Genetic diversity of the class II major histocompatibility DRA locus in European, Asiatic and African domestic donkeys Marie Vranova a , Ingrid Alloggio b , Moneeb Qablan c , Mirko Vyskocil a , Aneta Baumeisterova a , Michal Sloboda c , Lenka Putnova d , Irena Vrtkova d , David Modry c , Petr Horin a, * a Institute of Animal Genetics, Faculty of Veterinary Medicine, University of Veterinary and Pharmaceutical Sciences Brno, Palackeho 1/3, 612 42 Brno, Czech Republic b Department PROGESA, Agronomic Faculty, University of Bari, via Amendola 165/a, 70126 Bari, Italy c Department of Parasitology, Faculty of Veterinary Medicine, University of Veterinary and Pharmaceutical Sciences Brno, Palackeho 1/3, 612 42 Brno, Czech Republic d Laboratory of Agrigenomics, Mendel University Brno, Zemedelska 1/1665, 613 00 Brno, Czech Republic 1. Introduction The amount of genetic diversity has been associated with the ability to adapt to environmental changes and with the potential to evolve (Reed and Frankham, 2003). Immune functions represent one of major components of an organism’s fitness and determine the potential for evolutionary interactions with pathogens or with other species (Lazzaro and Little, 2009). Diversity of genes important for immune functions may be associated with resistance and susceptibility to pathogens (Trowsdale and Parham, 2004; Tibayrenc, 2007). The major histocompatibility complex (MHC) is a cluster of linked genes playing a central role in the presentation of antigenic peptides to T lymphocytes (Klein, 1986). The MHC genes are the most polymorphic genes in the vertebrate genome. Their high polymorphism seems to be maintained by balancing selection, predating speciation events and reflecting the co- evolution of hosts with their pathogens (Bernatchez and Landry, 2003). The mechanisms maintaining the genetic diversity and the role of pathogens have not yet been completely clarified. Empirical evidence for pathogen-driven selection on MHC genes is based on the population diversity analysis and on associations with pathogens (Spurgin and Richardson, 2010). For this purpose, specific model populations living in specific areas and exposed to various pathogens can be studied. The family Equidae is a suitable model for studying diversity, selection and evolution of the MHC genes (Janova et al., 2009). It is Infection, Genetics and Evolution 11 (2011) 1136–1141 ARTICLE INFO Article history: Received 15 December 2010 Received in revised form 6 April 2011 Accepted 7 April 2011 Available online 14 April 2011 Keywords: Domestic donkey Major histocompatibility class II DRA gene Genetic diversity Theileria equi Babesia caballi ABSTRACT The major histocompatibility complex (MHC) genes coding for antigen presenting molecules are the most polymorphic genes in vertebrate genome. The MHC class II DRA gene shows only small variation in many mammalian species, but it exhibits relatively high level of polymorphism in Equidae, especially in donkeys. This extraordinary degree of polymorphism together with signatures of selection in specific amino acids sites makes the donkey DRA gene a suitable model for population diversity studies. The objective of this study was to investigate the DRA gene diversity in three different populations of donkeys under infectious pressure of protozoan parasites, Theileria equi and Babesia caballi. Three populations of domestic donkeys from Italy (N = 68), Jordan (N = 43), and Kenya (N = 78) were studied. A method of the donkey MHC DRA genotyping based on PCR-RFLP and sequencing was designed. In addition to the DRA gene, 12 polymorphic microsatellite loci were genotyped. The presence of Theileria equi and Babesia caballi parasites in peripheral blood was investigated by PCR. Allele and genotype frequencies, observed and expected heterozygosities and F IS values were computed as parameters of genetic diversity for all loci genotyped. Genetic distances between the three populations were estimated based on F ST values. Statistical associations between parasite infection and genetic polymorphisms were sought. Extensive DRA locus variation characteristic for Equids was found. The results showed differences between populations both in terms of numbers of alleles and their frequencies as well as variation in expected heterozygosity values. Based on comparisons with neutral microsatellite loci, population sub-structure characteristics and association analysis, convincing evidence of pathogen-driven selection at the population level was not provided. It seems that genetic diversity observed in the three populations reflects mostly effects of selective breeding and their different genetic origins. ß 2011 Elsevier B.V. All rights reserved. * Corresponding author. Tel.: +420 541 562 292; fax: +420 549 248 841. E-mail addresses: marie.vranova@gmail.com (M. Vranova), ingrid.alloggio@agr.uniba.it (I. Alloggio), moneeb_78@hotmail.com (M. Qablan), vyskocilm@vfu.cz (M. Vyskocil), Abby89@seznam.cz (A. Baumeisterova), slobodam@vfu.cz (M. Sloboda), lenka.putnova@mendelu.cz (L. Putnova), irena.vrtkova@mendelu.cz (I. Vrtkova), modryd@vfu.cz (D. Modry), horin@dior.ics.muni.cz (P. Horin). Contents lists available at ScienceDirect Infection, Genetics and Evolution journal homepage: www.elsevier.com/locate/meegid 1567-1348/$ – see front matter ß 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.meegid.2011.04.010