In macrophages, HIV-1 has been shown to bud into intracellular structures that contain the late endosome marker CD63. We show that these organelles are not endosomes, but an internally sequestered plasma membrane domain. Using immunofluorescence microscopy and immunoelectron microscopy, we find that HIV-1 buds into a compartment that contains the tetraspanins CD81, CD9, and CD53. On uninfected macrophages, these proteins are seen at the cell surface and in intracellular vacuole-like structures with a complex content of vesicles and interconnected membranes that lack endosome markers, including CD63. Significantly, these structures are accessible to small tracers (horseradish peroxidase or ruthenium red) applied to cells at 4°C, indicating that they are connected to the cell surface. HIV assembles on, and accumulates within, these intracellular compartments. Furthermore, CD63 is recruited to the virus-containing structures and incorporated into virions. These results indicate that, in macrophages, HIV-1 exploits a previously undescribed intracellular plasma membrane domain to assemble infectious particles.

LN inflammation in chronic HIV is associated with accumulation of follicular CD8 T cells that could be redirected to kill infected cells.

High-energy inositol pyrophosphates, such as IP ₇ (diphosphoinositol pentakisphosphate), can directly donate a β-phosphate to a prephosphorylated serine residue generating pyrophosphorylated proteins. Here, we show that the β subunit of AP-3, a clathrin-associated protein complex required for HIV-1 release, is a target of IP ₇ -mediated pyrophosphorylation. We have identified Kif3A, a motor protein of the kinesin superfamily, as an AP3B1-binding partner and demonstrate that Kif3A, like the AP-3 complex, is involved in an intracellular process required for HIV-1 Gag release. Importantly, IP ₇ -mediated pyrophosphorylation of AP3B1 modulates the interaction with Kif3A and, as a consequence, affects the release of HIV-1 virus-like particles. This study identifies a cellular process that is regulated by IP ₇ -mediated pyrophosphorylation.

Immune selection footprints in proviral sequences distinguish individuals with natural, drug-free control of HIV-1.