VIRAL AND HOST DETERMINANTS OF ORTHOBUNYAVIRUS ENTRY. - PROJECT SUMMARY LA CROSSE VIRUS (LACV) IS THE LEADING CAUSE OF PEDIATRIC ARBOVIRAL ENCEPHALITIS IN THE U.S., CAUSING SEVERE NEUROLOGICAL CONSEQUENCES AND ECONOMIC BURDENS. UNDERSTANDING LACV ENTRY MECHANISMS IS ESSENTIAL, AS THIS KNOWLEDGE WILL AID IN THE DEVELOPMENT OF TARGETED ANTIVIRAL THERAPIES. THE PROPOSED RESEARCH PLANS TO ELUCIDATE THE MOLECULAR MECHANISMS UNDERLYING LA CROSSE VIRUS ENTRY VIA A NEWLY IDENTIFIED HOST FACTOR, JAGGED2 (JAG2). AIM 1 OF THIS PROPOSAL SEEKS TO DETERMINE THE ROLE OF JAG2 AND ITS HOMOLOGS IN LACV GLYCOPROTEIN-MEDIATED ENTRY (AIM 1). THE ROLE OF JAG2 AS A CELLULAR RECEPTOR FOR LACV ENTRY WILL BE INVESTIGATED USING CUTTING-EDGE GENETIC, BIOCHEMICAL, AND LIVE IMAGING APPROACHES. INVESTIGATE THE IMPACT OF JAG2 HOMOLOGS FROM INSECT AND RODENT RESERVOIRS ON LACV INFECTION. AIM 2 WILL DELINEATE KEY INTERACTIONS BETWEEN LACV GLYCOPROTEINS AND JAG2, SHOWING THAT JAG2 EPIDERMAL GROWTH FACTOR (EGF)-LIKE DOMAINS BIND DIRECTLY TO LACV GLYCOPROTEIN GC. DEEP MUTATIONAL SCANNING, NEUTRALIZATION ASSAYS, AND BIOLAYER INTERFEROMETRY (BLI) WILL BE USED TO IDENTIFY INTERACTION SITES. INFECTIOUS LACV GC MUTANTS WILL MAP VIRAL DETERMINANTS OF JAG2 NEUTRALIZATION. THIS STUDY WILL DEFINE THE ROLE OF JAG2 IN LACV INFECTION, UNCOVER NEW VIRAL ENTRY MECHANISMS, AND LAY THE GROUNDWORK FOR FUTURE IN VIVO STUDIES IN BOTH THE MAMMALIAN HOST AND THE INSECT VECTOR. THESE FINDINGS COULD CONTRIBUTE TO BROAD- SPECTRUM ANTIVIRAL STRATEGIES TARGETING SIMILAR VIRAL PATHOGENS. THE PROPOSED RESEARCH PLAN WILL BE COMPLEMENTED BY A PERSONALIZED AND COMPREHENSIVE TRAINING PLAN TO ENSURE THAT JANA LIESE DEVELOPS A DEEP UNDERSTANDING OF CELLULAR BIOLOGY, VIROLOGY, AND BIOCHEMISTRY AS WELL AS TECHNICAL AND LEADERSHIP SKILLS ESSENTIAL FOR A CAREER AS A PHYSICIAN-SCIENTIST. THIS TRAINING WILL BE FURTHER ENRICHED BY ACTIVE PARTICIPATION IN A HIGHLY SUPPORTIVE AND COLLABORATIVE INTERDISCIPLINARY RESEARCH COMMUNITY AT WASHINGTON UNIVERSITY IN ST. LOUIS SCHOOL OF MEDICINE.