** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** THE OVERALL PROJECT GOAL IS TO GENERATE NEW KNOWLEDGE NEEDED TO DEVELOP IMPROVED VACCINES CAPABLE OF PROTECTING CALVES AGAINST MULTIPLE STRAINS OF BOVINE PARAINFLUENZA VIRUS 3 [BPIV3] AND BOVINE VIRAL DIARRHEA VIRUS [BVDV]. THESE VIRAL PATHOGENS ARE INVOLVED IN CAUSING BOVINE RESPIRATORY DISEASE COMPLEX, WHICH LEADS TO PNEUMONIA AND DEATH OF CALVES. THE CURRENT BPIV3A VACCINE IS NOT VERY EFFECTIVE AGAINST BPIV3B AND BPIV3C STRAINS THAT WERE PREVIOUSLY REPORTED IN OTHER COUNTRIES, BUT THEY ARE NOW CIRCULATING IN US CATTLE HERDS. SIMILARLY, BVDV VACCINES ARE NOT VERY EFFECTIVE AGAINST DIVERSE STRAINS. WE HAVE DEMONSTRATED THAT AN EXPERIMENTAL VACCINE CONTAINING ENGINEERED PROTEINS THAT INCORPORATE PROTECTIVE COMPONENTS FROM MULTIPLE DIVERSE BVDV STRAINS, INDUCED BROAD PROTECTION. WE HAVE ALSO USED THIS APPROACH TO DESIGN NEW PROTEINS BASED ON INFORMATION DERIVED FROM ALL SEQUENCED BPIV3 GENOMES. IMPORTANTLY, WE HAVE CREATED A VACCINE VECTOR BASED ON BPIV3C AND USED IT TO DEVELOP NEW VACCINE CANDIDATES THAT CONTAIN BPI3V AND BVDV COMPONENTS. WE EXPECT THAT THIS NEW VACCINE WILL BE SAFE, AFFORDABLE, AND CAPABLE OF INDUCING PROTECTION AGAINST MULTIPLE BPI3V AND BVDV STRAINS. THESE EXPECTED OUTCOMES WILL REDUCE LOSSES CAUSED BY THESE PATHOGENS AND THEREBY CONTRIBUTE TO AN INCREASE IN THE EFFICIENCY OF BEEF AND DAIRY ANIMAL PRODUCTION SYSTEMS.