Investigating BoLA Class II DRB3*009:02 carrying cattle in Japan

Area of Science:

• Veterinary Immunology
• Animal Genetics
• Epidemiology

Background:

• Enzootic bovine leukosis (EBL) is a significant cattle malignancy primarily caused by bovine leukemia virus (BLV).
• Understanding genetic resistance in cattle populations is crucial for managing BLV transmission and its economic impact.
• Herd management practices can influence both BLV prevalence and the distribution of genetic resistance alleles.

Purpose of the Study:

• To investigate the frequency of the DRB3*009:02 allele, a potential BLV resistance marker, in Japanese cattle populations.
• To correlate the prevalence of BLV infection with the presence of the DRB3*009:02 allele across different farm management systems.
• To provide insights into genetic strategies for controlling BLV in cattle herds.

Main Methods:

• PCR-RFLP was employed to genotype the DRB3*009:02 allele in 742 Holstein and Japanese Black cattle.
• Quantitative PCR (qPCR) was used to detect BLV provirus in peripheral blood mononuclear cells (PBMCs).
• BLV antibodies were identified using a commercial ELISA kit to determine seroprevalence.

Main Results:

• The DRB3*009:02 allele was found in 35 cattle, with allele frequencies varying significantly between farms.
• BLV prevalence and seroprevalence rates were observed to be lower than in previous studies (4.7% incidence, 14.4% seroprevalence).
• Cattle lacking BLV resistance genes exhibited a higher BLV provirus load, indicating a genetic susceptibility to infection.

Conclusions:

• Herd composition and selective breeding for BLV-resistant sires are essential for controlling the BLV epidemic.
• Targeting genetic resistance, specifically the DRB3*009:02 allele, can be a viable strategy to reduce BLV spread.
• Improving livestock productivity necessitates proactive measures in herd management and genetic improvement programs.