title: Signal sequences modulate the immunogenic performance of human hepatitis C virus E2 gene.
abstract: Envelope protein E2 of human hepatitis C virus (HCV) is an attractive component of a prototype HCV vaccine. Delivered by DNA immunogens, E2 evokes specific immune response of Th1-type, failing to induce either considerable antibody production, or T-helper cell proliferation. We aimed at modulating the immunogenic performance of E2 gene by changing the mode of protein expression in eukaryotic cells. Plasmids were constructed encoding full-length E2 and nonstructural protein 1 (p7) fused to either 13 or 38 C-terminal amino acids (aa) of HCV E1 that contain second hydrophobic segment of E1 stop-transfer signal, or a complete E1 stop-transfer signal with duplicated second hydrophobic segment. Injected into BALB/c mice, E2/p7 genes induced potent antibody and T-helper cell response targeted against hypervariable region 1, aa 472-586 of E2, and a novel epitope at aa 774-796 of p7. Profile of cytokines secreted by proliferating mouse splenocytes stimulated in vitro with E2- and p7-derived peptides, indicated mixed Th1/Th2 type of immune response. Thus, the full-length E2 and p7 genes supplied in one cassette were both immunogenic. E2/p7 containing a complete E1 stop-transfer signal with prolonged membrane spanning domain was superior to the shorter E2/p7 version in terms of both antibody and cellular immunogenicity. Optimal performance of HCV E2 could thus be achieved without the aid of external/heterologous signals by easing, through modification of the E2 signal sequence, the release of E2 from the rough ER while retaining full-length E2 and p7 sequences. This finding may help to improve the Th2 performance of HCV envelope genes as prototype vaccines.
authors.affiliation: Biomedical Research and Study Centre, University of Latvia, LV-1067 Riga, Latvia.
authors.forename: Irina
authors.initials: I
authors.lastname: Sominskaya
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Alekseeva
authors.forename: Dace
authors.initials: D
authors.lastname: Skrastina
authors.forename: Vladislav
authors.initials: V
authors.lastname: Mokhonov
authors.forename: Elizaveta
authors.initials: E
authors.lastname: Starodubova
authors.forename: Juris
authors.initials: J
authors.lastname: Jansons
authors.forename: Mikael
authors.initials: M
authors.lastname: Levi
authors.forename: Alexei
authors.initials: A
authors.lastname: Prilipov
authors.forename: Tatyana
authors.initials: T
authors.lastname: Kozlovska
authors.forename: Valeri
authors.initials: V
authors.lastname: Smirnov
authors.forename: Paul
authors.initials: P
authors.lastname: Pumpens
authors.forename: Maria G
authors.initials: MG
authors.lastname: Isaguliants
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002461:Cell Line, Transformed; D002472:Cell Transformation, Viral; D002522:Chlorocebus aethiops; D004926:Escherichia coli / Q000235:genetics; D005814:Genes, Viral; D014644:Genetic Variation; D006367:HeLa Cells; D016174:Hepacivirus / Q000235:genetics / Q000276:immunology*; D006801:Humans; D007273:Injections, Intramuscular; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D010957:Plasmids; D021382:Protein Sorting Signals / Q000502:physiology*; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D014761:Viral Hepatitis Vaccines / Q000276:immunology*; D014764:Viral Proteins / Q000276:immunology; D000086082:Viroporin Proteins
chemical_list: D021382:Protein Sorting Signals; D014759:Viral Envelope Proteins; D014761:Viral Hepatitis Vaccines; D014764:Viral Proteins; C088369:p7 protein, Hepatitis C virus; D000086082:Viroporin Proteins; C091015:glycoprotein E2, Hepatitis C virus