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Genetic diversity of expressed Plasmodium falciparum var genes from Tanzanian children with severe malaria

Mugasa, J. and Qi, W. and Rusch, S. and Rottmann, M. and Beck, H. P.. (2012) Genetic diversity of expressed Plasmodium falciparum var genes from Tanzanian children with severe malaria. Malaria journal, Vol. 11 , 230.

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Official URL: http://edoc.unibas.ch/dok/A6094188

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Abstract

ABSTRACT: BACKGROUND: Severe malaria has been attributed to the expression of a restricted subset of the var multigene family, which encodes for Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1). PfEMP1 mediates cytoadherence and sequestration of infected erythrocytes into the post-capillary venules of the vital organs such as the brain, lung or placenta. Var genes are highly diverse and can be classified in three major groups (ups A, B and C) and two intermediate groups (B/A and B/C) based on the genomic location, gene orientation and upstream sequences. The genetic diversity of expressed var genes in relation to severity of disease in Tanzanian children was analysed. METHODS: Children with defined severe (SM) and asymptomatic malaria (AM) were recruited. Fulllength var mRNA was isolated and reversed transcribed into var cDNA. Subsequently, the DBL and N-terminal domains, and up-stream sequences were PCR amplified, cloned and sequenced. Sequences derived from SM and AM isolates were compared and analysed. RESULTS: The analysis confirmed that the var family is highly diverse in natural Plasmodium falciparum populations. Sequence diversity of amplified var DBL-1alpha and upstream regions showed minimal overlap among isolates, implying that the var gene repertoire is vast and most probably indefinite in endemic areas. var DBL-1alpha sequences from AM isolates were more diverse with more singletons found (p>0.05) than those from SM infections. Furthermore, few var DBL-1alpha sequences from SM patients were rare and restricted suggesting that certain PfEMP1 variants might induce severe disease. CONCLUSIONS: The genetic sequence diversity of var genes of P. falciparum isolates from Tanzanian children is large and its relationship to disease severity has been studied. Observed differences suggest that different var genes might have fundamentally different roles in the host-parasite interaction. Further research is required to examine clear disease-associations of var gene subsets in different geographical settings. The importance of very strict clinical definitions and appropriate large control groups needs to be emphasized for future studies on disease associations of PfEMP1
Faculties and Departments:09 Associated Institutions > Swiss Tropical and Public Health Institute (Swiss TPH) > Former Units within Swiss TPH > Molecular Parasitology and Epidemiology (Beck)
UniBasel Contributors:Beck, Hans-Peter and Rottmann, Matthias
Item Type:Article, refereed
Article Subtype:Research Article
Bibsysno:Link to catalogue
Publisher:BioMed Central
ISSN:1475-2875
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:19 Jul 2013 07:43
Deposited On:19 Jul 2013 07:38

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