title: [Positive selection analysis of hepatitis C virus genotype 1b envelope 2 gene and its significance during natural chronic infection].
abstract: OBJECTIVE
  To elucidate adaptive evolution patterns and perform a positive selection analysis of hepatitis C virus(HCV) genotype 1b envelope 2 gene(E2) during natural chronic infection by a longitudinal study.
  
  
  METHODS
  HCV E2 quasispecies profiles were derived from partially sequenced domains of 6 000 bp recombinant clones. Phylogenetic trees for HCV E2 gene were constructed by MEGA software and the specific codons undergoing diversifying positive selection were identified by FEL method.
  
  
  RESULTS
  HCV phylogenies, coupled with the number and distribution of selected sites were differed markedly between patients. HCV quasispecies complexity during chronic infection was not associated with the evolutionary time and the dominant viriant alternation of HCV quasispecies may occur after more than six months apart. Five sites under positive selection were identified within the ectodomain of the E2 protein.
  
  
  CONCLUSIONS
  A series of serum specimens for studies based on dominant viriant of HCV dynamic quasispecies is recommended to be collected at every six months. Several individual sites of HCV E2 gene are under a strong host immune pressure, position aa384, aa399 and aa410 may be involved in escape from neutralizing antibodies, while position aa475, aa522 may correlate to modulate the virus-receptor interaction which result in evading immunity.
authors.affiliation: Institute of Infectious Diseases of Chinese PLA, Southwest Hospital, Third Military Medical University, Chongqing 400038, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhu
authors.forename: Qing
authors.initials: Q
authors.lastname: Mao
authors.forename: Lin
authors.initials: L
authors.lastname: Lan
authors.forename: Ya-jun
authors.initials: YJ
authors.lastname: Hu
authors.forename: Zhao-xia
authors.initials: ZX
authors.lastname: Tan
authors.forename: Chang-jiang
authors.initials: CJ
authors.lastname: Zhang
authors.forename: Yu-ming
authors.initials: YM
authors.lastname: Wang
authors.forename: Xiao-hong
authors.initials: XH
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D019143:Evolution, Molecular; D005838:Genotype; D016174:Hepacivirus / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity*; D019698:Hepatitis C, Chronic / Q000821:virology*; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D014759:Viral Envelope Proteins / Q000145:classification* / Q000235:genetics / Q000378:metabolism*
chemical_list: D014759:Viral Envelope Proteins; C091015:glycoprotein E2, Hepatitis C virus