Efficient and Long-lived Brain Delivery of Neutralizing Antibodies Against Eastern Equine Encephalitis Virus for Post-exposure Therapy

Eastern equine encephalitis virus (EEEV) is a lethal alphavirus transmitted by mosquitoes. Aerosol exposure to the virus results in rapid viral entry into the brain via the olfactory neuroepithelium. While potently neutralizing antibodies have been identified that provide some post-exposure protection when the virus is administered subcutaneously (especially at early time points), they are much less effective when administered after aerosol exposure. The lack of therapeutic protection in the latter case is likely due to the inability of antibodies to efficiently penetrate the blood-brain barrier (BBB) and neutralize and/or clear virus already in the brain. Given that clinical diagnosis is typically not made until patients manifest symptoms of encephalitis, the availability of therapeutics capable of efficiently penetrating the BBB and inhibiting virus that has already entered the CNS represents a major unmet medical need for EEEV, and arguably for all other encephalitic viruses. The overall objective of this proof-of-concept study is to address this need by developing BBB-penetrating bispecific antibodies (bAbs) for rapid, concentrated, and sustained delivery of anti-EEEV neutralizing antibodies to the brain after IV administration. Members of our team (Tessier and Greineder) recently reported bAbs that target CD98hc – the heavy chain of the large neutral amino acid transporter (LAT1) – and mediate the delivery of IgGs into the brain parenchyma after IV administration. Notably, we observe superior brain retention and less parenchymal cellular internalization of IgGs shuttled via CD98hc compared to those shuttled via transferrin receptor-1 (TfR-1). Moreover, we (Diamond) have identified a panel of potently neutralizing mAbs against EEEV and confirmed their protective ability in lethal challenges in mice at early but not late time points. Here, we propose to test our primary hypotheses that anti-EEEV/CD98hc bAbs will be both i) effective at protecting against direct intracranial inoculation of EEEV (Madariaga strain) and ii) more protective than equivalent TfR-1 bAbs. Therefore, in Aim 1, we will evaluate the impact of anti-EEEV antibody, level of Fc-mediated effector functions, and dose on the kinetics of brain uptake, maximum brain levels, and potential dose-limiting toxicities of anti-EEEV/CD98hc bAbs relative to equivalent TfR-1 bAbs. Next, in Aim 2, we will evaluate the therapeutic effectiveness of anti-EEEV/CD98hc bAbs relative to equivalent TfR-1 bAbs after intracranial administration of EEEV-Madariaga. A key outcome of this study will be the evaluation of the feasibility of using bAbs with advanced properties to protect against EEEV-mediated lethality after the virus has entered the brain. We expect to identify key factors that impact antibody-mediated protection after intracranial administration, which could inform the design of therapeutics against other viruses that involve brain-mediated lethality. Project Number: 1R21AI190578-01 | Fiscal Year: 2025 | NIH Institute/Center: National Institute of Allergy and Infectious Diseases (NIAID) | Principal Investigator: Peter Tessier | Institution: UNIVERSITY OF MICHIGAN AT ANN ARBOR, ANN ARBOR, MI | Award Amount: $240,300 | Activity Code: R21 | Study Section: Special Emphasis Panel[ZRG1 CN-A (81)] View on NIH RePORTER: https://reporter.nih.gov/project-details/1R21AI19057801