Researchers at the La Jolla Institute for Immunology (LJI) identified human monoclonal antibodies that neutralize measles virus by blocking viral entry through two essential surface proteins: hemagglutinin (H) and fusion (F). In their reported work, antibodies derived from memory B cells of an MMR-vaccinated donor bound to these targets and demonstrated efficacy in a rodent measles model. LJI reported that the antibody infusion produced a 500-fold lower viral load in the animal study and that the antibodies could function both as prophylaxis and as post-exposure treatment. The study was published in Cell Host & Microbe, with LJI framing it as an avenue for therapies for people who cannot receive standard live-attenuated vaccines. The scientific significance is the dual blockade mechanism, which LJI said can prevent infection by disrupting the steps required for viral fusion and entry. Erica Ollmann Saphire, LJI’s president and CEO, said the antibody panel may protect the most vulnerable patients where vaccination is not feasible. For biopharma, the work provides a clear therapeutic template for emerging measles risk: antibody-based interventions designed for high-risk populations and outbreak settings could reduce dependence on vaccine eligibility and timing.