Optimization of the MhcOvar-DRB1 gene typing.

The variability of the sheep major histocompatibility complex (MHC) class II DRB1 locus has been analyzed in this work. Exon 2 of Ovar-DRB1 was amplified by polymerase chain reaction (PCR) with the primers designed by Amills et al. for goats. In a total of 187 sheep of Latxa breed, we identified by PCR-single-strand conformation polymorphism (SSCP) 19 alleles, eight of them previously unpublished. Moreover, the observed heterozygosity reached 91-95%. A new allelic type named DRB*14 was defined, which brings to light once more the discussion as to the ancestor of the domestic sheep. Although all the defined alleles can be discriminated by PCR-SSCP, sequence-based typing is proposed as the technique of choice for sheep DRB1 gene typing.