title: [Genetic characteristics of HIV-1 CRF01_AE strains circulating in Beijing].
abstract: OBJECTIVE
  To analyze the genetic characteristics of HIV-1 CRF01_AE strains prevailing in Beijing.
  
  
  METHODS
  Plasma samples were collected from the newly diagnosed HIV-1 individuals being reported during 2006 to 2008 in Beijing. Gag gene fragments were amplified from RNA template which were extracted from plasma by RT and nested PCR methods. 105 CRF01_AE sequences were analyzed by phylogcnetic methods and characterized through calculating the genetic distance and Entropy analysis.
  
  
  RESULTS
  There were four main sub-clusters in the phylogenetic tree. We named them as sub-clusters Homo-Max (67 sequences), Hetero (6 sequences), Mix (8 sequences) and Homo-Min (18 sequences) respectively, based on the mode of transmission. It was found that no international reference strain was closely related to the sub-cluster Homo-Max, Hetero or Homo-Min, including 91 samples. The strains in sub-cluster Mix consisting 8 cases that were closely related to the strains identified in Thailand and Vietnam. Genetic distance analysis on gag genes showed that the diversity of sub-clusters Homo-Max and Homo-Min was obviously less than that of the sub-cluster Hetero or Mix. When compared with sub-cluster Mix, there were 37, 29 and 11 significantly different nucleotides polymorphism compositions sites in sub-clusers Homo-Max Homo-Min and Hetero.
  
  
  CONCLUSIONS
  This was the first report describing that four main epidemic sub-clusters were existed in CRF01_AE strains prevailing in Beijing. The virus with sub-cluster Homo-Max was the dominant strain in this region with shorter period of circulation and higher proportion seen in the HIV-infected persons. The virus in sub-cluster Mix was highly homologic with the CRF01_AE strains from Thailand and Vietnam.
authors.affiliation: National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 100052, China; Beijing Center for Disease Control and Prevention. Email: basketball197602@hotmail.com.
authors.forename: Jing-Rong
authors.initials: JR
authors.lastname: Ye
authors.forename: Hong-Yan
authors.initials: HY
authors.lastname: Lu
authors.forename: Li-Shi
authors.initials: LS
authors.lastname: Bai
authors.forename: Ruo-Lei
authors.initials: RL
authors.lastname: Xin
authors.forename: Yi
authors.initials: Y
authors.lastname: Zeng
mesh_terms: D000068476:Beijing; D015658:HIV Infections / Q000453:epidemiology; D015497:HIV-1 / Q000235:genetics; D006801:Humans; D010802:Phylogeny; D016133:Polymerase Chain Reaction