title: [Biological characteristics of HIV-1 isolates circulating in China are linked to its env V3 loop sequence variability].
abstract: OBJECTIVE
  To investigate the biological characteristics of the HIV-1 isolates circulating in China and to define the association of these properties with env V3 loop sequence variability.
  
  
  METHODS
  Primary viruses were isolated from fresh peripheral blood mononuclear cells (PBMCs) using the traditional co-culture method and their capacity of inducing syncytium was tested in MT-2 cells; meanwhile, their coreceptor usage was determined with GHOST-cell lines which stably express CD4 and the chemokine receptor CCR5 or CXCR4. Furthermore, HIV-1 V3 and its flanking region sequences were amplified by nest-polymerase chain reaction (nest-PCR) and sequenced. A GCG software was used to translate the DNA sequences into polypeptide sequences.
  
  
  RESULTS
  Five primary viral strains were isolated from 3 different regions in China. The isolates LTG0213 and LTG0214 induced syncytia in MT-2 cells and used CXCR4 as coreceptor. The isolates XJN0021, XJN0091, and SHXDC0041 did not induce syncytia and used CCR5 as coreceptor. There were obvious differences between X4/SI and R5/NSI viruses in env V3 loop sequences. A consensus motif at the positions 8, 11, 18, and 25 in V3 loop was identified as follows: a sequence as "8-TXXS/GXXXXXXR/QXXXXXXE/D-25" will predict the usage of CCR5 coreceptor; a sequence replacing these positions with basic amino acids (except position 25) will very likely predict the usage of CXCR4 coreceptor.
  
  
  CONCLUSIONS
  The biological characteristics of HIV isolates are linked to env V3 loop sequence variability: introducing basic amino acids (or translating from acidic amino acids into neutral amino acids) at the positions 8, 11, 18, and 25 in V3 loop will change viral strain's biological phenotype from NSI/CCR5 to SI/CXCR4. The biological phenotype of HIV-1 can be predicted with V3 loop sequence analysis.
authors.affiliation: Department of Virology and Immunology, National Center for AIDS/STD Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
authors.forename: Fa-xin
authors.initials: FX
authors.lastname: Hei
authors.forename: Kun-xue
authors.initials: KX
authors.lastname: Hong
authors.forename: Yan-hui
authors.initials: YH
authors.lastname: Song
authors.forename: Hai-li
authors.initials: HL
authors.lastname: Tang
authors.forename: Hong
authors.initials: H
authors.lastname: Peng
authors.forename: Jian-qing
authors.initials: JQ
authors.lastname: Xu
authors.forename: Hui
authors.initials: H
authors.lastname: Xing
authors.forename: Yi-ming
authors.initials: YM
authors.lastname: Shao
mesh_terms: D002681:China; D018920:Coculture Techniques / Q000379:methods; D004252:DNA Mutational Analysis; D015686:Gene Products, env / Q000235:genetics* / Q000378:metabolism; D014644:Genetic Variation; D015699:HIV Envelope Protein gp120 / Q000235:genetics* / Q000378:metabolism; D015658:HIV Infections / Q000821:virology*; D015497:HIV-1 / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D016297:Mutagenesis, Site-Directed; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D019713:Receptors, CCR5 / Q000235:genetics / Q000378:metabolism; D019718:Receptors, CXCR4 / Q000235:genetics / Q000378:metabolism; D020539:Sequence Analysis, Protein; D014779:Virus Replication
chemical_list: D015686:Gene Products, env; D015699:HIV Envelope Protein gp120; D010446:Peptide Fragments; D019713:Receptors, CCR5; D019718:Receptors, CXCR4