Programmed transcription of the var gene family, but not of stevor, in Plasmodium falciparum gametocytes

TY - JOUR

T1 - Programmed transcription of the var gene family, but not of stevor, in Plasmodium falciparum gametocytes

AU - Sharp, Sarah

AU - Lavstsen, Thomas

AU - Fivelman, Quinton L

AU - Saeed, Maha

AU - McRobert, Louisa

AU - Templeton, Thomas J

AU - Jensen, Anja T R

AU - Baker, David A

AU - Theander, Thor G

AU - Sutherland, Colin J

N1 - Keywords: Animals; Antigenic Variation; Antigens, Protozoan; Base Sequence; Gametogenesis; Gene Expression Profiling; Gene Expression Regulation, Developmental; Life Cycle Stages; Molecular Sequence Data; Plasmodium falciparum; Protozoan Proteins; RNA, Messenger; Reverse Transcriptase Polymerase Chain Reaction; Transcription, Genetic

PY - 2006

Y1 - 2006

N2 - The var genes encode Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) proteins, a set of highly diverse surface-expressed proteins that mediate adhesion of erythrocytes infected with asexual blood-stage parasites to host endothelium. Switching among expressed PfEMP1 variants in the course of a blood-stage infection is a key component of antigenic variation, and thus immune evasion, by the parasite. The majority of var loci are found in the subtelomeric regions of P. falciparum chromosomes associated with members of other multigene families, including stevor. Both PfEMP1 and STEVOR are expressed in gametocytes, the transmissible parasite stage, but the role of these proteins in the biology of sexual-stage parasites remains unknown. PfEMP1 may continue to mediate antigenic variation in gametocytes, which need to persist in the host for many days before reaching maturity. Using quantitative reverse transcription-PCR and Northern hybridization, we demonstrate that transcription of a defined subset of type C var loci occurs during gametocyte development in vitro. This transcriptional program occurs in gametocytes regardless of the var expression phenotype of their asexual progenitors and therefore is subject to regulatory processes distinct from those that manage antigenic variation in the asexual parasite. In contrast, the same stevor variants are transcribed in both gametocytes and their asexual progenitors. We also provide evidence that for both asexual parasites and gametocytes, var and stevor transcription patterns are not linked to each other.

AB - The var genes encode Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) proteins, a set of highly diverse surface-expressed proteins that mediate adhesion of erythrocytes infected with asexual blood-stage parasites to host endothelium. Switching among expressed PfEMP1 variants in the course of a blood-stage infection is a key component of antigenic variation, and thus immune evasion, by the parasite. The majority of var loci are found in the subtelomeric regions of P. falciparum chromosomes associated with members of other multigene families, including stevor. Both PfEMP1 and STEVOR are expressed in gametocytes, the transmissible parasite stage, but the role of these proteins in the biology of sexual-stage parasites remains unknown. PfEMP1 may continue to mediate antigenic variation in gametocytes, which need to persist in the host for many days before reaching maturity. Using quantitative reverse transcription-PCR and Northern hybridization, we demonstrate that transcription of a defined subset of type C var loci occurs during gametocyte development in vitro. This transcriptional program occurs in gametocytes regardless of the var expression phenotype of their asexual progenitors and therefore is subject to regulatory processes distinct from those that manage antigenic variation in the asexual parasite. In contrast, the same stevor variants are transcribed in both gametocytes and their asexual progenitors. We also provide evidence that for both asexual parasites and gametocytes, var and stevor transcription patterns are not linked to each other.

U2 - 10.1128/EC.00029-06

DO - 10.1128/EC.00029-06

M3 - Journal article

C2 - 16896206

SN - 2379-5042

VL - 5

SP - 1206

EP - 1214

JO - mSphere

JF - mSphere

IS - 8

ER -