Respiratory Syncytial Virus Fusion Protein Epitope-Specific Antibodies and Neutralizing Activities Against Various Respiratory Syncytial Virus Strains.

Abstract

Respiratory syncytial virus (RSV) fusion protein contains major neutralizing epitopes (sites II, III, IV, V, and Ø), targeted by new vaccines and monoclonal antibodies. However, data on serum epitope-specific antibodies (ESAs) and their association with neutralizing activity (NA) are limited. We aimed to evaluate ESA in healthy Japanese adults and their association with NA against various clinical isolates. Serum samples were collected from pediatricians from February to March 2020. ESA and NA levels were quantified by enzyme-linked immunosorbent assays and neutralizing assays. Pearson correlation analysis was used to estimate the association. Ninety-two healthy adults aged 28 to 75 years were included. The ESA levels differed significantly across all sites. ESA levels were lower at sites IV and Ø (median [IQR], 2.7 μg/mL [2.2-3.4] and 10.2 [8.1-13.5], respectively) than at other sites (41.9 [35.0-56.7] at II, 16.6 [9.4-44.1] at III, and 35.3 [28.4-42.4] at V). Associations between ESA and NA levels differed by subtype and mutation. ESA and NA levels should be considered in the development and application of vaccines and monoclonal antibody therapies. Monitoring serum ESA levels and RSV fusion protein genes is essential for treatment selection.