HIV-1 buds predominantly at the plasma membrane of primary human macrophages.
HIV-1 assembly and release are believed to occur at the plasma membrane in most host cells with the exception of primary macrophages, for which exclusive budding at late endosomes has been reported. Here, we applied a novel ultrastructural approach to assess HIV-1 budding in primary macrophages in an immunomarker-independent manner. Infected macrophages were fed with BSA-gold and stained with the membrane-impermeant dye ruthenium red to identify endosomes and the plasma membrane, respectively. Virus-filled vacuolar structures with a seemingly intracellular localization displayed intense staining with ruthenium red, but lacked endocytosed BSA-gold, defining them as plasma membrane. Moreover, HIV budding profiles were virtually excluded from gold-filled endosomes while frequently being detected on ruthenium red-positive membranes. The composition of cellular marker proteins incorporated into HIV-1 supported a plasma membrane-derived origin of the viral envelope. Thus, contrary to current opinion, the plasma membrane is the primary site of HIV-1 budding also in infected macrophages.
Welsch
Sonja
S
Department of Virology, University of Heidelberg, Heidelberg, Germany.
Keppler
Oliver T
OT
Habermann
Anja
A
Allespach
Ina
I
Krijnse-Locker
Jacomine
J
Kräusslich
Hans-Georg
HG
D015703:Antigens, CD / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure / Q000821:virology*; D002478:Cells, Cultured; D011992:Endosomes / Q000648:ultrastructure; D006046:Gold; D015497:HIV-1 / Q000254:growth & development* / Q000502:physiology; D006801:Humans; D051861:Kangai-1 Protein / Q000378:metabolism; D051907:Lysosomal Membrane Proteins / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism / Q000648:ultrastructure / Q000821:virology*; D008969:Molecular Sequence Data; D009024:Morphogenesis / Q000502:physiology*; D010980:Platelet Membrane Glycoproteins / Q000378:metabolism; D012430:Ruthenium Red; D060225:Tetraspanin 28; D060149:Tetraspanin 30; D014617:Vacuoles / Q000648:ultrastructure / Q000821:virology; D052118:Lysosomal-Associated Membrane Protein 1
D015703:Antigens, CD; D006046:Gold; D051861:Kangai-1 Protein; D051907:Lysosomal Membrane Proteins; D010980:Platelet Membrane Glycoproteins; D012430:Ruthenium Red; D060225:Tetraspanin 28; D060149:Tetraspanin 30; C554586:CD63 protein, human; C554798:CD81 protein, human; C489116:LAMP1 protein, human; D052118:Lysosomal-Associated Membrane Protein 1