FIGURE 1.

In vitro-assembling (two-component) nanoparticles allow for greater control over Env quality than in vivo-assembling (one-component) nanoparticles. In contrast to in vivo-assembling nanoparticles such as Env-ferritin (top panel) or VLPs presenting Env, in vitro-assembling nanoparticles such as Env-liposomes or Env-I53-50 nanoparticles (bottom) allow purification of Env trimers prior to assembly ensuring that native-like trimers (green) are selected and nonnative trimers (red) are excluded from the nanoparticles.