Nucleotide sequence and T cell epitopes of a membrane protein of Francisella tularensis.
A 17-kDa major membrane protein of the facultative intracellular bacterium Francisella tularensis is recognized by T cells from individuals previously undergoing tularemia or tularemia vaccination. Here the nucleotide sequence of the encoding gene is presented. The A + T rich sequence deduced a protein of 149 amino acids with a predicted m.w. of 15,772. Evidence is presented suggesting that the 17-kDa protein is a lipoprotein. Also, homology was found to a peptidoglycan-associated lipoprotein of Escherichia coli. Thirteen overlapping synthetic peptides encompassing the entire deduced protein were tested on lymphocytes from F. tularensis-primed individuals. Three peptides induced a T cell response, as disclosed by lymphocyte proliferation and production of IL-2 and IFN-gamma. Out of five responding individuals, only one recognized more than one of the peptides. A murine mAb recognized an epitope separate from the T cell-reactive peptides. The identified T cell epitopes are presumably relevant to the host defense against F. tularensis, especially because IFN-gamma is known to enhance the antimicrobial activity of the host against intracellular bacteria.
Department of Cell- and Microbiology, National Defence Research Establishment, Umeå, Sweden.
A
A
Sjöstedt
G
G
Sandström
A
A
Tärnvik
B
B
Jaurin
D000595:Amino Acid Sequence; D000942:Antigens, Bacterial / Q000276:immunology*; D001426:Bacterial Proteins / Q000235:genetics / Q000648:ultrastructure; D001483:Base Sequence; D003001:Cloning, Molecular; D000939:Epitopes; D005604:Francisella tularensis / Q000276:immunology*; D005798:Genes, Bacterial; D006681:HLA-D Antigens / Q000276:immunology; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology* / Q000648:ultrastructure; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000276:immunology; D011487:Protein Conformation; D012045:Regulatory Sequences, Nucleic Acid; D015183:Restriction Mapping; D013601:T-Lymphocytes / Q000276:immunology*
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D000939:Epitopes; D006681:HLA-D Antigens; D008565:Membrane Proteins; D010446:Peptide Fragments