title: Enhanced immunogenicity of HPV 16 E7 fusion proteins in DNA vaccination.
abstract: DNA vaccination is a promising approach for inducing both humoral and cellular immune responses. For immunotherapy of HPV-16-associated diseases the E7 protein is considered a prime candidate, as it is expressed in all HPV-16-positive tumors. Unfortunately, the E7 protein is a very poor inducer of a cytotoxic T-cell response, when being used as antigen in DNA vaccination. Here we demonstrate that after fusion to protein export/import signals such as the herpes simplex virus ferry protein VP22, E7 can translocate in vitro from VP22-E7-expressing cells to neighboring cells that do not carry the VP22-E7 gene. In vivo, the VP22-E7 fusion shows significantly increased efficiency in inducing a cytotoxic T-cell response. Our data suggest that the export function of VP22 plays a major role in this phenomenon, since VP22 can be replaced by classical protein export signals, without impairing the induction of the E7-specific cellular immune response. However, all E7 fusion constructs showed significantly elevated protein steady-state levels, which might also account for the observed boost in immunogenicity.
authors.affiliation: Institut für Angewandte Tumorvirologie, Deutsches Krebsforschungszentrum Heidelberg, Im Neuenheimer Feld 242, 69120 Heidelberg, Germany.
authors.forename: Nico
authors.initials: N
authors.lastname: Michel
authors.forename: Wolfram
authors.initials: W
authors.lastname: Osen
authors.forename: Lutz
authors.initials: L
authors.lastname: Gissmann
authors.forename: Ton N M
authors.initials: TN
authors.lastname: Schumacher
authors.forename: Hanswalter
authors.initials: H
authors.lastname: Zentgraf
authors.forename: Martin
authors.initials: M
authors.lastname: Müller
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D005260:Female; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D009856:Oncogene Proteins, Viral / Q000737:chemistry / Q000235:genetics* / Q000276:immunology*; D027383:Papillomaviridae / Q000276:immunology; D050725:Papillomavirus E7 Proteins; D030361:Papillomavirus Infections / Q000517:prevention & control; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D014412:Tumor Virus Infections / Q000517:prevention & control; D014611:Vaccination; D019444:Vaccines, DNA / Q000276:immunology*; D014764:Viral Proteins / Q000235:genetics / Q000276:immunology; D014765:Viral Vaccines / Q000276:immunology
chemical_list: D009856:Oncogene Proteins, Viral; D050725:Papillomavirus E7 Proteins; D011993:Recombinant Fusion Proteins; D019444:Vaccines, DNA; D014764:Viral Proteins; D014765:Viral Vaccines; C059731:oncogene protein E7, Human papillomavirus type 16