Generation of antigenic diversity in Plasmodium falciparum by structured rearrangement of Var genes during mitosis.

The most polymorphic gene family in P. falciparum is the ∼60 var genes distributed across parasite chromosomes, both in the subtelomeres and in internal regions. They encode hypervariable surface proteins known as P. falciparum erythrocyte membrane protein 1 (PfEMP1) that are critical for pathogenes...

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Main Authors: Antoine Claessens, William L Hamilton, Mihir Kekre, Thomas D Otto, Adnan Faizullabhoy, Julian C Rayner, Dominic Kwiatkowski
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2014-12-01
Series:PLoS Genetics
Online Access:https://doi.org/10.1371/journal.pgen.1004812
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author Antoine Claessens
William L Hamilton
Mihir Kekre
Thomas D Otto
Adnan Faizullabhoy
Julian C Rayner
Dominic Kwiatkowski
author_facet Antoine Claessens
William L Hamilton
Mihir Kekre
Thomas D Otto
Adnan Faizullabhoy
Julian C Rayner
Dominic Kwiatkowski
author_sort Antoine Claessens
collection DOAJ
description The most polymorphic gene family in P. falciparum is the ∼60 var genes distributed across parasite chromosomes, both in the subtelomeres and in internal regions. They encode hypervariable surface proteins known as P. falciparum erythrocyte membrane protein 1 (PfEMP1) that are critical for pathogenesis and immune evasion in Plasmodium falciparum. How var gene sequence diversity is generated is not currently completely understood. To address this, we constructed large clone trees and performed whole genome sequence analysis to study the generation of novel var gene sequences in asexually replicating parasites. While single nucleotide polymorphisms (SNPs) were scattered across the genome, structural variants (deletions, duplications, translocations) were focused in and around var genes, with considerable variation in frequency between strains. Analysis of more than 100 recombination events involving var exon 1 revealed that the average nucleotide sequence identity of two recombining exons was only 63% (range: 52.7-72.4%) yet the crossovers were error-free and occurred in such a way that the resulting sequence was in frame and domain architecture was preserved. Var exon 1, which encodes the immunologically exposed part of the protein, recombined in up to 0.2% of infected erythrocytes in vitro per life cycle. The high rate of var exon 1 recombination indicates that millions of new antigenic structures could potentially be generated each day in a single infected individual. We propose a model whereby var gene sequence polymorphism is mainly generated during the asexual part of the life cycle.
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spelling doaj-art-0e370c14b68042e286aeb23588cb9e2b2025-08-20T03:46:13ZengPublic Library of Science (PLoS)PLoS Genetics1553-73901553-74042014-12-011012e100481210.1371/journal.pgen.1004812Generation of antigenic diversity in Plasmodium falciparum by structured rearrangement of Var genes during mitosis.Antoine ClaessensWilliam L HamiltonMihir KekreThomas D OttoAdnan FaizullabhoyJulian C RaynerDominic KwiatkowskiThe most polymorphic gene family in P. falciparum is the ∼60 var genes distributed across parasite chromosomes, both in the subtelomeres and in internal regions. They encode hypervariable surface proteins known as P. falciparum erythrocyte membrane protein 1 (PfEMP1) that are critical for pathogenesis and immune evasion in Plasmodium falciparum. How var gene sequence diversity is generated is not currently completely understood. To address this, we constructed large clone trees and performed whole genome sequence analysis to study the generation of novel var gene sequences in asexually replicating parasites. While single nucleotide polymorphisms (SNPs) were scattered across the genome, structural variants (deletions, duplications, translocations) were focused in and around var genes, with considerable variation in frequency between strains. Analysis of more than 100 recombination events involving var exon 1 revealed that the average nucleotide sequence identity of two recombining exons was only 63% (range: 52.7-72.4%) yet the crossovers were error-free and occurred in such a way that the resulting sequence was in frame and domain architecture was preserved. Var exon 1, which encodes the immunologically exposed part of the protein, recombined in up to 0.2% of infected erythrocytes in vitro per life cycle. The high rate of var exon 1 recombination indicates that millions of new antigenic structures could potentially be generated each day in a single infected individual. We propose a model whereby var gene sequence polymorphism is mainly generated during the asexual part of the life cycle.https://doi.org/10.1371/journal.pgen.1004812
spellingShingle Antoine Claessens
William L Hamilton
Mihir Kekre
Thomas D Otto
Adnan Faizullabhoy
Julian C Rayner
Dominic Kwiatkowski
Generation of antigenic diversity in Plasmodium falciparum by structured rearrangement of Var genes during mitosis.
PLoS Genetics
title Generation of antigenic diversity in Plasmodium falciparum by structured rearrangement of Var genes during mitosis.
title_full Generation of antigenic diversity in Plasmodium falciparum by structured rearrangement of Var genes during mitosis.
title_fullStr Generation of antigenic diversity in Plasmodium falciparum by structured rearrangement of Var genes during mitosis.
title_full_unstemmed Generation of antigenic diversity in Plasmodium falciparum by structured rearrangement of Var genes during mitosis.
title_short Generation of antigenic diversity in Plasmodium falciparum by structured rearrangement of Var genes during mitosis.
title_sort generation of antigenic diversity in plasmodium falciparum by structured rearrangement of var genes during mitosis
url https://doi.org/10.1371/journal.pgen.1004812
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