HIV-1 vaccine design through minimizing envelope metastability

SUMMARY Overcoming envelope metastability is crucial to trimer-based HIV-1 vaccine design. Here, we present a coherent vaccine strategy by minimizing metastability. For ten strains across five clades, we demonstrate that gp41 ectodomain (gp41 ECTO ) is the main source of envelope metastability by replacing wild-type gp41 ECTO with BG505 gp41 ECTO of the uncleaved prefusion-optimized (UFO) design. These gp41 ECTO -swapped trimers can be produced in CHO cells with high yield and high purity. Crystal structure of a gp41 ECTO -swapped trimer elucidates how a neutralization-resistant tier 3 virus evades antibody recognition of the V2 apex. UFO trimers of transmitted/founder (T/F) viruses and UFO trimers containing a consensus-based ancestral gp41 ECTO suggest an evolutionary root of the metastability. Gp41ECTO-stabilized trimers can be readily displayed on 24- and 60-meric nanoparticles, with incorporation of additional T cell help illustrated for a hyperstable 60-mer. In mice and rabbits, gp140 nanoparticles induced more effective tier 2 neutralizing antibody response than trimers with statistical significance. HIGHLIGHTS gp41 is the main source of HIV-1 envelope metastability BG505 gp41 of the UFO design stabilizes gp140 trimers of diverse subtypes gp41 stabilization facilitates gp140 nanoparticle assembly and improves production Nanoparticles elicit tier 2 neutralizing antibodies more effectively than trimers