Objective:To investigate the association between amplification of the two regulatory genes controlling glutathione(GSH) levels,glutathione reductase(PfGR) and glutathione S-transferase (PfGST) genes and sensitivity of...Objective:To investigate the association between amplification of the two regulatory genes controlling glutathione(GSH) levels,glutathione reductase(PfGR) and glutathione S-transferase (PfGST) genes and sensitivity of Plasmodium falciparum(P.falciparum) isolates collected from different malaria endemic areas of Thailand to standard antimalarial drugs.Methods:A total of 70 P.falciparum isolates were collected from endemic areas of multi-drug resistance (Tak,Chantaburi and Ranong Provinces) during the year 2008-2009.The in vitro assessment of antimalarial activity of P.falciparum clones(K1- and Dd2 chloroquine resistant and 3D7- chloroquine sensitive) and isolates to chloroquine,quinine,mefloquine and arteusnate was performed based on SYBR Green modified assay.Results:68(97.14%),11(15.71%) and 28(40%) isolates respectively were classified as chloroquine-,quinine- and mefloquine-resistant isolates. With this limited number of P.falciparum isolates included in the analysis,no significant association between amplification of PfGST gene and sensitivity of the parasite to chloroquine, quinine,mefloquine and quinine was found.Based on PCR analysis,Dd2,Kl and 3D7 clones all contained only one copy of the PfGST gene.All isolates(70) also carried only one copy number of PfGST gene.There appears to be an association between amplification of PfGR gene and chloroquine resistance.The 3D7 and Dd2 clones were found to carry only one PfGR gene copy, whereas the K1 clone carried two gene copies.Conclusions:Chloroquine resistance is likely to be a consequence of multi-factors and enzymes in the GSH system may be partly involved. Larger number of parasite isolates are required to increase power of the hypothesis testing in order to confirm the involvement of both genes as well as other genes implicated in glutathione metabolism in conferring chloroquine resistance.展开更多
Objective:To analyse the structure and function of NADPH-cytochrome p450 reductase(CYPOR or CPR) from Plasmodium falciparum(Pf),and to predict its’ drug target and vaccine target. Methods:The structure,function,drug ...Objective:To analyse the structure and function of NADPH-cytochrome p450 reductase(CYPOR or CPR) from Plasmodium falciparum(Pf),and to predict its’ drug target and vaccine target. Methods:The structure,function,drug target and vaccine target of CPR from Plasmodium falciparum were analyzed and predicted by bioinformatics methods.Results:PfCPR,which was older CPR,had close relationship with the CPR from other Plasmodium species,but it was distant from its hosts,such as Homo sapiens and Anopheles.PfCPR was located in the cellular nucleus of Plasmodium falciparum.335aa-352aa and 591aa - 608aa were inserted the interior side of the nuclear membrane,while 151aa-265aa was located in the nucleolus organizer regions.PfCPR had 40 function sites and 44 protein-protein binding sites in amino acid sequence.The teriary structure of laa-700aa was forcep-shaped with wings.15 segments of PfCPR had no homology with Homo sapien CPR and most were exposed on the surface of the protein.These segments had 25 protein-protein binding sites.While 13 other segments all possessed function sites. Conclusions:The evolution or genesis of Plasmodium falciparum is earlier than those of Homo sapiens.PfCPR is a possible resistance site of antimalarial drug and may involve immune evasion, which is associated with parasite of sporozoite in hepatocytes.PfCPR is unsuitable as vaccine target,but it has at least 13 ideal drug targets.展开更多
Two DNA fragments, designated as P190CRI (AA1-55) and P190CRV (AA1597-1667)respectively, which encode amino acid residues of conserved region Ⅰ and Ⅴ on the P190 antigen were amplified by polymerase chain reaction f...Two DNA fragments, designated as P190CRI (AA1-55) and P190CRV (AA1597-1667)respectively, which encode amino acid residues of conserved region Ⅰ and Ⅴ on the P190 antigen were amplified by polymerase chain reaction from genomic DNA in FCCl/HN strain of Plasmodium falciparum isolated from Hainan Province, China. It was found that there were five base substitutions in the P190CR V, in comparison with the nucleotide sequences of MAD20 strain. These two fragments sequenced were inserted into pGEX-2T plasmid. E. coli JM109 (DE3) were transformed with the recombinant plasmids and the parental plasmid. The results showed that the two fragments were expressed as high-level C-terminal fusions with glutathione S-transferase (GST). The fusion proteins were easily purified from bacterial lysates by affinity chromatography using glutathione Sepharose 4B.展开更多
The research scenario for malaria has improved in the last three decades to understand the epidemiology and host immune responses to plasmodial infection.Due to the augmented episodes of resistance development against...The research scenario for malaria has improved in the last three decades to understand the epidemiology and host immune responses to plasmodial infection.Due to the augmented episodes of resistance development against the commonly used antimalarials in plasmodium parasites,especially in Plasmodium falciparum,neutralization of infection through effective vaccine(s) remains the feasible alternative in malaria control.In this direction,lot of attention was paid towards the identification of stage specific malaria antigens targeted by host ’s immune system.Preparation of synthetic or recombinant peptides and evaluation of their immunogenecity in naturally occurring antibody response were also given much importance,as these studies could help in finding potential candidates for future malaria vaccine(s).Attention was also paid.on the pathogenic consequences of antibody formation in malaria infection as polyclonal activation of B cells,which is a very prominent feature in malaria infection.Formation of circulating immune complexes in chronic malaria infection was also viewed as pathogenic parameter of severe malaria.The present survey focuses mainly on protective and pathogenic aspects of malaria antibodies(eliciting against various,stage specific antigens),and future research plan in antibodymediated immune response.展开更多
Objective: p195, the major protein on the surface of Plasmodium falciparum merozoites, has been found to have ability to bind sialic acid residues on the surface of human erythrocytes, and this binding is thought to b...Objective: p195, the major protein on the surface of Plasmodium falciparum merozoites, has been found to have ability to bind sialic acid residues on the surface of human erythrocytes, and this binding is thought to be a prerequisite for recognition of human erythrocyte by merozoite- This study attempted to map out the binding site of p195, thus providing a theoretical clue to developing an antimalaria vaccine which blockades invasion of merozoites into human erythrocytes. Methods: Eight proteins derived from pl95 were expressed in E. coli, and purified by Ni-chelate affinity chromatography. The re folded proteins were labelled with colloidal gold. The labelled protein complexes were co-incubated with human erythrocytes separately and simultaneously, and the proteins were put into the culture supernatant of P- falciParum to observe their effect on invasion of merozoites into erythrocytes. Results: A fragment of p195, M6 (amino acid sequence: 384 - 595), was found to have the ability to bind human erythrocytes. M6 gold complexes showed no ability to bind erythrocytes treated with trypsin or neuraminidase. M6 was also found to have the ability to inhibit invasion of merozoites of P. falciparym into human erythrocytes. Conclusiou: A fragment of p195, M6, has the ability to bind human erythrocytes. The binding is dependent on sialic acid residues, and may be a prerequisite to recognition of erythrocytes by merozoites.展开更多
基金supported by Thammasat University and The Commission on Higher Education,Ministry of Education of Thailand
文摘Objective:To investigate the association between amplification of the two regulatory genes controlling glutathione(GSH) levels,glutathione reductase(PfGR) and glutathione S-transferase (PfGST) genes and sensitivity of Plasmodium falciparum(P.falciparum) isolates collected from different malaria endemic areas of Thailand to standard antimalarial drugs.Methods:A total of 70 P.falciparum isolates were collected from endemic areas of multi-drug resistance (Tak,Chantaburi and Ranong Provinces) during the year 2008-2009.The in vitro assessment of antimalarial activity of P.falciparum clones(K1- and Dd2 chloroquine resistant and 3D7- chloroquine sensitive) and isolates to chloroquine,quinine,mefloquine and arteusnate was performed based on SYBR Green modified assay.Results:68(97.14%),11(15.71%) and 28(40%) isolates respectively were classified as chloroquine-,quinine- and mefloquine-resistant isolates. With this limited number of P.falciparum isolates included in the analysis,no significant association between amplification of PfGST gene and sensitivity of the parasite to chloroquine, quinine,mefloquine and quinine was found.Based on PCR analysis,Dd2,Kl and 3D7 clones all contained only one copy of the PfGST gene.All isolates(70) also carried only one copy number of PfGST gene.There appears to be an association between amplification of PfGR gene and chloroquine resistance.The 3D7 and Dd2 clones were found to carry only one PfGR gene copy, whereas the K1 clone carried two gene copies.Conclusions:Chloroquine resistance is likely to be a consequence of multi-factors and enzymes in the GSH system may be partly involved. Larger number of parasite isolates are required to increase power of the hypothesis testing in order to confirm the involvement of both genes as well as other genes implicated in glutathione metabolism in conferring chloroquine resistance.
基金Supported in part by the Research Program in Higher Educational Institutes of Education Department in Hainan(No.Hjkj2009-50)
文摘Objective:To analyse the structure and function of NADPH-cytochrome p450 reductase(CYPOR or CPR) from Plasmodium falciparum(Pf),and to predict its’ drug target and vaccine target. Methods:The structure,function,drug target and vaccine target of CPR from Plasmodium falciparum were analyzed and predicted by bioinformatics methods.Results:PfCPR,which was older CPR,had close relationship with the CPR from other Plasmodium species,but it was distant from its hosts,such as Homo sapiens and Anopheles.PfCPR was located in the cellular nucleus of Plasmodium falciparum.335aa-352aa and 591aa - 608aa were inserted the interior side of the nuclear membrane,while 151aa-265aa was located in the nucleolus organizer regions.PfCPR had 40 function sites and 44 protein-protein binding sites in amino acid sequence.The teriary structure of laa-700aa was forcep-shaped with wings.15 segments of PfCPR had no homology with Homo sapien CPR and most were exposed on the surface of the protein.These segments had 25 protein-protein binding sites.While 13 other segments all possessed function sites. Conclusions:The evolution or genesis of Plasmodium falciparum is earlier than those of Homo sapiens.PfCPR is a possible resistance site of antimalarial drug and may involve immune evasion, which is associated with parasite of sporozoite in hepatocytes.PfCPR is unsuitable as vaccine target,but it has at least 13 ideal drug targets.
文摘Two DNA fragments, designated as P190CRI (AA1-55) and P190CRV (AA1597-1667)respectively, which encode amino acid residues of conserved region Ⅰ and Ⅴ on the P190 antigen were amplified by polymerase chain reaction from genomic DNA in FCCl/HN strain of Plasmodium falciparum isolated from Hainan Province, China. It was found that there were five base substitutions in the P190CR V, in comparison with the nucleotide sequences of MAD20 strain. These two fragments sequenced were inserted into pGEX-2T plasmid. E. coli JM109 (DE3) were transformed with the recombinant plasmids and the parental plasmid. The results showed that the two fragments were expressed as high-level C-terminal fusions with glutathione S-transferase (GST). The fusion proteins were easily purified from bacterial lysates by affinity chromatography using glutathione Sepharose 4B.
文摘The research scenario for malaria has improved in the last three decades to understand the epidemiology and host immune responses to plasmodial infection.Due to the augmented episodes of resistance development against the commonly used antimalarials in plasmodium parasites,especially in Plasmodium falciparum,neutralization of infection through effective vaccine(s) remains the feasible alternative in malaria control.In this direction,lot of attention was paid towards the identification of stage specific malaria antigens targeted by host ’s immune system.Preparation of synthetic or recombinant peptides and evaluation of their immunogenecity in naturally occurring antibody response were also given much importance,as these studies could help in finding potential candidates for future malaria vaccine(s).Attention was also paid.on the pathogenic consequences of antibody formation in malaria infection as polyclonal activation of B cells,which is a very prominent feature in malaria infection.Formation of circulating immune complexes in chronic malaria infection was also viewed as pathogenic parameter of severe malaria.The present survey focuses mainly on protective and pathogenic aspects of malaria antibodies(eliciting against various,stage specific antigens),and future research plan in antibodymediated immune response.
文摘Objective: p195, the major protein on the surface of Plasmodium falciparum merozoites, has been found to have ability to bind sialic acid residues on the surface of human erythrocytes, and this binding is thought to be a prerequisite for recognition of human erythrocyte by merozoite- This study attempted to map out the binding site of p195, thus providing a theoretical clue to developing an antimalaria vaccine which blockades invasion of merozoites into human erythrocytes. Methods: Eight proteins derived from pl95 were expressed in E. coli, and purified by Ni-chelate affinity chromatography. The re folded proteins were labelled with colloidal gold. The labelled protein complexes were co-incubated with human erythrocytes separately and simultaneously, and the proteins were put into the culture supernatant of P- falciParum to observe their effect on invasion of merozoites into erythrocytes. Results: A fragment of p195, M6 (amino acid sequence: 384 - 595), was found to have the ability to bind human erythrocytes. M6 gold complexes showed no ability to bind erythrocytes treated with trypsin or neuraminidase. M6 was also found to have the ability to inhibit invasion of merozoites of P. falciparym into human erythrocytes. Conclusiou: A fragment of p195, M6, has the ability to bind human erythrocytes. The binding is dependent on sialic acid residues, and may be a prerequisite to recognition of erythrocytes by merozoites.
