title: Transcription of the var genes from a freshly-obtained field isolate of Plasmodium falciparum shows more variable switching patterns than long laboratory-adapted isolates.
abstract: BACKGROUND
  Antigenic variation in Plasmodium falciparum involves switching among multicopy var gene family and is responsible for immune evasion and the maintenance of chronic infections. Current understanding of var gene expression and switching patterns comes from experiments conducted on long laboratory-adapted strains, with little known about their wild counterparts.
  
  
  METHODS
  Genome sequencing was used to obtain 50 var genes from a parasite isolated from the China-Myanmar border. Four clones with different dominant var genes were cultured in vitro in replicates for 50 generations. Transcription of the individual var gene was detected by real-time PCR and then the switching process was analysed.
  
  
  RESULTS
  The expression of multicopy var genes is mutually exclusive in clones of a wild P. falciparum isolate. The activation of distinct primary dominant var genes leads to different and favoured switching patterns in the four clones. The on/off rates of individual var genes are variable and the choice of subsequent dominant var genes are random, which results in the different switching patterns among replicates of each clonal wild P. falciparum isolate with near identical initial transcription profiles.
  
  
  CONCLUSIONS
  This study suggests that the switching patterns of var genes are abundant, which consist of both conserved and random parts.
authors.affiliation: Department of Tropical Infectious Disease, Second Military Medical University, Shanghai, 200433, China. yerun85@163.com.
authors.forename: Run
authors.initials: R
authors.lastname: Ye
authors.affiliation: Department of Tropical Infectious Disease, Second Military Medical University, Shanghai, 200433, China. dm_zhangcn@yahoo.com.
authors.forename: Dongmei
authors.initials: D
authors.lastname: Zhang
authors.affiliation: Department of Tropical Infectious Disease, Second Military Medical University, Shanghai, 200433, China. condor_cbb@163.com.
authors.forename: Biaobang
authors.initials: B
authors.lastname: Chen
authors.affiliation: Shanghai-Ministry of Science and Technology Key Laboratory of Health and Disease Genomics, Chinese National Human Genome Center at Shanghai, Shanghai, 201203, China. zhuyq@chgc.sh.cn.
authors.forename: Yongqiang
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Institute for Infectious Diseases and Vaccine Development, Tongji University School of Medicine, Shanghai, 200092, China. jamesyilong1010@aliyun.com.
authors.forename: Yilong
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Shanghai-Ministry of Science and Technology Key Laboratory of Health and Disease Genomics, Chinese National Human Genome Center at Shanghai, Shanghai, 201203, China. wangsy@chgc.sh.cn.
authors.forename: Shengyue
authors.initials: S
authors.lastname: Wang
authors.affiliation: Department of Tropical Infectious Disease, Second Military Medical University, Shanghai, 200433, China. wqpan0912@aliyun.com.|Institute for Infectious Diseases and Vaccine Development, Tongji University School of Medicine, Shanghai, 200092, China. wqpan0912@aliyun.com.
authors.forename: Weiqing
authors.initials: W
authors.lastname: Pan
mesh_terms: D000940:Antigenic Variation; D002681:China; D008969:Molecular Sequence Data; D002052:Myanmar; D010963:Plasmodium falciparum / Q000235:genetics* / Q000378:metabolism; D015800:Protozoan Proteins / Q000235:genetics* / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D014158:Transcription, Genetic
chemical_list: D015800:Protozoan Proteins; C085731:erythrocyte membrane protein 1, Plasmodium falciparum