title: HIV-2 interaction with cell coreceptors: amino acids within the V1/V2 region of viral envelope are determinant for CCR8, CCR5 and CXCR4 usage.
abstract: BACKGROUND
  Human immunodeficiency virus 1 and 2 (HIV-1 and HIV-2) use cellular receptors in distinct ways. Besides a more promiscuous usage of coreceptors by HIV-2 and a more frequent detection of CD4-independent HIV-2 isolates, we have previously identified two HIV-2 isolates (HIV-2MIC97 and HIV-2MJC97) that do not use the two major HIV coreceptors: CCR5 and CXCR4. All these features suggest that in HIV-2 the Env glycoprotein subunits may have a different structural organization enabling distinct - although probably less efficient - interactions with cellular receptors.
  
  
  RESULTS
  By infectivity assays using GHOST cell line expressing CD4 and CCR8 and blocking experiments using CCR8-specific ligand, I-309, we show that efficient replication of HIV-2MIC97 and HIV-2MJC97 requires the presence of CCR8 at plasma cell membrane. Additionally, we disclosed the determinants of chemokine receptor usage at the molecular level, and deciphered the amino acids involved in the usage of CCR8 (R8 phenotype) and in the switch from CCR8 to CCR5 or to CCR5/CXCR4 usage (R5 or R5X4 phenotype). The data obtained from site-directed mutagenesis clearly indicates that the main genetic determinants of coreceptor tropism are located within the V1/V2 region of Env surface glycoprotein of these two viruses.
  
  
  CONCLUSIONS
  We conclude that a viral population able to use CCR8 and unable to infect CCR5 or CXCR4-positive cells, may exist in some HIV-2 infected individuals during an undefined time period, in the course of the asymptomatic stage of infection. This suggests that in vivo alternate molecules might contribute to HIV infection of natural target cells, at least under certain circumstances. Furthermore we provide direct and unequivocal evidence that the usage of CCR8 and the switch from R8 to R5 or R5X4 phenotype is determined by amino acids located in the base and tip of V1 and V2 loops of HIV-2 Env surface glycoprotein.
authors.affiliation: Host-Pathogen Interaction Unit, Research Institute for Medicines and Pharmaceutical Sciences (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003, Lisboa, Portugal. quirina.c@ff.ul.pt.|Instituto de Medicina Molecular (IMM), Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028, Lisboa, Portugal. quirina.c@ff.ul.pt.|Centro de Patogénese Molecular, Unidade dos Retrovírus e Infecções Associadas (CPM-URIA), Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003, Lisboa, Portugal. quirina.c@ff.ul.pt.
authors.forename: Quirina
authors.initials: Q
authors.lastname: Santos-Costa
authors.affiliation: Centro de Patogénese Molecular, Unidade dos Retrovírus e Infecções Associadas (CPM-URIA), Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003, Lisboa, Portugal. mlopes@ff.ul.pt.
authors.forename: Maria Manuel
authors.initials: MM
authors.lastname: Lopes
authors.affiliation: Host-Pathogen Interaction Unit, Research Institute for Medicines and Pharmaceutical Sciences (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003, Lisboa, Portugal. mrtcalado@ff.ul.pt.|Instituto de Medicina Molecular (IMM), Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028, Lisboa, Portugal. mrtcalado@ff.ul.pt.|Centro de Patogénese Molecular, Unidade dos Retrovírus e Infecções Associadas (CPM-URIA), Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003, Lisboa, Portugal. mrtcalado@ff.ul.pt.
authors.forename: Marta
authors.initials: M
authors.lastname: Calado
authors.affiliation: Host-Pathogen Interaction Unit, Research Institute for Medicines and Pharmaceutical Sciences (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003, Lisboa, Portugal. miguel.pereira@ff.ul.pt.|Instituto de Medicina Molecular (IMM), Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028, Lisboa, Portugal. miguel.pereira@ff.ul.pt.|Centro de Patogénese Molecular, Unidade dos Retrovírus e Infecções Associadas (CPM-URIA), Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003, Lisboa, Portugal. miguel.pereira@ff.ul.pt.
authors.forename: José Miguel
authors.initials: JM
authors.lastname: Azevedo-Pereira
mesh_terms: D000328:Adult; D000596:Amino Acids / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D004252:DNA Mutational Analysis; D015498:HIV-2 / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D006801:Humans; D016297:Mutagenesis, Site-Directed; D019713:Receptors, CCR5 / Q000378:metabolism*; D054401:Receptors, CCR8 / Q000378:metabolism*; D019718:Receptors, CXCR4 / Q000378:metabolism*; D015728:Receptors, HIV / Q000378:metabolism; D053585:Virus Attachment; D014779:Virus Replication; D054299:env Gene Products, Human Immunodeficiency Virus / Q000235:genetics / Q000378:metabolism*
chemical_list: D000596:Amino Acids; C584933:CCR5 protein, human; C103330:CCR8 protein, human; C527276:CXCR4 protein, human; D019713:Receptors, CCR5; D054401:Receptors, CCR8; D019718:Receptors, CXCR4; D015728:Receptors, HIV; D054299:env Gene Products, Human Immunodeficiency Virus