Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 4 de 4
Filtrar
Más filtros












Base de datos
Intervalo de año de publicación
1.
PLoS One ; 19(6): e0298585, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38900782

RESUMEN

Single nucleotide polymorphisms (SNPs) in the Plasmodium falciparum multi-drug resistance protein 1 (Pfmrp1) gene have previously been reported to confer resistance to Artemisinin-based Combination Therapies (ACTs) in Southeast Asia. A total of 300 samples collected from six sites between 2008 and 2019 under an ongoing malaria drug sensitivity patterns in Kenya study were evaluated for the presence of SNPs at Pfmrp1 gene codons: H191Y, S437A, I876V, and F1390I using the Agena MassARRAY® platform. Each isolate was further tested against artemisinin (ART), lumefantrine (LU), amodiaquine (AQ), mefloquine (MQ), quinine (QN), and chloroquine (CQ) using malaria the SYBR Green I-based method to determine their in vitro drug sensitivity. Of the samples genotyped, polymorphism at Pfmrp1 codon I876V was the most frequent, with 59.3% (163/275) mutants, followed by F1390I, 7.2% (20/278), H191Y, 4.0% (6/151), and S437A, 3.3% (9/274). A significant decrease in median 50% inhibition concentrations (IC50s) and interquartile range (IQR) was noted; AQ from 2.996 ng/ml [IQR = 2.604-4.747, n = 51] in 2008 to 1.495 ng/ml [IQR = 0.7134-3.318, n = 40] (P<0.001) in 2019, QN from 59.64 ng/ml [IQR = 29.88-80.89, n = 51] in 2008 to 18.10 ng/ml [IQR = 11.81-26.92, n = 42] (P<0.001) in 2019, CQ from 35.19 ng/ml [IQR = 16.99-71.20, n = 30] in 2008 to 6.699 ng/ml [IQR = 4.976-9.875, n = 37] (P<0.001) in 2019, and ART from 2.680 ng/ml [IQR = 1.608-4.857, n = 57] in 2008 to 2.105 ng/ml [IQR = 1.266-3.267, n = 47] (P = 0.0012) in 2019, implying increasing parasite sensitivity to the drugs over time. However, no significant variations were observed in LU (P = 0.2692) and MQ (P = 0.0939) respectively, suggesting stable parasite responses over time. There was no statistical significance between the mutation at 876 and parasite sensitivity to selected antimalarials tested, suggesting stable sensitivity for the parasites with 876V mutations. These findings show that Kenyan parasite strains are still sensitive to AQ, QN, CQ, ART, LU, and MQ. Despite the presence of Pfmrp1 mutations in parasites among the population.


Asunto(s)
Antimaláricos , Combinación Arteméter y Lumefantrina , Malaria Falciparum , Plasmodium falciparum , Polimorfismo de Nucleótido Simple , Antimaláricos/farmacología , Antimaláricos/uso terapéutico , Humanos , Plasmodium falciparum/efectos de los fármacos , Plasmodium falciparum/genética , Combinación Arteméter y Lumefantrina/uso terapéutico , Malaria Falciparum/tratamiento farmacológico , Malaria Falciparum/parasitología , Proteínas Asociadas a Resistencia a Múltiples Medicamentos/genética , Kenia , Mefloquina/farmacología , Mefloquina/uso terapéutico , Amodiaquina/farmacología , Amodiaquina/uso terapéutico , Resistencia a Medicamentos/genética , Artemisininas/farmacología , Artemisininas/uso terapéutico , Cloroquina/farmacología , Cloroquina/uso terapéutico , Quinina/farmacología , Quinina/uso terapéutico , Masculino , Femenino
2.
Biochem Biophys Rep ; 37: 101596, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38146350

RESUMEN

The molecular mechanism underlying Plasmodium falciparum's persistence in the asymptomatic phase of infection remains largely unknown. However, large-scale shifts in the parasites' gene expression during asymptomatic infections may enhance phenotypic plasticity, maximizing their fitness and leading to the persistence of the asymptomatic infections. To uncover these mechanisms, we aimed to identify parasite genetic factors implicated in asymptomatic infections through whole transcriptome analysis. We analyzed publicly available transcriptome datasets containing asymptomatic malaria (ASM), uncomplicated malaria (SM), and malaria-naïve (NSM) samples from 35 subjects for differentially expressed genes (DEGs) and long noncoding RNAs. Our analysis identified 755 and 1773 DEGs in ASM vs SM and NSM, respectively. These DEGs revealed sets of genes coding for proteins of unknown functions (PUFs) upregulated in ASM vs SM and ASM, suggesting their role in underlying fundamental molecular mechanisms during asymptomatic infections. Upregulated genes in ASM vs SM revealed a subset of 24 clonal variant genes (CVGs) involved in host-parasite and symbiotic interactions and modulation of the symbiont of host erythrocyte aggregation pathways. Moreover, we identified 237 differentially expressed noncoding RNAs in ASM vs SM, of which 11 were found to interact with CVGs, suggesting their possible role in regulating the expression of CVGs. Our results suggest that P. falciparum utilizes phenotypic plasticity as an adaptive mechanism during asymptomatic infections by upregulating clonal variant genes, with long noncoding RNAs possibly playing a crucial role in their regulation. Thus, our study provides insights into the parasites' genetic factors that confer a fitness advantage during asymptomatic infections.

3.
BMC Med ; 20(1): 448, 2022 11 18.
Artículo en Inglés | MEDLINE | ID: mdl-36397090

RESUMEN

BACKGROUND: Dihydroartemisinin-piperaquine (DHA-PPQ) is an alternative first-line antimalarial to artemether-lumefantrine in Kenya. However, recent reports on the emergence of PPQ resistance in Southeast Asia threaten its continued use in Kenya and Africa. In line with the policy on continued deployment of DHA-PPQ, it is imperative to monitor the susceptibility of Kenyan parasites to PPQ and other antimalarials. METHODS: Parasite isolates collected between 2008 and 2021 from individuals with naturally acquired P. falciparum infections presenting with uncomplicated malaria were tested for in vitro susceptibility to piperaquine, dihydroartemisinin, lumefantrine, artemether, and chloroquine using the malaria SYBR Green I method. A subset of the 2019-2021 samples was further tested for ex vivo susceptibility to PPQ using piperaquine survival assay (PSA). Each isolate was also characterized for mutations associated with antimalarial resistance in Pfcrt, Pfmdr1, Pfpm2/3, Pfdhfr, and Pfdhps genes using real-time PCR and Agena MassARRAY platform. Associations between phenotype and genotype were also determined. RESULTS: The PPQ median IC50 interquartile range (IQR) remained stable during the study period, 32.70 nM (IQR 20.2-45.6) in 2008 and 27.30 nM (IQR 6.9-52.8) in 2021 (P=0.1615). The median ex vivo piperaquine survival rate (IQR) was 0% (0-5.27) at 95% CI. Five isolates had a PSA survival rate of ≥10%, consistent with the range of PPQ-resistant parasites, though they lacked polymorphisms in Pfmdr1 and Plasmepsin genes. Lumefantrine and artemether median IC50s rose significantly to 62.40 nM (IQR 26.9-100.8) (P = 0.0201); 7.00 nM (IQR 2.4-13.4) (P = 0.0021) in 2021 from 26.30 nM (IQR 5.1-64.3); and 2.70 nM (IQR 1.3-10.4) in 2008, respectively. Conversely, chloroquine median IC50s decreased significantly to 10.30 nM (IQR 7.2-20.9) in 2021 from 15.30 nM (IQR 7.6-30.4) in 2008, coinciding with a decline in the prevalence of Pfcrt 76T allele over time (P = 0.0357). The proportions of piperaquine-resistant markers including Pfpm2/3 and Pfmdr1 did not vary significantly. A significant association was observed between PPQ IC50 and Pfcrt K76T allele (P=0.0026). CONCLUSIONS: Circulating Kenyan parasites have remained sensitive to PPQ and other antimalarials, though the response to artemether (ART) and lumefantrine (LM) is declining. This study forms a baseline for continued surveillance of current antimalarials for timely detection of resistance.


Asunto(s)
Antimaláricos , Artemisininas , Parásitos , Animales , Antimaláricos/farmacología , Antimaláricos/uso terapéutico , Plasmodium falciparum/genética , Kenia/epidemiología , Proteínas Protozoarias/genética , Combinación Arteméter y Lumefantrina , Arteméter , Cloroquina/farmacología , Cloroquina/uso terapéutico , Lumefantrina , Genómica
4.
Plants (Basel) ; 11(1)2021 Dec 24.
Artículo en Inglés | MEDLINE | ID: mdl-35009051

RESUMEN

Malaria is the most lethal parasitic disease in the world. The frequent emergence of resistance by malaria parasites to any drug is the hallmark of sustained malaria burden. Since the deployment of artemisinin-based combination therapies (ACTs) it is clear that for a sustained fight against malaria, drug combination is one of the strategies toward malaria elimination. In Sub-Saharan Africa where malaria prevalence is the highest, the identification of plants with a novel mechanism of action that is devoid of cross-resistance is a feasible strategy in drug combination therapy. Thus, artemether and lumefantrine were separately combined and tested with extracts of Securidaca longipedunculata, a plant widely used to treat malaria, at fixed extract-drug ratios of 4:1, 3:1, 1:1, 1:2, 1:3, and 1:4. These combinations were tested for antiplasmodial activity against three strains of Plasmodium falciparum (W2, D6, and DD2), and seven field isolates that were characterized for molecular and ex vivo drug resistance profiles. The mean sum of fifty-percent fractional inhibition concentration (FIC50) of each combination and singly was determined. Synergism was observed across all fixed doses when roots extracts were combined with artemether against D6 strain (FIC50 0.403 ± 0.068) and stems extract combined with lumefantrine against DD2 strain (FIC50 0.376 ± 0.096) as well as field isolates (FIC50 0.656 ± 0.067). Similarly, synergism was observed in all ratios when leaves extract were combined with lumefantrine against W2 strain (FIC50 0.456 ± 0.165). Synergism was observed in most combinations indicating the potential use of S. longipedunculata in combination with artemether and lumefantrine in combating resistance.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...