Assessment of Plasmodium falciparum anti-malarial drug resistance markers in pfk13-propeller, pfcrt and pfmdr1 genes in isolates from treatment failure patients in Democratic Republic of Congo, 2018-2019

Detection of Artemisinin Resistance Marker Kelch-13 469Y in Plasmodium falciparum, South Kivu, Democratic Republic of the Congo, 2022

Partial artemisinin resistance has emerged in East Africa, posing a threat to malaria control across the continent. The Democratic Republic of the Congo carries one of the heaviest malaria burdens globally, and the South Kivu province directly borders current artemisinin resistance hot spots, but indications of such resistance have not been observed so far. We assessed molecular markers of antimalarial drug resistance in 256 Plasmodium falciparum isolates collected in 2022 in South Kivu, Democratic Republic of the Congo. One isolate carried the P. falciparum Kelch-13 469Y variant, a marker associated with partial artemisinin resistance and decreased lumefantrine susceptibility in Uganda. In addition, the multidrug resistance-1 mutation pattern suggested increased lumefantrine tolerance.

The landscape of drug resistance in Plasmodium falciparum malaria in the Democratic Republic of Congo: a mapping systematic review

CONTEXT

The Democratic Republic of Congo (DRC), one of the most malaria-affected countries worldwide, is a potential hub for global drug-resistant malaria. This study aimed at summarizing and mapping surveys of malaria parasites carrying molecular markers of drug-resistance across the country.

METHODS

A systematic mapping review was carried out before July 2023 by searching for relevant articles through seven databases (PubMed, Embase, Scopus, African Journal Online, African Index Medicus, Bioline and Web of Science).

RESULTS

We identified 1541 primary studies of which 29 fulfilled inclusion criteria and provided information related to 6385 Plasmodium falciparum clinical isolates (collected from 2000 to 2020). We noted the PfCRT K76T mutation encoding for chloroquine-resistance in median 32.1% [interquartile interval, IQR: 45.2] of analyzed malaria parasites. The proportion of parasites carrying this mutation decreased overtime, but wide geographic variations persisted. A single isolate had encoded the PfK13 R561H substitution that is invoked in artemisinin-resistance emergence in the Great Lakes region of Africa. Parasites carrying various mutations linked to resistance to the sulfadoxine-pyrimethamine combination were widespread and reflected a moderate resistance profile (PfDHPS A437G: 99.5% [IQR: 3.9]; PfDHPS K540E: 38.9% [IQR: 47.7]) with median 13.1% [IQR: 10.3] of them being quintuple IRN-GE mutants (i.e., parasites carrying the PfDHFR N51I-C59R-S108N and PfDHPS A437G-K540E mutations). These quintuple mutants tended to prevail in eastern regions of the country. Among circulating parasites, we did not record any parasites harboring mutations related to mefloquine-resistance, but we could suspect those with decreased susceptibility to quinine, amodiaquine, and lumefantrine based on corresponding molecular surrogates.

CONCLUSIONS

Drug resistance poses a serious threat to existing malaria therapies and chemoprevention options in the DRC. This review provides a baseline for monitoring public health efforts as well as evidence for decision-making in support of national malaria policies and for implementing regionally tailored control measures across the country.

A multi-epitope vaccine designed against blood-stage of malaria: an immunoinformatic and structural approach

Malaria is a complex disease caused by parasites of the genus Plasmodium and is the leading cause of morbidity and mortality worldwide. The most severe form of malaria disease is caused by Plasmodium falciparum. Thus, a combination of different approaches is needed to control malaria. Resistance to first-line drugs and insecticides, on the other hand, makes the need for an effective vaccination more urgent than ever. Because erythrocyte parasites cause the most clinical symptoms, developing a vaccination for this stage of infection might be highly beneficial. In this research, we employed various bioinformatics methods to create an efficient multi-epitope vaccine that induces antibodies against the blood stage of malaria infection. For this purpose, we selected the malaria PfGARP protein as the target here. The B, HTL epitopes, and epitope conservation were predicted. The predicted epitopes (including 5 B and 5 HTL epitopes) were connected using suitable linkers, and the flagellin molecule was used as an adjuvant to improve its immunogenicity. The final construct vaccine with 414 amino acids long was designed. The vaccine's allergenicity, antigenicity, solubility, physicochemical characteristics, 2D and 3D structure modeling, molecular docking, molecular dynamics simulation, in silico cloning, and immunological simulation were tested. In silico immune simulation results showed significantly elevated IgG1 and IgM and T helper cells, INF γ, IL 2, and B-cell populations after the injection of the designed vaccine. These significant computational analyses indicated that our proposed vaccine candidate might activate suitable immune responses against malaria. However, in vitro and in vivo studies are essential for further validation.

Identification of polymorphisms in genes associated with drug resistance in Plasmodium falciparum isolates from school-age children in Kinshasa, Democratic Republic of Congo

BACKGROUND

The emergence and spread of Plasmodium falciparum parasites resistant to antimalarial drugs constitutes an obstacle to malaria control and elimination. This study aimed to identify the prevalence of polymorphisms in pfk13, pfmdr1, pfdhfr, pfdhps and pfcrt genes in isolates from asymptomatic and symptomatic school-age children in Kinshasa.

METHODS

Nested-PCR followed by sequencing was performed for the detection of pfk13, pfmdr1, pfdhfr, pfdhps and pfcrt polymorphisms.

RESULTS

Two mutations in pfk13, C532S and Q613E were identified in the Democratic Republic of Congo for the first time. The prevalence of the drug-resistance associated mutations pfcrt K76T, pfdhps K540E and pfmdr1 N86Y was low, being 27%, 20% and 9%, respectively.

CONCLUSION

We found a low prevalence of genetic markers associated with chloroquine and sulfadoxine-pyrimethamine resistance in Kinshasa. Furthermore, no mutations previously associated with resistance against artemisinin and is derivatives were observed in the pfK13 gene. These findings support the continued use of ACTs and IPTp-SP. Continuous molecular monitoring of antimalarial resistance markers is recommended.

Prevalence of potential mediators of artemisinin resistance in African isolates of Plasmodium falciparum

Background

The devastating public health impact of malaria has prompted the need for effective interventions. Malaria control gained traction after the introduction of artemisinin-based combination therapy (ACT). However, the emergence of artemisinin (ART) partial resistance in Southeast Asia and emerging reports of delayed parasite sensitivity to ACT in African parasites signal a gradual trend towards treatment failure. Monitoring the prevalence of mutations associated with artemisinin resistance in African populations is necessary to stop resistance in its tracks. Mutations in Plasmodium falciparum genes pfk13, pfcoronin and pfatpase6 have been linked with ART partial resistance.

Methods

Findings from published research articles on the prevalence of pfk13, pfcoronin and pfatpase6 polymorphisms in Africa were collated. PubMed, Embase and Google Scholar were searched for relevant articles reporting polymorphisms in these genes across Africa from 2014 to August 2021, for pfk13 and pfcoronin. For pfatpase6, relevant articles between 2003 and August 2021 were retrieved.

Results

Eighty-seven studies passed the inclusion criteria for this analysis and reported 742 single nucleotide polymorphisms in 37,864 P. falciparum isolates from 29 African countries. Five validated-pfk13 partial resistance markers were identified in Africa: R561H in Rwanda and Tanzania, M476I in Tanzania, F446I in Mali, C580Y in Ghana, and P553L in an Angolan isolate. In Tanzania, three (L263E, E431K, S769N) of the four mutations (L263E, E431K, A623E, S769N) in pfatpase6 gene associated with high in vitro IC₅₀ were reported. pfcoronin polymorphisms were reported in Senegal, Gabon, Ghana, Kenya, and Congo, with P76S being the most prevalent mutation.

Conclusions

This meta-analysis provides an overview of the prevalence and widespread distribution of pfk13, pfcoronin and pfatpase6 mutations in Africa. Understanding the phenotypic consequences of these mutations can provide information on the efficacy status of artemisinin-based treatment of malaria across the continent.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-021-03987-6.