Structural Basis for Childhood Antibody Recognition of The Human Metapneumovirus Fusion Protein

Area of Science:

• Virology
• Immunology
• Structural Biology

Background:

• Human metapneumovirus (hMPV) causes significant respiratory illness, particularly in vulnerable populations.
• The hMPV fusion (F) protein is crucial for viral entry and the primary target for neutralizing antibodies.
• Antibody responses to hMPV F protein epitopes in children are not well understood.

Purpose of the Study:

• To characterize the antibody response to the hMPV F protein in children.
• To identify novel neutralizing epitopes on the hMPV F protein targeted by pediatric antibodies.
• To evaluate the therapeutic potential of pediatric-derived monoclonal antibodies (mAbs) against hMPV.

Main Methods:

• Isolation and characterization of human monoclonal antibodies (mAbs) from hMPV-infected children.
• Assessment of mAb binding avidity, neutralization potency, and epitope specificity.
• Determination of cryo-electron microscopy (cryo-EM) structures of mAb-hMPV F protein complexes.
• Evaluation of prophylactic efficacy of mAbs in a mouse model.

Main Results:

• A panel of neutralizing human mAbs targeting distinct epitopes on the hMPV F protein was generated.
• Cryo-EM structures revealed epitopes on the F protein surface and within its trimer interface.
• Epitope mapping identified four different antigenic sites targeted by the pediatric mAbs.
• Prophylactic administration of mAbs demonstrated efficacy in protecting mice against hMPV challenge.

Conclusions:

• This study elucidates immunodominant antigenic epitopes on the hMPV F protein in children.
• Identified epitopes and derived mAbs represent promising candidates for hMPV disease prevention and therapy.
• Understanding pediatric antibody responses is critical for developing effective hMPV interventions.