Monomorphism and polymorphism at Mhc DRB loci in domestic and wild ruminants

Genetic polymorphism at Mhc class II DRB loci was investigated in samples o f musk-ox from Canada and Greenland; moose from Sweden, Norway Canada, and Alaska; roe deer from Norway and Sweden; reindeer from Svalbard and Norway; fallow deer from Norway and Sweden; and red deer from Norway The results w ere compared with published data on cattle, bison, goat, sheep, and red dee r. Cattle-specific primers amplified a single DRB locus in all species exce pt fellow deer and red deer, in which two loci were found. Single strand co nformation polymorphism analysis and DNA sequence analysis were employed to detect genetic polymorphism. Complete monomorphism was found in musk-ox an d fallow deer. Limited polymorphism was found in the moose, roe deer, and r eindeer from Svalbard, whereas intermediate to extensive DRB diversity was present in reindeer from Norway and in bison, sheep, goat, cattle, and red deer. The restricted Mhc diversity in moose, roe deer, and fallow deer is n otable in relation to the dramatic population expansion of moose and roe de er in Sweden during this century and since fallow deer is used for meat and game production with good results and without any marked disease problems. The results question the view that species or populations with restricted Mhc diversity have poor resistance to infectious diseases. A phylogenetic t ree analysis revealed a clustering of DRB sequences within species rather t han within allelic lineages across species. The results suggest trans-speci es persistence of polymorphic sequence motifs rather than of allelic lineag es.