A PCR-RFLP TYPING METHOD FOR THE CAPRINE MHC CLASS-II DRB GENE

A polymerase chain reaction (PCR) technique associated with restrictio n fragment length polymorphism (RFLP) analysis has been developed for typing the second exon of the caprine Mhc class II DRB gene. By using a maximum of three restriction enzymes, corresponding to different com binations of RsaI, BsaI, AccI, NdeII, HaeIII and HpaII, this procedure allows to distinguish unequivocally 18 of the 22 caprine DRB alleles. Forty goats of several breeds were typed with this technique and two new RsaI restriction patterns which did not match with previously publ ished sequence data were identified. Close associations have been foun d between RFLPs and amino acid substitutions at positions which are ex pected to be involved in the formation of the antigen-recognition site (ARS) of the DR molecule. These results suggest that PCR-RFLP may be a useful tool in typing the caprine DRB gene and in relating amino aci d substitutions at the ARS of the DR molecule with disease resistance.