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Principal Investigator: Erich R Mackow
Organization: STATE UNIVERSITY NEW YORK STONY BROOK
Fiscal Year: 2024
Award: $237,569
Funding agency: National Institute of Allergy and Infectious Diseases
Powassan virus (POWV) is a neurovirulent tick-borne flavivirus (FV) emerging in the N.E. US. POWV is
present in tick saliva, injected into the skin during a 15-minute tick bite and causes a 10% fatal encephalitis
resulting in severe long-term neurologic damage in 50% of patients. There are currently no approved POWV
vaccines or prophylactics and the role of innate immunity in regulating POWV neuroinvasion, CNS cell
targeting and neuroinflammatory pathology is unknown.
To reflect POWV spread from skin to the CNS, POWV LI9 was isolated from deer ticks directly in epithelial
cells. Mice inoculated s.c. with POWV LI9 develop lethal neurovirulent disease with overt murine brain damage.
Noting lethality in older mice, LI9 was found to be lethal in 90% of 50 week (wk), and <10% of 10 wk, old
C57/Bl6 mice. Consistent with age-dependent LI9 lethality, brains of 50 wk old mice had dramatically increased
CNS virus, chemokines, immune infiltrates and histopathology. Persistent passage of LI9 in IFN deficient
VeroE6 cells, resulted in an attenuated POWV (LI9-P), that fails to cause disease and instead protects mice
from lethal LI9 challenge. LI9-P is lethal if i.c. injected into mice, implying a block to CNS entry after peripheral
inoculation. LI9-P and LI9 differ by 9 residues in proteins associated with cell attachment, spread and IFN
regulation. In vitro, IFN prevents LI9/LI9-P infection, while LI9, but not LI9-P, inhibit IFNβ/λ induction. In vivo,
IFNλ treatment reduced LI9 levels by 2 logs in mouse brains. These findings suggest innate immune regulation
is a key determinant of LI9 neurovirulence and LI9-P attenuation, and rationalize analyzing neuroinvasive
mechanisms and IFNλ as a potential inhibitor of POWV spread to the CNS.
Entering the CNS is critical for POWV neurovirulence, and the blood-brain-barrier (BBB) and the blood-
cerebrospinal-fluid-barrier (BCSFB) are distinct defenses that protect the CNS. The BBB is formed by brain
microvascular endothelial cells (BMECs), while the BCSFB is created by tight junctions of epithelial cells
(CPEpCs) in the choroid plexus. BBBs and BCSFBs are uniquely regulated by IFNs with IFNλ receptors
(IFNLRs) expressed on CPEpCs, not BMECs, and IFNλ responses are linked to CNS repair. In vitro, LI9 and
LI9-P infect CPEpCs and BMECs, suggesting that BBB or BCSFBs could function as CNS entry portals in vivo,
and that IFNλ may selectively block POWV neuroinvasion via BCSFBs to prevent lethal neurovirulent disease.
In mice, IFN regulation by LI9 vs LI9-P in BBB, BCSFB cells, and the role of IFNs in restricting POWV
spread to the CNS are unknown. Proposed studies use a novel reverse genetics system to produce infectious
recombinant POWVs, chimeras and mutants that uniquely permit analysis of POWV IFN regulation
mechanisms and neurovirulence determinants in vivo. Studies define IFN responses that determine LI9 and
LI9-P infection and spread across neurovascular barriers in vitro and in vivo. Studies evaluate the therapeutic
potential of IFNλ inhibiting POWV neuroinvasion through BCSFBs in a lethal murine model.
Terms: <(IFN) α><(IFN)-α><(IFN)α><AVP, Type II><Acquired brain injury><Acute><Airway infections><Alferon><American><Anti-viral Response><Antiviral Protein, Type II><Attenuated><Black-legged Tick><Blood - brain barrier anatomy><Blood-Brain Barrier><Brain><Brain Diseases><Brain Disorders><Brain Inflammation><Brain Injuries><Brain Nervous System><C57BL/6 Mouse><CD119><CD119 Antigen><CDw119 antigen><COVID infected patient><COVID patient><COVID positive patient><COVID-19 infected patient><COVID-19 patient><COVID-19 positive patient><COVID19 patient><COVID19 positive patient><Cell Attachment><Cell Body><Cell Protection><Cell-Matrix Adhesions><Cell-Matrix Junction><Cells><Chemotactic Cytokines><Chimera><Chimera organism><Choroid Plexus><Choroid Plexus Epithelium><Coma><Comatose><Cytoprotection><Data><Deer Tick><Disease><Disorder><Elderly><Encephalitis><Encephalon><Encephalon Diseases><Epithelial Cell Junction><Epithelial Cells><Fever><Health><Hemato-Encephalic Barrier><Hepatitis><Histopathology><Homologous Chemotactic Cytokines><Hospital Admission><Hospitalization><Human><I scapularis><I. scapularis><IFN><IFN Alpha><IFN α><IFN-Gamma><IFN-g><IFN-gamma receptor 1><IFN-gammaR><IFN-α><IFN-γ><IFN-γR><IFNG><IFNGR><IFNGR1><IFNGR1 gene><IFNa><IFNα><IFNγ><Immune Interferon><Immune infiltrates><Immunomodulation><In Vitro><Incidence><Infection><Inflammatory><Innate Immunity><Intercrines><Interferon Alfa-n3><Interferon Gamma><Interferon Gamma Receptor-1><Interferon Type II><Interferon alpha><Interferon-Gamma Receptor 1><Interferon-α><Interferons><Intracranial CNS Disorders><Intracranial Central Nervous System Disorders><Ix scalpularis><Ix. scapularis><Ixodes dammini><Ixodes scapularis><Ixodida><Leukocyte Interferon><Licensing><Link><Long Island><Lymphoblast Interferon><Lymphoblastoid Interferon><Mammalia><Mammals><Mice><Mice Mammals><Modeling><Modern Man><Murine><Mus><Native Immunity><Natural Immunity><Nervous System Injuries><Nervous System Trauma><Nervous System damage><Neurological Damage><Neurological Injury><Neurological trauma><Non-Specific Immunity><Nonspecific Immunity><Occluding Junctions><Pathology><Pathway interactions><Patients><Peripheral><Phase><Powassan><Powassan virus><Proteins><Pyrexia><Rationalization><Recombinants><Regulation><Repression><Respiratory Infections><Respiratory Tract Infections><Role><SARS-CoV-2 infected patient><SARS-CoV-2 patient><SARS-CoV-2 positive patient><SIS cytokines><Seizures><Skin><Slice><Staining method><Stains><Structure of choroid plexus><System><Therapeutic><Therapeutic Uses><Ticks><Tight Junctions><Vaccines><Vascular Endothelial Cell><Viral><Viral Burden><Viral Diseases><Viral Load><Viral Load result><Virus><Virus Diseases><Zonula Occludens><advanced age><age associated><age correlated><age dependent><age linked><age related><age specific><aged mice><aged mouse><attenuate><attenuates><attenuation><blacklegged tick><blood cerebrospinal fluid barrier><bloodbrain barrier><brain control><brain damage><brain endothelial cell><brain microvascular endothelial cell><brain vascular endothelial cell><brain-injured><cerebral endothelial cell><cerebral microvascular endothelial cell><cerebral vascular endothelial cell><chemoattractant cytokine><chemokine><chimeras><coronavirus disease 2019 infected patient><coronavirus disease 2019 patient><coronavirus disease 2019 positive patient><coronavirus disease infected patient><coronavirus disease patient><coronavirus disease positive patient><coronavirus disease-19 patient><coronavirus patient><cytoprotective><elderly mice><elderly patient><emergent virus><emerging virus><febrile><febris><geriatric><immune cell infiltrate><immune modulation><immune regulation><immunologic reactivity control><immunomodulatory><immunoregulation><immunoregulatory><in vivo><inhibitor><interferon gamma receptor><lFN-Gamma><mouse model><murine model><mutant><neural inflammation><neuro-vascular><neuroinflammation><neuroinflammatory><neurotrauma><neurovascular><neurovirulence><novel><old mice><older patient><pathway><patient infected with COVID><patient infected with COVID-19><patient infected with SARS-CoV-2><patient infected with coronavirus disease><patient infected with coronavirus disease 2019><patient infected with severe acute respiratory syndrome coronavirus 2><patient with COVID><patient with COVID-19><patient with COVID19><patient with SARS-CoV-2><patient with coronavirus disease><patient with coronavirus disease 2019><patient with severe acute respiratory distress syndrome coronavirus 2><prevent><preventing><prophylactic><repair><repaired><response><reverse genetics><scRNA-seq><senior citizen><severe acute respiratory syndrome coronavirus 2 infected patient><severe acute respiratory syndrome coronavirus 2 patient><severe acute respiratory syndrome coronavirus 2 positive patient><single cell RNA-seq><single cell RNAseq><single cell expression profiling><single cell transcriptomic profiling><single-cell RNA sequencing><social role><tick bite><tick saliva><tick-borne flavivirus><tick-borne virus><tickborne flavivirus><tickborne virus><viral emergence><viral infection><virus infection><virus-induced disease>