Resumo

ZAMBRANO, Juan C; ECHEVERRI, Julián  e  LOPEZ-HERRERA, Albeiro. Alleles of the BoLA DRB3.2 gene are associated with mastitis in dairy cows. Rev Colom Cienc Pecua [online]. 2011, vol.24, n.2, pp.145-156. ISSN 0120-0690.

The Mayor Histocompatibility Complex (MHC) is a pool of genes which regulate both processing and recognition of antigens. The MHC is the main genetic component of the resistance or susceptibility to infectious diseases. In bovines, MHC is known as Bovine Leukocyte Antigen (BoLA), and some of its alleles have been associated with udder health issues. This study evaluated exon-2 polymorphisms of BoLA DRB3 gene in 91 cows of a dairy farm. A total of 66 Holstein and 25 cross breed BON x Holstein (BxH) cows were evaluated. Twenty seven alleles were identified by PCR-RFLP and PCR-SBT. Allelic frequencies varied from 0.8 to 15.9% for the Holstein, and from 2 to 20% for BxH cows. The BoLA DRB3.2*23 was the most frequent allele in both groups. A prospective study was also conducted for cows in production (n=47) during one lactation to determine subclinical mastitis incidence using the California Mastitis Test (CMT). A 38.69% frequency of positive cases was observed. Additionally, a retrospective study was conducted for all the cows (n=91), finding 9.2% incidence of clinical mastitis per year. Possible associations were established using a statistical model to determine the effect of genetic substitution, in which BoLA DRB3.2*24 was used as the substitution allele. Alleles associated with susceptibility to subclinical mastitis were DRB3.2*8 (p<0.10) and DRB3.2*14 (p< 0.01). Allele DRB3.2*33 was associated with resistance to subclinical mastitis (p<0.01). No significant associations were found for clinical mastitis.

Palavras-chave : bovine; CMT; immune response; major histocompatibility complex.

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