title: Cell-free human immunodeficiency virus type 1 transcytosis through primary genital epithelial cells.
abstract: Although the transport of human immunodeficiency virus type 1 (HIV-1) through the epithelium is critical for HIV-1 colonization, the mechanisms controlling this process remain obscure. In the present study, we investigated the transcellular migration of HIV-1 as a cell-free virus through primary genital epithelial cells (PGECs). The absence of CD4 on PGECs implicates an unusual entry pathway for HIV-1. We found that syndecans are abundantly expressed on PGECs and promote the initial attachment and subsequent entry of HIV-1 through PGECs. Although CXCR4 and CCR5 do not contribute to HIV-1 attachment, they enhance viral entry and transcytosis through PGECs. Importantly, HIV-1 exploits both syndecans and chemokine receptors to ensure successful cell-free transport through the genital epithelium. HIV-1-syndecan interactions rely on specific residues in the V3 of gp120 and specific sulfations within syndecans. We found no obvious correlation between coreceptor usage and the capacity of the virus to transcytose. Since viruses isolated after sexual transmission are mainly R5 viruses, this suggests that the properties conferring virus replication after transmission are distinct from those conferring cell-free virus transcytosis through the genital epithelium. Although we found that cell-free HIV-1 crosses PGECs as infectious particles, the efficiency of transcytosis is extremely poor (less than 0.02% of the initial inoculum). This demonstrates that the genital epithelium serves as a major barrier against HIV-1. Although one cannot exclude the possibility that limited passage of cell-free HIV-1 transcytosis through an intact genital epithelium occurs in vivo, it is likely that the establishment of infection via cell-free HIV-1 transmigration is a rare event.
authors.affiliation: Department of Immunology, The Scripps Research Institute, IMM-9, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Bobardt
authors.forename: Udayan
authors.initials: U
authors.lastname: Chatterji
authors.forename: Suganya
authors.initials: S
authors.lastname: Selvarajah
authors.forename: Bernadette
authors.initials: B
authors.lastname: Van der Schueren
authors.forename: Guido
authors.initials: G
authors.lastname: David
authors.forename: Bruce
authors.initials: B
authors.lastname: Kahn
authors.forename: Philippe A
authors.initials: PA
authors.lastname: Gallay
mesh_terms: D001692:Biological Transport; D015704:CD4 Antigens / Q000378:metabolism / Q000502:physiology; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000821:virology*; D005260:Female; D005699:Galactosylceramides / Q000502:physiology; D015699:HIV Envelope Protein gp120 / Q000378:metabolism; D015497:HIV-1 / Q000502:physiology*; D006493:Heparin / Q000031:analogs & derivatives / Q000502:physiology; D006801:Humans; D037181:Lectins, C-Type / Q000502:physiology; D011509:Proteoglycans / Q000502:physiology; D019713:Receptors, CCR5 / Q000378:metabolism / Q000502:physiology; D019718:Receptors, CXCR4 / Q000378:metabolism / Q000502:physiology; D053667:Syndecans / Q000378:metabolism; D014621:Vagina / Q000166:cytology / Q000821:virology*
chemical_list: D015704:CD4 Antigens; D005699:Galactosylceramides; D015699:HIV Envelope Protein gp120; D037181:Lectins, C-Type; D011509:Proteoglycans; D019713:Receptors, CCR5; D019718:Receptors, CXCR4; D053667:Syndecans; C036090:heparin proteoglycan; D006493:Heparin