Diversity of the var gene family of Indonesian Plasmodium falciparum isolates
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vor 11 Jahren
Background: The large polymorphic protein PfEMP1 is encoded by the
var gene family. PfEMP1 has been shown to play an important role as
cytoadherence ligand on the surface of infected erythrocytes and
thereby contributes to the distinct pathogenesis of malaria. The
study explored the diversity of the DBL1 alpha and DBL2 beta-C2
domains of the protein from Indonesian Plasmodium falciparum field
isolates. Methods: Samples of patients with severe and
uncomplicated malaria from two different malaria-endemic areas in
Indonesia were collected and DNA directly extracted. Dried blood on
filter paper was prepared for RNA extraction. PCR amplicons were
either cloned and subsequently sequenced or directly sequenced for
analysis on nucleotide and amino acid level. Recently published as
well as self-designed primers were used for amplification. Results:
Blood from eight patients was finally used for analysis.
Seventy-one different sequences out of over 500 DBL1 alpha
sequenced clones were observed, resulting in an average of 8.9
different DBL1 alpha sequences per isolate. The average DBL1 alpha
sequence similarity within isolates was similar to between
isolates. Phylogenetic analysis demonstrated no clustering of
sequences regarding strain or geographical origin. The DBL1 alpha
sequences were analysed by distribution of semi-conserved features
(cysteine/PoLV1-4 grouping) and classified into six sequence
groups. The DBL1 alpha cys2 type was observed in all expressed
sequences in vivo. Expression of certain DBL sequences implied
potential involvement in the pathogenesis. As expected, the DBL2
beta-C2 domains showed high to moderate homology among each other.
Conclusion: The DBL1 alpha domains of PfEMP1 from clinical
Indonesian isolates showed high divergence among same isolates and
some similarities with other Asia-Pacific strains. Further
investigations of important var gene domains with a larger sample
size are required to confirm with statistical significance observed
associations with severe malaria in Indonesian samples.
var gene family. PfEMP1 has been shown to play an important role as
cytoadherence ligand on the surface of infected erythrocytes and
thereby contributes to the distinct pathogenesis of malaria. The
study explored the diversity of the DBL1 alpha and DBL2 beta-C2
domains of the protein from Indonesian Plasmodium falciparum field
isolates. Methods: Samples of patients with severe and
uncomplicated malaria from two different malaria-endemic areas in
Indonesia were collected and DNA directly extracted. Dried blood on
filter paper was prepared for RNA extraction. PCR amplicons were
either cloned and subsequently sequenced or directly sequenced for
analysis on nucleotide and amino acid level. Recently published as
well as self-designed primers were used for amplification. Results:
Blood from eight patients was finally used for analysis.
Seventy-one different sequences out of over 500 DBL1 alpha
sequenced clones were observed, resulting in an average of 8.9
different DBL1 alpha sequences per isolate. The average DBL1 alpha
sequence similarity within isolates was similar to between
isolates. Phylogenetic analysis demonstrated no clustering of
sequences regarding strain or geographical origin. The DBL1 alpha
sequences were analysed by distribution of semi-conserved features
(cysteine/PoLV1-4 grouping) and classified into six sequence
groups. The DBL1 alpha cys2 type was observed in all expressed
sequences in vivo. Expression of certain DBL sequences implied
potential involvement in the pathogenesis. As expected, the DBL2
beta-C2 domains showed high to moderate homology among each other.
Conclusion: The DBL1 alpha domains of PfEMP1 from clinical
Indonesian isolates showed high divergence among same isolates and
some similarities with other Asia-Pacific strains. Further
investigations of important var gene domains with a larger sample
size are required to confirm with statistical significance observed
associations with severe malaria in Indonesian samples.
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