title: From in vivo to in vitro: dynamic analysis of Plasmodium falciparum var gene expression patterns of patient isolates during adaptation to culture.
abstract: Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1), encoded by the var gene family, plays a crucial role in disease virulence through its involvement in binding to various host cellular receptors during infection. Growing evidence suggests that differential expression of the various var subgroups may be involved in parasite virulence. To further explore this issue, we have collected isolates from symptomatic patients in south China-Myanmar border, and characterized their sequence diversity and transcription profiles over time of var gene family, and cytoadherence properties from the time of their initial collection and extending through a two month period of adaptation to culture. Initially, we established a highly diverse, DBLα (4 cysteines) subtype-enriched, but unique local repertoire of var-DBL1α sequences by cDNA cloning and sequencing. Next we observed a rapid transcriptional decline of upsA- and upsB-subtype var genes at ring stage through qRT-PCR assays, and a switching event from initial ICAM-I binding to the CD36-binding activity during the first week of adaptive cultivation in vitro. Moreover, predominant transcription of upsA var genes was observed to be correlated with those isolates that showed a higher parasitemia at the time of collection and the ICAM-1-binding phenotype in culture. Taken together, these data indicate that the initial stage of adaptive process in vitro significantly influences the transcription of virulence-related var subtypes and expression of PfEMP1 variants. Further, the specific upregulation of the upsA var genes is likely linked to the rapid propagation of the parasite during natural infection due to the A-type PfEMP1 variant-mediated growth advantages.
authors.affiliation: Institute of Infectious Disease and Vaccine Development, Tongji University School of Medicine, Shanghai, China.
authors.forename: Qingfeng
authors.initials: Q
authors.lastname: Zhang
authors.forename: Yilong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yufu
authors.initials: Y
authors.lastname: Huang
authors.forename: Xiangyang
authors.initials: X
authors.lastname: Xue
authors.forename: He
authors.initials: H
authors.lastname: Yan
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Sun
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.forename: Thomas F
authors.initials: TF
authors.lastname: McCutchan
authors.forename: Weiqing
authors.initials: W
authors.lastname: Pan
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D000293:Adolescent; D000328:Adult; D020816:Amino Acid Motifs; D000818:Animals; D002448:Cell Adhesion / Q000235:genetics; D002648:Child; D017124:Conserved Sequence; D046508:Culture Techniques; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D008018:Life Cycle Stages / Q000235:genetics; D016778:Malaria, Falciparum / Q000469:parasitology*; D008297:Male; D008875:Middle Aged; D018512:Parasitemia / Q000469:parasitology; D010963:Plasmodium falciparum / Q000166:cytology / Q000235:genetics* / Q000254:growth & development* / Q000472:pathogenicity; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D055815:Young Adult
chemical_list: D015800:Protozoan Proteins; D012333:RNA, Messenger; C085731:erythrocyte membrane protein 1, Plasmodium falciparum