One-Pot Expression and Assembly of Resurfaced Zika Virus E Domain III Nanoparticle Immunogens in Mammalian Cells

The presentation of antigens on self-assembling nanoparticles is a promising approach for augmenting the B-cell response of vaccines. In many cases, the nanoparticle and antigen are recombinantly expressed and purified separately prior to conjugation, requiring multiple steps that may be inefficient for large-scale production. Here, we describe a genetically encodable method and "one-pot" production of nanoparticle immunogens from mammalian cells. Our approach relies on the in situ assembly of the nanoparticle-antigen conjugate, between protein nanoparticles bearing SpyCatcher003 and antigen fused to SpyTag003, using simple cotransfection in mammalian cells, which can then be purified to homogeneity in a single step. We demonstrate this method with an antigen based on Zika virus E glycoprotein domain III ("rsZDIII-2.39") and compare the biochemical properties and immunogenicity in mice relative to genetic fusions. This work provides a framework for streamlining immunogen production and raises the possibility of employing such approaches for encoding nanoparticle immunogens as nucleic acid vaccines.