Distribution of bovine lymphocyte antigen (BoLA-DRB3) alleles in Brazilian dairy Gir cattle (Bos indicus).

Brazilian dairy Gir (Bos indicus) cattle are a tropical, well-adapted breed, for which no information on the major histocompatibility complex (MHC) is presently available. The second exon of the bovine lymphocyte antigen (BoLA-DRB3) was amplified by polymerase chain reaction (PCR) of DNA samples from 28 Brazilian dairy Gir cows. Two experimental genotyping approaches were used: direct sequencing of PCR gene products (PCR-DS) and sequencing of cloned PCR fragments (S-CLO). Results demonstrate the viability of both typing approaches. PCR-DS allowed typing of 39% of the animals while the remainder were genotyped by S-CLO. Seventeen BoLA-DRB3 alleles were assigned, including some that were only recently described for zebu cattle. Allelic frequencies ranged from 0.02 to 0.18. The most frequent alleles were *3601 (frequency = 0.18), *2201 (0.14) and *2101 (0.11).