Influenza A viruses cause considerable morbidity and mortality annually, posing threats to public health worldwide. Monoclonal antibodies represent a viable approach for the treatment of influenza. Antibodies targeting hemagglutinin (HA) and neuraminidase (NA), the two important surface glycoproteins of influenza virus, can disrupt viral entry into host cells and block viral egress or prevent virus from budding, respectively. Earlier work defined the structure of NA and NA-fragment antigen-binding (Fab) complexes and demonstrated the protective effects of immune responses to NA.