Project Grant F31AI197801

THE ROLE AND THERAPEUTIC POTENTIAL OF LRP1 IN OROPOUCHE VIRUS INFECTION - ABSTRACT BUNYAVIRUSES ARE A LARGE AND DIVERSE GROUP OF VECTOR-BORNE VIRUSES, MANY OF WHICH POSE A SIGNIFICANT BIOSECURITY THREAT TO HUMAN AND ANIMAL POPULATIONS IN THE U.S. AND WORLD-WIDE. EMERGING AND RE-EMERGING BUNYAVIRUSES SUCH AS RIFT VALLEY FEVER VIRUS (RVFV), CRIMEAN-CONGO HEMORRHAGIC FEVER VIRUS (CCHFV), AND JUNIN VIRUS (JUNV) POSE A SEVERE BIOSECURITY THREAT DUE TO HIGH MORBIDITY AND CONSIDERABLE MORTALITY. OTHER BUNYAVIRUSES, INCLUDING OROPOUCHE VIRUS (OROV) AND LA CROSSE ENCEPHALITIS VIRUS (LACV), CAUSE WIDESPREAD MORBIDITY AND LESS FREQUENT SEVERE DISEASE. THE ONGOING OROV OUTBREAK HAS SEEN OVER A 1650% INCREASE IN CASES FROM 2023 TO 2024 AND THE EXPANSION OF THE GEOGRAPHIC RANGE WITH ONGOING CIRCULATION IN CUBA UTILIZING NEW VECTORS. THE INCREASE IN CASES HAS COINCIDED WITH REPORTS OF PREVIOUSLY UNDERREPORTED OUTCOMES INCLUDING VERTICAL TRANSMISSION, MISCARRIAGE, MICROENCEPHALY, ENCEPHALITIS, HEMORRHAGIC FEVER, AND DEATH. IN FY24, OROV WAS ADDED TO THE NIAID BIODEFENSE PATHOGENS LIST. GIVEN THE SUDDEN INCREASE IN OROV CASES AND RECOGNITION OF MORE SEVERE HUMAN CLINICAL OUTCOMES, ADDITIONAL RESEARCH ON OROV AND TESTING OF POTENTIAL THERAPEUTICS IS DESPERATELY NEEDED TO SUPPORT BIOPREPAREDNESS INITIATIVES. NOTABLY, THERE ARE NO FDA-APPROVED THERAPEUTICS OR VACCINES AVAILABLE FOR HUMAN USE IN THE UNITED STATES FOR ANY BUNYAVIRUS, INCLUDING OROV. OUR GROUP PREVIOUSLY IDENTIFIED LRP1 AS A CRITICAL ENTRY FACTOR FOR BOTH RVFV AND OROV; WE SHOWED THAT BOTH VIRUSES DIRECTLY BIND LRP1, AND THAT COMPETITIVE INHIBITION DECREASES INFECTIVITY IN VITRO AND PATHOGENESIS IN VIVO. WE DEMONSTRATED THAT LRP1 IS REQUIRED FOR RVFV-INDUCED LETHAL HEPATIC DISEASE. HOWEVER, THE MECHANISM BY WHICH LRP1 MEDIATES VIRAL ENTRY AND THE ROLE OF LRP1 IN OROV PATHOGENESIS REMAINS UNDEFINED. IN THIS PROPOSAL, WE WILL DEFINE THE OROV ENTRY MECHANISM AND DETERMINE THE ROLE OF LRP1 FOR OROV PATHOGENESIS. TO DEFINE THE OROV ENTRY MECHANISM (AIM 1), WE WILL (A) TEST THE HYPOTHESIS THAT LRP1-INITIATED, CLATHRIN-MEDIATED ENDOCYTOSIS IS REQUIRED FOR OROV ENTRY BY GENERATING HUH7 CELLS WITH ENDOCYTOSIS-DEFICIENT LRP1 AND (B) CHARACTERIZE THE OROV ENTRY MECHANISM BY UTILIZING SUPER RESOLUTION AND LIVE-CELL MICROSCOPY TO DETERMINE THE NATURE OF BOTH CLATHRIN-MEDIATED AND CLATHRIN-INDEPENDENT OROV ENDOCYTOSIS. USING NOVEL MOUSE MODELS (AIM 2), WE WILL TEST THE HYPOTHESIS THAT ALTERING VIRAL ACCESS TO LRP1 IN A TISSUE-SPECIFIC MANNER CAN ALTER THE PATHOGENESIS OF OROV IN MICE AND TEST THE THERAPEUTIC POTENTIAL OF LRP1 DECOY RECEPTORS. TAKEN TOGETHER, THE PROPOSED STUDIES WILL WORK TO ADDRESS GAPS IN OROV BASIC BIOLOGY, PATHOGENESIS, AND THERAPEUTICS. THESE STUDIES ARE AN IMPORTANT STEP IN RESPONDING TO THE ACTIVE THREAT OF OROV EMERGENCE IN THE UNITED STATES.