Association of the BoLA-DRB3*12:01 allele with resistance to bovine leukosis virus infection in Crioula Lageana cattle.

Enzootic bovine leukosis (EBL) caused by the bovine leukosis virus (BLV) disturbs the immune response in bovines, leading to severe economic losses, with a possible impact on public health. EBL has no treatment or vaccine available, making the identification of genetic polymorphisms related to BLV resistance in locally adapted breeds like Crioula Lageana cattle valuable perspectives. This study aims to determine the presence of the BoLA-DRB3 alleles associated with susceptibility or resistance to BLV in Crioula Lageana cattle. For that, 208 Crioula Lageana bovines, spanning various ages, categories, and sexes, were subjected to blood sampling for DNA extraction for genetic characterization. The PCR targeted the 440-bp fragment of the env gene of the BLV and 284-bp for the alleles of the BoLA-DRB3 gene. The alleles were identified using Sanger sequencing, and the allele amount and frequency were determined by direct counting. For the determination of resistance or susceptibility, firstly the association between each allele and infection by BLV was determined using the chi-square test (p < 0.05), and then it was followed by an odds ratio analysis. The occurrence of BLV was 38.46% (80/208). The DRB3*12:01 allele was associated with resistance to BLV infection (p = 0.035, O.R. = 0.000. The presence of alleles linked to resistance to disease incidence highlights the potential to enhance genetic approaches in formulating management and control strategies for EBL in diverse cattle populations, with potential implications for livestock production, food safety, and public health.