Resistance of Plasmodium falciparum to antimalarial drugs in a highly endemic area of southern Viet Nam: a study in vivo and in vitro

ABSTRACTPlasmodium falciparumhas the capacity to escape the actions of essentially all antimalarial drugs. ATP-binding cassette (ABC) transporter proteins are known to cause multidrug resistance in a large range of organisms, including theApicomplexaparasites.P. falciparumgenome analysis has revealed two genes coding for the multidrug resistance protein (MRP) type of ABC transporters:Pfmrp1, previously associated with decreased parasite drug susceptibility, and the poorly studiedPfmrp2. The role ofPfmrp2polymorphisms in modulating sensitivity to antimalarial drugs has not been established. We herein report a comprehensive account of thePfmrp2genetic variability in 46 isolates from Thailand. A notably high frequency of 2.8 single nucleotide polymorphisms (SNPs)/kb was identified for this gene, including some novel SNPs. Additionally, we found thatPfmrp2harbors a significant number of microindels, some previously not reported. We also investigated the potential association of the identifiedPfmrp2polymorphisms with alteredin vitrosusceptibility to several antimalarials used in artemisinin-based combination therapy and with parasite clearance time. Association analysis suggestedPfmrp2polymorphisms modulate the parasite'sin vitroresponse to quinoline antimalarials, including chloroquine, piperaquine, and mefloquine, and association within vivoparasite clearance. In conclusion, our study reveals that thePfmrp2gene is the most diverse ABC transporter known inP. falciparumwith a potential role in antimalarial drug resistance.

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Evaluation of antimalarial prescription pattern and susceptibility of Plasmodium falciparum isolates in Kaduna, Nigeria

International Journal of Biological and Chemical Sciences ◽

10.4314/ijbcs.v13i7.34 ◽

2020 ◽

Vol 13 (7) ◽

pp. 3398-3410

Author(s):

O. Ifeoluwa Akanni ◽

J.O. Ehinmidu ◽

R.O. Bolaji

Keyword(s):

Plasmodium Falciparum ◽

Combination Therapy ◽

Antimalarial Drug ◽

Drug Prescription ◽

Artemisinin Combination Therapy ◽

Therapy Resistance ◽

Antimalarial Drugs ◽

In Vitro Susceptibility

Nigeria carries the highest burden of malaria in terms of morbidity and mortality. This is compounded by continuous resistance of Plasmodium falciparum to antimalarial drugs. This study was designed to evaluate the profile of malaria patients’ antimalarial drug prescription and in vitro susceptibility of P. falciparum isolates to commonly prescribed antimalarial drugs in Kaduna, Nigeria. Three years’ records of patients antimalarial drug prescriptions were collated (2013 to 2015) and the in vitro antimalarial agent susceptibility was determined for 28 clinical isolates using WHO Mark III microtest. Artemisinin-based combination therapy (ACT) was the most prescribed antimalarial for the period under review (92.3-93.7%). Among the ACTs, Artemether-lumefantrine was most prescribed. Of the 28 P. falciparum isolates evaluated, 3 (10.71%) were resistant to chloroquine with a median IC50 of 4.82μM (4.60-8.14μM), while five (17.86%) were resistant to mefloquine with a median IC50 of 25μM (10.3-41μM), 7(25.00%) to artemether with a median IC50 of 2.69μM (2.09-8.77μM), 9 (32.14%) to artesunate-mefloquine combination with a median IC50 of 9.0μM (7.98-35μM) and to artesunate, 11(39.29%) were resistant with a median IC50 of 2.4μM (1.56-5.65μM). This result shows a decline in resistance of P. falciparum to chloroquine compared to period prior to artemisinin-combination therapy as well as reduced susceptibility to artesunate and artemether. Further in vitro and in vivo monitoring will be required to inform antimalarial drug policy change.Keywords: Antimalarial, Artemisinin-combination therapy, resistance, susceptibility, microtest.

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A Study of Synergy of Combination of Eosin B with Chloroquine, Artemisinin, and Sulphadoxine-Pyrimethamine on Plasmodium falciparum In Vitro and Plasmodium berghei In Vivo

Journal of Tropical Medicine ◽

10.1155/2020/3013701 ◽

2020 ◽

Vol 2020 ◽

pp. 1-10 ◽

Cited By ~ 1

Author(s):

Sedigheh Sadeghi ◽

Zarrintaj Valadkhani ◽

Alireza Sadeghi Tafreshi ◽

Mohammad Arjmand ◽

Hossein Nahravanian ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Plasmodium Berghei ◽

Combination Index ◽

Antimalarial Drugs ◽

Live Cells ◽

Eosin B ◽

Suppression Test ◽

Sulphadoxine Pyrimethamine

Background and Objectives. Artemisinin is the popular antimalarial medication, but it has to be used in combination with other drugs as its monotherapy causes resistance. The effectiveness of eosin B, a laboratory stain, as a competent antimalarial agent was identified earlier. It was tested in combination with different antimalarial drugs such as artesunate (a derivative of artemisinin) or chloroquine or sulphadoxine-pyrimethamine in vitro on Plasmodium falciparum and in vivo on Plasmodium berghei using Peter’s suppression test. Methods. Drug assessment was carried out singly or in combination on Plasmodium falciparum in vitro using the candle jar method at three inhibitory concentrations. Percent parasitemia of live cells was obtained by microscopic counting. Peter’s suppression test was carried out on mice infected with Plasmodium berghei after 3 administration of the drugs singly and in combination, and parasites were counted by microscopy for 10 days. Results. Synergy was exhibited by isobolograms of eosin B combined with artesunate and sulphadoxine-pyrimethamine with more than 10 fold reduction of all drugs in vitro. A good combination index was obtained with artesunate at 50% inibitory concentration with 3.4 nM eosin B and 1.7 nM artesunate in contrast to 124 nM eosin B and 7.6 nM artesunate singly. In vivo studies also showed a considerable lowering of the effective dose of eosin B 30 mg/kg: artesunate 3 mg/kg with 200 mg/kg eosin B and 60 mg/kg artesunate separately. Sulphadoxine-pyrimethamine seemed to have the greatest synergistic effect with a combination index of 0.007, but this could be due to it consisting of a combination of three drugs. Eosin B’s combination index with chloroquine was fair, and in vivo tests too did not show as much competence as the other two drugs. Conclusion and Interpretation. It can be concluded that eosin B can be used in combination with antimalarial drugs with favorable results.

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Antimalarial Activity of Curcuma Caesia Against 3D7 and K1 Strains of Plasmodium Falciparum

10.21203/rs.3.rs-32452/v1 ◽

2020 ◽

Author(s):

Monika Chaturvedi ◽

Reena Rani ◽

Dushyant Sharma ◽

Jaya Parkash Yadav

Keyword(s):

Plasmodium Falciparum ◽

Ethyl Acetate ◽

In Silico ◽

Antimalarial Activity ◽

Antimalarial Drugs ◽

Mechanism Study ◽

Effective Development ◽

Ethyl Acetate Extracts

Abstract Background: Malaria is a severe and sometimes mortal tropical disease that spreads through parasites. The purpose of the study was to evaluate in vitro and in-silicoantiplasmodial potential of Curcuma caesia extracts against Plasmodium falciparum.Methods: Lack of a vaccine and the widespread resistance to antimalarial drugs have resulted in emphasis on novel antimalarial drugs development. Ethyl acetate and methanol extracts of Curcuma caesia were prepared and analysed for their antiplasmodial activity against Chloroquine sensitive (3D7) and resistant (K1) strains of P. falciparumusingfluorescence-based SYBR Green assay. The cytotoxicity tests were carried out using the verocell lines by MTT assay.The phosphoethanolamine methyltransferase enzyme ((PfPMT) essential for growth of Plasmodium falciparum was used as protein target for in-silicostudy.Result: Curcuma caesia ethyl acetate extracts showedpotentantiplasmodial activitywith IC50 values of 3.37 µg/ml and 1.53 µg/ml against 3D7 and K1 strain respectively.Docking results show that β-selinenol an oxygenized sesquiterpene had the free binding energy of -6.76 Kcal/mol.Conclusion: Sesquiterpene present in the Curcuma caesia extract was responsible for antimalarial potential analyzed by molecular modeling. The present findings, however preliminary in nature. Further studies are required to proven the antimalarial efficacy C. caesia by isolating the active compounds and in vivo mechanism study that may contribute to more effective development of antimalarial drugs in the future.

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Stable Artesunate Resistance in A Humanized Mouse Model of Plasmodium falciparum

10.5772/intechopen.100381 ◽

2021 ◽

Author(s):

Sheetal Saini ◽

Rajinder Kumar ◽

Rajeev K. Tyagi

Keyword(s):

Plasmodium Falciparum ◽

Combination Therapy ◽

Malaria Infection ◽

Artemisinin Resistance ◽

Antimalarial Drugs ◽

Humanized Mouse ◽

Humanized Mouse Model ◽

Human Malaria

Plasmodium falciparum, the most devastating human malaria parasite, confers higher morbidity and mortality. Although efforts have been made to develop an effective malaria vaccine, stage- and species-specific short-lived immunity crippled these efforts. Hence, antimalarial drug treatment becomes a mainstay for the treatment of malaria infection in the wake of the unavailability of an effective vaccine. Further, there has been a wide array of antimalarial drugs effective against various developmental stages of P. falciparum due to their different structures, modes of action, and pharmacodynamics as well as pharmacokinetics. The development of resistance against almost all frontline drugs by P. falciparum indicates the need for combination therapy (artemisinin-based combination therapy; ACT) to treat patients with P. falciparum. A higher pool of parasitemia under discontinuous in vivo artemisinin drug pressure in a developed humanized mouse allows the selection of artesunate resistant (ART-R) P. falciparum. Intravenously administered artesunate, using either single flash doses or a 2-day regimen, to the P. falciparum-infected human blood chimeric NOD/SCID.IL-2Rγ−/− immunocompromised (NSG) mice, with progressive dose increments upon parasite recovery, was the strategy deployed to select resistant parasites. Parasite susceptibility to artemisinins and other antimalarial compounds was characterized in vitro and in vivo. P. falciparum has shown to evolve extreme artemisinin resistance as well as co-resistance to antimalarial drugs. Overall, the present information shall be very useful in devising newer therapeutic strategies to treat human malaria infection.

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Ultrastructural observations on the in vitro cytoadherence of Plasmodium falciparum infected red blood cells

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100162132 ◽

1990 ◽

Vol 48 (3) ◽

pp. 914-915

Author(s):

D.J.P. Ferguson ◽

A.R. Berendt ◽

J. Tansey ◽

K. Marsh ◽

C.I. Newbold

Keyword(s):

Plasmodium Falciparum ◽

Red Blood Cells ◽

Blood Cells ◽

Umbilical Vein ◽

Cell Types ◽

Amelanotic Melanoma ◽

Cytoplasmic Process ◽

Umbilical Vein Endothelial Cells

In human malaria, the most serious clinical manifestation is cerebral malaria (CM) due to infection with Plasmodium falciparum. The pathology of CM is thought to relate to the fact that red blood cells containing mature forms of the parasite (PRBC) cytoadhere or sequester to post capillary venules of various tissues including the brain. This in vivo phenomenon has been studied in vitro by examining the cytoadherence of PRBCs to various cell types and purified proteins. To date, three Ijiost receptor molecules have been identified; CD36, ICAM-1 and thrombospondin. The specific changes in the PRBC membrane which mediate cytoadherence are less well understood, but they include the sub-membranous deposition of electron-dense material resulting in surface deformations called knobs. Knobs were thought to be essential for cytoadherence, lput recent work has shown that certain knob-negative (K-) lines can cytoadhere. In the present study, we have used electron microscopy to re-examine the interactions between K+ PRBCs and both C32 amelanotic melanoma cells and human umbilical vein endothelial cells (HUVEC).We confirm previous data demonstrating that C32 cells possess numerous microvilli which adhere to the PRBC, mainly via the knobs (Fig. 1). In contrast, the HUVEC were relatively smooth and the PRBCs appeared partially flattened onto the cell surface (Fig. 2). Furthermore, many of the PRBCs exhibited an invagination of the limiting membrane in the attachment zone, often containing a cytoplasmic process from the endothelial cell (Fig. 2).

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Stage-dependent effect of deferoxamine on growth of Plasmodium falciparum in vitro

Blood ◽

10.1182/blood.v76.6.1250.1250 ◽

1990 ◽

Vol 76 (6) ◽

pp. 1250-1255 ◽

Cited By ~ 36

Author(s):

S Whitehead ◽

TE Peto

Keyword(s):

Plasmodium Falciparum ◽

Growth Inhibition ◽

Antimalarial Activity ◽

Clinical Malaria ◽

Inhibitory Effect ◽

Parasite Development ◽

And Control ◽

Speed Of Onset

Abstract Deferoxamine (DF) has antimalarial activity that can be demonstrated in vitro and in vivo. This study is designed to examine the speed of onset and stage dependency of growth inhibition by DF and to determine whether its antimalarial activity is cytostatic or cytocidal. Growth inhibition was assessed by suppression of hypoxanthine incorporation and differences in morphologic appearance between treated and control parasites. Using synchronized in vitro cultures of Plasmodium falciparum, growth inhibition by DF was detected within a single parasite cycle. Ring and nonpigmented trophozoite stages were sensitive to the inhibitory effect of DF but cytostatic antimalarial activity was suggested by evidence of parasite recovery in later cycles. However, profound growth inhibition, with no evidence of subsequent recovery, occurred when pigmented trophozoites and early schizonts were exposed to DF. At this stage in parasite development, the activity of DF was cytocidal and furthermore, the critical period of exposure may be as short as 6 hours. These observations suggest that iron chelators may have a role in the treatment of clinical malaria.

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In vitro and in vivo inhibition of malaria parasite infection by monoclonal antibodies against Plasmodium falciparum circumsporozoite protein (CSP)

Scientific Reports ◽

10.1038/s41598-021-84622-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Merricka C. Livingstone ◽

Alexis A. Bitzer ◽

Alish Giri ◽

Kun Luo ◽

Rajeshwer S. Sankhala ◽

...

Keyword(s):

Plasmodium Falciparum ◽

Monoclonal Antibodies ◽

Disease Burden ◽

Vaccine Candidate ◽

Specific Binding ◽

Circumsporozoite Protein ◽

Target Epitope ◽

Selection Of

AbstractPlasmodium falciparum malaria contributes to a significant global disease burden. Circumsporozoite protein (CSP), the most abundant sporozoite stage antigen, is a prime vaccine candidate. Inhibitory monoclonal antibodies (mAbs) against CSP map to either a short junctional sequence or the central (NPNA)n repeat region. We compared in vitro and in vivo activities of six CSP-specific mAbs derived from human recipients of a recombinant CSP vaccine RTS,S/AS01 (mAbs 317 and 311); an irradiated whole sporozoite vaccine PfSPZ (mAbs CIS43 and MGG4); or individuals exposed to malaria (mAbs 580 and 663). RTS,S mAb 317 that specifically binds the (NPNA)n epitope, had the highest affinity and it elicited the best sterile protection in mice. The most potent inhibitor of sporozoite invasion in vitro was mAb CIS43 which shows dual-specific binding to the junctional sequence and (NPNA)n. In vivo mouse protection was associated with the mAb reactivity to the NANPx6 peptide, the in vitro inhibition of sporozoite invasion activity, and kinetic parameters measured using intact mAbs or their Fab fragments. Buried surface area between mAb and its target epitope was also associated with in vivo protection. Association and disconnects between in vitro and in vivo readouts has important implications for the design and down-selection of the next generation of CSP based interventions.

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