Plasmodium vivax Drug Resistance Genes; Pvmdr1 and Pvcrt-o Polymorphisms in Relation to Chloroquine Sensitivity from a Malaria Endemic Area of Thailand

The aim of the study was to explore the possible molecular markers of chloroquine resistance in Plasmodium vivax isolates in Thailand. A total of 30 P. vivax isolates were collected from a malaria endemic area along the Thai-Myanmar border in Mae Sot district of Thailand. Dried blood spot samples were collected for analysis of Pvmdr1 and Pvcrt-o polymorphisms. Blood samples (100 mul) were collected by finger-prick for in vitro chloroquine susceptibility testing by schizont maturation inhibition assay. Based on the cut-off IC50 of 100 nM, 19 (63.3%) isolates were classified as chloroquine resistant P. vivax isolates. Seven non-synonymous mutations and 2 synonymous were identified in Pvmdr1 gene. Y976F and F1076L mutations were detected in 7 (23.3%) and 16 isolates (53.3%), respectively. Analysis of Pvcrt-o gene revealed that all isolates were wild-type. Our results suggest that chloroquine resistance gene is now spreading in this area. Monitoring of chloroquine resistant molecular markers provide a useful tool for future control of P. vivax malaria.

Plasmodium vivax Drug Resistance Genes; Pvmdr1 and Pvcrt-o Polymorphisms in Relation to Chloroquine Sensitivity from a Malaria Endemic Area of Thailand

The aim of the study was to explore the possible molecular markers of chloroquine resistance in Plasmodium vivax isolates in Thailand. A total of 30 P. vivax isolates were collected from a malaria endemic area along the Thai-Myanmar border in Mae Sot district of Thailand. Dried blood spot samples were collected for analysis of Pvmdr1 and Pvcrt-o polymorphisms. Blood samples (100 mul) were collected by finger-prick for in vitro chloroquine susceptibility testing by schizont maturation inhibition assay. Based on the cut-off IC50 of 100 nM, 19 (63.3%) isolates were classified as chloroquine resistant P. vivax isolates. Seven non-synonymous mutations and 2 synonymous were identified in Pvmdr1 gene. Y976F and F1076L mutations were detected in 7 (23.3%) and 16 isolates (53.3%), respectively. Analysis of Pvcrt-o gene revealed that all isolates were wild-type. Our results suggest that chloroquine resistance gene is now spreading in this area. Monitoring of chloroquine resistant molecular markers provide a useful tool for future control of P. vivax malaria.

Genetic Polymorphisms in Plasmodium vivax Dihydrofolate Reductase and Dihydropteroate Synthase in Isolates from the Philippines, Bangladesh, and Nepal

Genetic polymorphisms of pvdhfr and pvdhps genes of Plasmodium vivax were investigated in 83 blood samples collected from patients in the Philippines, Bangladesh, and Nepal. The SNP-haplotypes of the pvdhfr gene at the amino acid positions 13, 33, 57, 58, 61, 117, and 173, and that of the pvdhps gene at the positions 383 and 553 were analyzed by nested PCR-RFLP. Results suggest diverse polymorphic patterns of pvdhfr alone as well as the combination patterns with pvdhps mutant alleles in P. vivax isolates collected from the 3 endemic countries in Asia. All samples carried mutant combination alleles of pvdhfr and pvdhps. The most prevalent combination alleles found in samples from the Philippines and Bangladesh were triple mutant pvdhfr combined with single mutant pvdhps allele and triple mutant pvdhfr combined with double wild-type pvdhps alleles, respectively. Those collected from Nepal were quadruple mutant pvdhfr combined with double wild-type pvdhps alleles. New alternative antifolate drugs which are effective against sulfadoxine-pyrimethamine (SP)-resistant P. vivax are required.

Proteomics analysis of antimalarial targets of Garcinia mangostana Linn

Objective: To investigate possible protein targets for antimalarial activity of Garcinia mangostana Linn. (G. mangostana) (pericarp) in 3D7 Plasmodium falciparum clone using 2-dimensional electrophoresis and liquid chromatography mass-spectrometry (LC/MS/MS). Methods: 3D7 Plasmodium falciparum was exposed to the crude ethanolic extract of G. mangostana Linn. (pericarp) at the concentrations of 12μg/mL (IC

Proteomics analysis of antimalarial targets of Garcinia mangostana Linn

<p><b>OBJECTIVE</b>To investigate possible protein targets for antimalarial activity of Garcinia mangostana Linn. (G. mangostana) (pericarp) in 3D7 Plasmodium falciparum clone using 2-dimensional electrophoresis and liquid chromatography mass-spectrometry (LC/MS/MS).</p><p><b>METHODS</b>3D7 Plasmodium falciparum was exposed to the crude ethanolic extract of G. mangostana Linn. (pericarp) at the concentrations of 12µg/mL (IC50 level: concentration that inhibits parasite growth by 50%) and 30 µg/mL (IC90 level: concentration that inhibits parasite growth by 90%) for 12 h. Parasite proteins were separated by 2-dimensional electrophoresis and identified by LC/MS/MS.</p><p><b>RESULTS</b>At the IC50 concentration, about 82% of the expressed parasite proteins were matched with the control (non-exposed), while at the IC90 concentration, only 15% matched proteins were found. The selected protein spots from parasite exposed to the plant extract at the concentration of 12 µg/mL were identified as enzymes that play role in glycolysis pathway, i.e., phosphoglycerate mutase putative, L-lactate dehydrogenase/glyceraldehyde-3-phosphate dehydrogenase, and fructose-bisphosphate aldolase/phosphoglycerate kinase. The proteosome was found in parasite exposed to 30 µg/mL of the extract.</p><p><b>CONCLUSIONS</b>Results suggest that proteins involved in the glycolysis pathway may be the targets for antimalarial activity of G. mangostana Linn. (pericarp).</p>

The identities and anti-herpes simplex virus activity of Clinacanthusnutans and Clinacanthus siamensis

Objective: To distinguish the difference among the Clinacanthus nutans (Burm. f.) Lindau (C. nutans) and Clinacanthus siamensis Bremek (C. siamensis) by assessing pharmacognosy characteristics, molecular aspect and also to evaluate their anti-herpes simplex virus (HSV) type 1 and type 2 activities. Methods: Macroscopic and microscopic evaluation were performed according to WHO Geneva guideline. Stomatal number, stomatal index and palisade ratio of leaves were evaluated. Genomic DNA was extracted by modified CTAB method and ITS region was amplified using PCR and then sequenced. Dry leaves were subsequently extracted withn-hexane, dichloromethane and methanol and antiviral activity was performed using plaque reduction assay and the cytotoxicity of the extracts on Vero cells was determined by MTT assay. Results: Cross section of midrib and stem showed similar major components. Leaf measurement index of stomatal number, stomatal index and palisade ratio of C. nutans were 168.32±29.49, 13.83±0.86 and 6.84±0.66, respectively, while C. siamensis were 161.60±18.04, 11.93±0.81 and 3.37±0.31, respectively. The PCR amplification of ITS region generated the PCR product approximately 700 bp in size. There were 34 polymorphisms within the ITS region which consisted of 11 Indels and 23 nucleotide substitutions. The IC50 values of C. nutans extracted with n-hexane, dichloromethane and methanol against HSV-1 were (32.05±3.63) μg/mL, (44.50±2.66) μg/mL, (64.93±7.00) μg/mL, respectively where as those of C. siamensis were (60.00±11.61) μg/mL, (55.69±4.41) μg/mL, (37.39±5.85) μg/mL, respectively. Anti HSV-2 activity of n-hexane, dichloromethane and methanolC. nutans leaves extracts were (72.62±12.60) μg/mL, (65.19±21.45) μg/mL, (65.13±2.22) μg/mL, respectively where as those of C. siamensis were (46.52±4.08) μg/mL, (49.63±2.59) μg/mL, (72.64±6.52) μg/mL, respectively. Conclusions: The combination of macroscopic, microscopic and biomolecular method are able to authenticate these closely related plants and both of them have a potency to be an anti-HSV agent.

The identities and anti-herpes simplex virus activity of Clinacanthus nutans and Clinacanthus siamensis

<p><b>OBJECTIVE</b>To distinguish the difference among the Clinacanthus nutans (Burm. f.) Lindau (C. nutans) and Clinacanthus siamensis Bremek (C. siamensis) by assessing pharmacognosy characteristics, molecular aspect and also to evaluate their anti-herpes simplex virus (HSV) type 1 and type 2 activities.</p><p><b>METHODS</b>Macroscopic and microscopic evaluation were performed according to WHO Geneva guideline. Stomatal number, stomatal index and palisade ratio of leaves were evaluated. Genomic DNA was extracted by modified CTAB method and ITS region was amplified using PCR and then sequenced. Dry leaves were subsequently extracted with n-hexane, dichloromethane and methanol and antiviral activity was performed using plaque reduction assay and the cytotoxicity of the extracts on Vero cells was determined by MTT assay.</p><p><b>RESULTS</b>Cross section of midrib and stem showed similar major components. Leaf measurement index of stomatal number, stomatal index and palisade ratio of C. nutans were 168.32±29.49, 13.83±0.86 and 6.84±0.66, respectively, while C. siamensis were 161.60±18.04, 11.93±0.81 and 3.37±0.31, respectively. The PCR amplification of ITS region generated the PCR product approximately 700 bp in size. There were 34 polymorphisms within the ITS region which consisted of 11 Indels and 23 nucleotide substitutions. The IC50 values of C. nutans extracted with n-hexane, dichloromethane and methanol against HSV-1 were (32.05±3.63) µg/mL, (44.50±2.66) µg/mL, (64.93±7.00) µg/mL, respectively where as those of C. siamensis were (60.00±11.61) µg/mL, (55.69±4.41) µg/mL, (37.39±5.85) µg/mL, respectively. Anti HSV-2 activity of n-hexane, dichloromethane and methanol C. nutans leaves extracts were (72.62±12.60) µg/mL, (65.19±21.45) µg/mL, (65.13±2.22) µg/mL, respectively where as those of C. siamensis were (46.52±4.08) µg/mL, (49.63±2.59) µg/mL, (72.64±6.52) µg/mL, respectively.</p><p><b>CONCLUSIONS</b>The combination of macroscopic, microscopic and biomolecular method are able to authenticate these closely related plants and both of them have a potency to be an anti-HSV agent.</p>

Comparison of protein patterns between Plasmodium falciparum mutant clone T9/94-M1-1(b3) induced by pyrimethamine and the original parent clone T9/94

<p><b>OBJECTIVE</b>To 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).</p><p><b>METHODS</b>Proteins 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.</p><p><b>RESULTS</b>Differentially 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.</p><p><b>CONCLUSIONS</b>These 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.</p>

Assessment of in vitro sensitivity of Plasmodium vivax fresh isolates

<p><b>OBJECTIVE</b>To compare the applicability of the SYBR Green-I assay with the standard schizont maturation assay, for determination of sensitivity of Plasmodium vivax (P. vivax) to chloroquine and a new antifolate WR 99210.</p><p><b>METHODS</b>The study was conducted at Mae Tao Clinic for migrant workers, Tak Province during April 2009 to July 2010. A total of 64 blood samples (1 mL blood collected into sodium heparinized plastic tube) were collected from patients with mono-infection with P. vivax malaria prior to treatment with standard regimen of a 3-day chloroquine. In vitro sensitivity of P. vivax isolates was evaluated by schizont maturation inhibition and SYBR Green-I assays.</p><p><b>RESULTS</b>A total of 30 out of 64 blood samples collected from patients with P. vivax malaria were successfully analyzed using both the microscopic schizont maturation inhibition and SYBR Green-I assays. The failure rates of the schizont maturation inhibition assay (50%) and the SYBR Green-I assay (54%) were similar (P=0.51). The median IC10s, IC50s and IC90s of both chloroquine and WR99210 were not significantly different from the clinical isolates of P. vivax tested. Based on the cut-off of 100 nM, the prevalences of chloroquine resistance determined by schizont maturation inhibition and SYBR Green-I assays were 19 and 11 isolates, respectively. The strength of agreement between the two methods was very poor for both chloroquine and WR99210.</p><p><b>CONCLUSIONS</b>On the basis of this condition and its superior sensitivity, the microscopic method appears better than the SYBR Green-I Green assay for assessing in vitro sensitivity of fresh P. vivax isolates to antimalarial drugs.</p>