title: Characterization of bovine MHC class II DRB3 diversity in South American Holstein cattle populations.
abstract: Holstein cattle dominate the global milk production industry because of their outstanding milk production, however, this breed is susceptible to tropical endemic pathogens and suffers from heat stress and thus fewer Holstein populations are raised in tropical areas. The bovine major histocompatibility complex (BoLA)-DRB3 class II gene is used as a marker for disease and immunological traits, and its polymorphism has been studied extensively in Holstein cattle from temperate and cold regions. We studied the genetic diversity of the BoLA-DRB3 gene in South American Holstein populations to determine whether tropical populations have diverged from those bred in temperate and cold regions by selection and/or crossbreeding with local native breeds. We specifically studied Exon 2 of this gene from 855 South American Holstein individuals by a polymerase chain reaction (PCR) sequence-based typing method. We found a high degree of gene diversity at the allelic (Na > 20 and He > 0.87) and molecular (π > 0.080) levels, but a low degree of population structure (FST = 0.009215). A principal components analysis and tree showed that the Bolivian subtropical population had the largest genetic divergence compared with Holsteins bred in temperate or cold regions, and that this population was closely related to Bolivian Creole cattle. Our results suggest that Holstein genetic divergence can be explained by selection and/or gene introgression from local germplasms. This is the first examination of BoLA-DRB3 in Holsteins adapted to tropical environments, and contributes to an ongoing effort to catalog bovine MHC allele frequencies by breed and location.
authors.affiliation: Viral Infectious Diseases Unit, RIKEN, Saitama, Japan.
authors.forename: S-N
authors.initials: SN
authors.lastname: Takeshima
authors.affiliation: IGEVET, CCT LA PLATA CONICET, FCV, UNLP, La Plata, Argentina.
authors.forename: G
authors.initials: G
authors.lastname: Giovambattista
authors.affiliation: Laboratory for Computational Molecular Design, Computational Biology Research Core, Quantitative Biology Center (QBiC), RIKEN, Hyogo, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Okimoto
authors.affiliation: Viral Infectious Diseases Unit, RIKEN, Saitama, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Matsumoto
authors.affiliation: IGEVET, CCT LA PLATA CONICET, FCV, UNLP, La Plata, Argentina.
authors.forename: A
authors.initials: A
authors.lastname: Rogberg-Muñoz
authors.affiliation: Field Center of Animal Science and Agriculture, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Japan.
authors.forename: T J
authors.initials: TJ
authors.lastname: Acosta
authors.affiliation: Viral Infectious Diseases Unit, RIKEN, Saitama, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Onuma
authors.affiliation: Viral Infectious Diseases Unit, RIKEN, Saitama, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Aida
mesh_terms: D000222:Adaptation, Physiological; D000483:Alleles; D019943:Amino Acid Substitution; D000818:Animals; D001947:Breeding; D002417:Cattle / Q000235:genetics*; D005091:Exons / Q000235:genetics; D005802:Genes, MHC Class II; D014644:Genetic Variation; D005838:Genotype; D000949:Histocompatibility Antigens Class II / Q000235:genetics*; D007564:Japan; D009154:Mutation; D025341:Principal Component Analysis; D012641:Selection, Genetic; D013020:South America; D013696:Temperature; D014329:Tropical Climate
chemical_list: C423282:BoLA-DRB3 antigen; D000949:Histocompatibility Antigens Class II
keywords: BoLA-DRB3; Holstein; genetic diversity; principal components analysis; tropical disease resistance