Project Summary
Influenza remains a global health challenge. There is a pressing need for next-generation vaccines that can
protect against a broad range of influenza subtypes, particularly those of pandemic potential (e.g., H5, H7).
Hemagglutinin (HA) and neuraminidase (NA) are two surface glycoproteins, which facilitate virion binding and
egress, respectively. While contemporary influenza vaccines are not standardized for NA, recent studies have
underscored the importance of NA-directed antibodies in influenza protection. However, relative to HA, the
immunodominance of NA and its evolutionary response to immune pressure remain largely uncharacterized.
Furthermore, whether an NA-based immunogen(s) can focus the humoral response to conserved sites on NA
has yet to be determined. The NA catalytic site (CS) cleaves sialic acid to enable viral egress and is conserved
amongst NA subtypes. Here, I hypothesize that structure-guided immunogen design can focus the immune
response to the conserved NA CS and augment anti-NA antibody breadth. To elicit a focused, CS-directed
immune response, I will pursue two approaches. 1) l will engineer glycans on the NA periphery to mask variable
epitopes, leaving the conserved CS exposed. 2) I will graft the conformationally complex CS onto antigenically
distinct scaffolds to enrich the CS epitope relative to other epitopes. To elicit broader anti-NA immunity and
augment CS-directed B cell activation, I will increase NA valency using protein linkers and nanoparticle platforms.
I will then test the effects of these NA immunogens in vivo and characterize the resulting serum, germinal center,
and memory B cell repertoires. I further hypothesize that focused anti-NA immunity will complement focused
anti-HA immunity to restrict influenza escape pathways. After passaging an influenza strain with anti-HA
antibodies, anti-NA antibodies, or both, I will characterize viral escape mutants and compare growth kinetics
relative to the wildtype strain. The data generated from this proposal will elucidate the effectiveness of the
proposed immune-focusing strategies as a general approach to vaccine design and particularly inform the
optimization of NA immunogens for next-generation influenza vaccines. These results will also advance our
understanding of NA antigenicity and evolvability.