Tethered virions are intermediates in the assembly and release of HIV-1 particles.
Vpu enhances HIV-1 release by suppressing CD317-mediated tethering of virions to the cell surface. In HeLa H1 cells, Vpu(+) infection produces significant amounts of tethered virions, although efficient virus release requires Vpu. We have analyzed membrane targeting and assembly of newly synthesized Gag in infected HeLa H1 cells by quantitative pulse-chase assays in both Vpu(+) and ΔVpu virus backgrounds and in the presence and absence of CD317. Our results show that formation of tethered virions precedes release of viruses to the culture medium in the Vpu(+) infection, and CD317 knockdown reduces tethering in both Vpu(+) and ΔVpu virus backgrounds. Significantly, our results indicate that tethered Vpu(+) viruses represent precursors for extracellular viruses, and Vpu thus appears to reverse tethering in HeLa H1 cells after budding.
Karetnikov
Alexey
A
Department of Virology, Haartman Institute, PO Box 21, FIN-00014 University of Helsinki, Finland.
Suomalainen
Maarit
M
D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D003470:Culture Media; D058851:GPI-Linked Proteins; D015497:HIV-1 / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D006367:HeLa Cells; D054298:Human Immunodeficiency Virus Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D054334:Viral Regulatory and Accessory Proteins / Q000235:genetics / Q000378:metabolism*; D014771:Virion / Q000378:metabolism*; D019065:Virus Assembly / Q000502:physiology*; D057074:Virus Release / Q000502:physiology*; D000074010:Bone Marrow Stromal Antigen 2; D000086082:Viroporin Proteins
D015703:Antigens, CD; D003470:Culture Media; D058851:GPI-Linked Proteins; D054298:Human Immunodeficiency Virus Proteins; D008562:Membrane Glycoproteins; D054334:Viral Regulatory and Accessory Proteins; C094572:BST2 protein, human; D000074010:Bone Marrow Stromal Antigen 2; C514859:vpu protein, Human immunodeficiency virus 1; D000086082:Viroporin Proteins