摘要：Enhancing disease resistance in animal production can be achieved by genetic improvement programs. The best characterized genetic control of disease resistance and immune response in animals is that associated with the MHC. Respond to specific antigens is closely related to MHC genes and their associations might therefore provide precious answers to main questions about the host pathogen interactions. In cattle there is an association between possession of certain BoLA-DRB3 locus (MHC class II) and resistance or susceptibility to infectious diseases. Polymorphism of exon 2 of the BoLA-DRB3 gene was investigated by the PCR-RFLP method in 80 Iranian native cattle. In this study, 39 different alleles were recognized. As a second goal, allelic frequencies were determined in a total sample. The high frequencies of these alleles (gbb, fbd and fba) were 8.75, 8.75 and 6.25% respectively. Additionally, BoLA-DRB3.2*11, DRB3*2701 and DRB3*0701 were associated with resistant to BLV, whereas allele DRB3.2*01 was associated with higher stability to FMD. Finally, DRB3*2701 and DRB3*1101 alleles were also associated with higher mastitis risk. Frequencies of alleles mediating resistance and susceptibility to leukemia and FMD were revealed.
