title: Hot topic: Bovine leukemia virus (BLV)-infected cows with low proviral load are not a source of infection for BLV-free cattle.
abstract: The bovine leukemia virus (BLV) causes leukemia or lymphoma in cattle. Although most BLV-infected animals do not develop the disease, they maintain the transmission chain of BLV at the herd level. As a feasible approach to control the virus, selection of cattle carrying the BoLA-DRB3*0902 allele has been proposed, as this allele is strongly associated with a BLV infection profile or the low proviral load (LPL) phenotype. 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 cow was maintained during the 20mo of the experiment, and no BLV-negative cattle became infected. The BLV incidence rate in this herd was thus zero, whereas BLV incidence rates in different local herds varied from 0.06 to 0.17 cases per 100 cattle-days. This finding strongly suggests that LPL-BoLA-DRB3*0902 cattle disrupted the BLV-transmission chain in the study period.
authors.affiliation: Laboratorio de Virología del Departamento Sanidad Animal y Medicina Preventiva, Tandil B7000, Argentina; Departamento de Producción Animal, Centro de Investigación Veterinaria de Tandil, Facultad de Ciencias Veterinarias, Universidad Nacional del Centro de la Provincia de Buenos Aires, Campus Universitario, Tandil B7000, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires C1425FQB, Argentina. Electronic address: mjuliare@vet.unicen.edu.ar.
authors.forename: Marcela A
authors.initials: MA
authors.lastname: Juliarena
authors.affiliation: Laboratorio de Virología del Departamento Sanidad Animal y Medicina Preventiva, Tandil B7000, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires C1425FQB, Argentina; Centro Biotecnológico La Isleta, Cooperativa Tambera y Agropecuaria Nueva Alpina Ltda, Colonia Alpina G2341, Argentina.
authors.forename: Clarisa N
authors.initials: CN
authors.lastname: Barrios
authors.affiliation: Laboratorio de Virología del Departamento Sanidad Animal y Medicina Preventiva, Tandil B7000, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autónoma de Buenos Aires C1425FQB, Argentina.
authors.forename: M Carolina
authors.initials: MC
authors.lastname: Ceriani
authors.affiliation: Laboratorio de Virología del Departamento Sanidad Animal y Medicina Preventiva, Tandil B7000, Argentina; Centro Biotecnológico La Isleta, Cooperativa Tambera y Agropecuaria Nueva Alpina Ltda, Colonia Alpina G2341, Argentina.
authors.forename: Eduardo N
authors.initials: EN
authors.lastname: Esteban
mesh_terms: D000818:Animals; D001118:Argentina / Q000453:epidemiology; D002417:Cattle; D016583:Enzootic Bovine Leukosis / Q000453:epidemiology* / Q000235:genetics / Q000635:transmission / Q000821:virology; D005260:Female; D005819:Genetic Markers; D000949:Histocompatibility Antigens Class II / Q000032:analysis; D015994:Incidence; D001909:Leukemia Virus, Bovine / Q000502:physiology*; D015995:Prevalence; D011533:Proviruses / Q000502:physiology*; D019562:Viral Load / Q000502:physiology*
chemical_list: C423282:BoLA-DRB3 antigen; D005819:Genetic Markers; D000949:Histocompatibility Antigens Class II
keywords: bovine leukemia virus; bovine leukocyte antigen DRB3*; dairy cow; transmission