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

JULIARENA MARCELA ALICIA; BARRIOS CLARISA NATALIA; CERIANI M. CAROLINA; ESTEBAN EDUARDO NESTOR

JOURNAL OF DAIRY SCIENCE

AMER DAIRY SCIENCE ASSOC-ADSA

Lugar: Champaign, Illinois; Año: 2016 vol. 99 p. 1 - 4

0022-0302

The bovine leukemia virus (BLV)causes leukemia/lymphoma in cattle. Although most BLV-infected animals do notdevelop the disease, they maintain the transmission chain of BLV at herd level.As a feasible approach to control the virus, selection of cattle having theBoLA-DRB3*0902 allele has been proposed, as this strongly associates with aBLV-infection profile or phenotype named Low Proviral Load (LPL). To testwhether these cattle affect the BLV-transmission chain under natural conditions,selected BLV-infected LPL-BoLA-DRB3*0902 heterozygous cows were incorporatedinto 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 20 mo of theexperiment and the result was that no BLV-negative cattle became infected. TheBLV incidence rate in this herd was thus zero, whereas the BLV incidence ratesin different local herds varied from 0.06 to 0.17 cases per one hundredcattle-days. This finding strongly suggests that LPL-BoLA-DRB3*0902 cattledisturbed the BLV-transmission chain in the study period.