scholarly journals Plasmodium Falciparum Genetic Factors Rather Than The Hosts' Are Likely To Drive Resistance To Acts In Ghana

2020 ◽  
Author(s):  
Peter Hodoameda ◽  
Nancy Odurowah Duah-Quashie ◽  
Charles Oheneba Hagan ◽  
Sena Matrevi ◽  
Benjamin Abuaku ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Genetic Factors ◽  
Wild Type ◽  
Factors Affecting ◽  
Archived Samples ◽  
Cytochrome 450 ◽  
High Prevalence ◽  
Low Prevalence

Abstract Background Artemisinin-based Combination Therapy (ACT) partner drugs, currently used in Ghana are lumefantrine, amodiaquine, and piperaquine. Plasmodium falciparum isolates with reduced susceptibility to these partner drugs may affect treatment outcome. Mutations in Pfmdr1 gene is linked to reduced parasite susceptibility to amodiaquine and lumefantrine. In addition, the potency of the partner drugs in vivo depends on the metabolism by the cytochrome P450 (CYP) enzyme in the host. Mutations in the CYP2C8 and CYP3A4 genes are linked to reduced metabolism of amodiaquine and lumefantrine respectively in vitro. This study investigated the host and parasite genetic factors affecting the susceptibility of the malaria parasite to ACT partner drugs.Methods Archived samples from 240 patients aged ≤ 9 years participating in antimalarial drug resistance survey in of Ghana and given AL or AA were selected and analyzed. Polymerase chain reaction (PCR) followed by Sanger sequencing was used to determine the polymorphisms in CYP2C8, CYP3A4, and Pfmdr1 genes.Results For CYP3A4, all had wild type alleles suggesting that the hosts are good metabolizers of lumefantrine. For CYP2C8 60% had wild type alleles, 35% heterozygous and 5% homozygous recessive alleles suggesting efficient metabolism of amodiaquine by the hosts. For Pfmdr1 gene, at codon 86, 95% were wild type (N86) and 5% mutant (Y86). For codon 184, 36% were wild type (Y184) and 64% mutant (F184) while for codons 1034, 1042 and 1246, 100% (all) were wild type. The high prevalence of NFD suggest presence of parasites with reduced susceptibility to lumefantrine and not amodiaquine. Delayed clearance was observed in individuals with mutations in the Pfmdr1 gene and not Cytochrome 450 gene. Both synonymous and nonsynonymous mutations were observed in the Pfmdr1 at low prevalence.Conclusion The outcome of this study indicates that parasite's genetic factors rather than the hosts' are likely to drive resistance to ACTs in Ghana.

scholarly journals Plasmodium falciparum genetic factors rather than the hosts' are likely to drive resistance to ACTs in Ghana

2020 ◽  
Author(s):  
Peter Hodoameda ◽  
Nancy Odurowah Duah-Quashie ◽  
Charles Oheneba Hagan ◽  
Sena Matrevi ◽  
Benjamin Abuaku ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Genetic Factors ◽  
Wild Type ◽  
Factors Affecting ◽  
Archived Samples ◽  
Cytochrome 450 ◽  
High Prevalence ◽  
Low Prevalence

Abstract Background: Artemisinin-based Combination Therapy (ACT) partner drugs, currently used in Ghana are lumefantrine, amodiaquine, and piperaquine. Plasmodium falciparum isolates with reduced susceptibility to these partner drugs may affect treatment outcome. Mutations in Pfmdr1 gene is linked to reduced parasite susceptibility to amodiaquine and lumefantrine. In addition, the potency of the partner drugs in vivo depends on the metabolism by the cytochrome P450 (CYP) enzyme in the host. Mutations in the CYP2C8 and CYP3A4 genes are linked to reduced metabolism of amodiaquine and lumefantrine respectively in vitro. This study investigated the host and parasite genetic factors affecting the susceptibility of the malaria parasite to ACT partner drugs.Methods: Archived samples from 240 patients aged ≤9years participating in antimalarial drug resistance survey in of Ghana and given AL or AA were selected and analyzed. Polymerase chain reaction (PCR) followed by Sanger sequencing was used to determine the polymorphisms in CYP2C8, CYP3A4, and Pfmdr1 genes. Results: For CYP3A4, all had wild type alleles suggesting that the hosts are good metabolizers of lumefantrine. For CYP2C8 60% had wild type alleles, 35% heterozygous and 5% homozygous recessive alleles suggesting efficient metabolism of amodiaquine by the hosts. For Pfmdr1 gene, at codon 86, 95% were wild type (N86) and 5% mutant (Y86). For codon 184, 36% were wild type (Y184) and 64% mutant (F184) while for codons 1034, 1042 and 1246, 100% (all) were wild type. The high prevalence of N86-F184-D1246 haplotype (NFD) suggest presence of parasites with reduced susceptibility to lumefantrine and not amodiaquine. Delayed clearance was observed in individuals with mutations in the Pfmdr1 gene and not Cytochrome 450 gene. Both synonymous and nonsynonymous mutations were observed in the Pfmdr1 at low prevalence. Conclusion: The outcome of this study indicates that parasite's genetic factors rather than the hosts' are likely to drive resistance to ACTs in Ghana.

scholarly journals Plasmodium falciparum genetic factors rather than host factors are likely to drive resistance to ACT in Ghana

2020 ◽  
Author(s):  
Peter Hodoameda ◽  
Nancy Odurowah Duah-Quashie ◽  
Charles Oheneba Hagan ◽  
Sena Matrevi ◽  
Benjamin Abuaku ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Genetic Factors ◽  
Wild Type ◽  
Factors Affecting ◽  
Synonymous Mutations ◽  
Archived Samples ◽  
Cytochrome 450 ◽  
Low Prevalence

Abstract Background Artemisinin-based combination therapy (ACT) partner drugs, currently used in Ghana are lumefantrine, amodiaquine and piperaquine. Plasmodium falciparum isolates with reduced susceptibility to these partner drugs may affect treatment outcome. Mutations in pfmdr1 gene is linked to reduced parasite susceptibility to amodiaquine and lumefantrine. In addition, the potency of the partner drugs in vivo depends on the metabolism by the cytochrome P450 (CYP) enzyme in the host. Mutations in the CYP2C8 and CYP3A4 genes are linked to reduced metabolism of amodiaquine and lumefantrine in vitro, respectively. This study investigated the host and parasite genetic factors affecting the susceptibility of the malaria parasite to ACT partner drugs.Methods Archived samples from 240 patients age ≤9 years participating in anti-malarial drug resistance survey in Ghana, and given artemether with lumefantrine (AL) or artesunate with amodiaquine (AA), were selected and analysed. Polymerase chain reaction (PCR) followed by Sanger sequencing was used to determine the polymorphisms in CYP2C8, CYP3A4 and pfmdr1 genes. Results For CYP3A4, all had wild type alleles, suggesting that the hosts are good metabolizers of lumefantrine. For CYP2C8 60% had wild type alleles, 35% heterozygous and 5% homozygous recessive alleles suggesting efficient metabolism of amodiaquine by the hosts. For pfmdr1 gene, at codon 86, 95% were wild type (N86) and 5% mutant (Y86). For codon 184, 36% were wild type (Y184) and 64% mutant (F184) while for codons 1034, 1042 and 1246, 100% (all) were wild type. The high prevalence of N86-F184-D1246 haplotype (NFD) suggest presence of parasites with reduced susceptibility to lumefantrine and not amodiaquine. Delayed clearance was observed in individuals with mutations in the pfmdr1 gene and not cytochrome 450 gene. Both synonymous and non-synonymous mutations were observed in the Pfmdr1 at low prevalence. Conclusion The outcome of this study indicates that the parasite's genetic factors rather than the host’s are likely to drive resistance to ACT in Ghana.

scholarly journals Plasmodium falciparum genetic factors rather than the hosts' are likely to drive resistance to acts in ghana.

2020 ◽  
Author(s):  
Peter Hodoameda ◽  
Nancy Duah Quashie ◽  
Charles Oheneba Hagan ◽  
Sena Matrevi ◽  
Benjamin Abuaku ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Genetic Factors ◽  
Multidrug Resistant ◽  
Wild Type ◽  
Factors Affecting ◽  
Archived Samples ◽  
Cytochrome 450 ◽  
Low Prevalence

Abstract Background: Artemisinin-based Combination Therapy (ACT), a combination of a fast-acting artemisinin derivative and a relatively slow-acting partner drug, is used for malaria treatment in disease-endemic areas. The ACT partner drugs, currently used in Ghana are lumefantrine, amodiaquine, and piperaquine. Plasmodium falciparum isolates with reduced susceptibility to these partner drugs may affect treatment outcome. Mutations in the parasite multidrug-resistant 1 (Pfmdr1) gene is linked to reduced susceptibility to amodiaquine and lumefantrine. In addition, the potency of the partner drugs in vivo depends on the metabolism by the cytochrome P450 (CYP) enzyme in the host. Mutations in the CYP2C8 gene are linked to reduced metabolism of amodiaquine in vitro while mutations in CYP3A4 may be linked to reduced metabolism to lumefantrine in vitro. Methods: This study investigated the host and parasite genetic factors affecting the susceptibility of the malaria parasite to ACT partner drugs. Archived samples from 240 patients (120 given AL and the other half given AA) aged ≤9years participating in antimalarial drug resistance survey in sites representing the three ecological areas of Ghana were used. Polymerase chain reaction (PCR) followed by Sanger sequencing was used to determine the polymorphisms in CYP2C8, CYP3A4, and Pfmdr1 genes. Results: Of the 93 samples successfully genotyped for CYP3A4, all had wild type alleles which suggest that the hosts are good metabolizers of lumefantrine. Ninety-four samples were successfully genotyped for CYP2C8 of which 60% had wild type alleles, 35% heterozygous and 5% homozygous recessive alleles. The high percentage of wild type alleles observed also suggests that amodiaquine was metabolized efficiently by the hosts. Ninety-five samples were successfully genotyped for the Pfmdr1 gene. At codon 86, 95% were wild type (N86), 5% mutant (Y86). For codon 184, 36% were wild type (Y184) and 64% mutant (F184) while for codons 1034, 1042 and 1246, 100% (all) were wild type. The high prevalence of N86, F184, and D1246 (NFD) suggest the presence of strains of the parasites with reduced susceptibility to lumefantrine and not amodiaquine. Delayed clearance was observed in individuals with mutations in the Pfmdr1 gene and not Cytochrome 450 gene. There were both synonymous and nonsynonymous mutations observed in the Pfmdr1 at low prevalence. Conclusion: The outcome of this study indicates that parasite's genetic factors rather than the hosts' are likely to drive resistance to ACTs in Ghana.

scholarly journals Chemical Attenuation of Plasmodium berghei Sporozoites Induces Sterile Immunity in Mice

2008 ◽  
Vol 76 (3) ◽  
pp. 1193-1199 ◽  
Author(s):  
Lisa A. Purcell ◽  
Stephanie K. Yanow ◽  
Moses Lee ◽  
Terry W. Spithill ◽  
Ana Rodriguez
Keyword(s):  
Plasmodium Falciparum ◽  
Plasmodium Berghei ◽  
Alkylating Agent ◽  
Blood Stage ◽  
Wild Type ◽  
Vaccine Strategy ◽  
Liver Stage ◽  
Stage Development

ABSTRACT Radiation and genetic attenuation of Plasmodium sporozoites are two approaches for whole-organism vaccines that protect against malaria. We evaluated chemical attenuation of sporozoites as an alternative vaccine strategy. Sporozoites were treated with the DNA sequence-specific alkylating agent centanamycin, a compound that significantly affects blood stage parasitemia and transmission of murine malaria and also inhibits Plasmodium falciparum growth in vitro. Here we show that treatment of Plasmodium berghei sporozoites with centanamycin impaired parasite function both in vitro and in vivo. The infection of hepatocytes by sporozoites in vitro was significantly reduced, and treated parasites showed arrested liver stage development. Inoculation of mice with sporozoites that were treated in vitro with centanamycin failed to produce blood stage infections. Furthermore, BALB/c and C57BL/6 mice vaccinated with treated sporozoites were protected against subsequent challenge with wild-type sporozoites. Our findings demonstrate that chemically attenuated sporozoites could be a viable alternative for the production of an effective liver stage vaccine for malaria.

scholarly journals Artemisinin resistance phenotypes and K13 inheritance in a Plasmodium falciparum cross and Aotus model

2018 ◽  
Vol 115 (49) ◽  
pp. 12513-12518 ◽  
Author(s):  
Juliana M. Sá ◽  
Sarah R. Kaslow ◽  
Michael A. Krause ◽  
Viviana A. Melendez-Muniz ◽  
Rebecca E. Salzman ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Artemisinin Resistance ◽  
Parasite Clearance ◽  
Wild Type ◽  
Infected Monkey ◽  
Allelic Substitution ◽  
Survival Assay ◽  
Mean Differences

Concerns about malaria parasite resistance to treatment with artemisinin drugs (ARTs) have grown with findings of prolonged parasite clearance t1/2s (>5 h) and their association with mutations in Plasmodium falciparum Kelch-propeller protein K13. Here, we describe a P. falciparum laboratory cross of K13 C580Y mutant with C580 wild-type parasites to investigate ART response phenotypes in vitro and in vivo. After genotyping >400 isolated progeny, we evaluated 20 recombinants in vitro: IC50 measurements of dihydroartemisinin were at similar low nanomolar levels for C580Y- and C580-type progeny (mean ratio, 1.00; 95% CI, 0.62–1.61), whereas, in a ring-stage survival assay, the C580Y-type progeny had 19.6-fold (95% CI, 9.76–39.2) higher average counts. In splenectomized Aotus monkeys treated with three daily doses of i.v. artesunate, t1/2 calculations by three different methods yielded mean differences of 0.01 h (95% CI, −3.66 to 3.67), 0.80 h (95% CI, −0.92 to 2.53), and 2.07 h (95% CI, 0.77–3.36) between C580Y and C580 infections. Incidences of recrudescence were 57% in C580Y (4 of 7) versus 70% in C580 (7 of 10) infections (−13% difference; 95% CI, −58% to 35%). Allelic substitution of C580 in a C580Y-containing progeny clone (76H10) yielded a transformant (76H10C580Rev) that, in an infected monkey, recrudesced regularly 13 times over 500 d. Frequent recrudescences of ART-treated P. falciparum infections occur with or without K13 mutations and emphasize the need for improved partner drugs to effectively eliminate the parasites that persist through the ART component of combination therapy.

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

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).

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

Blood ◽  
1990 ◽  
Vol 76 (6) ◽  
pp. 1250-1255 ◽  
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.

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

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.

scholarly journals Arabidopsis Disulfide Reductase, Trx-h2, Functions as an RNA Chaperone under Cold Stress

2021 ◽  
Vol 11 (15) ◽  
pp. 6865
Author(s):  
Eun Seon Lee ◽  
Joung Hun Park ◽  
Seong Dong Wi ◽  
Ho Byoung Chae ◽  
Seol Ki Paeng ◽  
...  
Keyword(s):  
Cold Stress ◽  
Wild Type ◽  
Rna Chaperone ◽  
E Coli ◽  
Cold Sensitive ◽  
Thioredoxin H ◽  
Functional Rnas

The thioredoxin-h (Trx-h) family of Arabidopsis thaliana comprises cytosolic disulfide reductases. However, the physiological function of Trx-h2, which contains an additional 19 amino acids at its N-terminus, remains unclear. In this study, we investigated the molecular function of Trx-h2 both in vitro and in vivo and found that Arabidopsis Trx-h2 overexpression (Trx-h2OE) lines showed significantly longer roots than wild-type plants under cold stress. Therefore, we further investigated the role of Trx-h2 under cold stress. Our results revealed that Trx-h2 functions as an RNA chaperone by melting misfolded and non-functional RNAs, and by facilitating their correct folding into active forms with native conformation. We showed that Trx-h2 binds to and efficiently melts nucleic acids (ssDNA, dsDNA, and RNA), and facilitates the export of mRNAs from the nucleus to the cytoplasm under cold stress. Moreover, overexpression of Trx-h2 increased the survival rate of the cold-sensitive E. coli BX04 cells under low temperature. Thus, our data show that Trx-h2 performs function as an RNA chaperone under cold stress, thus increasing plant cold tolerance.

scholarly journals Silver Nanoparticles and Their Antibacterial Applications

2021 ◽  
Vol 22 (13) ◽  
pp. 7202
Author(s):  
Tamara Bruna ◽  
Francisca Maldonado-Bravo ◽  
Paul Jara ◽  
Nelson Caro
Keyword(s):  
Silver Nanoparticles ◽  
Antibacterial Agents ◽  
Multidrug Resistant ◽  
Secondary Effects ◽  
Cytotoxic Effects ◽  
Factors Affecting ◽  
Gram Positive Bacteria ◽  
Resistant Strains

Silver nanoparticles (AgNPs) have been imposed as an excellent antimicrobial agent being able to combat bacteria in vitro and in vivo causing infections. The antibacterial capacity of AgNPs covers Gram-negative and Gram-positive bacteria, including multidrug resistant strains. AgNPs exhibit multiple and simultaneous mechanisms of action and in combination with antibacterial agents as organic compounds or antibiotics it has shown synergistic effect against pathogens bacteria such as Escherichia coli and Staphylococcus aureus. The characteristics of silver nanoparticles make them suitable for their application in medical and healthcare products where they may treat infections or prevent them efficiently. With the urgent need for new efficient antibacterial agents, this review aims to establish factors affecting antibacterial and cytotoxic effects of silver nanoparticles, as well as to expose the advantages of using AgNPs as new antibacterial agents in combination with antibiotic, which will reduce the dosage needed and prevent secondary effects associated to both.

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