RIFT VALLEY FEVER VIRUS (RVFV) IS AN EMERGING PATHOGEN THAT MAINTAINS HIGH BIODEFENSE PRIORITY BASED ON ITS THREAT TO LIVESTOCK, ITS ABILITY TO CAUSE HUMAN HEMORRHAGIC FEVER, AND ITS POTENTIAL FOR AEROSOL SPREAD. WE HAVE DEVELOPED A BHV-1 MUTANT VIRUS BY REMOVING A PORTION OF OR THE ENTIRE GENE SEQUENCES OF FOUR BHV-1 NON-ESSENTIAL GENES. THE RESULTING MUTANT VIRUS, DESIGNATED BHV-1 QMV, CAN INFECT BOTH CATTLE AND SHEEP BUT DOES NOT CAUSE DISEASE AND IMMUNOSUPPRESSION. THE MUTANT VIRUS IS ALSO HIGHLY IMMUNOGENIC, IS WELL BALANCED IN ITS REPLICATION EFFICIENCY, AND ANTIGEN DELIVERY CAPACITY. VACCINE EFFICACY STUDIES AGAINST TWO DIFFERENT BOVINE VIRAL DISEASES, BOVINE VIRAL DIARRHEA VIRUS, AND BOVINE RESPIRATORY SYNCYTIAL VIRUS SHOWED THAT A COMBINED INTRANASAL/INTRAMUSCULAR ADMINISTRATION OF THE VACCINE PROTECTED THE ANIMALS AGAINST THE INFECTIONS USED AS THE REFERENCE CHALLENGE VIRUS DESIGNATED BY USDA-APHIS. IN THIS PROJECT, WE WILL USE A SIMILAR STRATEGY TO DEVELOP A SAFE AND EFFICIENT BHV-1 VECTORED SUB-UNIT VACCINE, AGAINST RVFV FOR USE IN CATTLE AND SHEEP. THE PROPOSED RESEARCH IS SIGNIFICANT BECAUSE THE VACCINE WILL HAVE A POSITIVE IMPACT NOT ONLY ON THE LIVESTOCK INDUSTRIES OF ENDEMIC COUNTRIES, THE U.S., AND ALSO THE PUBLIC HEALTH WHERE VECTORS AND SUSCEPTIBLE HOSTS EXIST IF THE RVFV ENTERS EITHER ACCIDENTALLY OR MALICIOUSLY.IMPACT:THE PROPOSED RESEARCH WILL HAVE A SIGNIFICANT AND POSITIVE IMPACT ON THE LIVESTOCK INDUSTRIES OF ENDEMIC COUNTRIES AND IN THE U.S. LIKE WEST NILE VIRUS, THE PRESENCE OF COMPETENT VECTORS AND SUSCEPTIBLE HOSTS IN THE U.S. SUGGESTS THAT THE INTRODUCTION OF RVFV COULD HAVE DEVASTATING CONSEQUENCES TO THE DOMESTIC LIVESTOCK INDUSTRY. THUS, RVFV IS CONSIDERED A POTENTIAL TOOL FOR AGROTERRORISM. THE AVAILABILITY OF A SAFE AND EFFICIENT LIVE SUBUNIT VACCINE AGAINST RVFV WILL BE HIGHLY DESIRABLE NOT ONLY IN THE U.S BUT ALSO IN RVF ENDEMIC COUNTRIES.?