title: Pathogen-driven selection and worldwide HLA class I diversity.
abstract: The human leukocyte antigen (HLA; known as MHC in other vertebrates) plays a central role in the recognition and presentation of antigens to the immune system and represents the most polymorphic gene cluster in the human genome [1]. Pathogen-driven balancing selection (PDBS) has been previously hypothesized to explain the remarkable polymorphism in the HLA complex, but there is, as yet, no direct support for this hypothesis [2 and 3]. A straightforward prediction coming out of the PDBS hypothesis is that populations from areas with high pathogen diversity should have increased HLA diversity in relation to their average genomic diversity. We tested this prediction by using HLA class I genetic diversity from 61 human populations. Our results show that human colonization history explains a substantial proportion of HLA genetic diversity worldwide. However, between-population variation at the HLA class I genes is also positively correlated with local pathogen richness (notably for the HLA B gene), thus providing support for the PDBS hypothesis. The proportion of variations explained by pathogen richness is higher for the HLA B gene than for the HLA A and HLA C genes. This is in good agreement with both previous immunological and genetic data suggesting that HLA B could be under a higher selective pressure from pathogens.
authors.affiliation: Theoretical and Molecular Population Genetics Group, Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3EH, United Kingdom. prugnolle@yahoo.fr
authors.forename: Franck
authors.initials: F
authors.lastname: Prugnolle
authors.forename: Andrea
authors.initials: A
authors.lastname: Manica
authors.forename: Marie
authors.initials: M
authors.lastname: Charpentier
authors.forename: Jean François
authors.initials: JF
authors.lastname: Guégan
authors.forename: Vanina
authors.initials: V
authors.lastname: Guernier
authors.forename: François
authors.initials: F
authors.lastname: Balloux
mesh_terms: D003141:Communicable Diseases / Q000235:genetics* / Q000382:microbiology / Q000469:parasitology / Q000821:virology; D016208:Databases, Factual; D005805:Genes, MHC Class I / Q000235:genetics*; D014644:Genetic Variation; D005828:Genetics, Population; D005843:Geography; D006790:Host-Parasite Interactions / Q000235:genetics; D006801:Humans; D008957:Models, Genetic; D011157:Population Dynamics; D012044:Regression Analysis; D012641:Selection, Genetic; D013045:Species Specificity