Correction: Corrigendum: Artemisinin-resistant Plasmodium falciparum clinical isolates can infect diverse mosquito vectors of Southeast Asia and Africa

Abstract Artemisinin-resistant Plasmodium falciparum parasites are rapidly spreading in Southeast Asia, yet nothing is known about their transmission. This knowledge gap and the possibility that these parasites will spread to Africa endanger global efforts to eliminate malaria. Here we produce gametocytes from parasite clinical isolates that displayed artemisinin resistance in patients and in vitro, and use them to infect native and non-native mosquito vectors. We show that contemporary artemisinin-resistant isolates from Cambodia develop and produce sporozoites in two Southeast Asian vectors, Anopheles dirus and Anopheles minimus, and the major African vector, Anopheles coluzzii (formerly Anopheles gambiae M). The ability of artemisinin-resistant parasites to infect such highly diverse Anopheles species, combined with their higher gametocyte prevalence in patients, may explain the rapid expansion of these parasites in Cambodia and neighbouring countries, and further compromise efforts to prevent their global spread.

Download Full-text

Gametocytes from K13 Propeller Mutant Plasmodium falciparum Clinical Isolates Demonstrate Reduced Susceptibility to Dihydroartemisinin in the Male Gamete Exflagellation Inhibition Assay

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01426-18 ◽

2018 ◽

Vol 62 (12) ◽

Cited By ~ 9

Author(s):

Sonia Lozano ◽

Pablo Gamallo ◽

Carolina González-Cortés ◽

Jesús-Luís Presa Matilla ◽

Rick M. Fairhurst ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Southeast Asia ◽

Male Gamete ◽

Clinical Isolates ◽

Inhibition Assay ◽

Wild Type ◽

Content Type ◽

Gamete Formation

ABSTRACT Mutations in the kelch propeller domain (K13 propeller) of Plasmodium falciparum parasites from Southeast Asia are associated with reduced susceptibility to artemisinin. We exposed in vitro-cultured stage V gametocytes from Cambodian K13 propeller mutant parasites to dihydroartemisinin and evaluated the inhibition of male gamete formation in an in vitro exflagellation inhibition assay (EIA). Gametocytes with the R539T and C580Y K13 propeller alleles were less susceptible to dihydroartemisinin and had significantly higher 50% inhibitory concentrations (IC50s) than did gametocytes with wild-type alleles.

Download Full-text

The Diversity of the Plasmodium falciparum K13 Propeller Domain Did Not Increase after Implementation of Artemisinin-Based Combination Therapy in Uganda

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01234-19 ◽

2019 ◽

Vol 63 (10) ◽

Author(s):

Melissa D. Conrad ◽

Sam L. Nsobya ◽

Philip J. Rosenthal

Keyword(s):

Plasmodium Falciparum ◽

Southeast Asia ◽

Artemisinin Resistance ◽

Standard Of Care ◽

Parasite Clearance ◽

Sub Saharan Africa ◽

Clinical Isolates ◽

Nucleotide Polymorphisms ◽

Content Type ◽

Sub Saharan

ABSTRACT Artemisinin-based combination therapies (ACTs) are the standard of care to treat uncomplicated falciparum malaria. However, resistance to artemisinins, defined as delayed parasite clearance after therapy, has emerged in Southeast Asia, and the spread of resistance to sub-Saharan Africa could have devastating consequences. Artemisinin resistance has been associated in Southeast Asia with multiple nonsynonymous single nucleotide polymorphisms (NS-SNPs) in the propeller domain of the gene encoding the Plasmodium falciparum K13 protein (K13PD). Some K13PD NS-SNPs have been seen in Africa, but the relevance of these mutations is unclear. To assess whether ACT use has selected for specific K13PD mutations, we compared the K13PD genetic diversity in clinical isolates collected before and after the implementation of ACT use from seven sites across Uganda. We detected K13PD NS-SNPs in 16 of 683 (2.3%) clinical isolates collected between 1999 and 2004 and in 26 of 716 (3.6%) isolates collected between 2012 and 2016 (P = 0.16), representing a total of 29 different polymorphisms at 27 codons. Individual NS-SNPs were usually detected only once, and none were found in more than 0.7% of the isolates. Three SNPs (C469F, P574L, and A675V) associated with delayed clearance in Southeast Asia were seen in samples collected between 2012 and 2016, each in a single isolate. No differences in diversity following implementation of ACT use were found at any of the seven sites, nor was there evidence of selective pressures acting on the locus. Our results suggest that selection by ACTs is not impacting on K13PD diversity in Uganda.

Download Full-text

Effect of Fluorescent Dyes onIn Vitro-Differentiated, Late-Stage Plasmodium falciparum Gametocytes

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.03772-14 ◽

2014 ◽

Vol 58 (12) ◽

pp. 7398-7404 ◽

Cited By ~ 14

Author(s):

Tamirat Gebru ◽

Benjamin Mordmüller ◽

Jana Held

Keyword(s):

Plasmodium Falciparum ◽

Late Stage ◽

Fluorescent Dyes ◽

Clinical Symptoms ◽

Laboratory Strain ◽

Clinical Isolates ◽

Synthetic Dyes ◽

Content Type ◽

Highly Active

ABSTRACTPlasmodium falciparumgametocytes are not associated with clinical symptoms, but they are responsible for transmitting the pathogen to mosquitoes. Therefore, gametocytocidal interventions are important for malaria control and resistance containment. Currently available drugs and vaccines are not well suited for that purpose. Several dyes have potent antimicrobial activity, but their use against gametocytes has not been investigated systematically. The gametocytocidal activity of nine synthetic dyes and four control compounds was tested against stage V gametocytes of the laboratory strain 3D7 and three clinical isolates ofP. falciparumwith a bioluminescence assay. Five of the fluorescent dyes had submicromolar 50% inhibitory concentration (IC50) values against mature gametocytes. Three mitochondrial dyes, MitoRed, dihexyloxacarbocyanine iodide (DiOC6), and rhodamine B, were highly active (IC50s < 200 nM). MitoRed showed the highest activity against gametocytes, with IC50s of 70 nM against 3D7 and 120 to 210 nM against clinical isolates. All compounds were more active against the laboratory strain 3D7 than against clinical isolates. In particular, the endoperoxides artesunate and dihydroartemisinin showed a 10-fold higher activity against 3D7 than against clinical isolates. In contrast to all clinically used antimalarials, several fluorescent dyes had surprisingly highin vitroactivity against late-stage gametocytes. Since they also act against asexual blood stages, they shall be considered starting points for the development of new antimalarial lead compounds.

Download Full-text

In vitro efficacy of act drugs on Plasmodium falciparum clinical isolates from Kano and Katsina States, Nigeria

Bayero Journal of Pure and Applied Sciences ◽

10.4314/bajopas.v10i1.10s ◽

2018 ◽

Vol 10 (1) ◽

pp. 49

Author(s):

B.M. Aminu ◽

M.D. Mukhtar

Keyword(s):

Plasmodium Falciparum ◽

Clinical Isolates

Download Full-text

Shedding Light on the Role of the Skin in Vaccine-Induced Protection against the Malaria Sporozoite

mBio ◽

10.1128/mbio.02555-18 ◽

2018 ◽

Vol 9 (6) ◽

Author(s):

Johanna Patricia Daily

Keyword(s):

Plasmodium Falciparum ◽

Blood Vessels ◽

Blood Stream ◽

Mosquito Vectors ◽

Protective Mechanisms ◽

Partial Protection ◽

Content Type ◽

Shed Light ◽

In Infants And Children

ABSTRACT The most advanced vaccine against Plasmodium falciparum malaria, RTS,S/AS01, provides partial protection in infants and children living in areas of malaria endemicity. Further understanding its mechanisms of protection may allow the development of improved second-generation vaccines. The RTS,S/AS01 vaccine targets the sporozoites injected by mosquito vectors into the dermis which then travel into the blood stream to establish infection in the liver. Flores-Garcia et al. (Y. Flores-Garcia, G. Nasir, C. S. Hopp, C. Munoz, et al., mBio 9:e02194-18, 2018, https://doi.org/10.1128/mBio.02194-18) shed light on early protective responses occurring in the dermis in immunized animals. They demonstrated that immunization impairs sporozoite motility and entry into blood vessels. Furthermore, they established that challenge experiments performed using a dermal route conferred greater protection than intravenous challenge in immunized mice. Thus, the dermal challenge approach captures the additional protective mechanisms occurring in the dermis that reflect the natural physiology of infection. Those studies highlighted the fascinating biology of skin-stage sporozoites and provided additional insights into vaccine-induced protection.

Download Full-text

Efficacy of dihydroartemisinin/piperaquine in patients with non-complicated Plasmodium falciparum malaria in Yaoundé, Cameroon

Journal of Antimicrobial Chemotherapy ◽

10.1093/jac/dkab281 ◽

2021 ◽

Author(s):

Mélissa Mairet-Khedim ◽

Sandrine Nsango ◽

Christelle Ngou ◽

Sandie Menard ◽

Camille Roesch ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Southeast Asia ◽

Falciparum Malaria ◽

Gene Polymorphisms ◽

Plasmodium Falciparum Malaria ◽

Molecular Profile ◽

Uncomplicated Plasmodium Falciparum Malaria ◽

In Vitro Survival ◽

Phenotypic Susceptibility

Abstract Background Dihydroartemisinin/piperaquine is increasingly used for the treatment of uncomplicated Plasmodium falciparum malaria in Africa. The efficacy of this combination in Cameroon is poorly documented, while resistance to dihydroartemisinin/piperaquine readily spreads in Southeast Asia. Objectives This study evaluated the clinical efficacy of dihydroartemisinin/piperaquine in Cameroon, as well as the molecular profile and phenotypic susceptibility of collected isolates to dihydroartemisinin and piperaquine. Patients and methods Dihydroartemisinin/piperaquine efficacy in 42 days was followed-up for 138 patients presenting non-complicated falciparum malaria. Piperaquine concentration was determined at day 7 for 124 patients. kelch13 gene polymorphisms (n = 150) and plasmepsin2 gene amplification (n = 148) were determined as molecular markers of resistance to dihydroartemisinin and piperaquine, respectively. Parasite susceptibility to dihydroartemisinin and piperaquine was determined using validated in vitro survival assays. Results The efficacy of dihydroartemisinin/piperaquine treatment was 100% after PCR correction. The reinfections were not associated with a variation of piperaquine concentration at day 7. Ninety-six percent (144/150) of the samples presented a WT allele of the kelch13 gene. Two percent (3/150) presented the non-synonymous mutation A578S, which is not associated with resistance to dihydroartemisinin. No duplication of the plasmepsin2 gene was observed (0/148). All the samples tested in vitro by survival assays (n = 87) were susceptible to dihydroartemisinin and piperaquine. Conclusions Dihydroartemisinin/piperaquine has demonstrated excellent therapeutic efficacy with no evidence of emerging artemisinin or piperaquine resistance in Yaoundé, Cameroon. This observation suggests that dihydroartemisinin/piperaquine could be a sustainable therapeutic solution for P. falciparum malaria if implemented in areas previously free of artemisinin- and piperaquine-resistant parasites, unlike Southeast Asia.

Download Full-text

Expansion of a Specific Plasmodium falciparum PfMDR1 Haplotype in Southeast Asia with Increased Substrate Transport

mBio ◽

10.1128/mbio.02093-20 ◽

2020 ◽

Vol 11 (6) ◽

Author(s):

Carla Calçada ◽

Miguel Silva ◽

Vitória Baptista ◽

Vandana Thathy ◽

Rita Silva-Pedrosa ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Multidrug Resistance ◽

Southeast Asia ◽

Gene Copy ◽

Multidrug Resistance Protein ◽

Combination Therapies ◽

Transport Capacity ◽

Multidrug Resistance Protein 1 ◽

Content Type ◽

Resistance Protein

ABSTRACT Artemisinin-based combination therapies (ACTs) have been vital in reducing malaria mortality rates since the 2000s. Their efficacy, however, is threatened by the emergence and spread of artemisinin resistance in Southeast Asia. The Plasmodium falciparum multidrug resistance protein 1 (PfMDR1) transporter plays a central role in parasite resistance to ACT partner drugs through gene copy number variations (CNV) and/or single nucleotide polymorphisms (SNPs). Using genomic epidemiology, we show that multiple pfmdr1 copies encoding the N86 and 184F haplotype are prevalent across Southeast Asia. Applying genome editing tools on the Southeast Asian Dd2 strain and using a surrogate assay to measure transporter activity in infected red blood cells, we demonstrate that parasites harboring multicopy N86/184F PfMDR1 have a higher Fluo-4 transport capacity compared with those expressing the wild-type N86/Y184 haplotype. Multicopy N86/184F PfMDR1 is also associated with decreased parasite susceptibility to lumefantrine. These findings provide evidence of the geographic selection and expansion of specific multicopy PfMDR1 haplotypes associated with multidrug resistance in Southeast Asia. IMPORTANCE Global efforts to eliminate malaria depend on the continued success of artemisinin-based combination therapies (ACTs) that target Plasmodium asexual blood-stage parasites. Resistance to ACTs, however, has emerged, creating the need to define the underlying mechanisms. Mutations in the P. falciparum multidrug resistance protein 1 (PfMDR1) transporter constitute an important determinant of resistance. Applying gene editing tools combined with an analysis of a public database containing thousands of parasite genomes, we show geographic selection and expansion of a pfmdr1 gene amplification encoding the N86/184F haplotype in Southeast Asia. Parasites expressing this PfMDR1 variant possess a higher transport capacity that modulates their responses to antimalarials. These data could help tailor and optimize antimalarial drug usage in different regions where malaria is endemic by taking into account the regional prevalence of pfmdr1 polymorphisms.

Download Full-text