APPROXIMATELY 100 MILLION METRIC TONS OF BROILER MEAT WAS PRODUCED IN THE WORLD IN 2019, WITH ABOUT 25% PRODUCED IN THE USA, RANKING POULTRY AS THE SECOND MOST-PRODUCED MEAT IN THE WORLD. THE COST OF MEAT AND EGG PRODUCTION HAS INCREASED OVER THE YEARS PARTLY DUE TO INCIDENCES OF DISEASES SUCH AS MAREK'S DISEASE (MD). MD IS CHARACTERIZED BY SUPPRESSION OF THE IMMUNE SYSTEM MAKING THE CHICKEN MORE SUSCEPTIBLE TO OTHER PATHOGENS; NEUROLOGICAL SYMPTOMS INCLUDING PARALYSIS; AND TUMORS THROUGHOUT THE BODY THAT ULTIMATELY LEAD TO DEATH OF THE CHICKEN OR CONDEMNATION AT PROCESSING. MD IS CAUSED BY A HERPESVIRUS CALLED MAREK'S DISEASE VIRUS (MDV). DESPITE REGULAR IMMUNIZATIONS, MDV CAN STILL INFECT VACCINATED CHICKENS BECAUSE THESE VACCINES DO NOT PREVENT SPREAD FROM CHICKEN-TO-CHICKEN, TERMED HORIZONTAL TRANSMISSION. A MAJOR OBSTACLE IN DESIGNING NEW VACCINES THAT COULD PREVENT HORIZONTAL TRANSMISSION IS THE LACK OF INFORMATION ON VIRAL GENES IMPORTANT FOR THIS STEP. WE HAVE IDENTIFIED SPECIFIC VIRUS GENES THAT ARE ESSENTIAL FOR TRANSMISSION OF MDV INCLUDING THE UL13 PROTEIN KINASE. THE LONG-TERM GOAL OF THIS PROJECT IS TO EXPAND OUR KNOWLEDGE OF HORIZONTAL TRANSMISSION OF MDV AND UTILIZE THIS KNOWLEDGE TO DEVELOP VACCINES AND CONTROL MEASURES THAT REDUCE OR BLOCK THE SPREAD OF MDV IN A FLOCK. WE HAVE IDENTIFIED TARGETS FOR THE UL13 PROTEIN KINASE AND HYPOTHESIZE THESE TARGETS ARE IMPORTANT FOR HORIZONTAL TRANSMISSION OF MDV. THE OVERALL GOAL OF THESE STUDIES IS TO DELINEATE THE ROLE UL13 PROTEIN KINASE MEDIATES HORIZONTAL TRANSMISSION THROUGH THE VIRAL US10 AND CELLULAR LY6E PROTEINS. SPECIFIC AIM 1 FOCUSES ON THE ROLE US10 PLAYS IN TRANSMISSION, WHILE SPECIFIC AIM 2 FOCUSES ON LY6E. THESE STUDIES COULD HAVE MAJOR IMPLICATIONS IN UNDERSTANDING GENETIC RESISTANCE TO MD AND THE DEVELOPMENT OF VACCINES OR THERAPIES TO BLOCK THE SHEDDING AND SPREAD OF MDV IN THE POULTRY HOUSE.