title: A role for CD81 on the late steps of HIV-1 replication in a chronically infected T cell line.
abstract: BACKGROUND
  HIV-1 uses cellular co-factors for virion formation and release. The virus is able to incorporate into the viral particles host cellular proteins, such as tetraspanins which could serve to facilitate HIV-1 egress. Here, we investigated the implication of several tetraspanins on HIV-1 formation and release in chronically infected T-lymphoblastic cells, a model that permits the study of the late steps of HIV-1 replication.
  
  
  RESULTS
  Our data revealed that HIV-1 Gag and Env structural proteins co-localized with tetraspanins in the form of clusters. Co-immunoprecipitation experiments showed that Gag proteins interact, directly or indirectly, with CD81, and less with CD82, in tetraspanin-enriched microdomains composed of CD81/CD82/CD63. In addition, when HIV-1 producing cells were treated with anti-CD81 antibodies, or upon CD81 silencing by RNA interference, HIV-1 release was significantly impaired, and its infectivity was modulated. Finally, CD81 downregulation resulted in Gag redistribution at the cell surface.
  
  
  CONCLUSIONS
  Our findings not only extend the notion that HIV-1 assembly can occur on tetraspanin-enriched microdomains in T cells, but also highlight a critical role for the tetraspanin CD81 on the late steps of HIV replication.
authors.affiliation: LaboRetro, Unité de Virologie Humaine INSERM U758, Ecole Normale Supérieure de Lyon, Lyon, France. Boyan.Grigorov@ens-lyon.fr
authors.forename: Boyan
authors.initials: B
authors.lastname: Grigorov
authors.forename: Valérie
authors.initials: V
authors.lastname: Attuil-Audenis
authors.forename: Fabien
authors.initials: F
authors.lastname: Perugi
authors.forename: Martine
authors.initials: M
authors.lastname: Nedelec
authors.forename: Sarah
authors.initials: S
authors.lastname: Watson
authors.forename: Claudine
authors.initials: C
authors.lastname: Pique
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Darlix
authors.forename: Hélène
authors.initials: H
authors.lastname: Conjeaud
authors.forename: Delphine
authors.initials: D
authors.lastname: Muriaux
mesh_terms: D015703:Antigens, CD / Q000378:metabolism*; D002460:Cell Line; D015536:Down-Regulation; D015658:HIV Infections / Q000821:virology*; D015497:HIV-1 / Q000472:pathogenicity / Q000502:physiology*; D047468:Immunoprecipitation; D008565:Membrane Proteins / Q000378:metabolism; D034622:RNA Interference; D013601:T-Lymphocytes / Q000821:virology*; D060225:Tetraspanin 28; D014764:Viral Proteins / Q000378:metabolism; D014771:Virion / Q000302:isolation & purification / Q000378:metabolism; D014779:Virus Replication / Q000502:physiology*; D054299:env Gene Products, Human Immunodeficiency Virus / Q000378:metabolism; D054301:gag Gene Products, Human Immunodeficiency Virus / Q000378:metabolism
chemical_list: D015703:Antigens, CD; C554798:CD81 protein, human; D008565:Membrane Proteins; D060225:Tetraspanin 28; D014764:Viral Proteins; D054299:env Gene Products, Human Immunodeficiency Virus; D054301:gag Gene Products, Human Immunodeficiency Virus