Effect of P. falciparum Kelch 13 and Pfmdr1 gene polymorphisms on parasite clearance characteristics following Artemether-Lumefantrine therapy

Abstract Because of concerns about possible emergence of artemisinin resistance strains of Plasmodium falciparum in mining areas of the interior of Guyana, a 7-day artesunate trial was conducted from March to December 2014. The day-3 parasite clearance rate, the efficacy of artesunate at day 28, and polymorphism of Kelch 13 (PfK13)—the marker of artemisinin resistance—were assessed. The study confirmed the continued sensitivity of P falciparum to artemisinin. A 7-day course of artesunate was 100% efficacious with only 2% (95% confidence interval, .1%–10.9%) of enrolled subjects positive at day 3. All day-0 parasite samples were wild type. Continued resistance monitoring is nevertheless recommended, given the widespread availability and uncontrolled use of artemisinin drugs in mining areas of Guyana.

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Imidazolopiperazines Kill both Rings and Dormant Rings in Wild-Type and K13 Artemisinin-Resistant Plasmodium falciparum In Vitro

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02235-17 ◽

2018 ◽

Vol 62 (5) ◽

Cited By ~ 5

Author(s):

Laurent Dembele ◽

Devendra Kumar Gupta ◽

Michelle Yi-Xiu Lim ◽

Xiaoman Ang ◽

Jeremy J. Selva ◽

...

Keyword(s):

Clinical Trials ◽

Plasmodium Falciparum ◽

Southeast Asia ◽

Active Metabolite ◽

Parasite Clearance ◽

Ring Stage ◽

Wild Type ◽

Content Type ◽

Kelch 13

ABSTRACT Artemisinin (ART) resistance has spread through Southeast Asia, posing a serious threat to the control and elimination of malaria. ART resistance has been associated with mutations in the Plasmodium falciparum kelch-13 ( Pfk13 ) propeller domain. Phenotypically, ART resistance is defined as delayed parasite clearance in patients due to the reduced susceptibility of early ring-stage parasites to the active metabolite of ART dihydroartemisinin (DHA). Early rings can enter a state of quiescence upon DHA exposure and resume growth in its absence. These quiescent rings are referred to as dormant rings or DHA-pretreated rings (here called dormant rings). The imidazolopiperazines (IPZ) are a novel class of antimalarial drugs that have demonstrated efficacy in early clinical trials. Here, we characterized the stage of action of the IPZ GNF179 and evaluated its activity against rings and dormant rings in wild-type and ART-resistant parasites. Unlike DHA, GNF179 does not induce dormancy. We show that GNF179 is more rapidly cidal against schizonts than against ring and trophozoite stages. However, with 12 h of exposure, the compound effectively kills rings and dormant rings of both susceptible and ART-resistant parasites within 72 h. We further demonstrate that in combination with ART, GNF179 effectively prevents recrudescence of dormant rings, including those bearing pfk13 propeller mutations.

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Prevalence of Plasmodium falciparum Kelch 13 (PfK13) and Ubiquitin-Specific Protease 1 (pfubp1) Gene Polymorphisms in Returning Travelers from Africa Reported in Eastern China

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00981-20 ◽

2020 ◽

Vol 64 (11) ◽

Author(s):

He Yan ◽

Xiangli Kong ◽

Tao Zhang ◽

Huihui Xiao ◽

Xinyu Feng ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Molecular Markers ◽

Eastern China ◽

Parasite Clearance ◽

African Countries ◽

Content Type ◽

Clinical Trial Research ◽

Specific Protease ◽

Ubiquitin Specific Protease ◽

Kelch 13

ABSTRACT Delayed clearance of Plasmodium falciparum by artemisinin-based combination therapies (ACTs) has already been observed for African isolates. Here, we aimed to investigate the prevalence, among travelers returning from African countries, of polymorphisms in two genes correlated with delayed parasite clearance (encoding P. falciparum Kelch 13 [PfK13] and ubiquitin-specific protease 1 [pfubp1]) reported in eastern China and to provide baseline data for antimalarial drug resistance (ART) surveillance and evaluation. A total of 153 filter paper blood spots collected in 2017–2019 from patients with uncomplicated P. falciparum cases in Anhui and Shandong Provinces were included in this study. Among them, 3.3% (5/153) of the isolates carried PfK13 mutations, and 3 of them harbored the same synonymous mutation, C469C. A total of 13.1% (20/153) of the isolates were found to contain pfubp1 mutations, and all were nonsynonymous. The pfubp1 genotypes associated with ART that occurred in this study included E1528D (6.5% [10/153]) and D1525E (2.6% [4/153]). However, a high prevalence of the previously unreported mutation E1531D (5.9% [9/153]) was also detected. In addition, two types of deletions (encoding KID and KIE, respectively) and two types of insertions (encoding KYE and KYDKYD, respectively) were found in 16 isolates and 6 isolates, respectively. This study showed limited variation in PfK13 among travelers returning from African countries and suggested other potential molecular markers, such as pfubp1, for use in the surveillance of African isolates in ACT susceptibility studies. Further clinical trial research is under way to investigate these PfK13 and pfubp1 mutations, as well as other candidate molecular markers, and their roles in delaying parasite clearance.

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Slow Parasite Clearance, Absent K-13 Propeller Gene Polymorphisms and Adequate Artesunate Levels Among Patients With Severe Malaria: A Prospective Observational Cohort Study From South India

Open Forum Infectious Diseases ◽

10.1093/ofid/ofw172.451 ◽

2016 ◽

Vol 3 (suppl_1) ◽

Author(s):

Angel Miraclin ◽

Joy Mammen ◽

Binu Mathew ◽

Priscilla Rupali

Keyword(s):

Cohort Study ◽

Severe Malaria ◽

Gene Polymorphisms ◽

South India ◽

Parasite Clearance ◽

Observational Cohort Study ◽

Prospective Observational Cohort Study ◽

Observational Cohort ◽

K 13

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Genetic Features of P. falciparum Parasites Collected in 2012-2016 and Anti-Malaria Resistance Along China-Myanmar Border

10.21203/rs.3.rs-81492/v1 ◽

2020 ◽

Author(s):

Mei Li ◽

Hui Liu ◽

Linhua Tang ◽

Henglin Yang ◽

Maria Dorina Geluz Bustos ◽

...

Keyword(s):

Yunnan Province ◽

Tandem Repeats ◽

Artemisinin Resistance ◽

Parasite Clearance ◽

Pfmdr1 Gene ◽

North West ◽

Copy Numbers ◽

Genetic Features ◽

The Mean

Abstract Backgrounds The therapeutic efficacy studies (TES) of T(DHA-PIP) for uncomplicated P. falciparum patients were implemented during 2012-2016 along China (Yunnan province)-Myanmar border, which verified the high efficacy of DHA-PIP. The study focusing on the genetic features of falciparum parasites and basing on in vivo parasite clearance time (PCT) were carried out to explore if they had produced potential resistance to DHA and PIP at molecular level. Methods The genetic features were investigated based on K13 propeller genotypes, Copy numbers of genes pfPM2 and pfmdr1 and 9 microsatellite loci (Short Tandem Repeats, STR) flanking the K13 gene on chromosome 13. The PCT 50s basing on different K13 genotypes, sites, periods and copy numbers were compared.Results In NW (North-West Yunnan province bordering with Myanmar) area, F446I prevalence was 58.96% (79/134). No significant different PCT 50s presented among 3 K13 groups (Chi-Square=2.35, P=0.31, df=2) classified by K13 genotypes within NW area, but all of them were significantly shorter than that in SW (South-West Yunnan province bordering with Myanmar) area (P=0.036, t=-2.11, df=174) where isolates only showed wild K13 genotype. For the copy numbers of pfmdr1 gene, 14.63% (18/123) and 62.5% (10/16) parasite isolates showed double copies (≥ 1.6) in NW and SW areas separately, but for those of pfM2 gene, no parasite isolates did. Between isolates with single and double copies of pfmdr1 gene, no different PCT 50 presented. According to the mean He values, the four K13 groups were arranged as ML group (Menglian County in SW), F446I group, Others (Non-F446I K13 mutation) group and W (wild K13 genotype) group from low to high. The mean Fst values between ML and W groups were significantly higher than other 2 K13 group-W pairs (Paired-T Test: t=-2.659，df=8，P=0.029; t=-4.966, df=8，P=0.001). Conclusions According to our study, P. falciparum isolates in NW area and SW area are very different in genetic features. Artemisinin partial resistance, inferred from genetic marker, F446I, had independently appeared and spread in NW area during 2012-2016. With global application of ACTs, this pattern of artemisinin resistance producing was worth more attention. Fortunately, PIP-resistant feature basing on genetic analysis showed negative results in both areas. So, DHA-PIP was still recommended in antimalarial treatment along China-Myanmar border based on molecular data, which was agreed with the conclusion drawn from in vivo data obtained with same falciparum isolates. Trial registration: ISRCTN, ISRCTN 11775446. Registered 13 April 2020 - Retrospectively registered, http://www.isrctn.com/ISRCTN11775446.

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