title: Leporid immunoglobulin G shows evidence of strong selective pressure on the hinge and CH3 domains.
abstract: Immunoglobulin G (IgG) is the predominant serum immunoglobulin and has the longest serum half-life of all the antibody classes. The European rabbit IgG has been of significant importance in immunological research, and is therefore well characterized. However, the IgG of other leporids has been disregarded. To evaluate the evolution of this gene in leporids, we sequenced the complete IGHG for six other genera: Bunolagus, Brachylagus, Lepus, Pentalagus, Romerolagus and Sylvilagus. The newly sequenced leporid IGHG gene has an organization and structure similar to that of the European rabbit IgG. A gradient in leporid IgG constant domain diversity was observed, with the CH1 being the most conserved and the CH3 the most variable domain. Positive selection was found to be acting on all constant domains, but with a greater incidence in the CH3 domain, where a cluster of three positively selected sites was identified. In the hinge region, only three polymorphic positions were observed. The same hinge length was observed for all leporids. Unlike the variation observed for the European rabbit, all 11 Lepus species studied share exactly the same hinge motif, suggesting its maintenance as a result of an advantageous structure or conformation.
authors.affiliation: CIBIO Centro de Investigação em Biodiversidade e Recursos Genéticos, InBio Laboratório Associado, Universidade do Porto, Campus Agrário de Vairão, Vairão 4485-661, Portugal Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, Porto 4169-007, Portugal SaBio IREC (CSIC-UCLM-JCCM), Ronda de Toledo s/n, Ciudad Real 13071, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Pinheiro
authors.affiliation: Division of Cancer Research, Medical Research Institute, University of Dundee Medical School, Ninewells Hospital, Dundee DD1 9SY, UK.
authors.forename: Jenny M
authors.initials: JM
authors.lastname: Woof
authors.affiliation: CIBIO Centro de Investigação em Biodiversidade e Recursos Genéticos, InBio Laboratório Associado, Universidade do Porto, Campus Agrário de Vairão, Vairão 4485-661, Portugal.
authors.forename: Tereza
authors.initials: T
authors.lastname: Almeida
authors.affiliation: CIBIO Centro de Investigação em Biodiversidade e Recursos Genéticos, InBio Laboratório Associado, Universidade do Porto, Campus Agrário de Vairão, Vairão 4485-661, Portugal.
authors.forename: Joana
authors.initials: J
authors.lastname: Abrantes
authors.affiliation: CIBIO Centro de Investigação em Biodiversidade e Recursos Genéticos, InBio Laboratório Associado, Universidade do Porto, Campus Agrário de Vairão, Vairão 4485-661, Portugal Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, Porto 4169-007, Portugal Wildlife Biology Program, College of Forestry and Conservation, University of Montana, Missoula, MT 59812, USA.
authors.forename: Paulo C
authors.initials: PC
authors.lastname: Alves
authors.affiliation: SaBio IREC (CSIC-UCLM-JCCM), Ronda de Toledo s/n, Ciudad Real 13071, Spain.
authors.forename: Christian
authors.initials: C
authors.lastname: Gortázar
authors.affiliation: CIBIO Centro de Investigação em Biodiversidade e Recursos Genéticos, InBio Laboratório Associado, Universidade do Porto, Campus Agrário de Vairão, Vairão 4485-661, Portugal Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, Porto 4169-007, Portugal CESPU, Instituto de Investigação e Formação Avançada em Ciências e Tecnologias da Saúde, Gandra PRD, Portugal pjesteves@cibio.up.pt.
authors.forename: Pedro J
authors.initials: PJ
authors.lastname: Esteves
mesh_terms: D000818:Animals; D019143:Evolution, Molecular; D014644:Genetic Variation; D034621:Hares / Q000145:classification* / Q000235:genetics* / Q000276:immunology; D052058:Hinge Exons; D007074:Immunoglobulin G / Q000737:chemistry* / Q000235:genetics*; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D011817:Rabbits; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA; D013045:Species Specificity
chemical_list: D007074:Immunoglobulin G
keywords: IGHG; evolution; genetic diversity; hinge region; immunoglobulins constant region; rabbit