Parasite Plasmodium Research Articles

Assessing the Oxidative Stress Reducing Potential of Spilanthes filicaulis (Schumach & Thonn) Ethyl-Acetate Sub-fractions on Plasmodium berghei Infected Female Mice.

Infections by Plasmodium parasite actuate oxidative stress. As malaria parasite actions overwhelm host antioxidant defense by producing excessive reactive species during haemoglobin degradation. This study aimed to evaluate the oxidative status by considering the antioxidant level of ethyl-acetate sub-fractions of Spilanthes filicaulis (ESSF) extract on Plasmodium berghei NK-65 parasitized mice. Sixty female mice weighing 20.0 ± 3.0g were inoculated intraperitoneally with 0.2mL of parasitized erythrocytes randomly selected into five groups of 12 mice, Groups I and II were orally administered with normal saline (10mL/kg) and chloroquine (10mg/kg) while, Groups III, IV and V were administered 250,500 and 750mg/kg per day respectively of ESSF. Mice in each group were sacrificed on days 4 and 8 post treatment, thereafter blood and liver samples were collected and prepared using standard methods to obtain erythrocytes and liver homogenates. Malondialdehyde (MDA), a measure of lipid peroxidation, superoxide dismutase (SOD) and catalase (CAT) level was assessed in the erythrocyte and liver. Administration of ESSF produced a significant (p < 0.05) decrease in the MDA concentration of the parasitized treated group when compared to parasitized untreated group on day 4. Concomitantly, a significant (p < 0.05) increase in SOD and CAT activity in the treated groups with a corresponding decrease in the untreated group on day 4. However, effects of this action were more pronounced on day 8 in both tissues. These findings suggest that ESSF might contribute to the protection of malaria infected mice against oxidative disruptions by improving antioxidant status.

A Convolutional Neural Network- Based Deep Learning To Detect Reticulocytes From Human Peripheral Blood

Machine learning approaches are rapidly augmenting, and in some cases, replacing the conventional methods in biomedical data analysis; to reduce time, cost, biases, and the need for sophisticated analytical platforms. Hence, significant interest has been compounded in the integration of automated image analysis for various clinical applications, such as the detection of infected or inflamed wounds, bone fractures or for the purpose of disease diagnosis – such as Plasmodium parasites or circulating tumour cells in blood. Here, we report the development of a Convolutional Neural Network (CNN)-based method on CPU to distinguish and count immature human red blood cells known as reticulocytes from blood smears. Reticulocytes represent a heterogeneous and relatively small percentage of cells in peripheral blood, and contain residual RNA in complex with proteins which generates thread-like patterns when stained with New Methylene Blue (NMB) dye. We used more than 200 NMB-stained images from leukocyte-depleted blood to train and optimize the model for immature reticulocytes (stained positive with NMB, intensity and pattern of which depends on the developmental stage of the reticulocyte) and mature RBCs (no staining with NMB). The training performance evaluation metrics demonstrated a mean average precision (mAP50) of 0.88, a precision of 0.83, a recall of 0.88, and an F1 score of 0.87. Our model was able to successfully count reticulocytes with accuracy more than 90% from unknown samples which were subsequently cross-verified through microscopy and counting. Given the importance of reticulocyte dynamics in blood and its clinical relevance, the newly developed model will find important easy to adopt biomedical applications that can be achieved on a simple PC.

REVIEW ARTIKEL: PENINGKATAN KELARUTAN SENYAWA OBAT ANTIMALARIA MENGGUNAKAN METODE MODIFIKASI KO-KRISTAL

Malaria is an infectious disease caused by the Plasmodium parasite that infects humans through the bite of female Anopheles mosquitoes. Most antimalarial drugs have limitations in terms of solubility. Drug solubility is a very important parameter that determines the effectiveness of the drug, with good drug solubility, the drug can achieve optimal bioavailability and pharmacological effects, based on this, efforts are needed to overcome these problems in order to provide effective and efficient therapy to patients using existing antimalarial drugs that have been modified in their physicochemical properties so that their solubility increases. The purpose of this study was to review various studies that used the co-crystal modification method to increase the solubility of antimalarial drug compounds. This study was designed using the Narrative Review method, article searches were carried out using two databases, namely Google Scholar and PubMed, with the keywords "Co-crystal" OR "Antimalaria". In this study, 7 articles were found that met the inclusion and exclusion criteria. The selected articles are articles that discuss antimalarial drugs (artesunate, artemisinin, pyrimethamine) developed by the co-crystal method which experienced a multi-fold increase in solubility compared to its pure preparation. The co-crystal method can be a solubility enhancing solution for antimalarial drugs that have low solubility in water, increasing the solubility of antimalarial drugs causes the bioavailability of the drug to increase, so that the drug can provide good therapeutic effects.

Contrasting genomic epidemiology between sympatric Plasmodium falciparum and Plasmodium vivax populations.

The malaria parasites Plasmodium falciparum and Plasmodium vivax differ in key biological processes and associated clinical effects, but consequences on population-level transmission dynamics are difficult to predict. This co-endemic malaria study from Guyana details important epidemiological contrasts between the species by coupling population genomics (1396 spatiotemporally matched parasite genomes, primarily from 2020-21) with sociodemographic analysis (nationwide patient census from 2019). We describe how P. falciparum forms large, interrelated subpopulations that sporadically expand but generally exhibit restrained dispersal, whereby spatial distance and patient travel statistics predict parasite identity-by-descent (IBD). Case bias towards working-age adults is also strongly pronounced. P. vivax exhibits 46% higher average nucleotidediversity (π) and 6.5x lower average IBD. It occupies a wider geographic range, without evidence for outbreak-like expansions, only microgeographic patterns of isolation-by-distance, and weaker case bias towards adults. Possible latency-relapse effects also manifest in various analyses. For example, 11.0% of patients diagnosed with P. vivax in Greater Georgetown report no recent travel to endemic zones, and P. vivax clones recur in 11of46 patients incidentally sampled twice during the study. Polyclonality rate is also 2.1x higher than in P. falciparum, does not trend positively with estimated incidence, and correlates uniquely to selected demographics. We discuss possible underlying mechanisms and implications for malaria control.

Identifying Plasmodium P36 and P52 antigens for co-administration with circumsporozoite protein to enhance vaccine efficacy.

Vaccines targeting the complex pre-erythrocytic stage of Plasmodium parasites may benefit from inclusion of multiple antigens. However, discerning protective effects can be difficult because newer candidates may not be as protective as leading antigens like the circumsporozoite protein (CSP) in the conventional pre-clinical mouse model. We developed a modified mouse model challenge strategy that maximizes the contribution of T cells induced by novel candidate antigens at the sporozoite challenge time point and used this approach to test Plasmodium P36 and P52 vaccine candidates alone and in concert with non-protective doses of CSP. Co-administration of P36 and/or P52 with CSP achieved 80-100% sterile protection in mice, compared to only 7-30% protection for each individual antigen. P36 and P52 vaccination induced murine CD4+ and CD8+ T cell responses, but not antibody responses. This study adds P36 and P52 as promising vaccine antigens that may enhance protection achieved by CSP vaccination.

NK cells contribute to the resolution of experimental malaria-associated acute respiratory distress syndrome after antimalarial treatment.

In both humans and mice, natural killer (NK) cells are important lymphocytes of the innate immune system. They are often considered pro-inflammatory effector cells but may also have a regulatory or pro-resolving function by switching their cytokine profile towards the production of anti-inflammatory cytokines, including interleukin-10 (IL-10) and transforming growth factor-β, and by killing pro-inflammatory immune cells. Here, the role of NK cells in the resolution of malaria lung pathology was studied. Malaria complications, such as malaria-associated acute respiratory distress syndrome (MA-ARDS), are often lethal despite the rapid and efficient killing of Plasmodium parasites with antimalarial drugs. Hence, studying the resolution and healing mechanisms involved in the recovery from these complications could be useful to develop adjunctive treatments. Treatment of Plasmodium berghei NK65-infected C57BL/6 mice with a combination of artesunate and chloroquine starting at the appearance of symptoms was used as a model to study the resolution of MA-ARDS. The role of NK cells was studied using anti-NK1.1 depletion antibodies and NK cell-deficient mice. Using both methods, NK cells were found to be dispensable in the development of MA-ARDS, as shown previously. In contrast, NK cells were crucial in the initiation of resolution upon antimalarial treatment, as survival was significantly decreased in the absence of NK cells. Considerably increased IL-10 expression by NK cells suggested an anti-inflammatory and pro-resolving phenotype. Despite the increase in Il10 expression in the NK cells, inhibition of the IL-10/IL-10R axis using anti-IL10R antibodies had no effect on the resolution for MA-ARDS, suggesting that the pro-resolving effect of NK cells cannot solely be attributed to their IL-10 production. In conclusion, NK cells contribute to the resolution of experimental MA-ARDS.

A cross-sectional analysis identifies a low prevalence of Plasmodium ovale species infections in symptomatic and asymptomatic individuals in Kilifi county, Kenya.

Background The focus on P. falciparum diagnosis has led to an underestimation of the global burden of malaria resulting from neglected Plasmodium species. However, there is still scarce data on the prevalence of P. ovale species (spp) globally. To address this knowledge gap, data collected from cross-sectional studies in Kilifi county were used to: 1) determine the prevalence of P. ovale spp infections; and 2) determine the sensitivity of different diagnostic assays in detecting P. ovale spp infections. Methods A total of 531 individuals were sampled across three study sites in Kilifi County, Kenya between 2009 and 2020. Blood smears were prepared from peripheral blood and screened for Plasmodium parasite stages using light microscopy. Molecular screening involved DNA extraction of dried blood spots and blood in ethylenediaminetetraacetic acid, polymerase chain reaction (PCR) using primers targeting the 18 small ribosomal subunit and sequencing. Results Microscopy screening revealed that the most prevalent species was P. falciparum (32.0%) followed by P. malariae (9.0%) and then P. ovale spp( 1.5%). PCR screening identified additional P. ovale spp positives cases. Overall PCR results indicate that43 (8.1%) out of the 531 individuals harbored P. ovale spp infection with the highest prevalence reported in the tertiary health facility, (14.6%, 95% CI 8-23.6%), followed by the primary health facility (8.3%, 95% CI 5.4-11.9%), and the community from a cross-sectional blood survey, (3.6%, 95% CI 1.2-8.2%). Microscopy screening for P. ovale spp had a low sensitivity of 7% (95% CI 1-19-30%) and a high specificity of 99% (95% CI 98-100%). Sequencing results confirmed the presence of P.ovale curtisi. Conclusions This study provides baseline data for P.ovale spp surveillance in Kilifi County, primarily using PCR to improve diagnosis. These results suggest that malaria elimination and eradication efforts should not only concentrate on P. falciparum but should embrace a holistic approach towards elimination of all Plasmodium spp.

DETERMINATION OF SOME PHARMACOKINETIC PROPERTIES OF ARTEMETHER-LUMEFANTRINE GRANULES IN ALBINO RATS

Aim and Objectives: Malaria is an infectious disease that is caused by plasmodium parasites which is rampant in Sahara Africa and children under 5 years of age are highly vulnerable to this infection by malaria. So the need for the formulation of dosage form for this population using naturally occurring excipients to replace imported ones being currently used by our local manufacturing industries in-order to formulate novel, readily available, affordable and effective antimalarial medicine for children. Methods: Using the local excipients and its hybrid, the formulated artemether-lumefantrine granules for oral suspension were administered to albino rats, blood samples were collected at predetermined time 0, 1.5, 3, 6, 9, 12, 15, 18, 21, and 24 h respectively and drug contents; artemether-lumefantrine were determined within the stipulated period. Results: Some pharmacokinetic parameters determined were; maximum concentration, Cmax, time to reach the maximum concentration, Tmax, half-life, t1/2, area under the curve, AUC, and mean residence time, MRT, which were for artemether-lumefantrine were 3.9, 3.4, μg/L; 3.2, 6.0 h; 12.5, 14 h; 75.8, 168.5 μg/L.h; 24, 24 h respectively, for the marketed artemether-lumefanthrine granules for oral suspension.4.1, 3.2 μg/L; 1.4, 3.0 h; 3.0, undefined h, 67.0, 65.7 μg/L. h; 18, 18 respectively for hybrid formulated artemether-lumefantrine granules for oral suspension and 3.1, 3.8 μg/L; 2.5, 12.5 h; 4.8, 15 h; 20.2, 281.6 μg/L .h; 18, 18 respectively for the extracted pectin formulated granules. Conclusion: Optimized formulated artemether-lumefantrine granules were superior to the marketed product in terms of pharmacokinetic values being closer to those of earlier workers. Peer Review History: Received 13 May 2024; Reviewed 16 July 2024; Accepted 22 August; Available online 15 September 2024 Academic Editor: Dr. Asia Selman Abdullah, Pharmacy institute, University of Basrah, Iraq, asia_abdullah65@yahoo.com Average Peer review marks at initial stage: 5.5/10 Average Peer review marks at publication stage: 7.0/10 Reviewers: Ahmad Najib, Universitas Muslim Indonesia, Makassar, Indonesia, ahmad.najib@umi.ac.id Dr. Sangeetha Arullappan, Universiti Tunku Abdul Rahman, Malaysia, sangeetha@utar.edu.my

Efficacy of Malaria Symptoms as an Indicator of Malaria Infection among Students of a Tertiary Institution in Ogun State Nigeria

Malaria is a life-threatening disease caused by the parasite Plasmodium, which is transmitted through the bite of an infected female Anopheles mosquito. Asymptomatic Plasmodium falciparum parasitemia refers to the presence of the parasite in the absence of fever or malaria-related symptoms. In Ijebu-Igbo, Ogun State, Nigeria, a study was conducted to ascertain the frequency of asymptomatic malaria among students attending higher education institutions and determine the efficacy of malaria symptoms as an indicator of malaria infection. A total of 115 students who consented to participate in the study were enrolled, and only a total of 93 of the respondents were recruited for the study, having met the inclusion criteria. A structured questionnaire was used to obtain data on socio-demographic characteristics, signs and symptoms of malaria, and malaria prevention strategy using Insecticide Treated Nets (ITN). Blood samples were collected from the respondents and diagnosed for malaria using Rapid Diagnostic Tests (RDT) kit. Of the 93 respondents, 32 (34%) were males while 61 (66%) were females. Analysis of the result showed that 77% of the respondents had malaria parasites, 38.7% of the respondents indicated that they do feel feverish sometimes while 47.3% responded that they rarely feel feverish, those who rarely show symptoms were observed to be asymptomatic as the result of the RDT was positive for malaria. On the use of Insecticide Treated Net (ITN) for both categories of students, those who are not using the net had a higher prevalence (64.5%) of malaria infection. The result of this study shows that malaria symptoms is not a good diagnostic tool for determining treatment. Asymptomatic malaria was a risk factor among the students therefore measures to reduce the prevalence are advocated.

A high content imaging assay for identification of specific inhibitors of native Plasmodium liver stage protein synthesis.

Plasmodium parasite resistance to antimalarial drugs is a serious threat to public health in malaria-endemic areas. Compounds that target core cellular processes like translation are highly desirable, as they should be capable of killing parasites in their liver and blood stage forms, regardless of molecular target or mechanism. Assays that can identify these compounds are thus needed. Recently, specific quantification of native Plasmodium berghei liver stage protein synthesis, as well as that of the hepatoma cells supporting parasite growth, was achieved via automated confocal feedback microscopy of the o-propargyl puromycin (OPP)-labeled nascent proteome, but this imaging modality is limited in throughput. Here, we developed and validated a miniaturized high content imaging (HCI) version of the OPP assay that increases throughput, before deploying this approach to screen the Pathogen Box. We identified only two hits; both of which are parasite-specific quinoline-4-carboxamides, and analogs of the clinical candidate and known inhibitor of blood and liver stage protein synthesis, DDD107498/cabamiquine. We further show that these compounds have strikingly distinct relationships between their antiplasmodial and translation inhibition efficacies. These results demonstrate the utility and reliability of the P. berghei liver stage OPP HCI assay for the specific, single-well quantification of Plasmodium and human protein synthesis in the native cellular context, allowing the identification of selective Plasmodium translation inhibitors with the highest potential for multistage activity.

Virus-like particle-based vaccines targeting the Anopheles mosquito salivary protein, TRIO.

Malaria is a highly lethal infectious disease caused by Plasmodium parasites. These parasites are transmitted to vertebrate hosts when mosquitoes of the Anopheles genus probe for a blood meal. Sporozoites, the infectious stage of Plasmodium , transit to the liver within hours of injection into the dermis. Vaccine efforts are hindered by the complexity of the parasite's lifecycle and the speed at which the infection is established in the liver. In an effort to enhance immunity against Plasmodium , we produced a virus-like particle (VLP)-based vaccine displaying an epitope of TRIO, an Anopheles salivary protein which has been shown to enhance mobility and dispersal of sporozoites in the dermis. Previous work demonstrated that passive immunization with TRIO offered protection from liver infection and acted synergistically with a Plasmodium targeted vaccine. Immunization of mice with TRIO VLPs resulted in high-titer and long-lasting antibody responses that did not significantly drop for over 18 months post-immunization. TRIO VLPs were similarly immunogenic when combined with an anti-malaria vaccine targeting the L9 epitope of the Plasmodium falciparum circumsporozoite protein.However, when used in a malaria challenge mouse model, TRIO VLPs only provided modest protection from infection and did not boost the protection provided by L9 VLPs.

A Pan Plasmodium lateral flow recombinase polymerase amplification assay for monitoring malaria parasites in vectors and human populations

Robust diagnostic tools and surveillance are crucial for malaria control and elimination efforts. Malaria caused by neglected Plasmodium parasites is often underestimated due to the lack of rapid diagnostic tools that can accurately detect these species. While nucleic-acid amplification technologies stand out as the most sensitive methods for detecting and confirming Plasmodium species, their implementation in resource-constrained settings poses significant challenges. Here, we present a Pan Plasmodium recombinase polymerase amplification lateral flow (RPA–LF) assay, capable of detecting all six human infecting Plasmodium species in low resource settings. The Pan Plasmodium RPA-LF assay successfully detected low density clinical infections with a preliminary limit of detection between 10–100 fg/µl for P. falciparum. When combined with crude nucleic acid extraction, the assay can serve as a point-of-need tool for molecular xenomonitoring. This utility was demonstrated by screening laboratory-reared Anopheles stephensi mosquitoes fed with Plasmodium-infected blood, as well as field samples of An. funestus s.l. and An. gambiae s.l. collected from central Africa. Overall, our proof-of-concept Pan Plasmodium diagnostic tool has the potential to be applied for clinical and xenomonitoring field surveillance, and after further evaluation, could become an essential tool to assist malaria control and elimination.

Multistage protective anti-CelTOS monoclonal antibodies with cross-species sterile protection against malaria

CelTOS is a malaria vaccine antigen that is conserved in Plasmodium and other apicomplexan parasites and plays a role in cell-traversal. The structural basis and mechanisms of CelTOS-induced protective immunity to parasites are unknown. Here, CelTOS-specific monoclonal antibodies (mAbs) 7g7 and 4h12 demonstrated multistage activity, protecting against liver infection and preventing parasite transmission to mosquitoes. Both mAbs demonstrated cross-species activity with sterile protection against in vivo challenge with transgenic parasites containing either P. falciparum or P. vivax CelTOS, and with transmission reducing activity against P. falciparum. The mAbs prevented CelTOS-mediated pore formation providing insight into the protective mechanisms. X-ray crystallography and mutant-library epitope mapping revealed two distinct broadly conserved neutralizing epitopes. 7g7 bound to a parallel dimer of CelTOS, while 4h12 bound to a novel antiparallel dimer architecture. These findings inform the design of antibody therapies and vaccines and raise the prospect of a single intervention to simultaneously combat P. falciparum and P. vivax malaria.

Seven Years Malaria Trend Analysis in Kori Public Health Centre, Southwest Sumba District East Nusa Tenggara Province, Indonesia: a Retrospective Study

Introduction: Malaria, caused by the Plasmodium parasite and transmitted by Anopheles mosquitoes, remains a significant global health challenge, particularly in tropical regions. Despite a rise in cases, global malaria-related deaths have declined, indicating the success of control programs. Indonesia, committed to eliminating malaria by 2030, faces challenges with uneven distribution of cases, particularly in Eastern regions, necessitating targeted efforts for elimination. Objectives: This retrospective study aimed to analyze the trends in malaria prevalence over seven years in the catchment area of Kori Community Health Centre, located in the Sub-district of North Kodi, Southwest Sumba District, East Nusa Tenggara Province, Indonesia. Methods: Statistical analysis included data scrutiny for completeness, the utilization of SPSS software, and the presentation of retrospective malaria data in graphs and tables Results: The analysis of demographic data, health statistics, and malaria cases yielded crucial findings and strategic recommendations to support malaria control efforts and healthcare service enhancements in the region. Conclusions: This study provides significant insights into the prevalence of malaria in the Kori Community Health Centre catchment area over the past seven years. The results of the analysis can serve as a foundation for more effective malaria control efforts and healthcare service improvements in the area. Further research is required to delve deeper into the factors influencing malaria prevalence and to develop more effective strategies for controlling this disease.

IMPLEMENTASI METODE FORWARD CHAINING PADA DIAGNOSA PENYAKIT MALARIA

Malaria is a serious disease caused by the Plasmodium parasite, transmitted through the bite of Anopheles mosquitoes. This disease can cause various symptoms, ranging from fever, headache, and chills to more severe complications such as severe anemia, organ damage, and even death if not treated properly. Therefore, rapid and accurate diagnosis of malaria is crucial for effective treatment and can save lives. This article discusses the implementation of the forward chaining method in a Python-based program for the diagnosis of malaria. Forward chaining is an inference technique in expert systems used to draw conclusions from a series of available facts or data. In this context, the forward chaining method enables the identification of symptoms associated with malaria based on input data provided by the user. By using the forward chaining algorithm, the system automatically processes this data to provide initial diagnosis recommendations and appropriate treatment. This implementation is expected to assist medical personnel in making faster and more accurate decisions, reducing workload, and improving efficiency in handling malaria cases, especially in endemic areas. This article also evaluates the performance of the developed system and discusses challenges and further development prospects in expert system-based diagnostic applications for malaria. The evaluation shows that this system has great potential in supporting medical personnel and speeding up the diagnosis process, which is crucial in managing malaria

Cd loop fusion enhances the immunogenicity and the potential transmission blocking activity of Plasmodium falciparum generative cell specific 1 (GCS1) antigen

TBVs are suggested to inhibit parasite transmission from humans to Anopheles mosquitoes. For the transmission of Plasmodium parasite, a variety of factors are included in gametes fusion phase. In this step, conserved male-specific generative cell specific 1 antigen is necessary for fusion of cytoplasmic membranes of micro- and macro-gametocytes and zygot formation. The partial blocking activities of elicited antibodies against either the HAP2-GCS1 domain or the cd loop of this antigen have been recorded to hinder the transmission of Plasmodium species in Anopheles mid-gut. Thus, the objective of the present study was to investigate if the cd loop-fusion can enhance the quantity and quality of humoral and cellular immune responses against Plasmodium falciparum GCS1 in comparison to non-fusion antigen (without cd loop), in the adjuvanted and non-adjuvanted mouse groups. The immunogenicity of two constructs of P. falciparum generative cell specific 1 antigen, a fusion protein composed of cd loop and HAP2-GCS1 domain (cd-HAP) and another recombinant PfGCS1 containing solo HAP2-GCS1 domain (HAP2) were assessed to impede Plasmodium gametocytes integration before zygote formation. The antibodies profiling, titer, and avidity of induced antibodies were measured by the immunized mice sera, and the released cytokines (IL-5, TNF, and INF-γ) were analyzed in the supernatants of stimulated splenocytes. Furthermore, the inhibitory potency of the elicited antibodies against HAP2 and cd-HAP was measured during oocyst development by Standard Membrane Feeding Assay (SMFA). The comparative results in the present study showed the higher titer of IgG antibodies and IgG2a subclass, avidity, and transmission-reducing activity (TRA = 72.5 %) when mice were immunized by cd-HAP rather than HAP2. Moreover, our findings confirmed intensified Th1-directed immune responses in group 4 received cd-HAP/Poly(I:C). These findings declared the potential ability of cd loop fusion (cd-HAP) to upsurge humoral and cellular immune responses. However, the immune responses may switch to stronger Th1-type using alternative formulations. Explicitly, the cd-HAP-based vaccine may enhance the overall efficiency of immune responses and present a promising implementation in aiming malaria transmission.

A broadly cross-reactive i-body to AMA1 potently inhibits blood and liver stages of Plasmodium parasites

Apical membrane antigen-1 (AMA1) is a conserved malarial vaccine candidate essential for the formation of tight junctions with the rhoptry neck protein (RON) complex, enabling Plasmodium parasites to invade human erythrocytes, hepatocytes, and mosquito salivary glands. Despite its critical role, extensive surface polymorphisms in AMA1 have led to strain-specific protection, limiting the success of AMA1-based interventions beyond initial clinical trials. Here, we identify an i-body, a humanised single-domain antibody-like molecule that recognises a conserved pan-species conformational epitope in AMA1 with low nanomolar affinity and inhibits the binding of the RON2 ligand to AMA1. Structural characterisation indicates that the WD34 i-body epitope spans the centre of the conserved hydrophobic cleft in AMA1, where interacting residues are highly conserved among all Plasmodium species. Furthermore, we show that WD34 inhibits merozoite invasion of erythrocytes by multiple Plasmodium species and hepatocyte invasion by P. falciparum sporozoites. Despite a short half-life in mouse serum, we demonstrate that WD34 transiently suppressed P. berghei infections in female BALB/c mice. Our work describes the first pan-species AMA1 biologic with inhibitory activity against multiple life-cycle stages of Plasmodium. With improved pharmacokinetic characteristics, WD34 could be a potential immunotherapy against multiple species of Plasmodium.

Challenges in Malaria Control and Prevention in East Africa

Malaria remains a critical public health issue in East Africa, where high transmission rates persist despite extensive control and prevention efforts. This review article explores the multifaceted challenges that hinder effective malaria control and prevention in the region, including the emergence of drug-resistant Plasmodium parasites, insecticide-resistant mosquito vectors, inadequate healthcare infrastructure, socio-economic barriers, and environmental factors. The review methodology involved analyzing recent studies, reports, and data from international health organizations. Drug resistance and vector control are significant issues, with resistance to both anti-malarial drugs and insecticides compromising treatment efficacy and prevention efforts. Additionally, socio-economic factors such as poverty and lack of education, coupled with climate variability and environmental changes, further complicate malaria control. Addressing these challenges requires a coordinated approach that integrates continuous monitoring, healthcare system strengthening, community engagement, and international collaboration. By tackling these issues, East Africa can improve its malaria control efforts and ultimately enhance the health outcomes of its populations. Keywords: Malaria Control, Drug Resistance, Insecticide Resistance, Healthcare Infrastructure, Socio-Economic Barriers.

MalariaFlow: A comprehensive deep learning platform for multistage phenotypic antimalarial drug discovery

Malaria remains a significant global health challenge due to the growing drug resistance of Plasmodium parasites and the failure to block transmission within human host. While machine learning (ML) and deep learning (DL) methods have shown promise in accelerating antimalarial drug discovery, the performance of deep learning models based on molecular graph and other co-representation approaches warrants further exploration. Current research has overlooked mutant strains of the malaria parasite with varying degrees of sensitivity or resistance, and has not covered the prediction of inhibitory activities across the three major life cycle stages (liver, asexual blood, and gametocyte) within the human host, which is crucial for both treatment and transmission blocking. In this study, we manually curated a benchmark antimalarial activity dataset comprising 407,404 unique compounds and 410,654 bioactivity data points across ten Plasmodium phenotypes and three stages. The performance was systematically compared among two fingerprint-based ML models (RF::Morgan and XGBoost:Morgan), four graph-based DL models (GCN, GAT, MPNN, and Attentive FP), and three co-representations DL models (FP-GNN, HiGNN, and FG-BERT), which reveal that: 1) The FP-GNN model achieved the best predictive performance, outperforming the other methods in distinguishing active and inactive compounds across balanced, more positive, and more negative datasets, with an overall AUROC of 0.900; 2) Fingerprint-based ML models outperformed graph-based DL models on large datasets (>1000 compounds), but the three co-representations DL models were able to incorporate domain-specific chemical knowledge to bridge this gap, achieving better predictive performance. These findings provide valuable guidance for selecting appropriate ML and DL methods for antimalarial activity prediction tasks. The interpretability analysis of the FP-GNN model revealed its ability to accurately capture the key structural features responsible for the liver- and blood-stage activities of the known antimalarial drug atovaquone. Finally, we developed a web server, MalariaFlow, incorporating these high-quality models for antimalarial activity prediction, virtual screening, and similarity search, successfully predicting novel triple-stage antimalarial hits validated through experimental testing, demonstrating its effectiveness and value in discovering potential multistage antimalarial drug candidates.

Evaluation of the binding interactions between Plasmodium falciparum Kelch-13 mutant recombinant proteins with artemisinin.

Malaria, an ancient mosquito-borne illness caused by Plasmodium parasites, is mostly treated with Artemisinin Combination Therapy (ACT). However, Single Nucleotide Polymorphisms (SNPs) mutations in the P. falciparum Kelch 13 (PfK13) protein have been associated with artemisinin resistance (ART-R). Therefore, this study aims to generate PfK13 recombinant proteins incorporating of two specific SNPs mutations, PfK13-V494I and PfK13-N537I, and subsequently analyze their binding interactions with artemisinin (ART). The recombinant proteins of PfK13 mutations and the Wild Type (WT) variant were expressed utilizing a standard protein expression protocol with modifications and subsequently purified via IMAC and confirmed with SDS-PAGE analysis and Orbitrap tandem mass spectrometry. The binding interactions between PfK13-V494I and PfK13-N537I propeller domain proteins ART were assessed through Isothermal Titration Calorimetry (ITC) and subsequently validated using fluorescence spectrometry. The protein concentrations obtained were 0.3 mg/ml for PfK13-WT, 0.18 mg/ml for PfK13-V494I, and 0.28 mg/ml for PfK13-N537I. Results obtained for binding interaction revealed an increased fluorescence intensity in the mutants PfK13-N537I (83 a.u.) and PfK13-V494I (143 a.u.) compared to PfK13-WT (33 a.u.), indicating increased exposure of surface proteins because of the looser binding between PfK13 protein mutants with ART. This shows that the PfK13 mutations may induce alterations in the binding interaction with ART, potentially leading to reduced effectiveness of ART and ultimately contributing to ART-R. However, this study only elucidated one facet of the contributing factors that could serve as potential indicators for ART-R and further investigation should be pursued in the future to comprehensively explore this complex mechanism of ART-R.