Fig. 1.

Multicolor three-dimensional superresolution microscopy enables quantitative interrogation of angular distributions of Env at HIV-1 assembly sites. a Hypothetical models for angular spatial arrangements of Env clusters around a viral lattice (plasma membrane, blue; Env, green; Gag, red). Neck-distributed Env clusters would result from late Env acquisition, following Gag lattice assembly (left). Crown-distributed Env clusters would result from assembly of Gag at sites of Env clustering (middle). Unbiased distributions of Env clusters are expected if Env is stochastically trapped throughout the lifetime of Gag lattice assembly (right). b Superresolution imaging in 3D resolves individual Env clusters (green) decorating four virus assembly sites (Gag, red) protruding from the plasma membrane (blue; center X–Y projection and lower and left Z (optical axis) projections). Diffraction-limited microscopy fails to resolve these budding events (right images, X–Y projection). Scale bar is 100 nm. Diffraction-limited pixel size is 133 nm. c Representative HIV-1 assembly sites segmented from CEM-A cells, observed by projection (X–Y, left) and perpendicular (X–Z, right) views. Scale bars are 100 nm