Antibody recognition of the Pneumovirus fusion protein trimer interface

• Published in: PLoS pathogens Vol. 16; no. 10; p. e1008942
• Main Authors: Huang, Jiachen, Diaz, Darren, Mousa, Jarrod J.
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 09.10.2020; Public Library of Science (PLoS)
• Subjects: Antibodies; Antibodies, Monoclonal - immunology; Antibodies, Neutralizing - immunology; Antibodies, Neutralizing - pharmacology; Antibodies, Viral - immunology; Antigens; BASIC BIOLOGICAL SCIENCES; Biology and Life Sciences; Crystallization; Engineering and Technology; Epidemics; Epitopes; Epitopes - immunology; F 2 region; F protein; Fusion protein; Genetic aspects; Glycan; Glycoproteins; Health aspects; Host-virus relationships; Human subjects; Humans; Identification and classification; Immune response; Immune response (humoral); Immune system; Immunocompromised hosts; Immunology; Infants; Infections; Infectious diseases; Interferometry; Medicine and Health Sciences; Metapneumovirus - immunology; Monoclonal antibodies; Mutation; Neutralization; Neutralizing; Paramyxoviridae Infections - virology; Peptides; Physical Sciences; Pneumovirus - immunology; Proteins; Recognition; Research and Analysis Methods; Respiratory diseases; Respiratory syncytial virus; Respiratory Syncytial Virus, Human - immunology; Respiratory tract; Respiratory tract diseases; RNA viruses; Severe acute respiratory syndrome coronavirus 2; Trimers; Vaccines; Veterinary colleges; Veterinary medicine; Viral Fusion Proteins - immunology; Viral infections; Viral proteins; Viruses; United States; United States > US
• ISSN: 1553-7374; 1553-7366; 1553-7374
• DOI: 10.1371/journal.ppat.1008942

Human metapneumovirus (hMPV) is a leading cause of viral respiratory infection in children, and can cause severe lower respiratory tract infection in infants, the elderly, and immunocompromised patients. However, there remain no licensed vaccines or specific treatments for hMPV infection. Although the hMPV fusion (F) protein is the sole target of neutralizing antibodies, the immunological properties of hMPV F remain poorly understood. To further define the humoral immune response to the hMPV F protein, we isolated two new human monoclonal antibodies (mAbs), MPV458 and MPV465. Both mAbs are neutralizing in vitro and were determined to target a unique antigenic site using competitive biolayer interferometry. We determined both MPV458 and MPV465 have higher affinity for monomeric hMPV F than trimeric hMPV F. MPV458 was co-crystallized with hMPV F, and the mAb primarily interacts with an alpha helix on the F2 region of the hMPV F protein. Surprisingly, the major epitope for MPV458 lies within the trimeric interface of the hMPV F protein, suggesting significant breathing of the hMPV F protein must occur for host immune recognition of the novel epitope. In addition, significant glycan interactions were observed with a somatically mutated light chain framework residue. The data presented identifies a novel epitope on the hMPV F protein for epitope-based vaccine design, and illustrates a new mechanism for human antibody neutralization of viral glycoproteins.