title: Human antibody expression in transgenic rats: comparison of chimeric IgH loci with human VH, D and JH but bearing different rat C-gene regions.
abstract: Expression of human antibody repertoires in transgenic animals has been accomplished by introducing large human Ig loci into mice and, more recently, a chimeric IgH locus into rats. With human VH, D and JH genes linked to the rat C-region antibody expression was significantly increased, similar to wild-type levels not found with fully human constructs. Here we compare four rat-lines containing the same human VH-region (comprising 22 VHs, all Ds and all JHs in natural configuration) but linked to different rat CH-genes and regulatory sequences. The endogenous IgH locus was silenced by zinc-finger nucleases. After breeding, all lines produced exclusively chimeric human H-chain with near normal IgM levels. However, in two lines poor IgG expression and inefficient immune responses were observed, implying that high expression, class-switching and hypermutation are linked to optimal enhancer function provided by the large regulatory region at the 3' end of the IgH locus. Furthermore, exclusion of Cδ and its downstream interval region may assist recombination. Highly diverse IgG and immune responses similar to normal rats were identified in two strains carrying diverse and differently spaced C-genes.
authors.affiliation: Recombinant Antibody Technology Ltd., Cambridge, UK.
authors.forename: Biao
authors.initials: B
authors.lastname: Ma
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Osborn
authors.forename: Suzanne
authors.initials: S
authors.lastname: Avis
authors.forename: Laure-Hélène
authors.initials: LH
authors.lastname: Ouisse
authors.forename: Séverine
authors.initials: S
authors.lastname: Ménoret
authors.forename: Ignacio
authors.initials: I
authors.lastname: Anegon
authors.forename: Roland
authors.initials: R
authors.lastname: Buelow
authors.forename: Marianne
authors.initials: M
authors.lastname: Brüggemann
mesh_terms: D000818:Animals; D000916:Antibody Diversity / Q000235:genetics*; D050438:Genes, Immunoglobulin Heavy Chain / Q000235:genetics*; D050439:Genes, Immunoglobulin Light Chain / Q000235:genetics; D056426:Genetic Loci; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000235:genetics / Q000378:metabolism*; D007135:Immunoglobulin Variable Region / Q000235:genetics; D051381:Rats; D011919:Rats, Inbred Strains; D055647:Rats, Transgenic; D011993:Recombinant Fusion Proteins / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D050441:VDJ Exons / Q000235:genetics
chemical_list: D007141:Immunoglobulin Fc Fragments; D007135:Immunoglobulin Variable Region; D011993:Recombinant Fusion Proteins
keywords: 3′RR; BAC; IgH 3′ regulatory region; IgH constructs; Regulatory region; Transgenic rats; YAC; ZFN; bacterial artificial chromosome; yeast artificial chromosome; zinc-finger nuclease.