Expression， purification and epitope analysis of Pla a 2 allergen from Platanus acerifolia pollen.

Platanus acerifolia is one of the major sources of outdoor allergens to humans， and can induce allergic asthma， rhinitis， dermatitis and other allergic diseases. Pla a 2 is a polygalacturonase and represents the major allergen identified in P. acerifolia pollen. The aim of the present study was to express and purify Pla a 2， and to predict B and T cell epitopes of Pla a 2. The gene encoding Pla a 2 was cloned into the pET28a vector and subsequently transfected into ArcticExpress™ (DE3) Escherichia coli cells; purified Pla a 2 was analyzed by western blot analysis. The results of the present study revealed that the Pla a 2 allergen has the ability to bind immunoglobulin E within the sera of patients allergic to P. acerifolia pollen. In addition， the B cell epitopes of Pla a 2 were predicted using the DNAStar Protean system， Bioinformatics Predicted Antigenic Peptides and BepiPred 1.0 software; T cell epitopes were predicted using NetMHCIIpan ‑3.0 and ‑2.2. In total， eight B cell epitopes (15‑24， 60‑66， 78‑86， 109‑124， 232‑240， 260‑269， 298‑306 and 315‑322) and five T cell epitopes (62‑67， 86‑91， 125‑132， 217‑222 and 343‑350) were predicted in the present study. These findings may be used to improve allergen immunotherapies and reduce the frequency of pollen‑associated allergic reactions.