A facile method for purifying viral immunogens using magnetic beads to generate neutralizing antibodies.

Human parainfluenza virus type 3 (HPIV-3), an increasingly significant respiratory pathogen affecting both pediatric and elderly populations, currently lacks effective prophylactic or therapeutic interventions. The development of antibody-based therapeutics with the potential to prevent or treat HPIV-3 infection remains an active area of investigation. However, a major limitation of such antibody therapies is the emergence of escape mutant strains. Combination therapy employing multiple neutralizing antibodies targeting distinct epitopes has been explored as a strategy to circumvent viral escape in influenza and human immunodeficiency virus infections. However, the probability of obtaining multiple neutralizing antibodies, including those against HPIV-3, is generally low. Here, to maximize the presentation of viral surface epitopes to immune cells, we purified HPIV-3 virus using magnetic bead-based technology. The resulting antigen-magnetic bead complexes were immobilized and used to immunize mice. This strategy employs viable and infectious virion as immunogens, thereby enabling immune cells to recognize the native antigenic architecture of the viral surface with high fidelity. This method, which permits immunization while preserving the viral surface structure to the greatest extent and may be broadly applicable to many viruses, provide a simple and rapid approach for developing therapeutic antibodies during public health emergencies.