Objective To predict and identify T cell epitopes of major group 3 allergen derived from Dermatophagoides fari-na(Der f 3). Methods The T cell epitopes of Der f 3 were analyzed through the sequence analysis by using the bioinformatics online tools. The five predicted peptides of T-cell epitopes were artificially synthesized. The spleen lymphocytes were co-cultured with the five T cell epitopes by using the modified MTT method and the levels of IL-2,IFN-γ,IL-4 and IL-5 in the supernatant of the cultures were detected by ELISA. Results Five T cell epitopes of Der f 3 were predicted and three of which could pro-mote the proliferation of the mouse spleen lymphocytes. The secretions of IL-2 and IFN-γwere significantly induced and the se-cretions of IL-4 and IL-5 were significantly decreased by three of five prediction epitopes of Der f 3:37GDCPYQISLQSSSHFC-GG54,98IYQHENYDSMTIDNDVALIKLKTPMT123 and 164SELQRVDIDVVSREQCDQLYS184. Conclusion Three T cell epitopes of Der f 3 have been initially identified,which lays the foundation of the diagnosis and treatment of asthma.

Objective To predict and identify the linear B-cell epitopes in the major group 3 allergen derived from Derma-tophagoides farina(Der f 3). Methods The linear B-cell epitopes of Der f 3 allergen were analyzed based on the physicochemi-cal properties of amino acids including antigenicity,surface accessibility,flexibility,hydrophilicity,beta-turn by online bioinfor-matics softwares. The eight predicted peptides of linear B-cell epitopes were artificially synthesized and incubated with three aller-gic serum pools(4 serum samples in each),which were consisted of total 12 serum samples from the allergic individuals,and the strong positive epitopes were selected. Results Eight B-cell epitopes from Der f 3 were predicted successfully. Five of eight B-cell epitopes were identified with strong IgE-binding abilities followed by specific IgE assay. The amino acid sequences of them were following:33KAKAGDCP40, 86HASGGEKIQVAEIYQHENYDSMTID110, 118LKTPMTLDQTNAKPVPLPPQGSDVKVG144, 156QEGSYSLP163 and 199DVANGGVDSCQGDSGGPVVD218. Conclusions Five linear B-cell epitopes of Der f 3 allergen have been identified successfully. This result might provide a basis of the diagnosis and treatment for asthma.

OBJECTIVETo construct a vector encoding T-cell epitopes of major allergen group 1 of Dermatophagoides pteronyssinus as a vaccine delivered by MHC class II pathway.

METHODSThe nucleotide sequences of the 3 target genes were synthesized, including TAT, IhC and the recombinant fragment of Der p 1 encoding 3 T-cell epitopes. After amplification of the 3 target fragments by PCR and digestion with corresponding restriction endonucleases, the recombinant gene TAT-IhC-Der p 1-3T was ligated using T4 DNA ligase and inserted into the prokaryotic expression vector pET28a(+) to construct the recombinant plasmid pET-28a(+)-TAT-IhC-Der p 1-3T, which was confirmed by digestion with restriction endonucleases and sequencing. The recombinant vector was transformed into E. coli strain BL21 (DE3) and induced with IPTG, and the induced protein TAT-IhC-Der p 1-3T was detected by SDS-PAGE. After purification, the recombinant protein was confirmed by Western blotting and its allergenicity tested using IgE-binding assay.

RESULTSThe recombinant plasmid pET-28a-TAT-IhC-Der p 1-3T was successfully constructed as confirmed by restriction endonuclease digestion and sequencing and the expression of the recombinant protein TAT-IhC-Der p 1-3T was induced in E. coli. Western blotting verified successfull purification of the target protein, which showed a stronger IgE-binding ability than Der p 1.

CONCLUSIONWe successfully constructed a recombinant expression vector pET-28a-TAT-IhC-Der p 1-3T expressing a T-cell epitope vaccine delivered by MHC II pathway with strong IgE-binding ability, which provides a basis for further study on specific immunotherapy via MHC class II pathway.

Allergens ; immunology ; Animals ; Antigens, Dermatophagoides ; immunology ; Arthropod Proteins ; immunology ; Base Sequence ; Cloning, Molecular ; Cysteine Endopeptidases ; immunology ; Dermatophagoides pteronyssinus ; Epitopes, T-Lymphocyte ; Escherichia coli ; Gene Expression ; Genes, MHC Class II ; Genetic Vectors ; Plasmids ; Polymerase Chain Reaction ; Recombinant Proteins ; immunology ; Vaccines ; immunology