title: Stop codon insertion restores the particle formation ability of hepatitis B virus core-hantavirus nucleocapsid protein fusions.
abstract: In recent years, epitopes of various origin have been inserted into the core protein of hepatitis B virus (HBc), allowing the formation of chimeric HBc particles. Although the C-terminus of a C-terminally truncated HBc (HBc) tolerates the insertion of extended foreign sequences, the insertion capacity is still a limiting factor for the construction of multivalent vaccines. Previously, we described a new system to generate HBc mosaic particles based on a read-through mechanism in an Escherichia coli suppressor strain [J Gen Virol 1997;78:2049-2053]. Those mosaic particles allowed the insertion of a 114-amino acid (aa)-long segment of a Puumala hantavirus (PUUV) nucleocapsid (N) protein. To study the value and the potential limitations of the mosaic approach in more detail, we investigated the assembly capacity of 'non-mosaic' HBc fusion proteins and the corresponding mosaic constructs carrying 94, 213 and 433 aa of the hantaviral N protein. Whereas the fusion proteins carrying 94, 114, 213 or 433 aa were not assembled into HBc particles, or only at a low yield, the insertion of a stop codon-bearing linker restored the ability to form particles with 94, 114 and 213 foreign aa. The mosaic particles formed exhibited PUUV-N protein antigenicity. Immunization of BALB/c mice with these mosaic particles carrying PUUV-N protein aa 1-114, aa 1-213 and aa 340-433, respectively, induced HBc-specific antibodies, whereas PUUV-N protein-specific antibodies were detected only in mice immunized with particles carrying N-terminal aa 1-114 or aa 1-213 of the N protein. Both the anti-HBc and anti-PUUV antibody responses were IgG1 dominated. In conclusion, stop codon suppression allows the formation of mosaic core particles carrying large-sized and 'problematic', e.g. hydrophobic, hantavirus sequences.
authors.affiliation: Biomedical Research and Study Centre, University of Latvia, Riga, Latvia.
authors.forename: Andris
authors.initials: A
authors.lastname: Kazaks
authors.forename: Sylvie
authors.initials: S
authors.lastname: Lachmann
authors.forename: Diana
authors.initials: D
authors.lastname: Koletzki
authors.forename: Ivars
authors.initials: I
authors.lastname: Petrovskis
authors.forename: Andris
authors.initials: A
authors.lastname: Dislers
authors.forename: Velta
authors.initials: V
authors.lastname: Ose
authors.forename: Dace
authors.initials: D
authors.lastname: Skrastina
authors.forename: Hans R
authors.initials: HR
authors.lastname: Gelderblom
authors.forename: Ake
authors.initials: A
authors.lastname: Lundkvist
authors.forename: Helga
authors.initials: H
authors.lastname: Meisel
authors.forename: Galina
authors.initials: G
authors.lastname: Borisova
authors.forename: Detlev H
authors.initials: DH
authors.lastname: Krüger
authors.forename: Paul
authors.initials: P
authors.lastname: Pumpens
authors.forename: Rainer
authors.initials: R
authors.lastname: Ulrich
mesh_terms: D000818:Animals; D001483:Base Sequence; D018388:Codon, Terminator; D006512:Hepatitis B Core Antigens / Q000235:genetics* / Q000276:immunology; D006515:Hepatitis B virus / Q000502:physiology*; D007114:Immunization; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D019251:Nucleocapsid / Q000235:genetics* / Q000276:immunology; D019590:Nucleocapsid Proteins; D011993:Recombinant Fusion Proteins / Q000276:immunology*; D014771:Virion / Q000502:physiology*
chemical_list: D018388:Codon, Terminator; D006512:Hepatitis B Core Antigens; D019590:Nucleocapsid Proteins; D011993:Recombinant Fusion Proteins; C100886:nucleocapsid protein, Puumala virus