** 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 PORCINEEPIDEMICDIARRHEA (PED) DISEASE, CAUSED BY A PORCINE CORONAVIRUS (PORCINEEPIDEMICDIARRHEA VIRUS - PEDV), HAS BEEN A LEADING THREAT TO THE US PORK INDUSTRY AND RESULTED INAT LEAST 8 MILLION (~10%) PIGS' DEATH AND AN ESTIMATED $1.8BILLION LOSS IN THE US FROM 2013 TO 2014.PED REMAINS CIRCULATING IN THE US WITH AN AVERAGE OF 10-15% POSITIVE RATE, YET A SAFE AND EFFECTIVE VACCINEIS CURRENTLY NOT AVAILABLE TO PORK PRODUCERS.CURRENT COMMERCIALLY AVAILABLE PED VACCINES, COMPRISED OF EITHER THE KILLED WHOLE VIRUS OR A PART OF THE VIRUS AND ADMINISTEREDINTRAMUSCULARLY,ARE RELATIVELY SAFE BUT PROVIDE LIMITED PROTECTION, DUE TO THE INABILITY OF THESE VACCINES TO STIMULATEHIGH-LEVELPROTECTIVE ANTIBODIESIN THE COLOSTRUM/MILK (KNOWN AS LACTOGENIC IMMUNITY)PROVIDED TOPIGLETS BYSOWS. THUS, THE OVERALL GOAL OF THIS PROJECT IS TO DEVELOPORAL LIVE PED VACCINE CANDIDATES THAT ARE MINIMALLY PATHOGENIC (SAFE) BUT HIGHLY IMMUNOGENIC (EFFECTIVE)AND CAN PRODUCE ROBUST LACTOGENIC IMMUNITYIN SOWS.OUR EARLIER RESEARCH DISCOVERED A HANDFUL OF PROTEIN MOLECULES ENCODED BY THEGENETIC MATERIALS OF PEDV ARE CRUCIAL FOR THE VIRUS COUNTERACTING THE PIG'S IMMUNE SYSTEM. OUR PRELIMINARY STUDIES REVEALEDTHESE MOLECULES, TERMED IMMUNE ANTAGONISTS, ARE KEY VIRULENCE FACTORS AND COULDBE TARGETED FOR DEVELOPING LIVE-ATTENUATED VACCINES THAT COULD PRODUCE STRONG LACTOGENIC IMMUNITY. IN THIS PROPOSAL, WE WILL COMBINE A REVERSE GENETIC ENGINEERING TECHNOLOGY AND MULTIPLE ANIMAL MODEL SYSTEMS TO PURSUE THE FOLLOWING SPECIFIC OBJECTIVES: I) IDENTIFYKEY IMMUNE ANTAGONISTS CONTRIBUTING TO PED; II) GENERATE PEDV MUTANTS BEARINGGENETIC MUTATIONS THAT RETAIN MINIMAL PATHOGENICITY BUT INDUCE STRONG ANTIBODY RESPONSES IN NEONATAL PIGS; III) EVALUATE THE VACCINE CANDIDACY OF THESE PEDV MUTANTSIN GROWING PIGS. WE ANTICIPATE THESELIVE-ATTENUATED PEDV MUTANTS WILL BESAFE ORAL VACCINE CANDIDATES THAT CAN PROVIDE ROBUST PROTECTION. THESUCCESSFUL IMPLEMENTATION OF THIS STUDY WILL NOT ONLY AID PORK PRODUCERS IN PED CONTROL AND PREVENTIONBUT ALSO PROVIDE VETERINARY RESEARCHERS AND VACCINE MANUFACTURERS WITH A GENERALIZABLE APPROACH FOR DEVELOPINGVACCINES AGAINST OTHER SWINE ENTERIC CORONAVIRUSES.