**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** CATTLE INFECTED WITH BOVINE LEUKEMIA VIRUS (BLV) HAVE COMPROMISED IMMUNE SYSTEMS WHICH ARE ASSOCIATED WITH A REDUCTION IN MILK PRODUCTION, SHORTENED LIFESPAN, AND PREDISPOSITION TO LYMPHOMA. OVER 21 NATIONS HAVE ERADICATED BLV BY ELIMINATING BLV ANTIBODY-POSITIVE ANIMALS. THE SERO-PREVALENCE IN U.S. DAIRY CATTLE IS ABOUT 50%, SO IT IS ECONOMICALLY AND PRACTICALLY IMPOSSIBLE TO CULL ALL INFECTED CATTLE TO ERADICATE THE DISEASE. IT IS PRIMARILY CATTLE WITH HIGH CONCENTRATIONS OF PROVIRUS (PVL) THAT ARE RESPONSIBLE FOR MOST TRANSMISSION OF BLV. THE PVL ASSAY PROVIDES A QUANTITATIVE MEASURE TO RANK THE MOST INFECTIOUS ANIMALS FOR SEGREGATION OR CULLING. OUR PILOT STUDY TO REMOVE HIGH PVL COWS WAS SUCCESSFUL IN GREATLY REDUCING BLV PREVALENCE AND INCIDENCE, BUT INCOMING INFECTED YOUNG STOCK HAVE PREVENTED ERADICATION IN SMALL HERDS. WE HYPOTHESIZE THAT BLV ERADICATION REQUIRES A COMPREHENSIVE APPROACH OF REMOVING ELISA-POSITIVE COWS AND PREVENTING INFECTED HEIFERS FROM ENTERING THE MILKING HERD. WE WILL ENROLL FIVE DAIRY HERDS (Μ =400) AND OBTAIN WHOLE-HERD BLV PREVALENCE VIA ELISA AND STRATIFY INFECTIOUSNESS VIA QPCR IN YEARS 1, 3, AND 5. PROVIRUS WILL BE MEASURED IN YOUNG STOCK TO PREVENT BLV-POSITIVE HEIFERS FROM ENTERING THE MILKING-HERD. REPEATED PVL TESTING OF THE HEIFERS WILL OCCUR AT WEANING, AFTER CONFIRMED PREGNANCY (~120 DAYS POST BREEDING), AND 60 DAYS IN MILK DURING LACTATION 1 THROUGH 3 TO DETERMINE BLV INCIDENCE. CONTROLLING BLV WILL MAKE THE U.S. DAIRY INDUSTRY MORE SUSTAINABLE AND PROFITABLE IN A GLOBAL MARKET WHERE MANY OTHER NATIONS HAVE MADE BLV CONTROL A PRIORITY.

Michigan State University, East Lansing MI

Investigators