RESUMEN
BACKGROUND: The spread of antimalarial drug resistance parasites is a major obstacle in eliminating malaria in endemic areas. This increases the urgency for developing novel antimalarial drugs with improved profiles to eliminate both sensitive and resistant parasites in populations. The invention of the drug candidates needs a model for sensitive and resistant parasites on a laboratory scale. METHODS: Repeated Incomplete Treatment (RIcT) method was followed in raising the rodent malaria parasite, Plasmodium berghei, resistant to sulfadoxine. Plasmodium berghei were exposed to an adequate therapeutic dose of sulfadoxine without finishing the treatment to let the parasite recover. Cycles of drug treatment and parasite recovery were repeated until phenotypic resistance appeared. RESULTS: After undergoing 3-4 cycles, phenotypic resistance was not yet found in mice treated with sulfadoxine. Nevertheless, the molecular biology of dhps gene (the target of sulfadoxine) was analyzed at the end of the RIcT cycle. There was no mutations found in the gene target. Interestingly, the appearance of gametocytes at the end of every cycle of drug treatment and parasite recovery was observed. These gametocytes later on would no longer extend their life in the RBC stage, unless mosquitoes bite the infected host. This phenomenon is similar to the case in human malaria infections treated with sulfadoxine-pyrimethamine (SP). CONCLUSIONS: In this study, the antimalarial drug sulfadoxine induced gametocytogenesis in P. berghei, which could raise the risk factor for malaria transmission.
Asunto(s)
Antimaláricos , Plasmodium berghei , Sulfadoxina , Plasmodium berghei/efectos de los fármacos , Antimaláricos/farmacología , Antimaláricos/uso terapéutico , Animales , Sulfadoxina/farmacología , Sulfadoxina/uso terapéutico , Ratones , Resistencia a Medicamentos/genética , Gametogénesis/efectos de los fármacos , Femenino , Malaria/tratamiento farmacológico , Malaria/parasitologíaRESUMEN
Despite the overall decline in malaria cases in Thailand, continuous surveillance in endemic areas remains crucial. This retrospective analysis examined Plasmodium falciparum samples from Tak province, Thailand, collected in 1998, 1999, and 2001, to investigate the prevalence and evolution of antimalarial genotypic drug resistance. The study revealed a high prevalence of drug-resistant P. falciparum, particularly to mefloquine and sulfadoxine/pyrimethamine, with significant mutations in genes associated with resistance. Notably, mutations indicative of artemisinin resistance, such as those in the kelch13 gene, were detected at low frequencies, suggesting an evolving resistance pattern. The underlying cause of these resistance mutations appears to be the historical and widespread use of these antimalarial drugs, which exerted selective pressure on the parasite population. These findings underscore the necessity of ongoing surveillance and adaptive control strategies to manage drug resistance, guide treatment policies, and prevent potential outbreaks, even as malaria cases decrease. Continuous monitoring and research are imperative to sustain malaria elimination efforts and address the dynamic challenges posed by evolving drug-resistant strains.
Asunto(s)
Antimaláricos , Resistencia a Medicamentos , Malaria Falciparum , Mutación , Plasmodium falciparum , Plasmodium falciparum/efectos de los fármacos , Plasmodium falciparum/genética , Antimaláricos/farmacología , Antimaláricos/uso terapéutico , Tailandia/epidemiología , Resistencia a Medicamentos/genética , Malaria Falciparum/parasitología , Malaria Falciparum/epidemiología , Malaria Falciparum/tratamiento farmacológico , Humanos , Estudios Retrospectivos , Prevalencia , Mefloquina/farmacología , Mefloquina/uso terapéutico , Animales , Artemisininas/farmacología , Artemisininas/uso terapéutico , Pirimetamina/farmacología , Pirimetamina/uso terapéutico , Sulfadoxina/farmacología , Sulfadoxina/uso terapéutico , Combinación de MedicamentosRESUMEN
The emergence of drug-resistant Plasmodium falciparum parasites in sub-Saharan Africa will substantially challenge malaria control. Here, we evaluated the frequency of common drug resistance markers among adolescents from Northern Uganda with asymptomatic infections. We used an established amplicon deep sequencing strategy to screen dried blood spot samples collected from 2016 to 2017 during a reported malaria epidemic within the districts of Kitgum and Pader in Northern Uganda. We screened single-nucleotide polymorphisms within: kelch13 (Pfk13), dihydropteroate synthase (Pfdhps), multidrug resistance-1 (Pfmdr1), dihydrofolate reductase (Pfdhfr), and apical membrane antigen (Pfama1) genes. Within the study population, the median age was 15 years (14.3-15.0, 95% CI), and 54.9% (78/142) were Plasmodium positive by 18S rRNA qPCR, which were subsequently targeted for sequencing analysis. We observed a high frequency of resistance markers particularly for sulfadoxine-pyrimethamine (SP), with no wild-type-only parasites observed for Pfdhfr (N51I, C59R, and S108N) and Pfdhps (A437G and K540E) mutations. Within Pfmdr1, mixed infections were common for NF/NY (98.5%). While for artemisinin resistance, in kelch13, there was a high frequency of C469Y (34%). Using the pattern for Pfama1, we found a high level of polygenomic infections with all individuals presenting with complexity of infection greater than 2 with a median of 6.9. The high frequency of the quintuple SP drug-resistant parasites and the C469Y artemisinin resistance-associated mutation in asymptomatic individuals suggests an earlier high prevalence than previously reported from symptomatic malaria surveillance studies (in 2016/2017). Our data demonstrate the urgency for routine genomic surveillance programs throughout Africa and the value of deep sequencing.
Asunto(s)
Antimaláricos , Infecciones Asintomáticas , Resistencia a Medicamentos , Malaria Falciparum , Plasmodium falciparum , Pirimetamina , Sulfadoxina , Plasmodium falciparum/genética , Plasmodium falciparum/efectos de los fármacos , Humanos , Uganda/epidemiología , Adolescente , Antimaláricos/farmacología , Antimaláricos/uso terapéutico , Malaria Falciparum/epidemiología , Malaria Falciparum/parasitología , Malaria Falciparum/tratamiento farmacológico , Pirimetamina/farmacología , Pirimetamina/uso terapéutico , Estudios Retrospectivos , Sulfadoxina/farmacología , Sulfadoxina/uso terapéutico , Resistencia a Medicamentos/genética , Femenino , Infecciones Asintomáticas/epidemiología , Masculino , Mutación , Proteínas Protozoarias/genética , Combinación de Medicamentos , Polimorfismo de Nucleótido Simple/genética , Prevalencia , Artemisininas/farmacología , Artemisininas/uso terapéutico , Tetrahidrofolato Deshidrogenasa/genéticaRESUMEN
BACKGROUND: Currently, there is no antiviral licensed to treat chikungunya fever, a disease caused by the infection with Alphavirus chikungunya (CHIKV). Treatment is based on analgesic and anti-inflammatory drugs to relieve symptoms. Our study aimed to evaluate the antiviral activity of sulfadoxine (SFX), an FDA-approved drug, and its derivatives complexed with silver(I) (AgSFX), salicylaldehyde Schiff base (SFX-SL), and with both Ag and SL (AgSFX-SL) against CHIKV. METHODS: The anti-CHIKV activity of SFX and its derivatives was investigated using BHK-21 cells infected with CHIKV-nanoluc, a marker virus-carrying nanoluciferase reporter. Dose-response and time of drug-addition assays were performed in order to assess the antiviral effects of the compounds, as well as in silico data and ATR-FTIR analysis for insights on their mechanisms of action. RESULTS: The SFX inhibited 34% of CHIKV replication, while AgSFX, SFX-SL, and AgSFX-SL enhanced anti-CHIKV activity to 84%, 89%, and 95%, respectively. AgSFX, SFX-SL, and AgSFX-SL significantly decreased viral entry and post-entry to host cells, and the latter also protected cells against infection. Additionally, molecular docking calculations and ATR-FTIR analysis demonstrated interactions of SFX-SL, AgSFX, and AgSFX-SL with CHIKV. CONCLUSIONS: Collectively, our findings suggest that the addition of metal ions and/or Schiff base to SFX improved its antiviral activity against CHIKV.
Asunto(s)
Antivirales , Fiebre Chikungunya , Virus Chikungunya , Sulfadoxina , Virus Chikungunya/efectos de los fármacos , Antivirales/farmacología , Antivirales/química , Animales , Línea Celular , Sulfadoxina/farmacología , Fiebre Chikungunya/tratamiento farmacológico , Fiebre Chikungunya/virología , Cricetinae , Bases de Schiff/farmacología , Plata/farmacología , Plata/química , Replicación Viral/efectos de los fármacos , Simulación del Acoplamiento Molecular , Relación Dosis-Respuesta a Droga , Humanos , AldehídosRESUMEN
BACKGROUND: Seasonal malaria chemoprevention (SMC) with sulfadoxine-pyrimethamine plus amodiaquine prevents millions of clinical malaria cases in children younger than 5 years in Africa's Sahel region. However, Plasmodium falciparum parasites partially resistant to sulfadoxine-pyrimethamine (with quintuple mutations) potentially threaten the protective effectiveness of SMC. We evaluated the spread of quintuple-mutant parasites and the clinical consequences. METHODS: We used an individual-based malaria transmission model with explicit parasite dynamics and drug pharmacological models to identify and quantify the influence of factors driving quintuple-mutant spread and predict the time needed for the mutant to spread from 1% to 50% of inoculations for several SMC deployment strategies. We estimated the impact of this spread on SMC effectiveness against clinical malaria. FINDINGS: Higher transmission intensity, SMC coverage, and expanded age range of chemoprevention promoted mutant spread. When SMC was implemented in a high-transmission setting (40% parasite prevalence in children aged 2-10 years) with four monthly cycles to children aged 3 months to 5 years (with 95% initial coverage declining each cycle), the quintuple mutant required 53·1 years (95% CI 50·5-56·0) to spread from 1% to 50% of inoculations. This time increased in lower-transmission settings and reduced by half when SMC was extended to children aged 3 months to 10 years, or reduced by 10-13 years when an additional monthly cycle of SMC was deployed. For the same setting, the effective reduction in clinical cases in children receiving SMC was 79·0% (95% CI 77·8-80·8) and 60·4% (58·6-62·3) during the months of SMC implementation when the quintuple mutant was absent or fixed in the population, respectively. INTERPRETATION: SMC with sulfadoxine-pyrimethamine plus amodiaquine leads to a relatively slow spread of sulfadoxine-pyrimethamine-resistant quintuple mutants and remains effective at preventing clinical malaria despite the mutant spread. SMC with sulfadoxine-pyrimethamine plus amodiaquine should be considered in seasonal settings where this mutant is already prevalent. FUNDING: Swiss National Science Foundation and Marie Curie Individual Fellowship.
Asunto(s)
Amodiaquina , Antimaláricos , Quimioprevención , Combinación de Medicamentos , Resistencia a Medicamentos , Malaria Falciparum , Plasmodium falciparum , Pirimetamina , Estaciones del Año , Sulfadoxina , Sulfadoxina/uso terapéutico , Sulfadoxina/farmacología , Pirimetamina/farmacología , Pirimetamina/uso terapéutico , Antimaláricos/farmacología , Antimaláricos/uso terapéutico , Humanos , Plasmodium falciparum/efectos de los fármacos , Plasmodium falciparum/genética , Preescolar , Malaria Falciparum/prevención & control , Malaria Falciparum/epidemiología , Malaria Falciparum/transmisión , Malaria Falciparum/parasitología , Resistencia a Medicamentos/genética , Niño , Lactante , Amodiaquina/uso terapéutico , Amodiaquina/farmacología , Mutación , FemeninoRESUMEN
BACKGROUND: Plasmodium vivax has become the predominant species in the border regions of Thailand. The emergence and spread of antimalarial drug resistance in P. vivax is one of the significant challenges for malaria control. Continuous surveillance of drug resistance is therefore necessary for monitoring the development of drug resistance in the region. This study aims to investigate the prevalence of the mutation in the P. vivax multidrug resistant 1 (Pvmdr1), dihydrofolate reductase (Pvdhfr), and dihydropteroate synthetase (Pvdhps) genes conferred resistance to chloroquine (CQ), pyrimethamine (P) and sulfadoxine (S), respectively. METHOD: 100 P. vivax isolates were obtained between January to May 2023 from a Kanchanaburi province, western Thailand. Nucleotide sequences of Pvmdr1, Pvdhfr, and Pvdhps genes were amplified and sequenced. The frequency of single nucleotide polymorphisms (SNPs)-haplotypes of drug-resistant alleles was assessed. The linkage disequilibrium (LD) tests were also analyzed. RESULTS: In Pvmdr1, T958M, Y976F, and F1076L, mutations were detected in 100%, 21%, and 23% of the isolates, respectively. In Pvdhfr, the quadruple mutant allele (I57R58M61T117) prevailed in 84% of the samples, followed by (L57R58M61T117) in 11%. For Pvdhps, the double mutant allele (G383G553) was detected (48%), followed by the triple mutant allele (G383M512G553) (47%) of the isolates. The most prevalent combination of Pvdhfr (I57R58M61T117) and Pvdhps (G383G553) alleles was sextuple mutated haplotypes (48%). For LD analysis, the association in the SNPs pairs was found between the intragenic and intergenic regions of the Pvdhfr and Pvdhps genes. CONCLUSION: The study has recently updated the high prevalence of three gene mutations associated with CQ and SP resistance. Genetic monitoring is therefore important to intensify in the regions to further assess the spread of drug resistant. Our data also provide evidence on the distribution of drug resistance for the early warning system, thereby threatening P. vivax malaria treatment policy decisions at the national level.
Asunto(s)
Antimaláricos , Resistencia a Medicamentos , Malaria Vivax , Plasmodium vivax , Polimorfismo de Nucleótido Simple , Plasmodium vivax/genética , Plasmodium vivax/efectos de los fármacos , Plasmodium vivax/aislamiento & purificación , Tailandia/epidemiología , Resistencia a Medicamentos/genética , Humanos , Antimaláricos/farmacología , Malaria Vivax/parasitología , Malaria Vivax/epidemiología , Malaria Vivax/tratamiento farmacológico , Tetrahidrofolato Deshidrogenasa/genética , Desequilibrio de Ligamiento , Mutación , Proteínas Protozoarias/genética , Cloroquina/farmacología , Dihidropteroato Sintasa/genética , Sulfadoxina/farmacología , Pirimetamina/farmacología , Proteínas Asociadas a Resistencia a Múltiples Medicamentos/genética , Haplotipos , Masculino , Femenino , AdultoRESUMEN
BACKGROUND: Sulfadoxine-pyrimethamine (SP), as a partner to artesunate as ACT is the treatment of choice for uncomplicated P. falciparum infections in the majority of India and SP-resistance has a potential to lead to ACT failure. In the lack of robust surveillance of therapeutic efficacy of SP, validate molecular markers of SP-resistance offer a hint of failing SP. However, studies reporting these validated markers often suffer from certain pitfalls that warrant a careful interpretation. MAIN BODY: Critical analyses of the results and their reported interpretations from a recent study and other studies conducted on the WHO-validated molecular markers of SP-resistance in India were analysed and the main problems with studying and reporting of these markers are presented here. It was noted that almost all studies analysed flawed either on the usage, estimation and/or interpretation of the standardized classification of the studies SP mutations. These flaws not only impart spatiotemporal incomparability of the published data but also have the potential of being misunderstood and wrongly translated. CONCLUSION: Based on this universal problem in studying, reporting and interpreting the data from the studies on molecular markers of SP-resistance, it is stressed that the future studies should be conducted with utmost caution so that robust evidence may be generated and correctly translated to policy.
Asunto(s)
Antimaláricos , Combinación de Medicamentos , Resistencia a Medicamentos , Malaria Falciparum , Plasmodium falciparum , Pirimetamina , Sulfadoxina , Sulfadoxina/farmacología , Sulfadoxina/uso terapéutico , Pirimetamina/farmacología , Pirimetamina/uso terapéutico , India , Resistencia a Medicamentos/genética , Antimaláricos/farmacología , Antimaláricos/uso terapéutico , Plasmodium falciparum/efectos de los fármacos , Plasmodium falciparum/genética , Humanos , Malaria Falciparum/tratamiento farmacológicoRESUMEN
Increasing sulfadoxine-pyrimethamine (SP) resistance in the Democratic Republic of the Congo (DRC) has threatened its use for prevention of malaria in one of the most malarious countries in the world. Using geographic information on mining operations in the DRC and genetic data on SP drug resistance markers from the 2013-2014 Demographic and Health Surveys, we evaluated associations between close residence to mining and the presence of mutations conferring resistance to sulfadoxine. Close residential proximity to mining was associated with increased prevalence odds ratio (POR) of the dhps540E mutation (POR: 2.11, 95% uncertainty interval: 1.15-3.96) with adjustments for confounding variables and space. Our findings indicate that exposure to mining is associated with increased presence of an antimalarial drug resistance haplotype that threatens effective use of SP for vulnerable populations. Areas actively engaged in mining could be considered for interventions to reduce the spread of emerging drug resistance in the DRC.
Asunto(s)
Antimaláricos , Resistencia a Medicamentos , Minería , Mutación , Pirimetamina , Sulfadoxina , República Democrática del Congo/epidemiología , Humanos , Antimaláricos/uso terapéutico , Antimaláricos/farmacología , Resistencia a Medicamentos/genética , Pirimetamina/farmacología , Pirimetamina/uso terapéutico , Sulfadoxina/uso terapéutico , Sulfadoxina/farmacología , Prevalencia , Plasmodium falciparum/genética , Plasmodium falciparum/efectos de los fármacos , Dihidropteroato Sintasa/genética , Combinación de Medicamentos , Malaria Falciparum/epidemiología , Malaria Falciparum/parasitología , FemeninoRESUMEN
Increasing antimicrobial resistance (AMR) is a global public health emergency. Although chemoprevention has improved malaria-related pregnancy outcomes, the downstream effects on AMR have not been characterized. We compared the abundance of 10 AMR genes in stool samples from pregnant women receiving sulfadoxine-pyrimethamine (SP) as intermittent preventive treatment against malaria in pregnancy (IPTp) to that in samples from women receiving dihydroartemisinin-piperaquine (DP) for IPTp. All participants had at least one AMR gene at baseline. Mean quantities of the antifolate gene dfrA17 were increased after two or more doses of SP (mean difference = 1.6, 95% CI: 0.4-2.7, P = 0.008). Antimicrobial resistance gene abundance tended to increase from baseline in SP recipients compared with a downward trend in the DP group. Overall, IPTp-SP had minimal effects on the abundance of antifolate resistance genes (except for dfrA17), potentially owing to a high starting prevalence. However, the trend toward increasing AMR in SP recipients warrants further studies.
Asunto(s)
Antimaláricos , Artemisininas , Combinación de Medicamentos , Heces , Pirimetamina , Quinolinas , Sulfadoxina , Humanos , Femenino , Pirimetamina/uso terapéutico , Pirimetamina/administración & dosificación , Pirimetamina/farmacología , Sulfadoxina/uso terapéutico , Sulfadoxina/administración & dosificación , Sulfadoxina/farmacología , Embarazo , Antimaláricos/uso terapéutico , Antimaláricos/farmacología , Antimaláricos/administración & dosificación , Quinolinas/uso terapéutico , Quinolinas/administración & dosificación , Artemisininas/uso terapéutico , Artemisininas/farmacología , Artemisininas/administración & dosificación , Adulto , Heces/microbiología , Adulto Joven , Complicaciones Parasitarias del Embarazo/prevención & control , Complicaciones Parasitarias del Embarazo/tratamiento farmacológico , Resistencia a Medicamentos/genética , Malaria Falciparum/prevención & control , Malaria Falciparum/epidemiología , Plasmodium falciparum/efectos de los fármacos , Plasmodium falciparum/genética , PiperazinasRESUMEN
One of the major challenges for malaria control and elimination is the spread and emergence of antimalarial drug resistance. Mutations in Plasmodium falciparum (Pf) and Plasmodium vivax (Pv) field isolates for five drug resistance genes viz. crt, mdr1, dhps, dhfr and kelch known to confer resistance to choloroquine (CQ), sulfadoxine-pyrimethamine (SP) and artemisinin (ART) and its derivatives were analyzed. A total of 342 symptomatic isolates of P. falciparum (Pf) and P. vivax (Pv) from 1993 to 2014 were retrieved from malaria parasite repository at National Institute of Malaria Research (NIMR). Sample DNA was extracted from dried blood spots and various targeted single nucleotide polymorphisms (SNPs) associated with antimalarial drug resistance were analysed for these isolates. 72S (67.7%) and 76T (83.8%) mutations along with SVMNT haplotype (67.7%) predominated the study population for Pfcrt. The most prevalent SNPs were 108N (73.2%) and 437G (24.8%) and the most prevalent haplotypes were ACNRNI (51.9%) and SAKAA (74.5%) in Pfdhfr and Pfdhps respectively. Only two mutations in Pfmdr1, 86Y (26.31%) and 184F (56.26%), were seen frequently in our study population. No mutations associated with Pfk13 were observed. For Pv, all the studied isolates showed two Pvdhps mutations, 383G and 553G, and two Pfdhfr mutations, 58R and 117N. Similarly, three mutations, viz. 958M, 908L and 1076L were found in Pvmdr1. No variations were observed in Pvcrt-o and Pvk12 genes. Overall, our study demonstrates an increase in mutations associated with SP resistance in both Pf and Pv, however, no single nucleotide polymorphisms (SNPs) associated with ART resistance have been observed for either species. Various SNPs associated with CQ resistance were seen in Pf; whereas only Pvmdr1 associated resistant SNPs were observed in Pv. Therefore, molecular characterization of drug resistance genes is essential for timely monitoring and prevention of malaria by identifying the circulating drug resistant parasites in the country.
Asunto(s)
Antimaláricos , Resistencia a Medicamentos , Malaria Falciparum , Malaria Vivax , Plasmodium falciparum , Plasmodium vivax , Polimorfismo de Nucleótido Simple , Proteínas Protozoarias , Plasmodium falciparum/genética , Plasmodium falciparum/efectos de los fármacos , Plasmodium falciparum/aislamiento & purificación , Resistencia a Medicamentos/genética , Antimaláricos/farmacología , Plasmodium vivax/genética , Plasmodium vivax/efectos de los fármacos , Plasmodium vivax/aislamiento & purificación , Humanos , Malaria Falciparum/parasitología , Malaria Falciparum/epidemiología , Proteínas Protozoarias/genética , Malaria Vivax/parasitología , India , Pirimetamina/farmacología , Mutación , Tetrahidrofolato Deshidrogenasa/genética , ADN Protozoario/genética , Sulfadoxina/farmacología , Artemisininas/farmacología , Masculino , Combinación de MedicamentosRESUMEN
Surveillance for genetic markers of resistance can provide valuable information on the likely efficacy of antimalarials but needs to be targeted to ensure optimal use of resources. We conducted a systematic search and review of publications in seven databases to compile resistance marker data from studies in India. The sample collection from the studies identified from this search was conducted between 1994 and 2020, and these studies were published between 1994 and 2022. In all, Plasmodium falciparum Kelch13 (PfK13), P. falciparum dihydropteroate synthase, and P. falciparum dihydrofolate reductase (PfDHPS) genotype data from 2,953, 4,148, and 4,222 blood samples from patients with laboratory-confirmed malaria, respectively, were extracted from these publications and uploaded onto the WorldWide Antimalarial Resistance Network molecular surveyors. These data were fed into hierarchical geostatistical models to produce maps with a predicted prevalence of the PfK13 and PfDHPS markers, and of the associated uncertainty. Zones with a predicted PfDHPS 540E prevalence of >15% were identified in central, eastern, and northeastern India. The predicted prevalence of PfK13 mutants was nonzero at only a few locations, but were within or adjacent to the zones with >15% prevalence of PfDHPS 540E. There may be a greater probability of artesunate-sulfadoxine-pyrimethamine failures in these regions, but these predictions need confirmation. This work can be applied in India and elsewhere to help identify the treatments most likely to be effective for malaria elimination.
Asunto(s)
Antimaláricos , Artemisininas , Combinación de Medicamentos , Resistencia a Medicamentos , Malaria Falciparum , Plasmodium falciparum , Pirimetamina , Sulfadoxina , Plasmodium falciparum/genética , Plasmodium falciparum/efectos de los fármacos , Pirimetamina/uso terapéutico , Pirimetamina/farmacología , Sulfadoxina/uso terapéutico , Sulfadoxina/farmacología , India/epidemiología , Resistencia a Medicamentos/genética , Antimaláricos/uso terapéutico , Antimaláricos/farmacología , Humanos , Malaria Falciparum/epidemiología , Malaria Falciparum/tratamiento farmacológico , Malaria Falciparum/parasitología , Artemisininas/uso terapéutico , Artemisininas/farmacología , Tetrahidrofolato Deshidrogenasa/genética , Marcadores Genéticos , Dihidropteroato Sintasa/genética , Proteínas Protozoarias/genéticaRESUMEN
Bacterial infections are rising, and antimicrobial resistance (AMR) in bacteria has worsened the scenario, requiring extensive research to find alternative therapeutic agents. Terpenoids play an essential role in protecting plants from herbivores and pathogens. The present study was designed to focus on in silico evaluation of terpenoids for their affinity towards two necessary enzymes, i.e. DHFR and DHPS, which are involved in forming 5, 6, 7, 8-tetrahydrofolate, a key component in bacterial DNA synthesis proteins. Additionally, to account for activity against resistant bacteria, their affinity towards the L28R mutant of DHFR was also assessed in the study. The structure-based drug design approach was used to screen the compound library of terpenes for their interaction with active sites of DHFR and DHPS. Further, compounds were screened based on their dock score, pharmacokinetic properties, and binding affinities. A total of five compounds for each target protein were screened, having dock scores better than their respective standard drug molecules. CNP0169378 (-8.4 kcal/mol) and CNP0309455 (-6.5 kcal/mol) have been identified as molecules with a higher affinity toward the targets of DHFR and DHPS, respectively. At the same time, one molecule CNP0298407 (-5.8 kcal/mol for DHPS, -7.6 kcal/mol for DHFR, -6.1 kcal/mol for the L28R variant), has affinity for both proteins (6XG5 and 6XG4). All the molecules have good pharmacokinetic properties. We further validated the docking study by binding free energy calculations using the MM/GBSA approach and molecular dynamics simulations.Communicated by Ramaswamy H. Sarma.
Asunto(s)
Antimaláricos , Antagonistas del Ácido Fólico , Antimaláricos/farmacología , Pirimetamina , Antagonistas del Ácido Fólico/farmacología , Sulfadoxina/farmacología , Sulfadoxina/uso terapéutico , Simulación de Dinámica Molecular , Dihidropteroato Sintasa/genética , Terpenos/farmacología , Plasmodium falciparum , Tetrahidrofolato Deshidrogenasa/genéticaRESUMEN
Malaria molecular surveillance remains critical in detecting and tracking emerging parasite resistance to anti-malarial drugs. The current study employed molecular techniques to determine Plasmodium species prevalence and characterize the genetic diversity of Plasmodium falciparum and Plasmodium malariae molecular markers of sulfadoxine-pyrimethamine resistance in humans and wild Anopheles mosquito populations in Cameroon. Anopheles mosquito collections and parasitological survey were conducted in villages to determine Plasmodium species infection, and genomic phenotyping of anti-folate resistance was accomplished by sequencing the dihydrofolate-reductase (dhfr) and dihydropteroate-synthase (dhps) genes of naturally circulating P. falciparum and P. malariae isolates. The malaria prevalence in Elende was 73.5% with the 5-15 years age group harboring significant P. falciparum (27%) and P. falciparum + P. malariae (19%) infections. The polymorphism breadth of the pyrimethamine-associated Pfdhfr marker revealed a near fixation (94%) of the triple-mutant -A16I51R59N108I164. The Pfdhps backbone mediating sulfadoxine resistance reveals a high frequency of the V431A436G437K540A581A613 alleles (20.8%). Similarly, the Pmdhfr N50K55L57R58S59S114F168I170 haplotype (78.4%) was predominantly detected in the asexual blood stage. In contrast, the Pmdhps- S436A437occured at 37.2% frequency. The combined quadruple N50K55L57R58S59S114F168I170_ S436G437K540A581A613 (31.9%) was the major circulating haplotype with similar frequency in humans and mosquitoes. This study highlights the increasing frequency of the P. malariae parasite mostly common in asymptomatic individuals with apparent P. falciparum infection. Interventions directed at reducing malaria transmission such as the scaling-up of SP are favoring the emergence and spread of multiple drug-resistant alleles between the human and mosquito host systems.
Asunto(s)
Anopheles , Antimaláricos , Malaria Falciparum , Malaria , Animales , Humanos , Pirimetamina/farmacología , Pirimetamina/uso terapéutico , Sulfadoxina/farmacología , Sulfadoxina/uso terapéutico , Anopheles/genética , Alelos , Camerún/epidemiología , Antimaláricos/farmacología , Antimaláricos/uso terapéutico , Malaria Falciparum/tratamiento farmacológico , Malaria Falciparum/epidemiología , Malaria Falciparum/genética , Combinación de Medicamentos , Plasmodium falciparum , Malaria/tratamiento farmacológico , Malaria/epidemiología , Malaria/genética , Resistencia a Medicamentos/genética , Tetrahidrofolato Deshidrogenasa/genéticaRESUMEN
Intermittent preventive therapy during pregnancy (IPTp) with sulfadoxine-pyrimethamine (SP) is recommended in areas of moderate to high malaria transmission intensity. As a result of the increasing prevalence of SP resistance markers, IPTp-SP was withdrawn from Rwanda in 2008. Nonetheless, more recent findings suggest that SP may improve birthweight even in the face of parasite resistance, through alternative mechanisms that are independent of antimalarial effects. The prevalence of single nucleotide polymorphisms in Plasmodium falciparum dihydropteroate synthase (pfdhps) and dihydrofolate reductase (pfdhfr) genes associated with SP resistance among 148 pregnant women from 2016 to 2018 within Rwanda's Southern Province (Huye and Kamonyi districts) was measured using a ligase detection reaction-fluorescent microsphere assay. The frequency of pfdhps K540E, A581G, and the quintuple (pfdhfr N51I + C59R + S108N/pfdhps A437G + K540E) and sextuple (pfdhfr N51I + C59R + S108N/pfdhps A437G + K540E + A581G) mutant genotypes was 90%, 38%, 75%, and 28%, respectively. No significant genotype difference was seen between the two districts, which are approximately 50 km apart. Observed agreements for matched peripheral to placental blood were reported and found to be 207 of 208 (99%) for pfdhfr and 239 of 260 (92%) for pfdhps. The peripheral blood sample did not miss any pfdhfr drug-resistant mutants or pfdhps except at the S436 loci. At this level of the sextuple mutant, the antimalarial efficacy of SP for preventing low birthweight is reduced, although overall SP still exerts a nonmalarial benefit during pregnancy. This study further reveals the need to intensify preventive measures to sustain malaria control in Rwanda to keep the overall incidence of malaria during pregnancy low.
Asunto(s)
Antimaláricos , Malaria Falciparum , Malaria , Femenino , Embarazo , Humanos , Antimaláricos/farmacología , Antimaláricos/uso terapéutico , Plasmodium falciparum/genética , Mujeres Embarazadas , Malaria Falciparum/tratamiento farmacológico , Malaria Falciparum/epidemiología , Malaria Falciparum/parasitología , Prevalencia , Rwanda/epidemiología , Peso al Nacer , Resistencia a Medicamentos/genética , Placenta , Pirimetamina/farmacología , Pirimetamina/uso terapéutico , Sulfadoxina/farmacología , Sulfadoxina/uso terapéutico , Combinación de Medicamentos , Malaria/tratamiento farmacológico , Polimorfismo de Nucleótido SimpleAsunto(s)
Antimaláricos , Malaria Falciparum , Humanos , Prevalencia , Pirimetamina/farmacología , Pirimetamina/uso terapéutico , Sulfadoxina/farmacología , Sulfadoxina/uso terapéutico , Combinación de Medicamentos , Antimaláricos/farmacología , Antimaláricos/uso terapéutico , Plasmodium falciparum , Malaria Falciparum/tratamiento farmacológico , Resistencia a MedicamentosRESUMEN
BACKGROUND: The effectiveness of community delivery of intermittent preventive treatment (C-IPT) of malaria in pregnancy (IPTp) with sulfadoxine-pyrimethamine has been evaluated in selected areas of the Democratic Republic of the Congo, Madagascar, Mozambique, and Nigeria. We aimed to assess the effect of C-IPTp on the potential development of Plasmodium falciparum resistance to sulfadoxine-pyrimethamine, since it could threaten the effectiveness of this strategy. METHODS: Health facility-based cross-sectional surveys were conducted at baseline and 3 years after C-IPTp implementation in two neighbouring areas per country, one with C-IPTp intervention, and one without, in the four project countries. Dried blood spots from children under five years of age with clinical malaria were collected. Sulfadoxine-pyrimethamine resistance-associated mutations of the P falciparum dhfr (Asn51Ile/Cys59Arg/Ser108Asn/Ile164Leu) and dhps (Ile431Val/Ser436Ala/Ala437Gly/Lys540Glu/Ala581Gly/Ala613Ser) genes were analysed. FINDINGS: 2536 children were recruited between June 19 and Oct 10, 2018, during baseline surveys. Endline surveys were conducted among 2447 children between July 26 and Nov 30, 2021. In the Democratic Republic of the Congo, the dhfr/dhps IRNI/ISGEAA inferred haplotype remained lower than 10%, from 2% (5 of 296) at baseline to 8% (24 of 292) at endline, and from 3% (9 of 300) at baseline to 6% (18 of 309) at endline surveys in intervention and non-intervention areas respectively with no significant difference in the change between the areas. In Mozambique, the prevalence of this haplotype remained stable at over 60% (194 [64%] of 302 at baseline to 194 [64%] of 303 at endline, and 187 [61%] of 306 at baseline to 183 [61%] of 301 in endline surveys, in non-intervention and intervention areas respectively). No isolates harbouring the dhps ISGEAA genotype were found in Nigeria. In Madagascar, only five isolates with this haplotype were found in the non-intervention area (2 [>1%] of 300 at baseline and 3 [1%] of 300 at endline surveys). No isolates were found carrying the dhps ISGEGA genotype. INTERPRETATION: C-IPTp did not increase the prevalence of molecular markers associated with sulfadoxine-pyrimethamine resistance after three years of programme implementation. These findings reinforce C-IPTp as a strategy to optimise the control of malaria during pregnancy, and support the WHO guidelines for prevention of malaria in pregnancy. FUNDING: UNITAID [2017-13-TIPTOP].
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Antimaláricos , Malaria Falciparum , Malaria , Embarazo , Niño , Femenino , Humanos , Preescolar , Antimaláricos/farmacología , Antimaláricos/uso terapéutico , Prevalencia , Estudios Transversales , Resistencia a Medicamentos/genética , Pirimetamina/farmacología , Pirimetamina/uso terapéutico , Sulfadoxina/farmacología , Sulfadoxina/uso terapéutico , Malaria/prevención & control , Malaria Falciparum/epidemiología , Malaria Falciparum/prevención & control , Malaria Falciparum/tratamiento farmacológico , Combinación de Medicamentos , Plasmodium falciparum/genética , Mozambique , BiomarcadoresRESUMEN
BACKGROUND: The 2022 malaria WHO reported around 4000 P. knowlesi infections in the South-East Asia region. In the same period, 72 positive cases were reported by the Department of Disease Control in Thailand, suggesting a persistent infection. Little is known about dihydrofolate reductase (pkdhfr) and dihydropteroate synthase (pkdhps), putative antimalarial resistance markers for P. knowlesi. The relevant amplification and sequencing protocol are presently unavailable. In this study, we developed a protocol for amplifying and evaluating pkdhps mutations. The haplotype pattern of pkdhfr-pkdhps in Thai isolates was analyzed, and the effects of these pkdhps mutations were predicted by using a computer program. METHODS: Pkdhps were amplified and sequenced from 28 P. knowlesi samples collected in 2008 and 2020 from nine provinces across Thailand. Combining pkdhfr sequencing data from previous work with pkdhps data to analyze polymorphisms of pkdhfr and pkdhps haplotype. Protein modeling and molecular docking were constructed using two inhibitors, sulfadoxine and sulfamethoxazole, and further details were obtained through analyses of protein-ligand interactions by using the Genetic Optimisation for Ligand Docking program. A phylogenetic tree cluster analysis was reconstructed to compare the P. knowlesi Malaysia isolates. RESULTS: Five nonsynonymous mutations in the pkdhps were detected outside the equivalence of the binding pocket sites to sulfadoxine and sulfamethoxazole, which are at N391S, E421G, I425R, A449S, and N517S. Based on the modeling and molecular docking analyses, the N391S and N517S mutations located close to the enzyme-binding pocket demonstrated a different docking score and protein-ligand interaction in loop 2 of the enzyme. These findings indicated that it was less likely to induce drug resistance. Of the four haplotypes of pkdhfr-pkdhps, the most common one is the R34L pkdhfr mutation and the pkdhps quadruple mutation (GRSS) at E421G, I425R, A449S, and N517S, which were observed in P. knowlesi in southern Thailand (53.57%). Based on the results of neighbor-joining analysis for pkdhfr and pkdhps, the samples isolated from eastern Thailand displayed a close relationship with Cambodia isolates, while southern Thailand isolates showed a long branch separated from the Malaysian isolates. CONCLUSIONS: A new PCR protocol amplification and evaluation of dihydropteroate synthase mutations in Knowlesi (pkdhps) has been developed. The most prevalent pkdhfr-pkdhps haplotypes (53.57%) in southern Thailand are R34L pkdhfr mutation and pkdhps quadruple mutation. Further investigation requires additional phenotypic data from clinical isolates, transgenic lines expressing mutant alleles, or recombinant proteins.
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Antimaláricos , Plasmodium knowlesi , Sulfadoxina/farmacología , Pirimetamina/farmacología , Tetrahidrofolato Deshidrogenasa/genética , Dihidropteroato Sintasa/genética , Plasmodium knowlesi/genética , Tailandia , Simulación del Acoplamiento Molecular , Ligandos , Filogenia , Antimaláricos/farmacología , Resistencia a Medicamentos/genética , Sulfametoxazol/farmacología , Plasmodium falciparum/genéticaRESUMEN
Malaria control initiatives require rapid and reliable methods for the detection and monitoring of molecular markers associated with antimalarial drug resistance in Plasmodium falciparum parasites. Ngodhe island, Kenya, presents a unique malaria profile, with lower P. falciparum incidence rates than the surrounding region, and a high proportion of sub-microscopic and low-density infections. Here, using custom dual-indexing and Illumina next generation sequencing, we generate resistance profiles on seventy asymptomatic and low-density P. falciparum infections from a mass drug administration program implemented on Ngodhe island between 2015 and 2016. Our assay encompasses established molecular markers on the Pfcrt, Pfmdr1, Pfdhps, Pfdhfr, and Pfk13 genes. Resistance markers for sulfadoxine-pyrimethamine were identified at high frequencies, including a quintuple mutant haplotype (Pfdhfr/Pfdhps: N51I, C59R, S108N/A437G, K540E) identified in 62.2% of isolates. The Pfdhps K540E biomarker, used to inform decision making for intermittent preventative treatment in pregnancy, was identified in 79.2% of isolates. Several variants on Pfmdr1, associated with reduced susceptibility to quinolones and lumefantrine, were also identified (Y184F 47.1%; D1246Y 16.0%; N86 98%). Overall, we have presented a low-cost and extendable approach that can provide timely genetic profiles to inform clinical and surveillance activities, especially in settings with abundant low-density infections, seeking malaria elimination.
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Antimaláricos , Malaria Falciparum , Malaria , Embarazo , Femenino , Humanos , Kenia/epidemiología , Malaria Falciparum/tratamiento farmacológico , Malaria Falciparum/epidemiología , Malaria Falciparum/parasitología , Antimaláricos/farmacología , Antimaláricos/uso terapéutico , Pirimetamina/farmacología , Pirimetamina/uso terapéutico , Sulfadoxina/farmacología , Sulfadoxina/uso terapéutico , Malaria/parasitología , Plasmodium falciparum , Resistencia a Medicamentos/genética , Combinación de Medicamentos , Secuenciación de Nucleótidos de Alto RendimientoRESUMEN
BACKGROUND: Artemisinin-based combinations therapy (ACT) is the current frontline curative therapy for uncomplicated malaria in Burkina Faso. Sulfadoxine-pyrimethamine (SP) is used for the preventive treatment of pregnant women (IPTp), while SP plus amodiaquine (SP-AQ) is recommended for children under five in seasonal malaria chemoprevention (SMC). This study aimed to assess the proportions of mutations in the P. falciparum multidrug-resistance 1 (Pfmdr1), P. falciparum chloroquine resistance transporter (Pfcrt), P. falciparum dihydrofolate reductase (pfdhfr), and P. falciparum dihydropteroate synthase (pfdhps), genes from isolates collected during household surveys in Burkina Faso. METHODS: Dried blood spots from Plasmodium falciparum-positive cases at three sites (Orodara, Gaoua, and Banfora) collected during the peak of transmission were analysed for mutations in Pfcrt (codons 72-76, 93, 97, 145, 218, 343, 350 and 353), Pfmdr-1 (codons 86, 184, 1034, 1042 and 1246) dhfr (codons 51, 59, 108, 164) and dhps (at codons 431, 436, 437, 540, 581, 613) genes using deep sequencing of multiplexed Polymerase chaine reaction (PCR) amplicons. RESULTS: Of the 377 samples analysed, 346 (91.7%), 369 (97.9%), 368 (97.6%), and 374 (99.2%) were successfully sequenced for Pfcrt, Pfmdr-1, dhfr, and dhps, respectively. Most of the samples had a Pfcrt wild-type allele (89.3%). The 76T mutation was below 10%. The most frequent Pfmdr-1 mutation was detected at codon 184 (Y > F, 30.9%). The single mutant genotype (NFSND) predominated (66.7%), followed by the wild-type genotype (NYSND, 30.4%). The highest dhfr mutations were observed at codon 59R (69.8%), followed by codons 51I (66.6%) and 108 N (14.7%). The double mutant genotype (ACIRSI) predominated (52.4%). For mutation in the dhps gene, the highest frequency was observed at codon 437 K (89.3%), followed by codons 436 A (61.2%), and 613 S (14.4%). The double mutant genotype (IAKKAA) and the single mutant genotype (ISKKAA) were predominant (37.7% and 37.2%, respectively). The most frequent dhfr/dhps haplotypes were the triple mutant ACIRSI/IAKKAA (23%), the wild-type ACNCSI/ISKKAA (19%) and the double mutant ACIRSI/ISKKAA (14%). A septuple mutant ACIRNI/VAKKGA was observed in 2 isolates from Gaoua (0.5%). CONCLUSION: The efficacy of ACT partner drugs and drugs used in IPTp and SMC does not appear to be affected by the low proportion of highly resistant mutants observed in this study. Continued monitoring, including molecular surveillance, is critical for decision-making on effective treatment policy in Burkina Faso.
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Antimaláricos , Malaria Falciparum , Malaria , Humanos , Niño , Femenino , Embarazo , Plasmodium falciparum , Antimaláricos/farmacología , Antimaláricos/uso terapéutico , Burkina Faso , Pirimetamina/farmacología , Pirimetamina/uso terapéutico , Sulfadoxina/farmacología , Sulfadoxina/uso terapéutico , Malaria Falciparum/epidemiología , Malaria Falciparum/prevención & control , Malaria Falciparum/tratamiento farmacológico , Malaria/tratamiento farmacológico , Mutación , Tetrahidrofolato Deshidrogenasa/genética , Combinación de Medicamentos , Resistencia a Medicamentos/genética , CodónRESUMEN
Sulfadoxine-pyrimethamine (SP) is used for prevention of malaria in pregnant women in Angola. We sequenced the Plasmodium falciparum dihydrofolate reductase (pfdhfr) and dihydropteroate synthase (pfdhps) genes, implicated in SP resistance, in samples collected during a 2019 study of artemisinin-based combination therapy efficacy in Benguela, Lunda Sul, and Zaire provinces. A total of 90 day 0 and day of failure samples were individually sequenced, while 508 day 0 samples from participants without recurrent parasitemia were pooled after DNA extraction into 61 pools. The N51I, C59R, and S108N pfdhfr mutations and A437G pfdhps mutations were present at high proportions in all provinces (weighted allele frequencies, 62% to 100%). The K540E pfdhps mutation was present at lower proportions (10% to 14%). The A581G pfdhps mutation was only observed in Zaire, at a 4.6% estimated prevalence. The I431V and A613S mutations were also only observed in Zaire, at a prevalence of 2.8% to 2.9%. The most common (27% to 66%) reconstructed haplotype in all three provinces was the canonical quadruple pfdhfr pfdhps mutant. The canonical quintuple mutant was absent in Lunda Sul and Benguela and present in 7.9% of samples in Zaire. A single canonical sextuple (2.6%) mutant was observed in Zaire Province. Proportions of the pfdhps K540E and A581G mutations were well below the World Health Organization thresholds for meaningful SP resistance (prevalence of 95% for K540E and 10% for A581G). Samples from therapeutic efficacy studies represent a convenient source of samples for monitoring SP resistance markers.