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1.
J Infect Dis ; 229(6): 1894-1903, 2024 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-38408353

RESUMO

BACKGROUND: Plasmodium falciparum and Plasmodium vivax account for >90% global malaria burden. Transmission intervention strategies encompassing transmission-blocking vaccines (TBV) and drugs represent ideal public health tools to eliminate malaria at the population level. The availability of mature P. falciparum gametocytes through in vitro culture has facilitated development of a standard membrane feeding assay to assess efficacy of transmission interventions against P. falciparum. The lack of in vitro culture for P. vivax has significantly hampered similar progress on P. vivax and limited studies have been possible using blood from infected patients in endemic areas. The ethical and logistical limitations of on-time access to blood from patients have impeded the development of P. vivax TBVs. METHODS: Transgenic murine malaria parasites (Plasmodium berghei) expressing TBV candidates offer a promising alternative for evaluation of P. vivax TBVs through in vivo studies in mice, and ex vivo membrane feeding assay (MFA). RESULTS: We describe the development of transmission-competent transgenic TgPbvs25 parasites and optimization of parameters to establish an ex vivo MFA to evaluate P. vivax TBV based on Pvs25 antigen. CONCLUSIONS: The MFA is expected to expedite Pvs25-based TBV development without dependence on blood from P. vivax-infected patients in endemic areas for evaluation.


Assuntos
Vacinas Antimaláricas , Malária Vivax , Plasmodium berghei , Plasmodium vivax , Animais , Vacinas Antimaláricas/imunologia , Vacinas Antimaláricas/genética , Plasmodium vivax/genética , Plasmodium vivax/imunologia , Malária Vivax/transmissão , Malária Vivax/prevenção & controle , Malária Vivax/parasitologia , Plasmodium berghei/genética , Plasmodium berghei/imunologia , Camundongos , Antígenos de Protozoários/imunologia , Antígenos de Protozoários/genética , Humanos , Feminino , Antígenos de Superfície
2.
Infect Immun ; 92(3): e0037423, 2024 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-38289124

RESUMO

Gamete surface protein P48/45 has been shown to be important for male gamete fertility and a strong candidate for the development of a malaria transmission-blocking vaccine (TBV). However, TBV development for Plasmodium vivax homolog Pvs48/45 has been slow because of a number of challenges: availability of conformationally suitable recombinant protein; the lack of an in vivo challenge model; and the inability to produce P. vivax gametocytes in culture to test transmission-blocking activity of antibodies. To support ongoing efforts to develop Pvs48/45 as a potential vaccine candidate, we initiated efforts to develop much needed reagents to move the field forward. We generated monoclonal antibodies (mAbs) directed against Pvs48/45 and characterized putative functional domains in Pvs48/45 using recombinant fragments corresponding to domains D1-D3 and their biological functionality through ex vivo direct membrane feeding assays (DMFAs) using P. vivax parasites from patients in a field setting in Brazil. While some mAbs partially blocked oocyst development in the DMFA, one mAb caused a significant enhancement of the infectivity of gametocytes in the mosquitoes. Individual mAbs exhibiting blocking and enhancing activities recognized non-overlapping epitopes in Pvs48/45. Further characterization of precise epitopes recognized by transmission-reducing and -enhancing antibodies will be crucial to design an effective immunogen with optimum transmission-reducing potential.


Assuntos
Vacinas Antimaláricas , Malária Vivax , Animais , Humanos , Masculino , Plasmodium vivax , Anticorpos Monoclonais , Proteínas de Membrana , Antígenos de Protozoários/genética , Epitopos , Células Germinativas , Anticorpos Antiprotozoários
3.
Genome Res ; 27(1): 133-144, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-28003436

RESUMO

Complementing genome sequence with deep transcriptome and proteome data could enable more accurate assembly and annotation of newly sequenced genomes. Here, we provide a proof-of-concept of an integrated approach for analysis of the genome and proteome of Anopheles stephensi, which is one of the most important vectors of the malaria parasite. To achieve broad coverage of genes, we carried out transcriptome sequencing and deep proteome profiling of multiple anatomically distinct sites. Based on transcriptomic data alone, we identified and corrected 535 events of incomplete genome assembly involving 1196 scaffolds and 868 protein-coding gene models. This proteogenomic approach enabled us to add 365 genes that were missed during genome annotation and identify 917 gene correction events through discovery of 151 novel exons, 297 protein extensions, 231 exon extensions, 192 novel protein start sites, 19 novel translational frames, 28 events of joining of exons, and 76 events of joining of adjacent genes as a single gene. Incorporation of proteomic evidence allowed us to change the designation of more than 87 predicted "noncoding RNAs" to conventional mRNAs coded by protein-coding genes. Importantly, extension of the newly corrected genome assemblies and gene models to 15 other newly assembled Anopheline genomes led to the discovery of a large number of apparent discrepancies in assembly and annotation of these genomes. Our data provide a framework for how future genome sequencing efforts should incorporate transcriptomic and proteomic analysis in combination with simultaneous manual curation to achieve near complete assembly and accurate annotation of genomes.


Assuntos
Genoma/genética , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Anotação de Sequência Molecular , Transcriptoma/genética , Animais , Anopheles/genética , Éxons/genética , Perfilação da Expressão Gênica , Proteoma/genética , Proteômica
4.
Microb Cell Fact ; 19(1): 183, 2020 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-32957994

RESUMO

Resistance towards known antimalarial drugs poses a significant problem, urging for novel drugs that target vital proteins in the malaria parasite Plasmodium falciparum. However, recombinant production of malaria proteins is notoriously difficult. To address this, we have investigated two putative K+ channels, PfKch1 and PfKch2, identified in the P. falciparum genome. We show that PfKch1 and PfKch2 and a C-terminally truncated version of PfKch1 (PfKch11-1094) could indeed be functionally expressed in vivo, since a K+-uptake deficient Saccharomyces cerevisiae strain was complemented by the P. falciparum cDNAs. PfKch11-1094-GFP and GFP-PfKch2 fusion proteins were overexpressed in yeast, purified and reconstituted in lipid bilayers to determine their electrophysiological activity. Single channel conductance amounted to 16 ± 1 pS for PfKch11-1094-GFP and 28 ± 2 pS for GFP-PfKch2. We predicted regulator of K+-conductance (RCK) domains in the C-terminals of both channels, and we accordingly measured channel activity in the presence of Ca2+.


Assuntos
Plasmodium falciparum/genética , Canais de Potássio/biossíntese , Proteínas de Protozoários/biossíntese , Saccharomyces cerevisiae/metabolismo , Sequência de Aminoácidos , Animais , Clonagem Molecular , Teste de Complementação Genética , Proteínas de Fluorescência Verde/metabolismo , Canais de Potássio/genética , Domínios Proteicos , Proteínas de Protozoários/genética , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/genética , Saccharomyces cerevisiae/genética
5.
Soft Matter ; 15(26): 5308-5318, 2019 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-31225545

RESUMO

Foaming, which is of significant importance to many industrial processes, is attributed to the reduced coalescence of bubbles due to the presence of stabilizing/foaming agents such as surfactants and nanoparticles. While foams have been extensively investigated for their rheological properties, their impact on the critical heat flux (CHF) during boiling is not well understood. The technical benefits of CHF enhancement with nanofluids are lost when surfactants are added to improve their stability. The actual mechanism of this decrease is unresolved, and thermal engineers are forced to look for alternative CHF enhancement solutions. Here, we showed that nucleating bubbles formed vapor-foam and crowded the heater surface to inhibit rewetting. Less frequent rewetting forces premature dryout, which is primarily responsible for the reported CHF deterioration. In this regime, strong foaming agents such as SDS mask the effect of nanoparticles on CHF. Using these insights, we presented a master curve that captured the effect of foamability on CHF and could be used to predict the value of CHF solely based on the foamability of the solution. We further showed that the CHF mechanism switched from the foamability regime to the conventional wettability regime upon lowering the surfactant concentration and/or with weakly foaming surfactants. In such cases, an increase in the nanoparticle concentration successfully increased CHF. We believe that the important clarifications regarding the CHF mechanism with nanofluids and the master curve of CHF versus foamability presented in this study will facilitate the design of energy-efficient boiling systems.

6.
Biochem Biophys Res Commun ; 493(1): 690-696, 2017 11 04.
Artigo em Inglês | MEDLINE | ID: mdl-28864420

RESUMO

K+ channels are integral membrane proteins, which contribute to maintain vital parameters such as the cellular membrane potential and cell volume. Malaria parasites encode two K+ channel homologues, Kch1 and Kch2, which are well-conserved among members of the Plasmodium genus. In the rodent malaria parasite P. berghei, the functional significance of K+ channel homologue PbKch2 was studied using targeted gene knock-out. The knockout parasites were characterized in a mouse model in terms of growth-kinetics and infectivity in the mosquito vector. Furthermore, using a tracer-uptake technique with 86Rb+ as a K+ congener, the K+ transporting properties of the knockout parasites were assessed. RESULTS: Genetic disruption of Kch2 did not grossly affect the phenotype in terms of asexual replication and pathogenicity in a mouse model. In contrast to Kch1-null parasites, Kch2-null parasites were fully capable of forming oocysts in female Anopheles stephensi mosquitoes. 86Rb+ uptake in Kch2-deficient blood-stage P. berghei parasites (Kch2-null) did not differ from that of wild-type (WT) parasites. About two-thirds of the 86Rb+ uptake in WT and in Kch2-null parasites could be inhibited by K+ channel blockers and could be inferred to the presence of functional Kch1 in Kch2 knockout parasites. Kch2 is therefore not required for transport of K+ in P. berghei and is not essential to mosquito-stage sporogonic development of the parasite.


Assuntos
Anopheles/parasitologia , Malária/parasitologia , Plasmodium berghei/metabolismo , Plasmodium berghei/patogenicidade , Canais de Potássio/metabolismo , Proteínas de Protozoários/metabolismo , Animais , Feminino , Masculino , Camundongos , Plasmodium berghei/genética , Canais de Potássio/genética , Proteínas de Protozoários/genética
7.
Pharm Res ; 34(9): 1796-1804, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28560696

RESUMO

PURPOSE: The present study investigated the immunogenic potential of different cationic liposome formulations with a DNA plasmid encoding Pfs25, a malaria transmission-blocking vaccine candidate. METHODS: Pfs25 plasmid DNA was complexed with cationic liposomes to produce lipoplexes at different charge ratios of the cationic lipid head group to the nucleotide phosphate (N:P). The formation of lipoplexes was visualized by Cryogenic-TEM. Confocal microscopy of lipoplexes formed with GFP encoding plasmid DNA, and flow cytometry was used to determine their in vitro transfection capability. Two different lipoplex formulations using plasmid DNA encoding Pfs25 were evaluated for in vivo immunogenicity after intramuscular administration in Balb/c mice. Immune sera were analyzed by ELISA. RESULTS: The results demonstrated that the cationic liposome-mediated DNA immunization with an N:P charge ratio of 1:3 (anionic lipoplexes) is more effective than the use of naked plasmid DNA alone. No antibody response was observed when lipoplexes with a higher N:P charge ratio of 10:3 (cationic lipoplexes) were used. Trehalose was added to some lipoplex formulations as a cryoprotectant and adjuvant, but it did not yield any further improvement of immunogenicity in vivo. CONCLUSIONS: The results suggest that Pfs25 plasmid DNA delivered as lipoplexes at a charge ratio of 1:3 elicited strong immunogenicity in mice and may be improved further to match the immune responses of DNA vaccines administered by in vivo electroporation.


Assuntos
Lipossomos/química , Vacinas Antimaláricas/administração & dosagem , Malária Falciparum/prevenção & controle , Transfecção , Vacinas de DNA/administração & dosagem , Animais , Formação de Anticorpos , Cátions/química , Feminino , Células HEK293 , Humanos , Vacinas Antimaláricas/genética , Vacinas Antimaláricas/imunologia , Malária Falciparum/imunologia , Camundongos Endogâmicos BALB C , Plasmídeos/administração & dosagem , Plasmídeos/genética , Plasmídeos/imunologia , Plasmodium falciparum/genética , Plasmodium falciparum/imunologia , Proteínas de Protozoários/genética , Proteínas de Protozoários/imunologia , Eletricidade Estática , Vacinas de DNA/genética , Vacinas de DNA/imunologia
8.
Immunology ; 148(4): 433-47, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-27177843

RESUMO

Sexual stages of Plasmodium are critical for malaria transmission and stage-specific antigens are important targets for development of malaria transmission-blocking vaccines. Plasmodium falciparum gamete surface antigen (Pfs48/45) is important for male gamete fertility and is being pursued as a candidate vaccine antigen. Vaccine-induced transmission-blocking antibodies recognize reduction-sensitive conformational epitopes in Pfs48/45. Processing and presentation of such disulphide-bond-constrained epitopes is critical for eliciting the desired immune responses. Mice lacking interferon-γ-inducible lysosomal thiol reductase (GILT), an enzyme that mediates reduction of S-S bonds during antigen processing, were employed to investigate immunogenicity of Pfs48/45. It has been well established that the ability to reduce S-S bonds in antigens guides effective T-cell immune responses; however, involvement of GILT in the induction of subsequent B-cell responses has not been explored. We hypothesized that the ability to reduce S-S bonds in Pfs48/45 will impact the generation of T-cell epitopes, and so influence helper T-cell responses required for specific B-cell responses. Non-reduced and reduced and alkylated forms of Pfs48/45 were employed to evaluate immune responses in wild-type and GILT knockout mice and studies revealed important differences in several immune response parameters, including differences in putative T-cell epitope recognition, faster kinetics of waning of Pfs48/45-specific IgG1 antibodies in knockout mice, differential patterns of interferon-γ and interleukin-4 secretions by splenocytes, and possible effects of GILT on induction of long-lived plasma cells and memory B cells responsible for antigen-recall responses. These studies emphasize the importance of antigen structural features that significantly influence the development of effective immune responses.


Assuntos
Linfócitos B/imunologia , Epitopos Imunodominantes/imunologia , Vacinas Antimaláricas , Malária/imunologia , Glicoproteínas de Membrana/imunologia , Oxirredutases/metabolismo , Plasmodium falciparum/imunologia , Proteínas de Protozoários/imunologia , Linfócitos T Auxiliares-Indutores/imunologia , Animais , Anticorpos Antiprotozoários/metabolismo , Apresentação de Antígeno , Células Cultivadas , Feminino , Epitopos Imunodominantes/química , Memória Imunológica , Interferon gama/metabolismo , Interleucina-4/metabolismo , Glicoproteínas de Membrana/química , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Oxirredutases/genética , Oxirredutases atuantes sobre Doadores de Grupo Enxofre , Conformação Proteica , Proteínas de Protozoários/química
9.
Malar J ; 15: 237, 2016 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-27113354

RESUMO

BACKGROUND: Malaria remains a public health challenge in sub-Saharan Africa with Plasmodium falciparum being the principal cause of malaria disease morbidity and mortality. Plasmodium falciparum virulence is attributed, in part, to its population-level genetic diversity-a characteristic that has yet to be studied in Rwanda. Characterizing P. falciparum molecular epidemiology in an area is needed for a better understand of malaria transmission and to inform choice of malaria control strategies. METHODS: In this health-facility based survey, malaria case clinical profiles and parasite densities as well as parasite genetic diversity were compared among P. falciparum-infected patients identified at two sites of different malaria transmission intensities in Rwanda. Data on demographics and clinical features and finger-prick blood samples for microscopy and parasite genotyping were collected(.) Nested PCR was used to genotype msp-2 alleles of FC27 and 3D7. RESULTS: Patients' variables of age group, sex, fever (both by patient report and by measured tympanic temperatures), parasite density, and bed net use were found differentially distributed between the higher endemic (Ruhuha) and lower endemic (Mubuga) sites. Overall multiplicity of P. falciparum infection (MOI) was 1.73 but with mean MOI found to vary significantly between 2.13 at Ruhuha and 1.29 at Mubuga (p < 0.0001). At Ruhuha, expected heterozygosity (EH) for FC27 and 3D7 alleles were 0.62 and 0.49, respectively, whilst at Mubuga, EH for FC27 and 3D7 were 0.26 and 0.28, respectively. CONCLUSIONS: In this study, a higher geometrical mean parasite counts, more polyclonal infections, higher MOI, and higher allelic frequency were observed at the higher malaria-endemic (Ruhuha) compared to the lower malaria-endemic (Mubuga) area. These differences in malaria risk and MOI should be considered when choosing setting-specific malaria control strategies, assessing p. falciparum associated parameters such as drug resistance, immunity and impact of used interventions, and in proper interpretation of malaria vaccine studies.


Assuntos
Antígenos de Protozoários/genética , Variação Genética , Malária Falciparum/epidemiologia , Plasmodium falciparum/genética , Proteínas de Protozoários/genética , Adolescente , Adulto , Idoso , Criança , Pré-Escolar , Estudos Transversais , Feminino , Frequência do Gene , Humanos , Lactente , Malária Falciparum/parasitologia , Masculino , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase , Ruanda/epidemiologia , Análise de Sequência de DNA , Adulto Jovem
10.
Emerg Infect Dis ; 21(7): 1122-7, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-26079141

RESUMO

A fast, precise, noninvasive, high-throughput, and simple approach for detecting malaria in humans and mosquitoes is not possible with current techniques that depend on blood sampling, reagents, facilities, tedious procedures, and trained personnel. We designed a device for rapid (20-second) noninvasive diagnosis of Plasmodium falciparum infection in a malaria patient without drawing blood or using any reagent. This method uses transdermal optical excitation and acoustic detection of vapor nanobubbles around intraparasite hemozoin. The same device also identified individual malaria parasite-infected Anopheles mosquitoes in a few seconds and can be realized as a low-cost universal tool for clinical and field diagnoses.


Assuntos
Malária/diagnóstico , Pele/patologia , Animais , Anopheles/parasitologia , Feminino , Humanos , Nanotecnologia , Pele/parasitologia , Vapor
11.
Antimicrob Agents Chemother ; 59(1): 317-25, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25348537

RESUMO

Artemisinin-based combination therapy (ACT) is the recommended first-line treatment for Plasmodium falciparum malaria. It has been suggested that the cytotoxic effect of artemisinin is mediated by free radicals followed by the alkylation of P. falciparum proteins. The endoperoxide bridge, the active moiety of artemisinin derivatives, is cleaved in the presence of ferrous iron, generating reactive oxygen species (ROS) and other free radicals. However, the emergence of resistance to artemisinin in P. falciparum underscores the need for new insights into the molecular mechanisms of antimalarial activity of artemisinin. Here we show that artesunate (ART) induces DNA double-strand breaks in P. falciparum in a physiologically relevant dose- and time-dependent manner. DNA damage induced by ART was accompanied by an increase in the intracellular ROS level in the parasites. Mannitol, a ROS scavenger, reversed the cytotoxic effect of ART and reduced DNA damage, and modulation of glutathione (GSH) levels was found to impact ROS and DNA damage induced by ART. Accumulation of ROS, increased DNA damage, and the resulting antiparasite effect suggest a causal relationship between ROS, DNA damage, and parasite death. Finally, we also show that ART-induced ROS production involves a potential role for NADPH oxidase, an enzyme involved in the production of superoxide anions. Our results with P. falciparum provide novel insights into previously unknown molecular mechanisms underlying the antimalarial activity of artemisinin derivatives and may help in the design of next-generation antimalarial drugs against the most virulent Plasmodium species.


Assuntos
Antimaláricos/farmacologia , Artemisininas/farmacologia , Dano ao DNA/efeitos dos fármacos , Plasmodium falciparum/efeitos dos fármacos , Artesunato , Quebras de DNA de Cadeia Dupla/efeitos dos fármacos , Glutationa/metabolismo , Cinética , Plasmodium falciparum/genética , Espécies Reativas de Oxigênio/metabolismo
12.
Pharm Res ; 32(12): 3827-36, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26113235

RESUMO

PURPOSE: To evaluate functional immunogenicity of CHrPfs25. a malaria transmission blocking vaccine antigen, using nanoemulsion and porous polymeric PLGA nanoparticles. METHODS: CHrPfs25 was formulated with nanoemulsions (NE) and poly(D,L-lactide-co-glycolide) nanoparticles (PLGA-NP) and evaluated via IM route in mice. Transmission blocking efficacy of antibodies was evaluated by standard mosquito membrane feeding assay using purified IgG from immune sera. Physicochemical properties and stability of various formulations were evaluated by measuring poly-dispersity index, particle size and zeta potential. RESULTS: Mice immunized with CHrPfs25 using alum via IP and IM routes induced comparable immune responses. The highest antibody response was obtained with CHrPfs25 formulated in 4% NE as compared to 8% NE and PLGA-NP. No further increases were observed by combining NE with MPL-A and chitosan. One hundred percent transmission blocking activity was demonstrated at 400 µg/ml of IgG for alum groups (both routes IP and IM), 4% NE and NE-MPL-A. Purified IgG from various adjuvant groups at lower doses (100 µg/mL) still exhibited >90% transmission blocking activity, while 52-81% blocking was seen at 50 µg/mL. CONCLUSION: Results suggest that CHrPfs25 delivered in various adjuvants/nanoparticles elicited strong functional immunogenicity in pre-clinical studies in mice. We are now continuing these studies to develop effective vaccine formulations for further evaluation of immune correlates of relative immunogenicity of CHrPfs25 in various adjuvants and clinical trials.


Assuntos
Ácido Láctico/química , Vacinas Antimaláricas/administração & dosagem , Malária Falciparum/prevenção & controle , Nanopartículas/química , Plasmodium falciparum/imunologia , Ácido Poliglicólico/química , Proteínas de Protozoários/administração & dosagem , Proteínas Recombinantes/administração & dosagem , Animais , Formação de Anticorpos , Emulsões/química , Feminino , Imunização , Vacinas Antimaláricas/imunologia , Vacinas Antimaláricas/uso terapêutico , Malária Falciparum/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Nanopartículas/ultraestrutura , Copolímero de Ácido Poliláctico e Ácido Poliglicólico , Proteínas de Protozoários/imunologia , Proteínas de Protozoários/uso terapêutico , Proteínas Recombinantes/imunologia , Proteínas Recombinantes/uso terapêutico
13.
BMC Infect Dis ; 15: 204, 2015 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-25930101

RESUMO

BACKGROUND: Although malaria is preventable and treatable, it still claims 660,000 lives every year globally with children under five years of age having the highest burden. In Zambia, malaria rapid diagnostic tests (RDTs) that only detect Plasmodium falciparum are the main confirmatory means for malaria diagnosis in most health facilities without microscopy services. As a consequence of this P. falciparum species diagnostic approach, non-falciparum malaria is not only under-diagnosed but entirely missed, thereby making the exact disease burden unknown. We thus investigated the prevalence of various Plasmodium spp. and associated burden of infection in selected communities in Zambia. METHODS: Data from two malaria hyper-endemic provinces (Eastern and Luapula) of the 2012 National Malaria Indicator Survey (MIS), conducted between April and May 2012, were used. The MIS is a nationally representative, two-stage cluster survey conducted to coincide with the end of the malaria transmission season. Social, behavioural and background information were collected from households as part of the survey. Thick blood smears, RDTs and dried blood spots (DBS) were collected from children below six years of age. Slides were stained using Giemsa and examined by microscopy while polymerase chain reaction (PCR) was used to analyse the DBS for malaria Plasmodium spp. Multivariate logistic regression was employed to examine the association between background factors and malaria. RESULTS: Overall, 873 children younger than six years of age were surveyed. The overall prevalence of Plasmodium spp. by PCR was 54.3% (95% CI 51-57.6%). Of the total Plasmodium isolates, 88% were P. falciparum, 10.6% were mixed infections and 1.4% were non-falciparum mono infections. Among the mixed infections, the majority were a combination of P. falciparum and P. malariae (6.5% of all mixed infections). Children two years and older (2-5 years) had three-fold higher risk of mixed malaria infections (aOR 2.8 CI 1.31-5.69) than children younger than two years of age. CONCLUSION: The high prevalence of mixed Plasmodium spp. infections in this population stresses review of the current malaria RDT diagnostic approaches. The observed less incidence of mixed infections in children under two years of age compared to their older two-to-five-year-old counterparts is probably due to the protective maternal passive immunity, among other factors, in that age group.


Assuntos
Malária/epidemiologia , Plasmodium/isolamento & purificação , Criança , Serviços de Saúde da Criança , Pré-Escolar , Testes Diagnósticos de Rotina , Doenças Endêmicas , Feminino , Humanos , Lactente , Recém-Nascido , Malária/parasitologia , Malária Falciparum/epidemiologia , Malária Falciparum/parasitologia , Masculino , Plasmodium/genética , Plasmodium falciparum/genética , Plasmodium falciparum/isolamento & purificação , Reação em Cadeia da Polimerase , Prevalência , Estações do Ano , Inquéritos e Questionários , Zâmbia/epidemiologia
14.
J Biol Chem ; 288(39): 27724-36, 2013 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-23943616

RESUMO

Small ubiquitin-related modifiers (SUMOs) are post-translationally conjugated to other proteins and are thereby essential regulators of a wide range of cellular processes. Sumoylation, and enzymes of the sumoylation pathway, are conserved in the malaria causing parasite, Plasmodium falciparum. However, the specific functions of sumoylation in P. falciparum, and the degree of functional conservation between enzymes of the human and P. falciparum sumoylation pathways, have not been characterized. Here, we demonstrate that sumoylation levels peak during midstages of the intra-erythrocyte developmental cycle, concomitant with hemoglobin consumption and elevated oxidative stress. In vitro studies revealed that P. falciparum E1- and E2-conjugating enzymes interact effectively to recognize and modify RanGAP1, a model mammalian SUMO substrate. However, in heterologous reactions, P. falciparum E1 and E2 enzymes failed to interact with cognate human E2 and E1 partners, respectively, to modify RanGAP1. Structural analysis, binding studies, and functional assays revealed divergent amino acid residues within the E1-E2 binding interface that define organism-specific enzyme interactions. Our studies identify sumoylation as a potentially important regulator of oxidative stress response during the P. falciparum intra-erythrocyte developmental cycle, and define E1 and E2 interactions as a promising target for development of parasite-specific inhibitors of sumoylation and parasite replication.


Assuntos
Plasmodium falciparum/metabolismo , Proteínas de Protozoários/metabolismo , Proteínas Modificadoras Pequenas Relacionadas à Ubiquitina/metabolismo , Enzimas Ativadoras de Ubiquitina/metabolismo , Enzimas de Conjugação de Ubiquitina/metabolismo , Sequência de Aminoácidos , Eritrócitos/metabolismo , Regulação da Expressão Gênica , Proteínas de Fluorescência Verde/metabolismo , Humanos , Microscopia de Fluorescência , Conformação Molecular , Dados de Sequência Molecular , Estresse Oxidativo , Ligação Proteica , Processamento de Proteína Pós-Traducional , Proteínas Recombinantes/metabolismo , Homologia de Sequência de Aminoácidos , Sumoilação , Ubiquitina/metabolismo
15.
Infect Immun ; 82(4): 1453-9, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24421036

RESUMO

Production of Pfs25, a Plasmodium falciparum transmission-blocking vaccine target antigen, in functional conformation with the potential to elicit effective immunogenicity still remains a major challenge. In the current study, codon-harmonized recombinant Pfs25 (CHrPfs25) was expressed in Escherichia coli, and purified protein after simple oxidative refolding steps retained reduction-sensitive conformational epitopes of transmission-blocking monoclonal antibodies. CHrPfs25 formulated in several adjuvants elicited strong immunogenicity in preclinical studies in mice. Antibodies elicited after immunization recognized native Pfs25 on the surface of live gametes of P. falciparum and demonstrated complete malaria transmission-blocking activity. The transmission-blocking efficacy was 100% even after a 1:128 dilution of sera from immunized mice in the complete Freund's adjuvant and Montanide ISA51 groups and after a 1:16 dilution of sera from mice in the alum group. The blocking was mediated by antibodies; purified IgG at concentrations as low as 31.25 µg/ml exhibited 100% transmission blocking in membrane feeding assays employing two different species of mosquitoes, Anopheles gambiae and Anopheles stephensi. This study provides the first evidence for successful expression of biologically functional rPfs25 in E. coli. The extremely potent malaria transmission-blocking activity of antibodies elicited by immunization with purified protein provides strong support for further evaluation of E. coli-derived CHrPfs25 as a malaria transmission-blocking vaccine in human clinical trials.


Assuntos
Escherichia coli/metabolismo , Vacinas Antimaláricas/imunologia , Malária Falciparum/prevenção & controle , Plasmodium falciparum/imunologia , Dobramento de Proteína , Proteínas de Protozoários/metabolismo , Animais , Anticorpos Antiprotozoários/imunologia , Antígenos de Protozoários/imunologia , Escherichia coli/imunologia , Feminino , Imunoglobulina G/imunologia , Malária Falciparum/transmissão , Camundongos , Camundongos Endogâmicos BALB C , Proteínas de Protozoários/química , Proteínas de Protozoários/imunologia
16.
Genome Res ; 21(11): 1872-81, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21795387

RESUMO

Anopheles gambiae is a major mosquito vector responsible for malaria transmission, whose genome sequence was reported in 2002. Genome annotation is a continuing effort, and many of the approximately 13,000 genes listed in VectorBase for Anopheles gambiae are predictions that have still not been validated by any other method. To identify protein-coding genes of An. gambiae based on its genomic sequence, we carried out a deep proteomic analysis using high-resolution Fourier transform mass spectrometry for both precursor and fragment ions. Based on peptide evidence, we were able to support or correct more than 6000 gene annotations including 80 novel gene structures and about 500 translational start sites. An additional validation by RT-PCR and cDNA sequencing was successfully performed for 105 selected genes. Our proteogenomic analysis led to the identification of 2682 genome search-specific peptides. Numerous cases of encoded proteins were documented in regions annotated as intergenic, introns, or untranslated regions. Using a database created to contain potential splice sites, we also identified 35 novel splice junctions. This is a first report to annotate the An. gambiae genome using high-accuracy mass spectrometry data as a complementary technology for genome annotation.


Assuntos
Anopheles/genética , Anopheles/metabolismo , Processamento Alternativo , Animais , Mapeamento Cromossômico , Códon de Iniciação , Éxons , Genes de Insetos , Genômica , Íntrons , Espectrometria de Massas , Anotação de Sequência Molecular , Dados de Sequência Molecular , Fases de Leitura Aberta , Peptídeos/genética , Proteômica , Sítios de Splice de RNA , Reprodutibilidade dos Testes , Regiões não Traduzidas/genética
17.
Expert Rev Vaccines ; 23(1): 645-654, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38888098

RESUMO

INTRODUCTION: Malaria continues to remain a major global health problem with nearly a quarter of a billion clinical cases and more than 600,000 deaths in 2022. There has been significant progress toward vaccine development, however, poor efficacy of approved vaccines requiring multiple immunizing doses emphasizes the need for continued efforts toward improved vaccines. Progress to date, nonetheless, has provided impetus for malaria elimination. AREAS COVERED: In this review we will focus on diverse immune mechanisms targeting gametocytes in the human host and gametocyte-mediated malaria transmission via the mosquito vector. EXPERT OPINION: To march toward the goal of malaria elimination it will be critical to target the process of malaria transmission by mosquitoes, mediated exclusively by the sexual stages, i.e. male, and female gametocytes, ingested from infected vertebrate host. Studies over several decades have established antigens in the parasite sexual stages developing in the mosquito midgut as attractive targets for the development of transmission blocking vaccines (TBVs). Immune clearance of gametocytes in the vertebrate host can synergize with TBVs and directly aid in maintaining effective transmission reducing immune potential.


Assuntos
Vacinas Antimaláricas , Malária , Mosquitos Vetores , Desenvolvimento de Vacinas , Humanos , Vacinas Antimaláricas/imunologia , Vacinas Antimaláricas/administração & dosagem , Animais , Malária/prevenção & controle , Malária/transmissão , Malária/imunologia , Malária/parasitologia , Mosquitos Vetores/parasitologia , Mosquitos Vetores/imunologia , Plasmodium/imunologia
18.
Data Brief ; 52: 109793, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38076469

RESUMO

Boiling is used for the thermal management of high-energy-density devices and systems. However, sudden thermal runaway at boiling crisis often results in catastrophic failures. Machine learning is a promising tool for in-situ monitoring of boiling-based systems for preemptive control of boiling crisis. A carefully acquired and well-labeled dataset is a primary requirement for utilizing any data-driven learning framework to extract valuable descriptors. Here, we present a comprehensive dataset of boiling acoustics presented in our recent work [1]. We collect the audio files through meticulously controlled near-saturated pool boiling experiments under steady-state conditions. To this end, we connect a high-sensitivity hydrophone to a pre-amplifier and a data acquisition unit for accurate and reliable acquisition of acoustic signals. We organize the audio files into four categories as per the respective boiling regimes: background or natural convection (BKG, 2-5W/cm2), nucleate boiling (NB, 8-140W/cm2), excluding those at higher heat flux values preceding the onset of boiling crisis or the critical heat flux (Pre-CHF, ≈145W/cm2), and transition boiling (TB, uncontrolled). Each audio file label provides explicit information about the heat flux value and the experimental conditions. This dataset, consisting of 2056 files for BKG, 13367 files for NB, 399 files for Pre-CHF, and 460 files for TB, serves as the foundation for training and evaluating a deep learning strategy to predict boiling regimes. The dataset also includes acoustic emission data from transient pool boiling experiments conducted with varying heating strategies, heater surface, and boiling fluid modifications, creating a valuable dataset for developing robust data-driven models to predict boiling regimes. We also provide the associated MATLAB® codes used to process and classify these audio files.

19.
Malar J ; 12: 216, 2013 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-23802619

RESUMO

Malaria is a vector-borne disease causing extensive morbidity, debility and mortality. Development of resistance to drugs among parasites and to conventional insecticides among vector-mosquitoes necessitates innovative measures to combat this disease. Identification of molecules involved in the maintenance of complex developmental cycles of the parasites within the vector and the host can provide attractive targets to intervene in the disease transmission. In the last decade, several efforts have been made in identifying such molecules involved in mosquito-parasite interactions and, subsequently, validating their role in the development of parasites within the vector. In this study, a list of mosquito proteins, which facilitate or inhibit the development of malaria parasites in the midgut, haemolymph and salivary glands of mosquitoes, is compiled. A total of 94 molecules have been reported and validated for their role in the development of malaria parasites inside the vector. This compendium of molecules will serve as a centralized resource to biomedical researchers investigating vector-pathogen interactions and malaria transmission.


Assuntos
Culicidae/parasitologia , Interações Hospedeiro-Parasita , Proteínas de Insetos/metabolismo , Plasmodium/fisiologia , Animais , Vetores de Doenças , Trato Gastrointestinal/parasitologia , Hemolinfa/parasitologia , Proteínas de Insetos/genética , Glândulas Salivares/parasitologia
20.
Pharmaceutics ; 15(7)2023 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-37513987

RESUMO

Malaria is a potentially fatal disease caused by protozoan parasites of the genus Plasmodium. It is responsible for significant morbidity and mortality in endemic countries of the tropical and subtropical world, particularly in Africa, Southeast Asia, and South America. It is estimated that 247 million malaria cases and 619,000 deaths occurred in 2021 alone. The World Health Organization's (WHO) global initiative aims to reduce the burden of disease but has been massively challenged by the emergence of parasitic strains resistant to traditional and emerging antimalarial therapy. Therefore, development of new antimalarial drugs with novel mechanisms of action that overcome resistance in a safe and efficacious manner is urgently needed. Based on the evolving understanding of the physiology of Plasmodium, identification of potential targets for drug intervention has been made in recent years, resulting in more than 10 unique potential anti-malaria drugs added to the pipeline for clinical development. This review article will focus on current therapies as well as novel targets and therapeutics against malaria.

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