Computational Design and Expression of Headless Influenza Hemagglutinin Antigens Toward a Modular Universal Nanoparticle Vaccine

Background: The elicitation of broadly neutralizing antibodies against conserved antigenic epitopes has been a focus of universal vaccine research. To facilitate immunofocusing on the conserved influenza hemagglutinin (HA) stalk, we designed headless trimeric antigens, initially focusing on subtypes H1, H3, and H5, and subsequently expanding to eight additional HA subtypes. Results: The designs were first evaluated in silico; they were predicted to fold correctly by AlphaFold2, and remained stable in molecular dynamics simulations in isolation, as well as bound to a broadly neutralizing antibody. The antigens expressed in HEK293-derived cells in high yields, and eluted predominantly as trimers in SEC-HPLC. Future work will explore the use of mosaic nanoparticles decorated with headless antigens of various subtypes for the optimal elicitation of broadly neutralizing anti-influenza antibodies. Overall, our study advances the use of headless HA trimers as modular antigens toward a universal influenza vaccine.