Clone 3D7 Research Articles

Survey of Plasmodium falciparum multidrug resistance-1 and chloroquine resistance transporter alleles in Haiti

BackgroundIn Haiti where chloroquine (CQ) is widely used for malaria treatment, reports of resistance are scarce. However, recent identification of CQ resistance genotypes in one site is suggestive of an emerging problem. Additional studies are needed to evaluate genetic mutations associated with CQ resistance, especially in the Plasmodium falciparum multi-drug resistance-1 gene (pfmdr1) while expanding the already available information on P. falciparum CQ transporter gene (pfcrt) in Haiti.MethodsBlood samples were collected on Whatman filter cards (FTA) from eight clinics spread across Haiti. Following the confirmation of P. falciparum in the samples, PCR protocols were used to amplify regions of pfmdr1and pfcrt codons of interest, (86, 184, 1034, 1042, and 1246) and (72-76), respectively. Sequencing and site-specific restriction enzyme digestions were used to analyse these DNA fragments for the presence of single nucleotide polymorphisms (SNPs) known to confer resistance to anti-malarial drugs.ResultsP. falciparum infection was confirmed in160 samples by amplifying a segment of the P. falciparum 18S small subunit ribosomal RNA gene (pfssurrna). The sequence of pfmdr1 in 54 of these samples was determined between codons 86,184 codons 1034, 1042 and 1246. No sequence differences from that of the NF54 clone 3D7 were found among the 54 samples except at codon 184, where a non-silent mutation was found in all samples predicted to alter the amino acid sequence replacing tyrosine with phenylalanine (Y184F). This altered sequence was also confirmed by restriction enzyme digestion. The sequence of pfmdr1 at codons 86, 184, 1034 and 1042 encoded the NFSN haplotype. The sequence of pfcrt codons 72-76 from 79 samples was determined and found to encode CVMNK, consistent with a CQ sensitive genotype.ConclusionThe presence of the Y184F mutation in pfmdr1 of P. falciparum parasites in Haiti may have implications for resistance to antimalarial drugs. The absence of mutation in pfcrt at codon 76 among 79 isolates tested suggests that sensitivity to CQ in Haiti remains common. Wide-spread screening of the pfmdr1 and pfcrt especially among patients experiencing treatment failure may be a useful tool in early detection of the emergence of antimalarial drug resistance in Haiti.

Relationship between Malaria Incidence and IgG Levels to Plasmodium falciparum Merozoite Antigens in Malian Children: Impact of Hemoglobins S and C

Heterozygous hemoglobin (Hb) AS (sickle-cell trait) and HbAC are hypothesized to protect against Plasmodium falciparum malaria in part by enhancing naturally-acquired immunity to this disease. To investigate this hypothesis, we compared antibody levels to four merozoite antigens from the P. falciparum 3D7 clone (apical membrane antigen 1, AMA1-3D7; merozoite surface protein 1, MSP1-3D7; 175 kDa erythrocyte-binding antigen, EBA175-3D7; and merozoite surface protein 2, MSP2-3D7) in a cohort of 103 HbAA, 73 HbAS and 30 HbAC children aged 3 to 11 years in a malaria-endemic area of Mali. In the 2009 transmission season we found that HbAS, but not HbAC, significantly reduced the risk of malaria compared to HbAA. IgG levels to MSP1 and MSP2 at the start of this transmission season inversely correlated with malaria incidence after adjusting for age and Hb type. However, HbAS children had significantly lower IgG levels to EBA175 and MSP2 compared to HbAA children. On the other hand, HbAC children had similar IgG levels to all four antigens. The parasite growth-inhibitory activity of purified IgG samples did not differ significantly by Hb type. Changes in antigen-specific IgG levels during the 2009 transmission and 2010 dry seasons also did not differ by Hb type, and none of these IgG levels dropped significantly during the dry season. These data suggest that sickle-cell trait does not reduce the risk of malaria by enhancing the acquisition of IgG responses to merozoite antigens.

Antimalarial activities of medicinal plants and herbal formulations used in Thai traditional medicine

Malaria is one of the world's leading killer infectious diseases with high incidence and morbidity. The problem of multidrug-resistant Plasmodium falciparum has been aggravating particularly in Southeast Asia. Therefore, development of new potential antimalarial drugs is urgently required. The present study aimed to investigate antimalarial activities of a total of 27 medicinal plants and 5 herbal formulations used in Thai traditional medicine against chloroquine-resistant (K1) and chloroquine-sensitive (3D7) P. falciparum clones. Antimalarial activity of the ethanolic extracts of all plants/herbal formulations against K1 and 3D7 P. falciparum clones was assessed using SYBR Green I-based assay. All plants were initially screened at the concentration of 50 μg/ml to select the candidate plants that inhibited malaria growth by ≥50%. Each candidate plant was further assessed for the IC50 value (concentration that inhibits malaria growth by 50%) to select the potential plants. Selectivity index (SI) of each extract was determined from the IC50 ratio obtained from human renal epithelial cell and K1 or 3D7 P. falciparum clone. The ethanolic extracts from 19 medicinal plants/herbal formulation exhibited promising activity against both K1 and 3D7 clones of P. falciparum with survival of less than 50% at the concentration of 50 μg/ml. Among these, the extracts from the eight medicinal plants (Plumbago indica Linn., Garcinia mangostana Linn., Dracaena loureiri Gagnep., Dioscorea membranacea Pierre., Artemisia annua Linn., Piper chaba Hunt., Myristica fragrans Houtt., Kaempferia galanga Linn.) and two herbal formulations (Benjakul Formulation 1 and Pra-Sa-Prao-Yhai Formulation) showed potent antimalarial activity with median range IC50 values of less than 10 μg/ml against K1 or 3D7 P. falciparum clone or both. All except G. mangostana Linn. and A. annua Linn. showed high selective antimalarial activity against both clones with SI>10. Further studies on antimalarial activities in an animal model including molecular mechanisms of action of the isolated active moieties are required.

Potential combinatorial effects of recombinant atypical chemokine receptors in breast cancer cell invasion: A research perspective

Apart from their major function in the coordination of leukocyte recruitment, chemokines, in cooperation with their receptors, have been implicated in the progression of various diseases including different types of cancer, affecting survival, proliferation and metastasis. A complex network of chemokines and receptors exists in the tumor microenvironment and affects tumor development in various ways where chemokines activate typical signalling pathways by binding to the respective receptors. The identification and characterization of a group of atypical chemokine receptors [D6, Duffy antigen receptor for chemokines (DARC), ChemoCentryx chemokine receptor (CCX-CKR) and CXCR7] which appear to use unique biochemical properties to regulate the biological activities of these chemokines, is useful in the effort to therapeutically manipulate chemokines in a broad spectrum of diseases in which these chemokines play a critical role. The aim of this review was to investigate the combinatorial effect of two reported atypical chemokine receptors, D6 and DARC, on breast cancer cell invasion to understand their role and therapeutic potential in cancer treatment. In this regard, findings of the present review should be confirmed via the construction of recombinant D6 and DARC clones as well as the expression of the respective recombinant proteins using the Pichia pastoris (P. pastoris) expression system is to be performed in a future study in order to support findings of the current review.

The Construction of Recombinant D6 Clone for in Vitro Breast Cancer Study

The Construction of Recombinant D6 Clone for in Vitro Breast Cancer Study

Differential Adhesive Properties of Sequestered Asexual and Sexual Stages of Plasmodium falciparum on Human Endothelial Cells Are Tissue Independent

The protozoan parasite Plasmodium falciparum, responsible for the most severe form of malaria, is able to sequester from peripheral circulation during infection. The asexual stage parasites sequester by binding to endothelial cell receptors in the microvasculature of various organs. P. falciparum gametocytes, the developmental stages responsible for parasite transmission from humans to Anopheles mosquitoes, also spend the almost ten days necessary for their maturation sequestered away from the peripheral circulation before they are released in blood mainstream. In contrast to those of asexual parasites, the mechanisms and cellular interactions responsible for immature gametocyte sequestration are largely unexplored, and controversial evidence has been produced so far on this matter. Here we present a systematic comparison of cell binding properties of asexual stages and immature and mature gametocytes from the reference P. falciparum clone 3D7 and from a patient parasite isolate on a panel of human endothelial cells from different tissues. This analysis includes assays on human bone marrow derived endothelial cell lines (HBMEC), as this tissue has been proposed as a major site of gametocyte maturation. Our results clearly demonstrate that cell adhesion of asexual stage parasites is consistently more efficient than that, virtually undetectable of immature gametocytes, irrespectively of the endothelial cell lines used and of parasite genotypes. Importantly, immature gametocytes of both lines tested here do not show a higher binding efficiency compared to asexual stages on bone marrow derived endothelial cells, unlike previously reported in the only study on this issue. This indicates that gametocyte-host interactions in this tissue are unlikely to be mediated by the same adhesion processes to specific endothelial receptors as seen with asexual forms.

Hábito de frutificação e produção de pereiras sobre diferentes porta‑enxertos

O objetivo deste trabalho foi avaliar o hábito de frutificação e produção de cultivares de pereira (Pyrus communis) enxertadas sobre porta‑enxertos de marmeleiro (Cydonia oblonga) e de pereira (P. calleryana). O experimento foi realizado durante o inverno de 2009 e 2010, em pomar de pereiras conduzido em líder central, em espaçamento 1,0x5,0 m com três cultivares de pereira (Carrick, Packham e Williams) combinadas com um porta‑enxerto de pereira (Clone D6 de P. calleryana) e 15 de marmeleiro. Foram avaliadas as seguintes variáveis: percentagem de dardos, lamburdas, brindilas vegetativas, brindilas floríferas e de bolsas; número total de gemas floríferas; produção por planta; e eficiência produtiva. O hábito de frutificação das cultivares de pereira é influenciado pelos porta‑enxertos, principalmente no que se refere à formação de lamburdas. Em geral, observou-se relação inversa entre percentagem de dardos e de lamburdas, e entre eficiência produtiva e vigor, para todas as combinações entre copa e porta‑enxerto. Para potencializar a produção, o manejo cultural nos pomares das cultivares avaliadas, principalmente por ocasião da poda, deve ser orientado de acordo com o porta‑enxerto utilizado e o hábito de frutificação de cada combinação.

Antimalarial Drug Sensitivity Profile of Western Kenya Plasmodium falciparum Field Isolates Determined by a SYBR Green I in vitro Assay and Molecular Analysis

In vitro drug sensitivity and molecular analyses of Plasmodium falciparum track drug resistance. DNA-binding fluorescent dyes like SYBR Green I may allow field laboratories, proximal to P. falciparum collection sites, to conduct drug assays. In 2007-2008, we assayed 121 P. falciparum field isolates from western Kenya for 50% inhibitory concentrations (IC(50)) against 6 antimalarial drugs using a SYBR Green I in vitro assay: 91 immediate ex vivo (IEV) and 30 culture-adapted, along with P. falciparum reference clones D6 (chloroquine [CQ] sensitive) and W2 (CQ resistant). We also assessed P. falciparum mdr1 (Pfmdr1) copy number and single nucleotide polymorphisms (SNPs) at four codons. The IC(50)s for IEV and culture-adapted P. falciparum isolates were similar, and approximated historical IC(50)s. For Pfmdr1, mean copy number was 1, with SNPs common at codons 86 and 184. The SYBR Green I assay adapted well to our field-based laboratory, for both IEV and culture-adapted P. falciparum, warranting continued use.

Antiprotozoal activities of Vincetoxicum stocksii and Carum copticum

The antileishmanial and antimalarial activities of different fractions of Vincetoxicum stocksii, Carum copticum, Gentiana olivierii and Zygophyllum fabago were determined. Amongst these, V. stocksii and C. copticum showed moderate to good antimalarial activity. The ethyl acetate fractions of C. copticum and hexane fraction of V. stocksii showed 94 % and 52% inhibition of Plasmodium falciparum (D6 Clone) respectively. The hexane ethyl acetate fraction of C. copticum and V. stocksi exhibited antileishmanial activity against, Leishmania donovani promastigotes with IC 50 of 30 µg/mL and 51 mg/mL, respectively.

Synergy of the antiretroviral protease inhibitor indinavir and chloroquine against malaria parasites in vitro and in vivo

Many malaria-endemic areas are also associated with high rates of human immunodeficiency virus (HIV) infection. An understanding of the chemotherapeutic interactions that occur during malaria and HIV co-infections is important. Our previous studies have demonstrated that some antiretroviral protease inhibitors are effective in inhibiting Plasmodium falciparum growth in vitro. Currently, studies examining the interactions between antiretroviral protease inhibitors and antimalarial drugs are being conducted, but the data are limited. In this study, we examined the synergistic interactions between the antiretroviral protease inhibitor indinavir and chloroquine (CQ) in chloroquine-resistant and chloroquine-sensitive malaria parasites in vitro and in vivo. In vitro, by using modified fixed-ratio isobologram method, fractional inhibitory concentrations index (FICI) was calculated to indicate the interaction between the two drugs. The results demonstrated that indinavir interacted synergistically with chloroquine against both chloroquine-sensitive P. falciparum clone 3D7 (mean FICI 0.784) and multidrug-resistant P. falciparum clone Dd2 (mean FICI 0.599). In vivo drug interactions were measured using a 4-day suppressive test in a rodent malaria model infected with Plasmodium chabaudi. We observed that indinavir enhanced the antimalarial activity of chloroquine against both the chloroquine-sensitive line P. chabaudi ASS and the chloroquine-resistant line P. chabaudi ASCQ. More importantly, chloroquine had a 100% clearance of asexual parasites when used in combination with indinavir at an appropriate dose ratio (10 mg/kg CQ + 1.8 g/kg indinavir) where there was no obvious toxicity. We conclude from this study that the combination of indinavir and chloroquine may become a novel antimalarial drug regimen.

Evidence for erythrocyte-binding antigen 175 as a component of a ligand-blocking blood-stage malaria vaccine

The ligands that pathogens use to invade their target cells have often proven to be good targets for vaccine development. However, Plasmodium falciparum has redundant ligands that mediate invasion of erythrocytes. The first requirement for the development of a successful ligand-blocking malaria vaccine is the demonstration that antibodies induced to each ligand can block the erythrocyte invasion of parasites with polymorphic sequences. Because of P. falciparum's redundancy in erythrocyte invasion, each ligand needs to be studied under artificial conditions in which parasite invasion is restricted in its use of alternative pathways. Here we investigate the role of erythrocyte-binding antigen 175 (EBA-175), a parasite ligand that binds to sialic acid on glycophorin A, in the invasion of erythrocytes by 10 P. falciparum clones under conditions in which invasion is partially limited to the EBA-175-glycophorin A pathway, using chymotrypsin-treated erythrocytes. We show that the ability to invade erythrocytes for both sialic acid-independent and sialic acid-dependent pathways requires the EBA-175-glycophorin A pathway for erythrocyte invasion. Importantly, antibodies against region II of EBA-175 from the 3D7 clone blocked invasion of chymotrypsin-treated erythrocytes by >50% by all parasite clones studied, including those with multiple different mutations described in the literature. The one exception was FCR3, which had a similar sequence to 3D7 but only 30% inhibition of invasion of chymotrypsin-treated erythrocytes, indicating alternative pathways for invasion of chymotrypsin-treated erythrocytes. Our findings suggest that antibodies to region II of EBA-175, as one component of a ligand-blocking malaria vaccine, are largely unaffected by polymorphism in EBA-175.

Confutation of the existence of sequence-conserved cytochrome P450 enzymes in Plasmodium falciparum

The aim of the present study was to find evidence for a homologous protein of the mammalian cytochrome P450 family member CYP2B1/B2 in Plasmodium falciparum at the nucleic acid level. Prior research had demonstrated enzyme activity in the parasite comparable to mammalian CYP1A, 2A, 2B and 2E enzymes and presence of CYP enzymes by spectrophotometric and electrophoretic analyses. In recent years, the transcriptome/proteome data of P. falciparum and other Plasmodium spp. have been published and we performed an in silico analysis to identify putative cytochrome P450 family members in the parasite. This analysis failed to identify homologs to CYP1A, 2A, 2B and 2E enzymes in Plasmodium. A prior study had also claimed the presence of a conserved CYP2B1/B2 gene in the parasite by using Northern analysis with a rat CYP2B1/B2 probe. We have repeated this analysis by cloning a rat CYP2B1/B2 cDNA and using it as a hybridization probe against total RNA extracted from P. falciparum K1 and 3D7 clones but did not obtain positive results. This is consistent with the transcriptome/proteome sequence data and suggests that the genus Plasmodium contains either only highly diverged CYP proteins which are not easily identified by their primary sequence or that they have been functionally replaced by other enzymes. It is suggested that further studies are performed that allow isolation and identification of such proteins through their functional activities.

Yield, Content, and Composition of Peppermint and Spearmints as a Function of Harvesting Time and Drying

Peppermint ( Mentha × piperita L.) and spearmints ('Scotch' spearmint, M. × gracilis Sole, and 'Native' spearmint, Mentha spicata L.) are widely grown essential oil crops in more northern latitudes; however, there is limited information on how harvest time and drying influence peppermint and spearmint yield, oil composition, and bioactivity, when grown south of the 41st parallel. In this 2-year study, the effects of harvest time and drying on the yield, oil composition, and bioactivity of peppermint ('Black Mitcham' and 'B90-9'), 'Scotch' spearmint, and 'Native' spearmint were evaluated. Peppermint oil from the dried material had higher menthol and eucalyptol concentrations. Menthone in both peppermint cultivars decreased from harvest 1 (late June) to harvest 5 (late August) or 6 (early September), whereas menthol increased. (-)-Carvone in spearmints accumulated early, before flowering, allowing for early harvest. Oil yields from the dried spearmint biomass reached the maximum at harvest 3 (mid-July). The essential oil compositions of the four mint genotypes were similar to that of 11 commercially available oils, suggesting that these genotypes can be grown in the hot, humid environment of the southeastern United States. The antioxidant activities (ORAC(oil) values) of the essential oils were 4372, 1713, 1107, and 471 μmol of TE L(-1) for 'Scotch' spearmint, 'Native' spearmint, peppermint, and Japanese cornmint ( Mentha canadensis ), respectively. The oils of the four mint genotypes did not affect ruminal fermentation in vivo, and did not exhibit antimicrobial, antileishmanial, or antimalarial activity at levels that would warrant bioassay-directed fractionation in a drug-discovery screening program. Specifically, the oils did not show greater than 50% growth inhibition against Leishmania donovani , Plasmodium falciparum clones D6 and W2, Candida albicans , Escherichia coli , Pseudomonas aeruginosa , Cryptococcus neoformans , Mycobacterium intracellulare , or Aspergillus fumigates at 50 μg mL(-1).

Chemometric modelling of antimalarial activity of aryltriazolylhydroxamates

We have performed quantitative structure–activity relationship (QSAR) and quantitative activity–activity relationship (QAAR) studies for aryltriazolylhydroxamates having antimalarial activity data against both chloroquine-sensitive (D6 clone) and chloroquine-resistant (W2 clone) strains of Plasmodium falciparum to understand the relationships between the biological activity and molecular properties for the design of new compounds. The QSAR studies were performed using 35 compounds among which 26 molecules were taken using k-means clustering technique in the training set for the derivation of the QSAR models and nine molecules were kept as the test-set compounds to evaluate the predictive ability of the derived models. The chemometric tool used for the analysis was the genetic function approximation. The developed models were analysed in terms of their predictive ability, and comparable results were obtained for cross-validated predictive variance (Q 2) and externally predicted variance (R 2 pred) values (0.761 and 0.829, respectively, for the D6 model, 0.708 and 0.748, respectively, for the W2 model and 0.984 and 0.982, respectively for the QAAR model). The QSAR models suggest that the number of methylene groups (between the triazolyl and hydroxamate moieties) and partially negatively charged surface areas of the molecules are important parameters for the antimalarial activity.

Polymorphisms of the oxidant enzymes glutathione S–transferase and glutathione reductase and their association with resistance of Plasmodium falciparum isolates to antimalarial drugs

Objective To investigate the association between amplification of the two regulatory genes controlling glutathione (GSH) levels, glutathione reductase (P fGR) and glutathione S-transferase (P fGST) 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 Dd 2 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 P fGST gene and sensitivity of the parasite to chloroquine, quinine, mefloquine and quinine was found. Based on PCR analysis, Dd2, K1 and 3D7 clones all contained only one copy of the P fGST gene. All isolates (70) also carried only one copy number of P fGST gene. There appears to be an association between amplification of P fGR gene and chloroquine resistance. The 3D7 and Dd2 clones were found to carry only one P fGR 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.

Antimalarial Activity ofAspilia pruliseta, a Medicinal Plant from Uganda

Aspilia pruliseta Schweinf. (Asteraceae) is a medicinal plant indigenous to Uganda and the neighboring countries of East Africa. It has been used extensively by the rural population for the treatment of fevers and malaria. During the antimalarial evaluation of this plant, four nontoxic diterpenes were isolated that possessed moderate activity against chloroquine-sensitive (D6) and chloroquine-resistant (W2) clones of Plasmodium falciparum, with IC(50) values ranging from 14 to 23 µM. These moderately active compounds included the previously undescribed diterpene, ENT-15 β-senecioyloxy-16,17-epoxy-kauran-18-oic acid that demonstrated an IC(50) value of 23.4 µM against clone D6, but was devoid of activity against clone W2. Four additional diterpenes were obtained from the aerial parts of A. pruliseta, but these known compounds were essentially inactive. The moderate activities of select diterpenes of A. pruliseta could account collectively for the historical and enduring use of this plant in traditional African medicine.

Mechanism-Based Inhibitors of the Aspartyl Protease Plasmepsin II as Potential Antimalarial Agents

Four aspartyl proteases known as plasmepsins are involved in the degradation of hemoglobin by Plasmodium falciparum, which causes a large percentage of malaria deaths. The enzyme plasmepsin II (Plm II) is the most extensively studied of these aspartyl proteases and catalyzes the initial step in the breakdown of hemoglobin by the parasite. Several groups have reported the design, synthesis, and evaluation of reversible peptidomimetic inhibitors of Plm II as potential antimalarial agents. We now report four peptidomimetic analogues, compounds 6-9, which are rationally designed to act as mechanism-based inhibitors of Plm II. Three of these analogues produce potent irreversible inactivation of the enzyme with IC(50) values in the low nanomolar range. Of these three compounds, two retain the low micromolar IC(50) values of the parent compound in Plasmodium falciparum (clone 3D7) infected erythrocytes. These analogues are the first examples of fully characterized mechanism-based inactivators for an aspartyl protease and show promise as novel antimalarial agents.

Safety and Immunogenicity of an AMA1 Malaria Vaccine in Malian Children: Results of a Phase 1 Randomized Controlled Trial

BackgroundThe objective was to evaluate the safety and immunogenicity of the AMA1-based malaria vaccine FMP2.1/AS02A in children exposed to seasonal falciparum malaria.Methodology/Principal FindingsA Phase 1 double blind randomized controlled dose escalation trial was conducted in Bandiagara, Mali, West Africa, a rural town with intense seasonal transmission of Plasmodium falciparum malaria. The malaria vaccine FMP2.1/AS02A is a recombinant protein (FMP2.1) based on apical membrane antigen 1 (AMA1) from the 3D7 clone of P. falciparum, formulated in the Adjuvant System AS02A. The comparator vaccine was a cell-culture rabies virus vaccine (RabAvert®). One hundred healthy Malian children aged 1–6 years were recruited into 3 cohorts and randomized to receive either 10 µg FMP2.1 in 0.1 mL AS02A, or 25 µg FMP2.1 in 0.25 mL AS02A, or 50 µg FMP2.1 50 µg in 0.5 mL AS02A, or rabies vaccine. Three doses of vaccine were given at 0, 1 and 2 months, and children were followed for 1 year. Solicited symptoms were assessed for 7 days and unsolicited symptoms for 30 days after each vaccination. Serious adverse events were assessed throughout the study. Transient local pain and swelling were common and more frequent in all malaria vaccine dosage groups than in the comparator group, but were acceptable to parents of participants. Levels of anti-AMA1 antibodies measured by ELISA increased significantly (at least 100-fold compared to baseline) in all 3 malaria vaccine groups, and remained high during the year of follow up.Conclusion/SignificanceThe FMP2.1/AS02A vaccine had a good safety profile, was well-tolerated, and induced high and sustained antibody levels in malaria-exposed children. This malaria vaccine is being evaluated in a Phase 2 efficacy trial in children at this site.Trial RegistrationClinicalTrials.gov NCT00358332 [NCT00358332]

Prediction of potential antimalarial targets of artemisinin based on protein information from whole genome of Plasmodium falciparum

On the basis of the genomic data and protein pathway information about Plasmodium falciparum clone 3D7 from the NCBI taxonomy database and the KEGG database, eight key protein enzymes in the signal pathways were selected to perform molecular docking with artemisinin. The binding modes obtained from the molecular docking suggested that purine nucleoside phosphorylase (pfPNP), peptide deformylase (pfPDF), and ribose 5-phosphate isomerase (pfRpiA) may be involved in the antimalarial mode of action of artemisinin. Artemisinin exhibited its antimalarial activity probably by interfering with the metabolic pathways of purine, pyrimidine, methionine, glyoxylate and dicarboxylate, or pentose phosphate.

Molecular cloning and characterisation of the RESA gene, a marker of genetic diversity of Plasmodium falciparum

To identity immunodiagnostic antigen genes, a Plasmodium falciparum (Dd2 clone) expression library was screened using human immune sera. The ring-infected erythrocyte surface antigen (RESA) was isolated: this antigen of the resistant clone presents repeat tandem sequences like the 3D7 clone, albeit in different numbers. RESA has been studied as a marker of genetic diversity, with different sizes being observed in different isolates and clones of Plasmodium falciparum. The native protein was localised in cultures by western-blot and immuno-transmission electron microscopy. The antigenicity of RESA was evaluated by ELISA, using the carboxy-terminal repeat region as antigen. The assay’s sensitivity and specificity were 78.2 and 94% respectively.