Bovine leukemia virus infected cows with low proviral load are not a source of infection for BLV-free cattle

BARRIOS CLARISA; JULIARENA MARCELA; ESTEBAN EN; CERIANI CAROLINA

JOURNAL OF DAIRY SCIENCE

AMER DAIRY SCIENCE ASSOC-ADSA

Lugar: Champaign, Illinois; Año: 2016 vol. 99 p. 4586 - 4589

0022-0302

The bovine leukemia virus (BLV) causes leukemia/lymphoma in cattle. Although most BLV-infected animals do not develop the disease, they maintain the transmission chain of BLV at herd level. As a feasible approach to control the virus, selection of cattle having the BoLA- DRB3*0902 allele has been proposed, as this strongly associates with a BLV-infection profile or phenotype named Low Proviral Load (LPL). To test whether these cattle affect the BLV- transmission chain under natural conditions, selected BLV-infected LPL-BoLA-DRB3*0902 heterozygous cows were incorporated into a BLV-negative dairy herd. An average ratio of 5.4 (range 4.17-6.37) BLV-negative cows per BLV-infected cattle was maintained during the 20mo of the experiment and the result was that no BLV-negative cattle became infected. The BLV incidence rate in this herd was thus zero, whereas the BLV incidence rates in differentlocal herds varied from 0.06 to 0.17 cases per one hundred cattle-days. This finding strongly suggests that LPL-BoLA-DRB3*0902 cattle disturbed the BLV-transmission chain in the study period.