RESUMEN
Plasmodium parasites, the causal agents of malaria, are eukaryotic organisms that obligately undergo sexual recombination within mosquitoes. However, in low transmission settings where most mosquitoes become infected with only a single parasite clone, parasites recombine with themselves, and the clonal lineage is propagated rather than broken up by outcrossing. We investigated whether stochastic/neutral factors drive the persistence and abundance of Plasmodium falciparum clonal lineages in Guyana, a country with relatively low malaria transmission, but the only setting in the Americas in which an important artemisinin resistance mutation (pfk13 C580Y) has been observed. To investigate whether this clonality was potentially associated with the persistence and spatial spread of the mutation, we performed whole genome sequencing on 1,727 Plasmodium falciparum samples collected from infected patients across a five-year period (2016-2021). We characterized the relatedness between each pair of monoclonal infections (n=1,409) through estimation of identity by descent (IBD) and also typed each sample for known or candidate drug resistance mutations. A total of 160 clones (mean IBD ≥ 0.90) were circulating in Guyana during the study period, comprising 13 highly related clusters (mean IBD ≥ 0.40). In the five-year study period, we observed a decrease in frequency of a mutation associated with artemisinin partner drug (piperaquine) resistance (pfcrt C350R) and limited co-occurence of pfcrt C350R with duplications of plasmepsin 2/3, an epistatic interaction associated with piperaquine resistance. We additionally report polymorphisms exhibiting evidence of selection for drug resistance or other phenotypes and reported a novel pfk13 mutation (G718S) as well as 61 nonsynonymous substitutions that increased markedly in frequency. However, P. falciparum clonal dynamics in Guyana appear to be largely driven by stochastic factors, in contrast to other geographic regions. The use of multiple artemisinin combination therapies in Guyana may have contributed to the disappearance of the pfk13 C580Y mutation.
RESUMEN
Antimalarial drug resistance has historically arisen through convergent de novo mutations in Plasmodium falciparum parasite populations in Southeast Asia and South America. For the past decade in Southeast Asia, artemisinins, the core component of first-line antimalarial therapies, have experienced delayed parasite clearance associated with several pfk13 mutations, primarily C580Y. We report that mutant pfk13 has emerged independently in Guyana, with genome analysis indicating an evolutionary origin distinct from Southeast Asia. Pfk13 C580Y parasites were observed in 1.6% (14/854) of samples collected in Guyana in 2016-2017. Introducing pfk13 C580Y or R539T mutations by gene editing into local parasites conferred high levels of in vitro artemisinin resistance. In vitro growth competition assays revealed a fitness cost associated with these pfk13 variants, potentially explaining why these resistance alleles have not increased in frequency more quickly in South America. These data place local malaria control efforts at risk in the Guiana Shield.
All recommended treatments against malaria include a drug called artemisinin or some of its derivatives. However, there are concerns that Plasmodium falciparum, the parasite that causes most cases of malaria, will eventually develop widespread resistance to the drug. A strain of P. falciparum partially resistant to artemisinin was seen in Cambodia in 2008, and it has since spread across Southeast Asia. The resistance appears to be frequently linked to a mutation known as pfk13 C580Y. Southeast Asia and Amazonia are considered to be hotspots for antimalarial drug resistance, and the pfk13 C580Y mutation was detected in the South American country of Guyana in 2010. To examine whether the mutation was still circulating in this part of the world, Mathieu et al. collected and analyzed 854 samples across Guyana between 2016 and 2017. Overall, 1.6% of the samples had the pfk13 C580Y mutation, but this number was as high as 8.8% in one region. Further analyses revealed that the mutation in Guyana had not spread from Southeast Asia, but that it had occurred in Amazonia independently. To better understand the impact of the pfk13 C580Y mutation, Mathieu et al. introduced this genetic change into non-resistant parasites from a country neighbouring Guyana. As expected, the mutation made P. falciparum highly resistant to artemisinin, but it also slowed the growth rate of the parasite. This disadvantage may explain why the mutation has not spread more rapidly through Guyana in recent years. Artemisinin and its derivatives are always associated with other antimalarial drugs to slow the development of resistance; there are concerns that reduced susceptibility to artemisinin leads to the parasites becoming resistant to the partner drugs. Further research is needed to evaluate how the pfk13 C580Y mutation affects the parasite's response to the typical combination of drugs that are given to patients.
Asunto(s)
Antimaláricos/farmacología , Artemisininas/farmacología , Malaria Falciparum/parasitología , Plasmodium falciparum/genética , Proteínas Protozoarias/genética , Antimaláricos/uso terapéutico , Artemisininas/uso terapéutico , Resistencia a Medicamentos/genética , Genes Protozoarios , Aptitud Genética , Guyana/epidemiología , Haplotipos , Humanos , Malaria Falciparum/tratamiento farmacológico , Malaria Falciparum/epidemiología , Mutación , Plasmodium falciparum/efectos de los fármacos , Plasmodium falciparum/crecimiento & desarrollo , Secuenciación Completa del GenomaRESUMEN
Malaria is a disease of global tropical distribution, being endemic in more than 90 countries and responsible for about 212 million cases worldwide in 2016. To date, the strategies used to eradicate this disease have been ineffective, without specific preventive measures such as vaccines. Currently, the existing therapeutic arsenal is limited and has become ineffective against the expansion of artemisinin-resistant Plasmodium, demonstrating the need for studies that would allow the development of new compounds against this disease. In this context, we studied the volatile oil obtained from rhizomes of Cyperus articulatus (VOCA), a plant species commonly found in the Amazon region and popularly used as a therapeutic alternative for the treatment of malaria, in order to confirm its potential as an antimalarial agent by in vitro and in vivo assays. We cultured Plasmodium falciparum W2 (chloroquine-resistant) and 3D7 (chloroquine-sensitive) strains in erythrocytes and exposed them to VOCA at different concentrations in 96-well microplates. In vivo antimalarial activity was tested in BALB/c mice inoculated with approximately 106 erythrocytes infected with Plasmodium berghei. VOCA showed a high antimalarial potential against the two P. falciparum strains, with IC50 = 1.21 μg mL-1 for W2 and 2.30 μg mL-1 for 3D7. VOCA also significantly reduced the parasitemia and anemia induced by P. berghei in mice. Our results confirmed the antimalarial potential of the volatile oil of Cyperus articulatus.(AU)
A malária é uma doença de distribuição tropical, sendo endêmica em mais de 90 países, responsável por cerca de 212 milhões de casos reportados ao redor do mundo em 2016. As estratégias de erradicação dessa doença são ineficazes até o presente, sem medidas de prevenção específica, como vacinas. Atualmente, o arsenal terapêutico existente é limitado e vem se tornando ineficaz frente à expansão de plasmódios resistentes a artemisinina, evidenciando a necessidade de estudos que viabilizem o desenvolvimento de novos compostos contra a doença. Nesse contexto, estudamos o óleo essencial obtido de rizomas de Cyperus articulatus (VOCA), uma espécie vegetal comumente encontrada na região amazônica, utilizada popularmente como alternativa terapêutica para o tratamento de malária. Visamos confirmar o potencial antimalárico da planta através de testes in vitro e in vivo. Utilizamos cepas de Plasmodium falciparum W2 (cloroquina-resistente) e 3D7 (cloroquina-sensível) cultivadas em hemácias e expostas ao VOCA em microplacas de 96 poços. A atividade antimalárica in vivo foi testada em camundongos da linhagem BALB/c infectados com aproximadamente 106 eritrócitos parasitados por Plasmodium berghei. O VOCA apresentou alto potencial antimalárico (IC50 < 10 µg ml-1) frente às duas cepas de P. falciparum testadas (IC50=1,21 µg ml-1 para W2 e 2,3 µg ml-1 para 3D7). Além disso, houve redução significativa da parasitemia induzida por P. Berghei em camundongos tratados com EOAC, e também observamos diminuição da anemia, uma sintomatologia provocada pela infecção. Nossos resultados confirmam o potencial antimalárico do óleo essencial de Cyperus articulatus.(AU)
Asunto(s)
Plasmodium falciparum , Malaria Falciparum/prevención & control , Plasmodium berghei , Artemisininas/antagonistas & inhibidores , Cloroquina/antagonistas & inhibidores , Cyperaceae/química , Plantas Medicinales , Extractos VegetalesRESUMEN
Malaria is a disease of global tropical distribution, being endemic in more than 90 countries and responsible for about 212 million cases worldwide in 2016. To date, the strategies used to eradicate this disease have been ineffective, without specific preventive measures such as vaccines. Currently, the existing therapeutic arsenal is limited and has become ineffective against the expansion of artemisinin-resistant Plasmodium, demonstrating the need for studies that would allow the development of new compounds against this disease. In this context, we studied the volatile oil obtained from rhizomes of Cyperus articulatus (VOCA), a plant species commonly found in the Amazon region and popularly used as a therapeutic alternative for the treatment of malaria, in order to confirm its potential as an antimalarial agent by in vitro and in vivo assays. We cultured Plasmodium falciparum W2 (chloroquine-resistant) and 3D7 (chloroquine-sensitive) strains in erythrocytes and exposed them to VOCA at different concentrations in 96-well microplates. In vivo antimalarial activity was tested in BALB/c mice inoculated with approximately 106 erythrocytes infected with Plasmodium berghei. VOCA showed a high antimalarial potential against the two P. falciparum strains, with IC50 = 1.21 µg mL-1 for W2 and 2.30 µg mL-1 for 3D7. VOCA also significantly reduced the parasitemia and anemia induced by P. berghei in mice. Our results confirmed the antimalarial potential of the volatile oil of Cyperus articulatus. (AU)
Asunto(s)
Plasmodium berghei , Plasmodium falciparum , Cloroquina , Artemisininas , MalariaRESUMEN
Abstract INTRODUCTION Mutations in the propeller domain of the Plasmodium falciparum kelch13 (k13) gene are associated with artemisinin resistance. METHODS: We developed a PCR protocol to sequence the pfk13 gene and determined its sequence in a batch of 50 samples collected from 2003 to 2016 in Brazil. RESULTS: We identified 1 K189T substitution located outside the propeller domain of the PfK13 protein in 36% of samples. CONCLUSIONS: Although the sample size is relatively small, these results suggest that P. falciparum artemisinin-resistant mutants do not exist in Brazil, thereby supporting the continuation of current treatment programs based on artemisinin-based combination therapy.
Asunto(s)
Humanos , Plasmodium falciparum/genética , Resistencia a Medicamentos/genética , Proteínas Protozoarias/genética , Malaria Falciparum/parasitología , Artemisininas/farmacología , Mutación/genética , Fenotipo , Plasmodium falciparum/efectos de los fármacos , GenotipoRESUMEN
We obtained 78 human blood samples from areas in Haiti with high transmission of malaria and found no drug resistance-associated mutations in Plasmodium falciparum chloroquine resistance transporter and Kelch 13 genes. We recommend maintaining chloroquine as the first-line drug for malaria in Haiti. Artemisinin-based therapy can be used as alternative therapy.
Asunto(s)
Antimaláricos/uso terapéutico , Artemisininas/uso terapéutico , Cloroquina/uso terapéutico , Malaria Falciparum/parasitología , Proteínas de Transporte de Membrana/genética , Plasmodium falciparum/genética , Proteínas Protozoarias/genética , Adolescente , Adulto , Anciano , Niño , Preescolar , Resistencia a Medicamentos/genética , Haití/epidemiología , Humanos , Lactante , Malaria Falciparum/tratamiento farmacológico , Malaria Falciparum/epidemiología , Persona de Mediana Edad , Mutación , Plasmodium falciparum/efectos de los fármacos , Plasmodium falciparum/aislamiento & purificación , Encuestas y Cuestionarios , Adulto JovenRESUMEN
To assess the prevalence of malaria among illegal gold miners in the French Guiana rainforest, we screened 205 miners during May-June 2014. Malaria prevalence was 48.3%; 48.5% of cases were asymptomatic. Patients reported self-medication with artemisinin-based combination therapy. Risk for emergence and spread of artemisinin resistance among gold miners in the rainforest is high.
Asunto(s)
Antimaláricos/farmacología , Artemisininas/farmacología , Resistencia a Medicamentos , Oro , Malaria/epidemiología , Malaria/parasitología , Mineros , Adulto , Antimaláricos/uso terapéutico , Artemisininas/uso terapéutico , Femenino , Guyana Francesa/epidemiología , Geografía , Humanos , Malaria/tratamiento farmacológico , Malaria Falciparum/tratamiento farmacológico , Malaria Falciparum/epidemiología , Malaria Falciparum/parasitología , Masculino , Persona de Mediana Edad , Plasmodium falciparum/efectos de los fármacos , Plasmodium falciparum/genética , Prevalencia , Riesgo , Adulto JovenRESUMEN
Suspected artemisinin resistance in Plasmodium falciparum can be explored by examining polymorphisms in the Kelch (PfK13) propeller domain. Sequencing of PfK13 and other gene resistance markers was performed on 98 samples from Guyana. Five of these samples carried the C580Y allele in the PfK13 propeller domain, with flanking microsatellite profiles different from those observed in Southeast Asia. These molecular data demonstrate independent emergence of the C580Y K13 mutant allele in Guyana, where resistance alleles to previously used drugs are fixed. Therefore, in Guyana and neighboring countries, continued molecular surveillance and periodic assessment of the therapeutic efficacy of artemisinin-based combination therapy are warranted.
Asunto(s)
Resistencia a Medicamentos/genética , Malaria Falciparum/parasitología , Plasmodium falciparum/efectos de los fármacos , Plasmodium falciparum/genética , Antimaláricos/farmacología , Artemisininas/farmacología , ADN Protozoario/análisis , ADN Protozoario/genética , Quimioterapia Combinada , Guyana/epidemiología , Humanos , Malaria Falciparum/epidemiología , Tipificación Molecular , Mutación/genéticaRESUMEN
The emerging resistance to artemisinin derivatives that has been reported in South-East Asia led us to assess the efficacy of artemether-lumefantrine as the first line therapy for uncomplicated Plasmodium falciparum infections in Suriname. This drug assessment was performed according to the recommendations of the World Health Organization in 2011. The decreasing number of malaria cases in Suriname, which are currently limited to migrating populations and gold miners, precludes any conclusions on artemether efficacy because adequate numbers of patients with 28-day follow-up data are difficult to obtain. Therefore, a comparison of day 3 parasitaemia in a 2011 study and in a 2005/2006 study was used to detect the emergence of resistance to artemether. The prevalence of day 3 parasitaemia was assessed in a study in 2011 and was compared to that in a study in 2005/2006. The same protocol was used in both studies and artemether-lumefantrine was the study drug. Of 48 evaluable patients in 2011, 15 (31%) still had parasitaemia on day 3 compared to one (2%) out of 45 evaluable patients in 2005/2006. Overall, 11 evaluable patients in the 2011 study who were followed up until day 28 had negative slides and similar findings were obtained in all 38 evaluable patients in the 2005/2006 study. The significantly increased incidence of parasite persistence on day 3 may be an indication of emerging resistance to artemether.