The parasite Plasmodium falciparum causes severe malaria and is the most dangerous to humans. However, it exhibits resistance to their drugs. Farnesyltransferase has been identified in pathogenic protozoa of the genera Plasmodium and the target of farnesyltransferase includes Ras family. Therefore, the inhibition of farnesyltransferase has been suggested as a new strategy for the treatment of malaria. However, the exact functional mechanism of this agent is still unknown. In addition, the effect of farnesyltransferase inhibitor (FTIs) on mitochondrial level of malaria parasites is not fully understood. In this study, therefore, the effect of a FTI R115777 on the function of mitochondria of P. falciparum was investigated experimentally. As a result, FTI R115777 was found to suppress the infection rate of malaria parasites under in vitro condition. It also reduces the copy number of mtDNA-encoded cytochrome c oxidase III. In addition, the mitochondrial membrane potential (DeltaPsim) and the green fluorescence intensity of MitoTracker were decreased by FTI R115777. Chloroquine and atovaquone were measured by the mtDNA copy number as mitochondrial non-specific or specific inhibitor, respectively. Chloroquine did not affect the copy number of mtDNA-encoded cytochrome c oxidase III, while atovaquone induced to change the mtDNA copy number. These results suggest that FTI R115777 has strong influence on the mitochondrial function of P. falciparum. It may have therapeutic potential for malaria by targeting the mitochondria of parasites.
Antimalarials/*pharmacology ; Enzyme Inhibitors/*pharmacology ; Farnesyltranstransferase/*antagonists & inhibitors/genetics/*metabolism ; Humans ; Malaria, Falciparum/drug therapy/*parasitology ; Mitochondria/*drug effects/metabolism ; Plasmodium falciparum/drug effects/*enzymology/genetics ; Protozoan Proteins/*antagonists & inhibitors/genetics/metabolism ; Quinolones/*pharmacology

Pyronaridine and artesunate have been shown to be effective in falciparum malaria treatment. However, pyronaridine is rarely used in Hainan Island clinically, and artesunate is not widely used as a therapeutic agent. Instead, conventional antimalarial drugs, chloroquine and piperaquine, are used, explaining the emergence of chloroquine-resistant Plasmodium falciparum. In this article, we investigated the sensitivity of P. falciparum to antimalarial drugs used in Hainan Island for rational drug therapy. We performed in vivo (28 days) and in vitro tests to determine the sensitivity of P. falciparum to antimalarial drugs. Total 46 patients with falciparum malaria were treated with dihydroartemisinin/piperaquine phosphate (DUO-COTECXIN) and followed up for 28 day. The cure rate was 97.8%. The mean fever clearance time (22.5+/-10.6 hr) and the mean parasite clearance time (27.3+/-12.2 hr) showed no statistical significance with different genders, ages, temperatures, or parasite density (P>0.05). The resistance rates of chloroquine, piperaquine, pyronarididine, and artesunate detected in vitro were 71.9%, 40.6%, 12.5%, and 0%, respectively (P<0.0001). The resistance intensities decreased as follows: chloroquine>piperaquine>pyronarididine>artesunate. The inhibitory dose 50 (IC50) was 3.77x10(-6) mol/L, 2.09x10(-6) mol/L, 0.09x10(-6) mol/L, and 0.05x10(-6) mol/L, and the mean concentrations for complete inhibition (CIMC) of schizont formation were 5.60x10(-6) mol/L, 9.26x10(-6) mol/L, 0.55x10(-6) mol/L, and 0.07x10(-6) mol/L, respectively. Dihydroartemisinin showed a strong therapeutic effect against falciparum malaria with a low toxicity.
Adolescent ; Adult ; Aged ; Antimalarials/*pharmacology/*therapeutic use ; Child ; Child, Preschool ; China ; Female ; Humans ; Inhibitory Concentration 50 ; Malaria, Falciparum/*drug therapy/parasitology ; Male ; Middle Aged ; Parasitic Sensitivity Tests ; Plasmodium falciparum/*drug effects ; Treatment Outcome ; Young Adult

Pyronaridine and artesunate have been shown to be effective in falciparum malaria treatment. However, pyronaridine is rarely used in Hainan Island clinically, and artesunate is not widely used as a therapeutic agent. Instead, conventional antimalarial drugs, chloroquine and piperaquine, are used, explaining the emergence of chloroquine-resistant Plasmodium falciparum. In this article, we investigated the sensitivity of P. falciparum to antimalarial drugs used in Hainan Island for rational drug therapy. We performed in vivo (28 days) and in vitro tests to determine the sensitivity of P. falciparum to antimalarial drugs. Total 46 patients with falciparum malaria were treated with dihydroartemisinin/piperaquine phosphate (DUO-COTECXIN) and followed up for 28 day. The cure rate was 97.8%. The mean fever clearance time (22.5+/-10.6 hr) and the mean parasite clearance time (27.3+/-12.2 hr) showed no statistical significance with different genders, ages, temperatures, or parasite density (P>0.05). The resistance rates of chloroquine, piperaquine, pyronarididine, and artesunate detected in vitro were 71.9%, 40.6%, 12.5%, and 0%, respectively (P<0.0001). The resistance intensities decreased as follows: chloroquine>piperaquine>pyronarididine>artesunate. The inhibitory dose 50 (IC50) was 3.77x10(-6) mol/L, 2.09x10(-6) mol/L, 0.09x10(-6) mol/L, and 0.05x10(-6) mol/L, and the mean concentrations for complete inhibition (CIMC) of schizont formation were 5.60x10(-6) mol/L, 9.26x10(-6) mol/L, 0.55x10(-6) mol/L, and 0.07x10(-6) mol/L, respectively. Dihydroartemisinin showed a strong therapeutic effect against falciparum malaria with a low toxicity.
Adolescent ; Adult ; Aged ; Antimalarials/*pharmacology/*therapeutic use ; Child ; Child, Preschool ; China ; Female ; Humans ; Inhibitory Concentration 50 ; Malaria, Falciparum/*drug therapy/parasitology ; Male ; Middle Aged ; Parasitic Sensitivity Tests ; Plasmodium falciparum/*drug effects ; Treatment Outcome ; Young Adult

While imported falciparum malaria has been increasingly reported in recent years in Korea, clinicians have difficulties in making a clinical diagnosis as well as in having accessibility to effective anti-malarial agents. Here we describe an unusual case of imported falciparum malaria with severe hemolytic anemia lasting over 2 weeks, clinically mimicking a coinfection with babesiosis. A 48-year old Korean man was diagnosed with severe falciparum malaria in France after traveling to the Republic of Benin, West Africa. He received a 1-day course of intravenous artesunate and a 7-day course of Malarone (atovaquone/proguanil) with supportive hemodialysis. Coming back to Korea 5 days after discharge, he was readmitted due to recurrent fever, and further treated with Malarone for 3 days. Both the peripheral blood smears and PCR test were positive for Plasmodium falciparum. However, he had prolonged severe hemolytic anemia (Hb 5.6 g/dl). Therefore, 10 days after the hospitalization, Babesia was considered to be potentially coinfected. A 7-day course of Malarone and azithromycin was empirically started. He became afebrile within 3 days of this babesiosis treatment, and hemolytic anemia profiles began to improve at the completion of the treatment. He has remained stable since his discharge. Unexpectedly, the PCR assays failed to detect DNA of Babesia spp. from blood. In addition, during the retrospective review of the case, the artesunate-induced delayed hemolytic anemia was considered as an alternative cause of the unexplained hemolytic anemia.
Anemia, Hemolytic/chemically induced/*etiology/*pathology ; Anti-Bacterial Agents/therapeutic use ; Antimalarials/therapeutic use ; Artemisinins/adverse effects/therapeutic use ; Atovaquone/therapeutic use ; Azithromycin/therapeutic use ; Babesiosis/complications/*diagnosis/drug therapy/*pathology ; Benin ; Blood/parasitology ; Coinfection/diagnosis/pathology ; Drug Combinations ; France ; Humans ; Korea ; Malaria, Falciparum/complications/*diagnosis/drug therapy/*pathology ; Male ; Middle Aged ; Plasmodium falciparum/*isolation & purification ; Proguanil/therapeutic use ; Travel ; Treatment Outcome

OBJECTIVETo compare the protein patterns from the extracts of the mutant clone T9/94-M1-1(b3) induced by pyrimethamine, and the original parent clone T9/94 following separation of parasite extracts by two-dimensional electrophoresis (2-DE).

METHODSProteins were solubilized and separated according to their charges and sizes. The separated protein spots were then detected by silver staining and analyzed for protein density by the powerful image analysis software.

RESULTSDifferentially expressed protein patterns (up- or down-regulation) were separated from the extracts from the two clones. A total of 223 and 134 protein spots were detected from the extracts of T9/94 and T9/94-M1-1(b3) clones, respectively. Marked reduction in density of protein expression was observed with the extract from the mutant (resistant) clone compared with the parent (sensitive) clone. A total of 25 protein spots showed at least two-fold difference in density, some of which exhibited as high as ten-fold difference.

CONCLUSIONSThese proteins may be the molecular targets of resistance of Plasmodium falciparum to pyrimethamine. Further study to identify the chemical structures of these proteins by mass spectrometry is required.

Antimalarials ; metabolism ; Drug Resistance ; Electrophoresis, Gel, Two-Dimensional ; Humans ; Image Processing, Computer-Assisted ; Mutation ; Plasmodium falciparum ; chemistry ; drug effects ; genetics ; Proteome ; analysis ; Protozoan Proteins ; analysis ; Pyrimethamine ; metabolism ; Staining and Labeling

Plasmodium falciparum (P. falciparum) is responsible for the majority of life-threatening cases of human malaria, causing 1.5-2.7 million annual deaths. The global emergence of drug-resistant malaria parasites necessitates identification and characterization of novel drug targets and their potential inhibitors. We identified the carbonic anhydrase (CA) genes in P. falciparum. The pfCA gene encodes anα-carbonic anhydrase, a Zn(2+)-metalloenzme, possessing catalytic properties distinct from that of the human host CA enzyme. The amino acid sequence of the pfCA enzyme is different from the analogous protozoan and human enzymes. A library of aromatic/heterocyclic sulfonamides possessing a large diversity of scaffolds were found to be very good inhibitors for the malarial enzyme at moderate-low micromolar and submicromolar inhibitions. The structure of the groups substituting the aromatic-ureido- or aromatic-azomethine fragment of the molecule and the length of the parent sulfonamide were critical parameters for the inhibitory properties of the sulfonamides. One derivative, that is, 4- (3, 4-dichlorophenylureido)thioureido-benzenesulfonamide (compound 10) was the most effective in vitro Plasmodium falciparum CA inhibitor, and was also the most effective antimalarial compound on the in vitro P. falciparum growth inhibition. The compound 10 was also effective in vivo antimalarial agent in mice infected with Plasmodium berghei, an animal model of drug testing for human malaria infection. It is therefore concluded that the sulphonamide inhibitors targeting the parasite CA may have potential for the development of novel therapies against human malaria.
Animals ; Antimalarials ; pharmacology ; therapeutic use ; Carbonic Anhydrase Inhibitors ; pharmacology ; therapeutic use ; Carbonic Anhydrases ; chemistry ; genetics ; metabolism ; Catalysis ; Genome, Protozoan ; Genomics ; Humans ; Life Cycle Stages ; Malaria, Falciparum ; drug therapy ; parasitology ; Parasites ; drug effects ; enzymology ; Plasmodium falciparum ; drug effects ; enzymology ; genetics ; growth & development ; Protein Conformation ; Sulfonamides ; pharmacology ; therapeutic use

The onset, severity, and ultimate outcome of malaria infection are influenced by parasite-expressed virulence factors as well as by individual host responses to these determinants. In both humans and mice, liver injury follows parasite entry, persisting to the erythrocytic stage in the case of infection with the fatal strain of Plasmodium falciparum. Hepatic nuclear factor (HNF)-1alpha is a master regulator of not only the liver damage and adaptive responses but also diverse metabolic functions. In this study, we analyzed the expression of host HNF-1alpha in relation to malaria infection and evaluated its interaction with the 5'-untranslated region of subtilisin-like protease 2 (subtilase, Sub2). Recombinant human HNF-1alpha expressed by a lentiviral vector (LV HNF-1alpha) was introduced into mice. Interestingly, differences in the activity of the 5'-untranslated region of the Pf-Sub2 promoter were detected in 293T cells, and LV HNF-1alpha was observed to influence promoter activity, suggesting that host HNF-1alpha interacts with the Sub2 gene.
5' Untranslated Regions/*genetics ; Animals ; Cell Line ; DNA, Protozoan/genetics ; Gene Expression Regulation/*genetics ; Genetic Vectors ; Hepatocyte Nuclear Factor 1-alpha/administration & dosage/genetics/*metabolism ; Host-Parasite Interactions ; Humans ; Injections, Intravenous ; Lentivirus/genetics ; Malaria, Falciparum/metabolism/*parasitology/pathology ; Mice ; Plasmodium falciparum/drug effects/*genetics ; Promoter Regions, Genetic/genetics ; RNA, Messenger/genetics ; RNA, Protozoan/genetics ; Recombinant Proteins ; Signal Transduction ; Subtilisins/*genetics/metabolism

The incidence of imported malaria has been increasing in Korea. We reviewed data retrospectively to evaluate the epidemiology, clinical features, and outcomes of imported malaria from 1995 to 2007 in a university hospital. All patients diagnosed with imported malaria were included. Imported malaria was defined as a positive smear for malaria that was acquired in a foreign country. A total of 49 patients (mean age, 35.7 year; M : F = 38 : 11) were enrolled. The predominant malarial species was Plasmodium falciparum (73.5%), and the most frequent area of acquisition was Africa (55.1%), followed by Southeast Asia (22.4%) and South Asia (18.4%). Fourteen-patients (30.6%) suffered from severe malaria caused by P. falciparum and 1 patient (2.0%) died of multiorgan failure. Most of the patients were treated with mefloquine (79.2%) or quinine (10.2%); other antimalarial agents had to be given in 13.2% treated with mefloquine and 44.4% with quinine due to adverse drug events (ADEs). P. falciparum was the most common cause of imported malaria, with the majority of cases acquired from Africa, and a significant number of patients had severe malaria. Alternative antimalarial agents with lower rates of ADEs might be considered for effective treatment instead of mefloquine and quinine.
Adult ; Animals ; Antimalarials/adverse effects/therapeutic use ; Female ; Humans ; Korea/epidemiology ; Malaria, Falciparum/drug therapy/epidemiology/*parasitology ; Male ; Middle Aged ; Plasmodium falciparum/drug effects/isolation & purification ; Retrospective Studies ; *Travel

BACKGROUNDDuring the blood stage of malaria infection, parasites internalize in the host red blood cells and degrade massive amounts of hemoglobin for their development. Although the morphology of the parasite's hemoglobin uptake pathway has been clearly observed, little has been known about its molecular mechanisms.

METHODSThe recombinant proteins from Plasmodium falciparum, dynamin like protein 1 (PfDYN1) and 2 (PfDYN2) GTPase domain, were expressed in E.coli and showed GTPase activity. By using a dynamin inhibitor, dynasore, we demonstrated the involvement of PfDYN1 in the hemoglobin uptake pathway.

RESULTSThe GTPase activity of the two recombinant proteins was inhibited by dynasore in vitro. Treatment of parasite cultures with 80 micromol/L dynasore at the ring and early trophozoite stage resulted in substantial inhibition of parasite growth and in an obvious decline of hemoglobin quantum. Furthermore, reduced intracellular hemozoin accumulation and decreased uptake of the FITC-dextran were also observed, together with distinctive changes in the ultrastructure of parasites after the dynasore treatment.

CONCLUSIONSOur results show that PfDYN1 plays an important role in the hemoglobin uptake pathway of P. falciparum and suggest its possibility of being a novel target for malaria chemotherapy.

Animals ; Antimalarials ; pharmacology ; Dynamins ; antagonists & inhibitors ; GTP Phosphohydrolases ; genetics ; metabolism ; Hemoglobins ; metabolism ; Hydrazones ; pharmacology ; Malaria, Falciparum ; metabolism ; Microscopy, Electron, Transmission ; Plasmodium falciparum ; drug effects ; metabolism ; ultrastructure ; Protozoan Proteins ; genetics ; metabolism ; Recombinant Proteins ; genetics ; metabolism

The aim of the present study was to investigate antimalarial drug pressure resulting from the clinical use of different antimalarials in Thailand. The phenotypic diversity of the susceptibility profiles of antimalarials, i.e., chloroquine (CQ), quinine (QN), mefloquine (MQ), and artesunate (ARS) in Plasmodium falciparum isolates collected during the period from 1988 to 2003 were studied. P. falciparum isolates from infected patients were collected from the Thai-Cambodian border area at different time periods (1988-1989, 1991-1992, and 2003), during which 3 different patterns of drug use had been implemented: MQ + sulphadoxine (S) + pyrimethamine (P), MQ alone and MQ + ARS, respectively. The in vitro drug susceptibilities were investigated using a method based on the incorporation of [3H] hypoxanthine. A total of 50 isolates were tested for susceptibilities to CQ, QN, MQ, and ARS. Of these isolates, 19, 16, and 15 were adapted during the periods 1988-1989, 1991-1993, and 2003, respectively. P. falciparum isolates collected during the 3 periods were resistant to CQ. Sensitivities to MQ declined from 1988 to 2003. In contrast, the parasite was sensitive to QN, and similar sensitivity profile patterns were observed during the 3 time periods. There was a significantly positive but weak correlation between the IC50 values of CQ and QN, as well as between the IC50 values of QN and MQ. Drug pressure has impact on sensitivity of P. falciparum to MQ. A combination therapy of MQ and ARS is being applied to reduce the parasite resistance, and also increasing the efficacy of the drug.
Animals ; Antimalarials/*pharmacology/therapeutic use ; Artemisinins/pharmacology/therapeutic use ; Chloroquine/pharmacology/therapeutic use ; *Drug Resistance ; Humans ; Malaria/drug therapy/*parasitology ; Mefloquine/pharmacology/therapeutic use ; Parasitic Sensitivity Tests/methods ; Plasmodium falciparum/*drug effects/isolation & purification ; Quinine/pharmacology/therapeutic use ; Thailand