Brief Communication


, Volume 61, Issue 2, pp 145-151

First online:

Duplication polymorphism at MHC class II DRB1 locus in the wild boar (Sus scrofa)

  • Federica BarbisanAffiliated withDepartment of Biology, University of Padua
  • , Claudia SavioAffiliated withDepartment of Biology, University of Padua
  • , Giorgio BertorelleAffiliated withDepartment of Biology, University of Ferrara
  • , Tomaso PatarnelloAffiliated withDepartment of Public Health, Comparative Pathology, and Veterinary Hygiene, University of Padova
  • , Leonardo CongiuAffiliated withDepartment of Biology, University of Padua Email author 

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The origin of allelic polymorphism in genes of the major histocompatibility complex represents a central topic in evolutionary genetics as it is probably the most polymorphic region in the nuclear genome of vertebrates. Accordingly, the analyses of genetic variability at these loci provide evidence complementary to the population genetics studies based on neutral loci. In this study, four wild boar populations, two from Italy (Florence region and Castelporziano Presidential Reserve, outside Rome) and one each from Hungary and Poland, were characterized at a highly polymorphic fragment including part of intron 1 and exon 2 of swine leukocyte antigen (SLA) class II DRB1 gene by direct sequencing and by cloning. Excluding the false alleles, a total of 18 different sequences were observed in 57 individuals. The high ratio of nonsynonymous (dN) vs synonymous (dS) substitution rates in the peptide-binding region supports the hypothesis that balancing selection is operating at this locus. A duplication event at the DRB1 gene was documented only in one Italian population with both copies being putatively active. This is the first evidence of a polymorphism for the number of copies of an SLA gene.


Wild boar Sus scrofa Major histocompatibility complex Duplication DRB1