of Morus alba lipid transfer protein and prediction of its allergenic epitopes

Background

White mulberry (Morus alba) pollen grains trigger allergic diseases including asthma, allergic rhinitis, and allergic conjunctivitis. Non-specific lipid transfer proteins (nsLTPs) are robust allergens found in higher plants. Although it was isolated and immunologically characterized in the fruits of Morus nigra, it has not yet been determined whether nsLTP is one of the M. alba pollen allergens.

Objective

This study aims to examine the possible allergenicity of M. alba pollen nsLTP by producing it recombinantly, followed by immunoblotting.

Methods

Total RNA was isolated from M. alba pollen grains, and the nsLTP gene was obtained by reverse transcriptase polymerase reaction. It was cloned into Escherichia coli using pQE2 plasmid and purified by immobilized metal affinity chromatography following the expression. To confirm the immunoreactivity of the purified r-nsLTP, immunoblotting was performed with the serum of patients allergic to M. alba pollen. B-cell epitopes of nsLTP were also predicted using the bioinformatics tools, namely Bioinformatics Predicted Antigenic Peptides, BepiPred-2.0, and the Immune Epitope Database, whereas T-cell epitopes were estimated by using NetMHCIIpan-4.0 and NetMHCII-2.3 servers.

Results

The r-nsLTP showed positive results in immunoblotting with sera of 7/7 (100%) of M. alba allergic patients. Five B-cell epitopes (26–31, 43–50, 65–71, 92–100, 105–115) and three T-cell epitopes (57–65, 78–86, 105–113) were predicted by in silico analyses.

Conclusion

Data obtained in this study are expected to support the use of r-nsLTP in solutions for diagnosis and treatment of M. alba allergy and cross-reactivities between nsLTPs, as well as recombinant allergen production for vaccination.