title: Fusion to Listeriolysin O and delivery by Listeria monocytogenes enhances the immunogenicity of HER-2/neu and reveals subdominant epitopes in the FVB/N mouse.
abstract: Five overlapping fragments of rat HER-2/neu have been expressed in recombinant Listeria monocytogenes. Each fragment of HER-2/neu is secreted as a fusion protein with a truncated, nonhemolytic form of listeriolysin O (LLO). Lm-LLO-EC1, Lm-LLO-EC2, and Lm-LLO-EC3 overlap the extracellular domain of HER-2/neu, whereas Lm-LLO-IC1 and Lm-LLO-IC2 span the intracellular domain. All five strains controlled the growth of established NT-2 tumors, a rat HER-2/neu-expressing tumor line derived from a spontaneously arising mammary tumor in a FVB/N HER-2/neu-transgenic mouse. The antitumor effect of each of these vaccine constructs was abrogated by the in vivo depletion of CD8(+) T cells, although only one known epitope has been defined previously and is present in Lm-LLO-EC2. Anti-HER-2/neu CTL responses were generated by each of the rLm vaccine constructs. With the use of a panel of 3T3 cell lines expressing overlapping fragments of HER-2/neu, regions of HER-2/neu with potential CD8(+) T cell epitopes have been defined. DNA vaccines expressing either a fragment or full-length HER-2/neu were constructed in LLO-fused and non-LLO-fused forms. CTL analysis of the DNA vaccines revealed a broadening in the regions of HER-2/neu recognizable as targets when the target Ag is fused to LLO. These studies show the efficacy of L. monocytogenes-based HER-2/neu vaccines in a murine model of breast cancer and also that the immunogenicity of self-Ags can be increased by fusion to LLO and delivery by L. monocytogenes revealing subdominant epitopes.
authors.affiliation: Department of Microbiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
authors.forename: Reshma
authors.initials: R
authors.lastname: Singh
authors.forename: Mary E
authors.initials: ME
authors.lastname: Dominiecki
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Jaffee
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Paterson
mesh_terms: D000818:Animals; D000951:Antigens, Neoplasm / Q000235:genetics / Q000276:immunology / Q000627:therapeutic use; D001427:Bacterial Toxins / Q000235:genetics; D001943:Breast Neoplasms / Q000628:therapy; D019496:Cancer Vaccines / Q000008:administration & dosage* / Q000494:pharmacology; D045744:Cell Line, Tumor; D018604:Epitope Mapping / Q000379:methods*; D005260:Female; D006360:Heat-Shock Proteins / Q000235:genetics; D006460:Hemolysin Proteins; D007109:Immunity; D008089:Listeria monocytogenes / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D010446:Peptide Fragments / Q000235:genetics / Q000276:immunology; D051381:Rats; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics / Q000276:immunology* / Q000627:therapeutic use; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology* / Q000627:therapeutic use; D013602:T-Lymphocytes, Cytotoxic; D014183:Transplantation, Heterologous; D019444:Vaccines, DNA / Q000008:administration & dosage / Q000494:pharmacology
chemical_list: D000951:Antigens, Neoplasm; D001427:Bacterial Toxins; D019496:Cancer Vaccines; D006360:Heat-Shock Proteins; D006460:Hemolysin Proteins; D010446:Peptide Fragments; D018719:Erb-b2 Receptor Tyrosine Kinases; D011993:Recombinant Fusion Proteins; D019444:Vaccines, DNA; C038705:hlyA protein, Listeria monocytogenes