In macrophages, HIV-1 assembles into an intracellular plasma membrane domain containing the tetraspanins CD81, CD9, and CD53.
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 degrees 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.
Deneka
Magdalena
M
Cell Biology Unit, Medical Research Council Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, England, UK.
Pelchen-Matthews
Annegret
A
Byland
Rahel
R
Ruiz-Mateos
Ezequiel
E
Marsh
Mark
M
D015703:Antigens, CD / Q000032:analysis*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis*; D045744:Cell Line, Tumor; D015497:HIV-1 / Q000502:physiology*; D006801:Humans; D007425:Intracellular Membranes / Q000737:chemistry / Q000648:ultrastructure / Q000821:virology*; D007963:Leukocytes, Mononuclear; D008264:Macrophages / Q000166:cytology / Q000378:metabolism / Q000821:virology*; D008562:Membrane Glycoproteins / Q000032:analysis*; D010980:Platelet Membrane Glycoproteins / Q000032:analysis; D060265:Tetraspanin 25; D060225:Tetraspanin 28; D060245:Tetraspanin 29; D060149:Tetraspanin 30; D019065:Virus Assembly
D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; C554894:CD53 protein, human; C554586:CD63 protein, human; C554798:CD81 protein, human; C554869:CD9 protein, human; D008562:Membrane Glycoproteins; D010980:Platelet Membrane Glycoproteins; D060265:Tetraspanin 25; D060225:Tetraspanin 28; D060245:Tetraspanin 29; D060149:Tetraspanin 30