Neuraminidase-on-a-string nanoparticles probe how antigenic distance shapes elicited humoral immunity.

Understanding how antigenic distance influences cross-reactive responses can inform vaccine design. Multivalent displays of viral proteins can improve B cell activation due to receptor cross-linking, and mosaic nanoparticles that incorporate variants can lead to cross-reactive B cell responses recognizing conserved epitopes. Here, we used the influenza virus neuraminidase to develop a neuraminidase-on-a-string platform displaying neuraminidase dimer pairs conjugated to a nanocarrier To systematically assess the influence of antigenic distance on humoral immunity, we paired H2N2 neuraminidase with either divergent H3N2 or H11N9 neuraminidases. We found that nanoparticle immunizations with heterologous antigens elicited sera with greater breadth and enhanced enzymatic inhibition relative to immunizations that incorporated a single neuraminidase strain. While sera reactivity for H2N2 neuraminidase was not impacted by inclusion of a second strain, strain-specific responses correlatively increased with the antigenic distance between neuraminidase components. These data show how neuraminidase strain selection for multivalent display immunizations influences elicited breadth and cross-reactivity, highlighting findings that may extend to other viral antigens.