Structural basis for respiratory syncytial virus and human metapneumovirus neutralization

Respiratory syncytial virus (RSV) and human metapneumovirus (hMPV) continue to be a global burden to infants, the elderly, and immunocompromised individuals. In the past ten years, there has been substantial progress in the development of new vaccine candidates and therapies against these viruses. These advancements were guided by the structural elucidation of the major surface glycoproteins for these viruses, the fusion (F) protein and attachment (G) protein. The identification of immunodominant epitopes on the RSV F and hMPV F proteins has expanded current knowledge on antibody-mediated immune responses, which has led to new approaches for vaccine and therapeutic development through the stabilization of pre-fusion constructs of the F protein and pre-fusion-specific monoclonal antibodies with high potency and efficacy. In this review, we describe structural characteristics of known antigenic sites on the RSV and hMPV proteins, their influence on the immune response, and current progress in vaccine and therapeutic development.