IN THE UNITED STATES AND WORLD-OVER, ROUNDWORM INFECTIONS ARE AMONG THE MOST ECONOMICALLY IMPORTANT HEALTH PROBLEMS OF LIVESTOCK, COSTING THE GLOBAL LIVESTOCK INDUSTRY BILLIONS OF DOLLARS ANNUALLY. THE ONLY RELIABLE WAY TO CONTROL ROUNDWORMS IN LIVESTOCK IS BY USING MEDICINES CALLED ANTHELMINTICS. HOWEVER, ROUNDWORMS INFECTING LIVESTOCK HAVE DEVELOPED RESISTANCE TO ALMOST ALL CURRENTLY AVAILABLE ANTHELMINTICS, LEAVING LIVESTOCK PRODUCERS WITH NO EFFECTIVE MEANS OF CONTROLLING ROUNDWORM INFECTIONS IN LIVESTOCK. THEREFORE, THERE IS URGENT NEED TO DEVELOP NEW EFFECTIVE ANTHELMINTICS. WE RECENTLY IDENTIFIED NEW UNIQUE MOLECULES CALLED PHOSPHOETHANOLAMINE METHYLTRANSFERASES (PMTS) THAT ROUNDWORMS USE TO REPRODUCE AND GROW, TO THE EXTENT THAT THEY CANNOT SURVIVE WITHOUT THEM WHILE LIVING IN LIVESTOCK. THE PMTS ARE USED TO PRODUCE A SPECIAL FAT MOLECULE CALLED PHOSPHATIDYLCHOLINE, WHICH IS IMPORTANT FOR SURVIVAL, REPRODUCTION AND GROWTH OF ROUNDWORMS. IMPORTANTLY, THOSE PMTS ARE NOT FOUND INLIVESTOCK, INDICATING THAT IF THEY ARE TARGETED FOR INACTIVATION USING SPECIFIC CHEMICAL COMPOUNDS, ROUNDWORMS WILL BE HARMED WHILE LIVESTOCK WILL REMAIN UNAFFECTED. THEREFORE, OUR MAIN AIM IS TO IDENTIFY AND VALIDATE NOVEL CHEMICALS THAT CAN SPECIFICALLY INACTIVATE PMTS IN VARIOUS TYPES OF ROUNDWORMS. WE WILL MODIFY THE IDENTIFIED CHEMICALS IN ORDER TO MAKE THEM OPTIMALLY EFFECTIVE IN KILLING THE VARIOUS TYPES OF LIVESTOCK ROUNDWORMS, INCLUDING THOSE THAT ARE RESISTANT TO CURRENT DRUGS. AT COMPLETION OF THIS PROJECT, WE ANTICIPATE TO HAVE UNVEILED NOVEL LEAD-CHEMICAL COMPOUNDS FOR DEVELOPING A NEW GENERATION OF FULLY EFFECTIVE ANTHELMINTIC DRUGS FOR KILLING ROUNDWORMS IN LIVESTOCK. THIS WILL LEAD TO IMPROVED LIVESTOCK PRODUCTIVITY AND ENHANCED FOOD SECURITY.THE SPECIFIC SCIENCE OBJECTIVES ARE:1.CLONE AND CHARACTERIZE PUTATIVE PHOSPHOETHANOLAMINE METHYLTRANSFERASES FROM DIFFERENT FAMILIES OF LIVESTOCK NEMATODES AND IDENTITY THEIR BROAD-SPECTRUM INHIBITORS. OVERVIEW: GENES ENCODING PUTATIVE PMTS FROM NEMATODE FAMILIES OF CHABERTIIDAE, TRICHOSTRONGYLIDAE, DICTYOCAULIDAE, ANCYLOSTOMATOIDEA AND ASCARIDIDAE WILL BE CLONED, EXPRESSED AND TESTED FOR PMT ENZYMATIC ACTIVITY. A CUSTOMIZED TARGETED LIBRARY OF COMPOUNDS WITH HIGH IN SILICO PREDICTABILITY OF AFFINITY FOR CANDIDATE PMT PROTEINS WILL BE SCREENED IN VITRO TO IDENTIFY BROAD-SPECTRUM INHIBITORS FOR THE NEMATODE PMTS.2.TEST THE ANTHELMINTIC EFFICACY OF OPTIMIZED PHOSPHOETHANOLAMINE METHYLTRANSFERASES INHIBITORS AGAINST A VARIETY OF IMPORTANT NEMATODE PARASITE SPECIES OF LIVESTOCK, INCLUDING MULTI-DRUG-RESISTANT STRAINS, USING BOTH IN VITRO AND IN VIVO ASSAYS. OVERVIEW: WE WILL OBTAIN A CUSTOMIZED SERIES OF COMPOUNDS WITH CONSERVATIVE STRUCTURAL MODIFICATIONS BASED ON THE CHEMICAL STRUCTURES OF THE FOUR CANDIDATE PMT INHIBITORS WE HAVE PREVIOUSLY IDENTIFIED (WITOLA ET AL., 2016B). THE COMPOUNDS WILL BE SCREENED FOR EFFICACY IN KILLING MIXED POPULATIONS OF BOTH DRUG-SUSCEPTIBLE AND MULTI-DRUG-RESISTANT NEMATODES IN VITRO AND IN VIVO. LIKEWISE, ANY NEW INHIBITORS THAT WILL BE IDENTIFIED IN OBJECTIVE 1 WILL ALSO BE TESTED.