THIS PROJECT SEEKS TO ANSWER A CRITICAL QUESTION: HOW DO BIRD FLU VIRUSES LIKE H5N1 ADAPT TO INFECT CATTLE, AND WHAT CAN BE DONE TO MITIGATE THE RISK? BIRD FLU VIRUSES, ONCE THOUGHT ONLY TO AFFECT BIRDS, ARE EVOLVING, AND H5N1 INFECTIONS HAVE RECENTLY EMERGED IN DAIRY COWS. WHILE NOT FATAL, THE INFECTION CAUSES LOSS OF APPETITE, NASAL DISCHARGE, REDUCED MILK PRODUCTION, AND VIRUS SHEDDING IN MILK, LEADING TO ECONOMIC LOSSES FOR FARMERS AND RAISING CONCERNS ABOUT FOOD SAFETY AND SECURITY. SINCE THE FIRST REPORTED CASE IN MARCH 2024, INFECTIONS IN DAIRY CATTLE HAVE CONTINUED TO RISE.TO BETTER UNDERSTAND AND PREVENT FUTURE OUTBREAKS, THIS PROJECT WILL EXAMINE HOW CERTAIN BIRD FLU STRAINS, PARTICULARLY H5, H7, AND H9, ADAPT TO INFECT CATTLE. INFLUENZA VIRUSES RELY ON SPECIFIC RECEPTORS ON HOST CELLS TO ENTER AND INITIATE INFECTION. WHILE SIALIC ACID (SA) MOLECULES ARE THE PRIMARY RECEPTORS, RECENT STUDIES SUGGEST THAT IMMUNE SYSTEM MOLECULES LIKE MHC CLASS-II MAY ALSO ACT AS ALTERNATIVE ENTRY POINTS. THIS RESEARCH WILL INVESTIGATE HOW THESE VIRUSES BIND TO VARIOUS CATTLE TISSUES, INCLUDING THE LUNGS, DIGESTIVE SYSTEM, AND MAMMARY GLANDS, TO ASSESS THEIR POTENTIAL RISK TO LIVESTOCK.ADDITIONALLY, WE WILL ANALYZE GENETIC CHANGES IN THE HEMAGGLUTININ (HA) PROTEIN, WHICH ENABLES THE VIRUS TO ATTACH TO HOST CELLS. UNDERSTANDING HOW THESE MUTATIONS AFFECT THE VIRUS'S ABILITY TO INFECT CATTLE COULD REVEAL THE RISK OF SPREADING BEYOND THE MAMMARY GLAND. TO ENSURE SAFETY AND ACCURACY, THESE EXPERIMENTS WILL BE CONDUCTED USING A SAFE, NON-INFECTIOUS PSEUDOVIRUS SYSTEM AND TISSUES COLLECTED POST-SLAUGHTER.BEYOND ANSWERING THESE SCIENTIFIC QUESTIONS, THIS PROJECT WILL DEVELOP A RISK ASSESSMENT TO GUIDE BETTER MITIGATION AND PREPAREDNESS STRATEGIES FOR PROTECTING CATTLE FROM EMERGING BIRD FLU STRAINS. THE FINDINGS WILL EVALUATE THE LIKELIHOOD OF VIRAL SPREAD, PROVIDE INSIGHTS INTO VIRAL EVOLUTION, AND INFORM VACCINE DEVELOPMENT TO SAFEGUARD LIVESTOCK. BY PROACTIVELY STUDYING HOW BIRD FLU SPREADS IN CATTLE, THIS RESEARCH WILL HELP PROTECT ANIMAL HEALTH, STRENGTHEN FOOD SECURITY, AND ENSURE THE RESILIENCE OF THE U.S. DAIRY AND BEEF INDUSTRIES.