title: Fundamental characteristics of the immunoglobulin VH repertoire of chickens in comparison with those of humans, mice, and camelids.
abstract: Examination of 1269 unique naive chicken V(H) sequences showed that the majority of positions in the framework (FW) regions were maintained as germline, with high mutation rates observed in the CDRs. Many FW mutations could be clearly related to the modulation of CDR structure or the V(H)-V(L) interface. CDRs 1 and 2 of the V(H) exhibited frequent mutation in solvent-exposed positions, but conservation of common structural residues also found in human CDRs at the same positions. In comparison with humans and mice, the chicken CDR3 repertoire was skewed toward longer sequences, was dominated by small amino acids (G/S/A/C/T), and had higher cysteine (chicken, 9.4%; human, 1.6%; and mouse, 0.25%) but lower tyrosine content (chicken, 9.2%; human, 16.8%; and mouse 26.4%). A strong correlation (R(2) = 0.97) was observed between increasing CDR3 length and higher cysteine content. This suggests that noncanonical disulfides are strongly favored in chickens, potentially increasing CDR stability and complexity in the topology of the combining site. The probable formation of disulfide bonds between CDR3 and CDR1, FW2, or CDR2 was also observed, as described in camelids. All features of the naive repertoire were fully replicated in the target-selected, phage-displayed repertoire. The isolation of a chicken Fab with four noncanonical cysteines in the V(H) that exhibits 64 nM (K(D)) binding affinity for its target proved these constituents to be part of the humoral response, not artifacts. This study supports the hypothesis that disulfide bond-constrained CDR3s are a structural diversification strategy in the restricted germline v-gene repertoire of chickens.
authors: Global Biotherapeutics Technologies, Pfizer, Cambridge, MA 02140, USA.
authors: Leeying
authors: L
authors: Wu
authors: Katarzyna
authors: K
authors: Oficjalska
authors: Matthew
authors: M
authors: Lambert
authors: Brian J
authors: BJ
authors: Fennell
authors: Alfredo
authors: A
authors: Darmanin-Sheehan
authors: Deirdre
authors: D
authors: Ní Shúilleabháin
authors: Bénédicte
authors: B
authors: Autin
authors: Emma
authors: E
authors: Cummins
authors: Lioudmila
authors: L
authors: Tchistiakova
authors: Laird
authors: L
authors: Bloom
authors: Janet
authors: J
authors: Paulsen
authors: Davinder
authors: D
authors: Gill
authors: Orla
authors: O
authors: Cunningham
authors: William J J
authors: WJ
authors: Finlay
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D000915:Antibody Affinity / Q000235:genetics; D002162:Camelus / Q000235:genetics / Q000276:immunology; D002645:Chickens / Q000235:genetics* / Q000276:immunology; D022801:Complementarity Determining Regions / Q000235:genetics* / Q000276:immunology; D004220:Disulfides / Q000276:immunology; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics* / Q000276:immunology; D051379:Mice; D009154:Mutation; D055550:Protein Stability; D013045:Species Specificity
chemical_list: D022801:Complementarity Determining Regions; D004220:Disulfides; D007143:Immunoglobulin Heavy Chains