scholarly journals Genetic profiling of the Plasmodium falciparum parasite population in uncomplicated malaria from India

2019 ◽  
Vol 18 (1) ◽  
Author(s):  
Amit Kumar ◽  
Shri Pat Singh ◽  
Rajendra Bhatt ◽  
Vineeta Singh
Keyword(s):  
Drug Resistance ◽  
Resistance Genes ◽  
Vitro Assay ◽  
Genetic Profiling ◽  
Field Isolates ◽  
Intervention Measures ◽  
Plasmodium Falciparum Parasite ◽  
Control Programmes ◽  
Drug Sensitivity Assay

Abstract Background The genetic complexity and the existence of several polymorphisms in parasites are the major hindrances for the malaria control programmes of the country. The genetic profiling in the parasite populations in India will provide useful baseline data for future studies elucidating the parasite structure and distribution of drug resistance genotypes in different regions. Methods The blood samples of symptomatic patients were collected and analysed for drug resistance genes (Pfcrt, Pfmdr-1, dhfr, dhps and k13) and gametocyte genes (Pfs25, Pfg377); in vitro drug sensitivity assay by schizont maturation inhibition (SMI) was also performed in adapted field isolates. Results Of the 122 field isolates analysed; 65.5% showed Pfcrt K76T mutant alleles, 61.4% Pfmdr-1 N86Y mutants, 59.5% dhfr mutants, 59.8% dhps mutants was observed, but no polymorphism was seen for k13. The sequence analysis of Pfg377 gene revealed five types of populations in the field isolates. The inhibitory concentrations (IC50) for anti-malarial drugs viz chloroquine (CQ), artesunate (AS), were in the range of 10.11–113.2 nM and 2.26–4.08 nM, respectively, in the field isolates evaluate by in vitro assay. The IC50 values for CQ have shown a remarkable reduction on comparison with the previous available data, whereas a slight increase in the IC50 values for AS was observed in the study. Conclusions The increase in mutation rate in drug resistance allelic loci with inhibitory concentration of CQ and AS drugs was observed in the field isolates and high diversity in Pfg377 gametocyte gene indicate towards parasite multifactorial behaviour. The knowledge of the prevalent drug resistance genes is important for intervention measures to be successful and efforts should also be made to prevent transmission of P. falciparum.

scholarly journals Piperaquine resistant Cambodian Plasmodium falciparum clinical isolates: in vitro genotypic and phenotypic characterization

2020 ◽  
Author(s):  
Nonlawat Boonyalai ◽  
Brian A Vesely ◽  
Chatchadaporn Thamnurak ◽  
Chantida Praditpol ◽  
Watcharintorn Fagnark ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Plasmodium Falciparum ◽  
Copy Number ◽  
Drug Susceptibility ◽  
Antagonistic Activity ◽  
Drug Combinations ◽  
Chloroquine Resistance ◽  
Phenotypic Characterization ◽  
Field Isolates

Abstract Background High rates of dihydroartemisinin-piperaquine (DHA-PPQ) treatment failures have been documented for uncomplicated Plasmodium falciparum in Cambodia. The genetic markers plasmepsin 2 ( pfpm2 ), exonuclease ( pfexo ) and chloroquine resistance transporter ( pfcrt ) genes are associated with PPQ resistance and are used for monitoring the prevalence of drug resistance and guiding malaria drug treatment policy.Methods To examine the relative contribution of each marker to PPQ resistance, in vitro culture and the PPQ survival assay were performed on seventeen P. falciparum isolates from northern Cambodia, and the presence of E415G-Exo and pfcrt mutations (T93S, H97Y, F145I, I218F, M343L, C350R, and G353V) as well as pfpm2 copy number polymorphisms were determined. Parasites were then cloned by limiting dilution and the cloned parasites were tested for drug susceptibility. Isobolographic analysis of several drug combinations for standard clones and newly cloned P. falciparum Cambodian isolates was also determined.Results The characterization of culture-adapted isolates revealed that the presence of novel pfcrt mutations (T93S, H97Y, F145I, and I218F) with E415G-Exo mutation can confer PPQ-resistance, in the absence of pfpm2 amplification. In vitro testing of PPQ resistant parasites demonstrated a bimodal dose-response, the existence of a swollen digestive vacuole phenotype, and an increased susceptibility to quinine, chloroquine, mefloquine and lumefantrine. To further characterize drug sensitivity, parental parasites were cloned in which a clonal line, 14-B5, was identified as sensitive to artemisinin and piperaquine, but resistant to chloroquine. Assessment of the clone against a panel of drug combinations revealed antagonistic activity for six different drug combinations. However, mefloquine-proguanil and atovoquone-proguanil combinations revealed synergistic antimalarial activity.Conclusions Surveillance for PPQ resistance in regions relying on DHA-PPQ as the first-line treatment is dependent on the monitoring of molecular markers of drug resistance. P. falciparum harbouring novel pfcrt mutations with E415G-exo mutations displayed PPQ resistant phenotype. The presence of pfpm2 amplification was not required to render parasites PPQ resistant suggesting that the increase in pfpm2 copy number alone is not the sole modulator of PPQ resistance. Genetic background of circulating field isolates appear to play a role in drug susceptibility and biological responses induced by drug combinations. The use of latest field isolates may be necessary for assessment of relevant drug combinations against P. falciparum strains and when down-selecting novel drug candidates.

scholarly journals Isolation and Characterization of a Distinct Subpopulation from the WM115 Cell Line That Resembles In Vitro Properties of Melanoma Cancer Stem Cells

2017 ◽  
Vol 22 (5) ◽  
pp. 484-493
Author(s):  
Sonia G. Escobar ◽  
Mark H. Chin ◽  
Mark L. Sandberg ◽  
Han Xu
Keyword(s):  
Drug Resistance ◽  
Cancer Cells ◽  
Cell Line ◽  
Malignant Tumors ◽  
Tumor Cell Line ◽  
Cancer Therapeutics ◽  
Serum Starvation ◽  
Vitro Assay ◽  
Isolation And Characterization

Despite key advances in cancer therapies, malignant tumors, such as melanoma, continue to be one of the leading causes of mortality. Recent debate on whether cancer can originate from a tumor-initiating subpopulation has permeated oncology and stem cell research. It has been well established that primary and immortalized tumor cells consist of heterogeneous cell populations. The profound effect of tumor heterogeneity on tumor growth and drug resistance remains elusive, but it is highly likely that subpopulations of cancer cells have different capabilities of self-renewal and drug resistance. Discrepancies between excellent in vitro potency and efficacy and poor patient response have been observed on multiple cancer therapeutics. Although this observation can be attributed to many factors, a better understanding of the contribution from subpopulations within a cancer will help bridge the gap between in vitro assay results and patient prognosis. To comprehend this impact, it is critical to isolate and characterize cancer subpopulations that possess higher growth and drug resistance properties so that novel therapeutics can be developed to eventually eradicate all cancer cells. In this article, we describe a method to enrich a subpopulation, CB4, from the melanoma cell line WM115. CB4 exhibited higher anchorage-independent growth, higher survival under serum starvation condition, and lower drug sensitivity to commonly used melanoma treatment compared with WM115. Details of functional properties and gene expression of CB4 compared with WM115 are reported. Our study demonstrates that it is feasible to isolate and enrich a subpopulation that exhibits higher growth capacity and treatment resistance from an immortalized tumor cell line.

Correlation of in vitro chemotherapy drug resistance assay to clinical response to carboplatin and paclitaxel combination chemotherapy in ovarian carcinoma.

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. e16546-e16546
Author(s):  
Kit Cheng ◽  
Iuliana Shapira ◽  
Lisa M Rosen ◽  
Veena S. John ◽  
John L. Lovecchio ◽  
...  
Keyword(s):  
Overall Survival ◽  
Drug Resistance ◽  
Statistical Significance ◽  
Retrospective Chart Review ◽  
Progression Free Survival ◽  
In Vitro Assays ◽  
Rank Test ◽  
Assay Sensitivity ◽  
Vitro Assay

e16546 Background: Carboplatin sensitivity in drug resistance assays has been shown to be an independent predictor of longer progression free interval with conflicting results in overall survival. We evaluated in vitro drug resistance for carboplatin and paclitaxel combination and its correlation with progression free survival (PFS) and overall survival (OS). Methods: From April 1, 2006 to December 12, 2011, in vitro drug resistance assays were sent after cytoreductive surgery for primary epithelial ovarian cancer. Patients were analyzed according to drug resistance scoring system of low drug resistance (S), intermediate drug resistance (I), and extreme drug resistance (R). Retrospective chart review was performed to evaluate PFS and OS. The Kaplan Meier product limit method was used to estimate OS and PFS. Survival curves were compared between groups using the log rank test. Results: From a total of 142 patients: 57 were S, 52 I, and 33 R; 77% were responsive (S+I) to carboplatin and paclitaxel combination. At median follow-up of 18 months, PFS and OS rates were 58.1 and 91.3% respectively for S, 66.1 and 78.7% for I, and 43.2% and 84.3% for R. At 36 months, the PFS and OS rates were 52.3 and 61.1% for S, 51.3 and 55.3% for I and 39.3% and 48.7% for R. There was OS advantage between the S and I compared to R. There were no significant differences in PFS curves (p<0.281) or OS curves (p<0.46). Conclusions: Although sensitivity to carboplatin/ paclitaxel resulted in longer OS, the results were not statistically significant. Our cohorts were small and we may not have had the power to capture statistical significance. A larger multicenter analysis would be needed to further evaluate this finding. In addition, one of the regimens our patients received on relapse was bevacizumab which was not evaluated in the in vitro assay sensitivity assay. Bevacizumab has also been included in first line treatment in combination with platinum/ taxane regimen. Future analysis of in vitro assays may need to include biologics.

scholarly journals Mapping the malaria parasite drug-able genome using in vitro evolution and chemogenomics

2017 ◽  
Author(s):  
Annie N. Cowell ◽  
Eva S. Istvan ◽  
Amanda K. Lukens ◽  
Maria G. Gomez-Lorenzo ◽  
Manu Vanaerschot ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Plasmodium Falciparum ◽  
Multidrug Resistance ◽  
Resistance Genes ◽  
Genome Analysis ◽  
Drug Targets ◽  
Malaria Parasite ◽  
Resistance Mechanisms ◽  
Whole Genome

AbstractChemogenetic characterization through in vitro evolution combined with whole genome analysis is a powerful tool to discover novel antimalarial drug targets and identify drug resistance genes. Our comprehensive genome analysis of 262 Plasmodium falciparum parasites treated with 37 diverse compounds reveals how the parasite evolves to evade the action of small molecule growth inhibitors. This detailed data set revealed 159 gene amplifications and 148 nonsynonymous changes in 83 genes which developed during resistance acquisition. Using a new algorithm, we show that gene amplifications contribute to 1/3 of drug resistance acquisition events. In addition to confirming known multidrug resistance mechanisms, we discovered novel multidrug resistance genes. Furthermore, we identified promising new drug target-inhibitor pairs to advance the malaria elimination campaign, including: thymidylate synthase and a benzoquinazolinone, farnesyltransferase and a pyrimidinedione, and a dipeptidylpeptidase and an arylurea. This deep exploration of the P. falciparum resistome and drug-able genome will guide future drug discovery and structural biology efforts, while also advancing our understanding of resistance mechanisms of the deadliest malaria parasite.One Sentence SummaryWhole genome sequencing reveals how Plasmodium falciparum evolves resistance to diverse compounds and identifies new antimalarial drug targets.

scholarly journals Piperaquine resistant Cambodian Plasmodium falciparum clinical isolates: in vitro genotypic and phenotypic characterization

2020 ◽  
Author(s):  
Nonlawat Boonyalai ◽  
Brian A Vesely ◽  
Chatchadaporn Thamnurak ◽  
Chantida Praditpol ◽  
Watcharintorn Fagnark ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Plasmodium Falciparum ◽  
Copy Number ◽  
Antimalarial Activity ◽  
Drug Susceptibility ◽  
Drug Combinations ◽  
Chloroquine Resistance ◽  
Phenotypic Characterization ◽  
Field Isolates

Abstract Background: High rates of dihydroartemisinin-piperaquine (DHA-PPQ) treatment failures have been documented for uncomplicated Plasmodium falciparum in Cambodia. The genetic markers plasmepsin 2 (pfpm2), exonuclease (pfexo) and chloroquine resistance transporter (pfcrt) genes are associated with PPQ resistance and are used for monitoring the prevalence of drug resistance and guiding malaria drug treatment policy.Methods: To examine the relative contribution of each marker to PPQ resistance, in vitro culture and the PPQ survival assay were performed on seventeen P. falciparum isolates from northern Cambodia, and the presence of E415G-Exo and PfCRT mutations (T93S, H97Y, F145I, I218F, M343L, C350R, and G353V) as well as pfpm2 copy number polymorphisms were determined. Parasites were then cloned by limiting dilution and the cloned parasites were tested for drug susceptibility. Isobolographic analysis of several drug combinations for standard clones and newly cloned P. falciparum Cambodian isolates was also determined.Results: The characterization of culture-adapted isolates revealed that the presence of novel PfCRT mutations (T93S, H97Y, F145I, and I218F) with E415G-Exo mutation can confer PPQ-resistance, in the absence of pfpm2 amplification. In vitro testing of PPQ resistant parasites demonstrated a bimodal dose-response, the existence of a swollen digestive vacuole phenotype, and an increased susceptibility to quinine, chloroquine, mefloquine and lumefantrine . To further characterize drug sensitivity, parental parasites were cloned in which a clonal line, 14-B5, was identified as sensitive to arteminsinin and piperaquine but resistant to chloroquine. Assessment of the clone against a panel of drug combinations revealed antagonistic activity for six different drug combinations. However, mefloquine-proguanil and atovoquone-proguanil combinations revealed synergistic antimalarial activity. Conclusions: Surveillance for PPQ resistance in regions relying on DHA-PPQ as the first-line treatment is dependent on the monitoring of molecular markers of drug resistance. P. falciparum harboring novel PfCRT mutations with E415G-exo mutations displayed PPQ resistant phenotype. The presence of pfpm2 amplification was not required to render parasites PPQ resistant suggesting that the increase in pfpm2 copy number alone is not the sole modulator of PPQ resistance. Genetic background of circulating field isolates appear to play a role in drug susceptibility and biological responses induced by drug combinations. The use of latest field isolates may be necessary for assessment of relevant drug combinations against P. falciparum strains and when down-selecting novel drug candidates.

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