Association of severe noncerebral Plasmodium falciparum malaria in Brazil with expressed PfEMP1 DBL1 alpha sequences lacking cysteine residues.
BACKGROUND
Cytoadherence and rosetting contribute to the development of severe Plasmodium falciparum malaria. In Brazil,severe falciparum malaria is mostly associated with renal or pulmonary complications and very rarely with cerebral malaria. The most N-terminal DBL1 alpha domain of PfEMP1, a protein encoded by the var multigene family mediates rosetting. We analyzed parasites of Brazilian patients with severe malaria to determine whether there were particular DBL1 alpha var sequences predominantly expressed in such patients.


METHODS
DBL1 alpha var sequences were obtained from parasites of Brazilian patients with severe and mild malaria and were analyzed by standard bioinformatic programs. Three hundred twenty var DBL1 alpha sequences obtained from 80 Brazilian patients with mild malaria were spotted in high-density filters and hybridized to probes representing predominantly expressed sequences in parasites from patients with severe malaria. A DBL1 alpha domain was expressed in bacteria and used to demonstrate its binding capacity to erythrocytes by immunofluorescence.


RESULTS
Forty-three different and unreported DBL1 alpha amino acid sequences were obtained. Sequences predominantly expressed in patients with severe malaria could be subgrouped due to deletions of 1-2-cysteine residues. These sequences were commonly found in the var gene repertoire of parasites from patients with mild malaria, yet they were rarely expressed in these patients. A recombinant protein representing the most abundantly expressed sequence detected in one patient with severe malaria bound directly to uninfected erythrocytes.


CONCLUSIONS
This is the first report showing an association of severe noncerebral malaria from Brazil with particular DBL1 alpha sequences.
Kirchgatter
Karin
K
Departmento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, Brazil.
Portillo
Hernando del A
Hdel A
D000293:Adolescent; D000328:Adult; D000595:Amino Acid Sequence; D000818:Animals; D015415:Biomarkers; D001938:Brazil / Q000453:epidemiology; D002116:Calcitonin / Q000097:blood; D003001:Cloning, Molecular; D003545:Cysteine / Q000032:analysis; D016054:DNA, Protozoan / Q000235:genetics; D004912:Erythrocytes / Q000378:metabolism; D004926:Escherichia coli; D005260:Female; D017125:Genes, Protozoan; D006801:Humans; D016778:Malaria, Falciparum / Q000097:blood / Q000453:epidemiology / Q000469:parasitology*; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D018512:Parasitemia / Q000469:parasitology; D010802:Phylogeny; D010963:Plasmodium falciparum / Q000145:classification / Q000235:genetics* / Q000502:physiology; D011498:Protein Precursors / Q000097:blood; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D016053:RNA, Protozoan / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012720:Severity of Illness Index
D015415:Biomarkers; D016054:DNA, Protozoan; D011498:Protein Precursors; D015800:Protozoan Proteins; D016053:RNA, Protozoan; D011993:Recombinant Fusion Proteins; C085731:erythrocyte membrane protein 1, Plasmodium falciparum; D002116:Calcitonin; D003545:Cysteine