Major histocompatibility complex variation at class II DQA locus in the brown hare (Lepus europaeus)

Abstract

The major histocompatability complex (MHC) is a multigene family of receptors that bind and present antigenic peptides to T-cells. Genes of the MHC are characterized by an outstanding genetic polymorphism, which is considered to be maintained by positive selection. Sites involved in peptide binding form binding pockets (P) that are collectively termed the peptide-binding region (PBR). In this study, we examined the level of MHC genetic diversity within and among natural populations of brown hare (Lepus europaeus) from Europe and Anatolia choosing for analysis of the second exon of the DQA locus, one of the most polymorphic class II loci. We aimed at an integrated population genetic analysis of L. europeaus by (i) correlating MHC polymorphism to genetic variability and phylogenetic status estimated previously from maternally (mtDNA) and biparentally (allozymes, microsatellites) inherited loci; and (ii) comparing full-length exon amino acid polymorphism with functional polymorphism in the PBR and the binding pockets P1, P6 and P9. A substantial level of DQA exon 2 polymorphism was detected with two completely different set of alleles between the Anatolian and European populations. However, the phylogeny of full-length exon 2 Leeu-DQA alleles did not show a strong phylogeographic signal. The presence of balancing selection was supported by a statistically significant excess of nonsynonymous substitutions over synonymous in the PBR and a trans-species pattern of evolution detected after phylogenetic reconstruction. The differentiating patterns detected between genetic and functional polymorphism, i.e. the number and the distribution of pocket variants within and among populations, indicated a hierarchical action of selection pressures.

MHC class II DQA gene variation across cohorts of brown hares (Lepus europaeus) from eastern Austria: Testing for different selection hypotheses

“…Our results contrast with others where support for NFDS and FSP have been reported (Westerdahl et al, 2004;Dionne et al, 2009). However, there is evidence for diversifying selection in space in Brown hare Koutsogiannouli et al, 2009). Indeed, differences in climate and parasite composition between the regions seem to have created contrasting selection regimes at class II MHC loci (Smith et al, 2009).…”

Genetic Contribution of MHC Class II Genes in Susceptibility to West Nile Virus Infection

“…Due to the underrepresentation of Greek populations in MHC class II studies and in the IMGT/HLA Database [24] as well as the low sample size of the existing studies, ethnic-specific rare alleles could have been “missed out”. On the other hand, the existence of population-specific alleles suggests that differential selective pressures maintained these MHC allelic differences [28]. It has been shown that population-specific variation at the HLA class I loci is positively correlated with local pathogen richness [29].…”

cDNA cloning and polymorphic domains of the major histocompatibility complex (MHC) class I in two Chinese native chicken breeds

“…No relationship was found between breeds feature and MHC class Iα gene in phylogenetic trees. Similarly, Koutsogiannouli et al (2009) surveyed the level of MHC genetic diversity of European and Asia brown hares (Lepus europaeus) in natural populations, and did not find a strong phylogeographic signal in the full-length exon 2eeu-DQA alleles' phylogeny. Xu et al (2009) found that three MHC alleles (DQB, DRA and MHC-I) of cetaceans showed similarity and identity when compared with the phylogenetic trees.…”

“…Fax: 0086-551-5786013. and Yang, 2008;O'Leary et al, 2009), whales (Xu et al, 2009) wild animals (Koutsogiannouli et al, 2009;Becker et al, 2009) and avian (Ewald and Livant, 2004;Westerdahl et al, 2000).…”