Receptor-like specificity of a Plasmodium knowlesi malarial protein that binds to Duffy antigen ligands on erythrocytes.

Abstract

Human erythrocytes that lack the Duffy blood group antigens are refractory to infection by Plasmodium knowlesi malaria parasites in vitro and Plasmodium vivax in vivo, suggesting that these antigens are used as ligands for invasion of erythrocytes by merozoites (1-5). This specificity has been the prototype for understanding malaria parasite invasion oferythrocytes . The molecule that carries a Duffy determinant was characterized recently as a 35-45-kD glycoprotein (6), but no parasite molecule with specificity for Duffy has been described . A study with Plasmodium falciparum demonstrated that after release of merozoites from cultured schizont-infected erythrocytes, a 175-kD protein accumulates in the culture supernatant . This molecule binds to both Duffy-positive and Duffy-negative human erythrocytes that are invaded, but does not bind to neuraminidase-or trypsin-treated human erythrocytes that are refractory to invasion by P. falciparum (7). We used modifications of methods of Camus and Hadley (reference 7, Haynes, J. D., manuscript in preparation) to determine whether P. knowlesi uses a receptor analogous to that of P. falciparum but with the appropriate specificity for Duffy blood group antigen . Erythrocytes were incubated with the metabolically labeled proteins in culture supernatant, centrifuged through oil, and the bound proteins were eluted with salt. We now describe a 135-kD protein synthesized by P. knowlesi that bound to Duffy blood group-positive, but not to Duffy blood group-negative, human erythrocytes . It seems likely that the 135-kD Duffy binding protein is one of the receptors responsible for invasion ofP. knowlesi merozoites into Duffy-positive erythrocytes . Materials and MethodsParasites and Labeled Culture Supernatants. Schizont-infected rhesus erythrocytes (Malaysian H strain of P. knowlesi) were enriched and metabolically labeled at 1 .5 x 10'/ml with 100 gCi/ml ["Slmethionine in methionine-deficient RPMI-1640 culture medium (3, 8) with 1% rabbit serum. The parasites were cultured for 6-10 h to allow the maturation of schizonts, J. P.

Adaptation of the genetically tractable malaria pathogen Plasmodium knowlesi to continuous culture in human erythrocytes

“…Ethical restrictions on this study did not permit donor genotyping to confirm this. The P. knowlesi Duffy binding protein-α (DBP-α) plays a key role in invasion of Duffypositive human RBC (22). Sequencing of the DBP-α gene from the A1-O, A1-H.1, and A1-C.1 parasites and comparison with that of the P. knowlesi H strain (12) identified just a single nonsynonymous polymorphism unique to the A1-H.1 clone (Fig.…”

A new release on life: emerging concepts in proteolysis and parasite invasion

“…1B) whereas capping is observed for apical invasion proteins. Shaving occurs continuously as the parasite penetrates and is (Dubremetz et al ., 1985;Grimwood and Smith, 1995) Yes (Mineo and Kasper, 1994;He et al ., 2002) Unknown TgMIC1/MIC4/MIC6 (Meissner et al ., 2002b) Yes (Fourmaux et al ., 1996;Brecht et al ., 2001) MPP1 TgMIC2/M2AP Yes (Carruthers et al ., 1999;Harper et al ., 2004) MPP1 Zhou et al ., 2004) TgMIC3/MIC8 (Meissner et al ., 2002b) Yes (Garcia-Reguet et al ., 2000;Meissner et al ., 2002b) MPP1 TgAMA1 (Donahue et al ., 2000;Hehl et al ., 2000) Unknown MPP1 (S. A. Howell, M. J. Blackman and V. B. Carruthers, unpublished) Plasmodium PfTRAP and PbTRAP (Bhanot et al, 2003;Silvie et al ., 2004) Yes (McCormick et al ., 1999;Akhouri et al ., 2004) Serine protease (Silvie et al .. 2004) PfCSP (Stewart and Vanderberg, 1988; Yes (Pinzon-Ortiz et al ., 2001) Unknown PfMSP1/MSP6/MSP7 (Stafford et al ., 1994) Yes (Goel et al ., 2003;Li et al ., 2004) MESH (Howell et al ., 2003) PkAMA1 and PfAMA1 (Deans et al ., 1984;Howell et al ., 2001) Yes (Fraser et al ., 2001) MESH (Howell et al ., 2003) EBL-DBP (Camus and Hadley, 1985;Haynes et al ., 1988) Yes (Camus and Hadley, 1985;Haynes et al ., 1988) Unknown Py235 (Ogun and Holder, 1996) Yes (Ogun and Holde...…”

Malaria parasite tyrosyl-tRNA synthetase secretion triggers pro-inflammatory responses

“…These were then washed three times in PBS and mounted in antifade with DAPI (Molecular Probes). Spleen cells were purified from P. yoelii-infected mice and PBMCs were isolated from both mouse and human blood as described earlier 54 . For the in vivo experiment, C57BL/6 mice were infected with ~1 million P. yoelii (17XNL strain) in the form of parasitized RBC's intraperitoneally.…”

“…P. falciparum (schizont stage) -infected human erythrocytes (1.5×107 parasites per ml) were enriched and parasites were cultured for 6-10 h to allow the maturation of schizonts, release of merozoites and their material 54 . Culture supernatant was collected in the presence of protease inhibitor cocktail after two rounds of centrifugation of 1,000 g for 15 min followed by 10,000 g for 20 min before freezing at − 70 °C.…”