EQUINE ROTAVIRUS A (ERVA) IS ONE OF THE MOST IMPORTANT DISEASES IN YOUNG HORSES UNDER 6 MONTHS OLD. WHEN FOALS GET INFECTED WITH AN EQUINE ROTAVIRUS, THEY CAN DEVELOP SEVERELY WATERY TO BLOODY DIARRHEA. THE DISEASE CAN BECOME RAPIDLY FATAL IF LEFT UNTREATED. DUE TO LACK OF EFFECTIVE CONTROL AND PREVENTION METHODS, ROTAVIRAL OUTBREAK HAPPENS IN FOALING SEASON EVERY YEAR, AND IT CAUSES SIGNIFICANT DAMAGE TO THE ANNUAL $122 BILLION U.S. EQUINE INDUSTRY. ERVA OFTEN MUTATES ITS COMPLETE SET OF GENES, CREATING MANY GENETIC VARIANTS. THE GENETIC VARIABILITY MAKES THE CURRENT VACCINE INEFFECTIVE TO PROTECT FOALS AGAINST AN ERVA INFECTION. ALL THESE OBSTACLES EMPHASIZE A CRITICAL NEED TO STUDY EQUINE ROTAVIRUSES, UNDERSTAND THEIR GENETIC VARIABILITY, AND INTERPRET CORRELATES OF PROTECTION TOWARDS DEVELOPING A SAFE AND EFFECTIVE EQUINE ROTAVIRUS VACCINE.OUR SHORT-TERM GOAL IN THIS PROJECT IS TO DEVELOP AN INNOVATIVE TOOLBOX FOR EQUINE ROTAVIRUS RESEARCH AND UTILIZE THEM TO DETECT AND CHARACTERIZE GENETIC VARIATIONS IN EQUINE ROTAVIRUSES. THE OTHER SHORT-TERM GOAL OF THIS WORK IS TO DETERMINE HOW GENETIC VARIATIONS AFFECT THE ABILITIES OF VIRUS-NEUTRALIZING ANTIBODIES TO DISARM VIRAL INFECTIVITY. OUR LONG-TERM GOAL IS TO STUDY HOW EQUINE ROTAVIRUSES SPREAD AND CAUSE DISEASE IN FOALS AND DEVELOP THE NEXT-GENERATION CONTROL AND PREVENTION STRATEGIES TO PROTECT HORSES AGAINST INFECTION BY DIFFERENT STRAINS OR GENOTYPES OF EQUINE ROTAVIRUS.THIS PROJECT HAS THREE OBJECTIVES. THE FIRST OBJECTIVE IS TO DEVELOP A GENETIC TOOL FOR EQUINE ROTAVIRUSES. WE WILL ISOLATE EQUINE ROTAVIRUSES AND DETERMINE THEIR FULL-LENGTH GENE SEQUENCES AND THEN PLACE THEIR SET OF GENES INTO SMALL DNA MOLECULES. FOLLOWING THE INTRODUCTION OF THESE DNA MOLECULES INTO MAMMALIAN CELLS, WE WILL PRODUCE EQUINE ROTAVIRUSES REPRESENTATIVE OF THE WELL-STUDIED REFERENCE VARIANTS. THE SECOND OBJECTIVE IS TO USE THE GENETIC TOOL DEVELOPED FROM OBJECTIVE 1 TO CHARACTERIZE GENETIC VARIATIONS OF EQUINE ROTAVIRUSES AND DETERMINE HOW THESE VARIATIONS, OCCURRING IN EQUINE ROTAVIRUSES OVER TIME, MAKE THE HORSE'S IMMUNE SYSTEM LESS ABLE TO RECOGNIZE AND FIGHT AGAINST THESE VARIANTS. THE CELL CULTURE-BASED VIRUS-NEUTRALIZING ANTIBODY ANALYSIS WILL BE USED TO ADDRESS THIS IMPORTANT QUESTION. THE THIRD OBJECTIVE IS TO ISOLATE AND CHARACTERIZE A LARGE PANEL OF EQUINE ROTAVIRUSES FROM DISEASED FOALS AND DETERMINE A RELATIONSHIP BETWEEN GENETIC VARIABILITY AND IMMUNE PROTECTION FOR EQUINE ROTAVIRUSES.SUCCESSFUL COMPLETION OF THE PROJECT WILL ALLOW US TO ISOLATE AND CHARACTERIZE A LARGE PANEL OF EQUINE ROTAVIRUSES. BY STUDYING THESE VIRUSES, WE EXPECT TO IDENTIFY A FULL SPECTRUM OF GENETIC CHANGES NATURALLY OCCURRING IN EQUINE ROTAVIRUSES OVER TIME. FURTHERMORE, WITH THE GENETIC TOOL DEVELOPED FROM THIS PROJECT, WE WILL DEMONSTRATE HOW GENETIC CHANGES ALTER THE ABILITY OF THE HORSE'S IMMUNE SYSTEM TO FIGHT AGAINST DIFFERENT EQUINE ROTAVIRUSES. FINALLY, USING THE FUNCTIONAL ANTIBODY ASSESSMENT, WE ANTICIPAT,E DISCOVERING THE LEVELS OFPROTECTIVE ANTIBODIES FOR EQUINE ROTAVIRUS DISEASE. THESE RESULTS WILL ADVANCE OUR KNOWLEDGE IN EQUINE ROTAVIRUS, WHICH CAN BE FURTHER EXPLORED TOWARDS DEVELOPMENT OF THE NEXT-GENERATION COUNTERMEASURES AGAINST ROTAVIRUS INFECTION IN HORSES.WE ANTICIPATE THAT SUCCESSFUL EXECUTION OF THIS PROJECT WILL ADVANCE OUR KNOWLEDGE CONCERNING THE FUNDAMENTAL MECHANISM EQUINE ROTAVIRUS EMPLOYS TO PROMOTE ITS REPLICATION, EVADE THE IMMUNE PROTECTION, AND CAUSE THE ASSOCIATED DISEASE IN HORSES. THIS WORK WILL ALSO REVEAL IMPORTANT IMMUNE CORRELATES OF PROTECTION AGAINST EQUINE ROTAVIRUSES. FURTHERMORE, IT WILL DETECT THE GENETIC CHANGES IN EQUINE ROTAVIRUSES AND DETERMINE THEIR IMPACT ON IMMUNE EVASION OF THE VACCINE-MEDIATED PROTECTION. THIS NEW KNOWLEDGE WILL PROVIDE A FOUNDATION FOR DEVELOPING NEXT-GENERATION BROADLY PROTECTIVE VACCINES AGAINST EMERGING EQUINE ROTAVIRUSES AS WELL AS OTHER IMPORTANT ROTAVIRAL DISEASES AFFLICTING OTHER AGRICULTURAL ANIMALS SUCH AS CATTLE AND PIGS. FINALLY, THIS PROJECT WILL EMPOWER THE EQUINE INDUSTRY WITH A NEW TOOLBOX INCLUDING THE GENETIC TOOL, FUNCTIONAL ANTIBODY ANALYSIS, VIRUS VARIANTS, AND REFERENCE SERUM SAMPLES THAT CAN BE USED TO FIGHT THESE IMPORTANT ENTERIC DISEASES IN HORSES. ALL THESE EFFORTS WILL REDUCE ECONOMIC LOSSES TO THE U.S. EQUINE AND ANIMAL INDUSTRY.