Structural basis for childhood antibody recognition of the human metapneumovirus fusion protein.

Summary

Five neutralizing mAbs isolated from hMPV-infected children map to four distinct epitopes on the F trimer, including a newly visualized intratrimer interface epitope, and confer prophylactic protection in mice. These structural and functional insights illuminate pediatric immunodominant targets to guide vaccine and monoclonal antibody design.

Key Findings

• Five human mAbs from hMPV-infected children were all neutralizing and targeted four distinct epitopes on hMPV F.
• Cryo-EM resolved four mAb–F complexes, revealing surface epitopes and a fully intratrimer epitope within the F trimer interface.
• Prophylactic administration of these mAbs protected mice from hMPV challenge, demonstrating in vivo efficacy.
• Findings define immunodominant pediatric epitopes distinct from adult-focused maps, informing antigen design.

Clinical Implications

Identified epitopes, especially the intratrimer interface, can inform next-generation vaccine antigens and prophylactic mAbs optimized for pediatric immunity against hMPV.

Limitations

• Small pediatric sampling with limited number of mAbs and donors
• Preclinical mouse protection may not fully predict human efficacy

Future Directions

Validate intratrimer and surface epitopes across larger pediatric cohorts; assess antibody breadth, escape risk, and synergistic mAb cocktails; translate to vaccine antigen engineering and clinical-grade mAb development.