Malaria-infected Erythrocytes Research Articles

Mechanical control of the adhesion of malaria-infected erythrocytes to the placenta

Mechanical control of the adhesion of malaria-infected erythrocytes to the placenta

Malaria Biomimetic for Tumor Targeted Drug Delivery.

Malaria infected erythrocytes utilize the parasite protein VAR2CSA to bind to a unique presentation of chondroitin sulfate (CS) for their placenta specific tropism. Interestingly, many cancers express a similar form of CS, thereby termed oncofetal CS (ofCS). The distinctive tropism of malaria infected erythrocytes and the identification of oncofetal CS, therefore, represent potentially potent tools for cancer targeting. Here we describe an intriguing drug delivery platform that effectively mimics infected erythrocytes and their specificity for ofCS. We used a lipid catcher-tag conjugation system for the functionalization of erythrocyte membrane-coated drug carriers with recombinant VAR2CSA (rVAR2). We show that these malaria mimicking erythrocyte nanoparticles (MMENPs) loaded with docetaxel (DTX) specifically target and kill melanoma cells in vitro. We further demonstrate effective targeting and therapeutic efficacy in a xenografted melanoma model. These data thus provide a proof of concept for the use of a malaria biomimetic for tumor targeted drug delivery. Given the broad presentation of ofCS found across various types of malignancies, this biomimetic may therefore show potential as a broadly targeted cancer therapy against multiple tumor indications.

Investigations on the Novel Antimalarial Ferroquine in Biomimetic Solutions Using Deep UV Resonance Raman Spectroscopy and Density Functional Theory

Deep ultraviolet (DUV) resonance Raman experiments are performed, investigating the novel, promising antimalarial ferroquine (FQ). Two buffered aqueous solutions with pH values of 5.13 and 7.00 are used, simulating the acidic and neutral conditions inside a parasite's digestive vacuole and cytosol, respectively. To imitate the different polarities of the membranes and interior, the buffer's 1,4-dioxane content was increased. These experimental conditions should mimic the transport of the drug inside malaria-infected erythrocytes through parasitophorous membranes. Supporting density functional theory (DFT) calculations on the drug's micro-speciation were performed, which could be nicely assigned to shifts in the peak positions of resonantly enhanced high-wavenumber Raman signals at λexc = 257 nm. FQ is fully protonated in polar mixtures like the host interior and the parasite's cytoplasm or digestive vacuole (DV) and is only present as a free base in nonpolar ones, such as the host's and parasitophorous membranes. Additionally, the limit of detection (LoD) of FQ at vacuolic pH values was determined using DUV excitation wavelengths at 244 and 257 nm. By applying the resonant laser line at λexc = 257 nm, a minimal FQ concentration of 3.1 μM was detected, whereas the pre-resonant excitation wavelength 244 nm provides an LoD of 6.9 μM. These values were all up to one order of magnitude lower than the concentration found for the food vacuole of a parasitized erythrocyte.

Exploring SARS-CoV-2 and Plasmodium falciparum coinfection in human erythrocytes.

The co-occurrence and the similarities between malaria and COVID-19 diseases raise the question of whether SARS-CoV-2 is capable of infecting red blood cells and, if so, whether these cells represent a competent niche for the virus. In this study, we first tested whether CD147 functions as an alternative receptor of SARS-CoV-2 to infect host cells. Our results show that transient expression of ACE2 but not CD147 in HEK293T allows SARS-CoV-2 pseudoviruses entry and infection. Secondly, using a SARS-CoV-2 wild type virus isolate we tested whether the new coronavirus could bind and enter erythrocytes. Here, we report that 10,94% of red blood cells had SARS-CoV-2 bound to the membrane or inside the cell. Finally, we hypothesized that the presence of the malaria parasite, Plasmodium falciparum, could make erythrocytes more vulnerable to SARS-CoV-2 infection due to red blood cell membrane remodelling. However, we found a low coinfection rate (9,13%), suggesting that P. falciparum would not facilitate the entry of SARS-CoV-2 virus into malaria-infected erythrocytes. Besides, the presence of SARS-CoV-2 in a P. falciparum blood culture did not affect the survival or growth rate of the malaria parasite. Our results are significant because they do not support the role of CD147 in SARS-CoV-2 infection, and indicate, that mature erythrocytes would not be an important reservoir for the virus in our body, although they can be transiently infected.

Molecular Docking and Analysis of some Ligands on Var2csA Target

Purpose: Prevalence of malaria during pregnancy and the spate of drug resistance by malaria parasites have constantly impacted maternal, perinatal and neonatal outcomes, especially in sub-Saharan Africa. This study aims to discover “in silico” non-recombinant molecules which can interact with placental chondroitin sulfate to inhibit binding or displace bound var2csA from the placenta in order to prevent pregnancy associated malaria.
 Methodology: Protein data bank (rcsb.org) and PubChem were used to download the chemical structures of the receptor (3bqk) and those of the ligands. Canonical SMILES and other information about the ligands and the receptor were extracted from PubChem. Toxtree, Toxicity Estimation Software Tool (TEST), SwissADMET, Molinspiration and Lazar Toxicity Predicter were employed to test various toxicity and safety parameters of lead compounds. The structure of the macromolecule – chondroitin sulfate A (CSA) was retrieved by searching in the protein data bank (PDB) (rcsb.org/structure/3bqk); downloaded, and saved as a PDB format.
 Findings: Molecular modeling and toxicity predictors used in this study indicated that among the ligands screened, IH3 had the lowest binding energy of -9.8Kcal/mol while var2csA had -2.8Kcal/mol. Var2csA is parasite’s adhesive protein. It was also observed that out of the 90 ligands (binding affinity range -9.8 to -1.0 Kcal/mol) screened, IH3 (-9.8Kcal/mol), FAD (-8.4 Kcal/mol), NDP (-8.2 Kcal/mol), A5A (-8.2 Kcal/mol), ABO (-8.1 Kcal/mol), IH2 (-7.8 Kcal/mol), 2RT (-7.7 Kcal/mol), CRO (-7.7 Kcal/mol) and IH1 (-7.7 Kcal/mol) appear to be the most promising lead compounds to occupy var2csA binding pocket in pCSA in order to prevent adhesion of malaria infected erythrocytes to the placenta. SwissADME and Molinspiration Cheminformatics for LogP (mean of 1.07 and range of -2.79 to 4.18) of the lead compounds showed no correlations between lipophilicity and interaction with receptors. Of all the compounds selected for analysis, only ABO and 2RT exhibited drug-like properties based on Ghose, Lipinski and Veber filters.
 Conclusion: Data obtained from the study therefore suggests that IH3, FAD, NDP, A5A, ABO, IH2, 2RT, CRO, IH1 and var2csA make favourable lead candidates for targeting pCSA and therefore require further in vitro and in vivo evaluations.
 Recommendation: This study therefore recommends the repurposing and extending the use of flavin adenine dinucleotide (FAD) to cover prophylactic management of malaria among pregnant women.

Towards rainbow portable Cytophone with laser diodes for global disease diagnostics

In vivo, Cytophone has demonstrated the capability for the early diagnosis of cancer, infection, and cardiovascular disorders through photoacoustic detection of circulating disease markers directly in the bloodstream with an unprecedented 1,000-fold improvement in sensitivity. Nevertheless, a Cytophone with higher specificity and portability is urgently needed. Here, we introduce a novel Cytophone platform that integrates a miniature multispectral laser diode array, time-color coding, and high-speed time-resolved signal processing. Using two-color (808 nm/915 nm) laser diodes, we demonstrated spectral identification of white and red clots, melanoma cells, and hemozoin in malaria-infected erythrocytes against a blood background and artifacts. Data from a Plasmodium yoelii murine model and cultured human P. falciparum were verified in vitro with confocal photothermal and fluorescent microscopy. With these techniques, we detected infected cells within 4 h after invasion, which makes hemozoin promising as a spectrally selective marker at the earliest stages of malaria progression. Along with the findings from our previous application of Cytophone with conventional lasers for the diagnosis of melanoma, bacteremia, sickle anemia, thrombosis, stroke, and abnormal hemoglobin forms, this current finding suggests the potential for the development of a portable rainbow Cytophone with multispectral laser diodes for the identification of these and other diseases.

Visible microspectrophotometry coupled with machine learning to discriminate the erythrocytic life cycle stages of P. falciparum malaria parasites in functional single cells.

Malaria was regarded as the most devastating infectious disease of the 21st century until the COVID-19 pandemic. Asexual blood staged parasites (ABS) play a unique role in ensuring the parasite's survival and pathogenesis. Hitherto, there have been no spectroscopic reports discriminating the life cycle stages of the ABS parasite under physiological conditions. The identification and quantification of the stages in the erythrocytic life cycle is important in monitoring the progression and recovery from the disease. In this study, we explored visible microspectrophotometry coupled to machine learning to discriminate functional ABS parasites at the single cell level. Principal Component Analysis (PCA) showed an excellent discrimination between the different stages of the ABS parasites. Support Vector Machine Analysis provided a 100% prediction for both schizonts and trophozoites, while a 92% and 98% accuracy was achieved for predicting control and ring staged infected RBCs, respectively. This work shows proof of principle for discriminating the life cycle stages of parasites in functional erythrocytes using visible microscopy and thus eliminating the drying and fixative steps that are associated with other optical-based spectroscopic techniques.

Identifying Targets of Protective Antibodies against Severe Malaria in Papua, Indonesia, Using Locally Expressed Domains of Plasmodium falciparum Erythrocyte Membrane Protein 1.

Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1), a diverse family of multidomain proteins expressed on the surface of malaria-infected erythrocytes, is an important target of protective immunity against malaria. Our group recently studied transcription of the var genes encoding PfEMP1 in individuals from Papua, Indonesia, with severe or uncomplicated malaria. We cloned and expressed domains from 32 PfEMP1s, including 22 that were upregulated in severe malaria and 10 that were upregulated in uncomplicated malaria, using a wheat germ cell-free expression system. We used Luminex technology to measure IgG antibodies to these 32 domains and control proteins in 63 individuals (11 children). At presentation to hospital, levels of antibodies to PfEMP1 domains were either higher in uncomplicated malaria or were not significantly different between groups. Using principal component analysis, antibodies to 3 of 32 domains were highly discriminatory between groups. These included two domains upregulated in severe malaria, a DBLβ13 domain and a CIDRα1.6 domain (which has been previously implicated in severe malaria pathogenesis), and a DBLδ domain that was upregulated in uncomplicated malaria. Antibody to control non-PfEMP1 antigens did not differ with disease severity. Antibodies to PfEMP1 domains differ with malaria severity. Lack of antibodies to locally expressed PfEMP1 types, including both domains previously associated with severe malaria and newly identified targets, may in part explain malaria severity in Papuan adults.

CS-ABC: Cuckoo Search based adaptive boosting classifier for malaria infected erythrocyte detection

The contribution of this manuscript is a supervised learning technique that enables to detect the malaria scope in given erythrocyte. Contrast to former efforts in this region, this study utilises multiple observable phase images of the unspotted cells. Automatically, erythrocytes are segmented utilising optical phase thresholds and redeployed to allow quantitative association of the phase images. Redeployed images are examined to extract manifold morphological descriptors on the basis of phase information. When the entire individual descriptors are statistically diverse among uninfected and infected cells, every descriptor will not allow parting of the populations at the satisfactory level aimed at clinical service. The experimental study carried on the proposal and other contemporary models evincing that the proposed CS-ABC (Cuckoo Search based Adaptive Boosting Classifier) is considerably significant with maximal prediction accuracy and minimal misclassification rate that compared to other contemporary models.

CS-ABC: Cuckoo Search based adaptive boosting classifier for malaria infected erythrocyte detection

The contribution of this manuscript is a supervised learning technique that enables to detect the malaria scope in given erythrocyte. Contrast to former efforts in this region, this study utilises multiple observable phase images of the unspotted cells. Automatically, erythrocytes are segmented utilising optical phase thresholds and redeployed to allow quantitative association of the phase images. Redeployed images are examined to extract manifold morphological descriptors on the basis of phase information. When the entire individual descriptors are statistically diverse among uninfected and infected cells, every descriptor will not allow parting of the populations at the satisfactory level aimed at clinical service. The experimental study carried on the proposal and other contemporary models evincing that the proposed CS-ABC (Cuckoo Search based Adaptive Boosting Classifier) is considerably significant with maximal prediction accuracy and minimal misclassification rate that compared to other contemporary models.

Innate immune responses to malaria-infected erythrocytes in pregnant women: Effects of gravidity, malaria infection, and geographic location.

BackgroundMalaria in pregnancy causes maternal, fetal and neonatal morbidity and mortality, and maternal innate immune responses are implicated in pathogenesis of these complications. The effects of malaria exposure and obstetric and demographic factors on the early maternal immune response are poorly understood.MethodsPeripheral blood mononuclear cell responses to Plasmodium falciparum-infected erythrocytes and phytohemagglutinin were compared between pregnant women from Papua New Guinea (malaria-exposed) with and without current malaria infection and from Australia (unexposed). Elicited levels of inflammatory cytokines at 48 h and 24 h (interferon γ, IFN-γ only) and the cellular sources of IFN-γ were analysed.ResultsAmong Papua New Guinean women, microscopic malaria at enrolment did not alter peripheral blood mononuclear cell responses. Compared to samples from Australia, cells from Papua New Guinean women secreted more inflammatory cytokines tumor necrosis factor-α, interleukin 1β, interleukin 6 and IFN-γ; p<0.001 for all assays, and more natural killer cells produced IFN-γ in response to infected erythrocytes and phytohemagglutinin. In both populations, cytokine responses were not affected by gravidity, except that in the Papua New Guinean cohort multigravid women had higher IFN-γ secretion at 24 h (p = 0.029) and an increased proportion of IFN-γ+ Vδ2 γδ T cells (p = 0.003). Cytokine levels elicited by a pregnancy malaria-specific CSA binding parasite line, CS2, were broadly similar to those elicited by CD36-binding line P6A1.ConclusionsGeographic location and, to some extent, gravidity influence maternal innate immunity to malaria.

Automatic Detection of Malaria Infected Erythrocytes Based on the Concavity Point Identification and Pseudo-Valley Based Thresholding

Automatic malaria diagnosis requires the segmentation of the erythrocytes from the microscopic blood smears images. In this paper, the system for the analysis of the erythrocyte to detect the malaria infection has been proposed. The challenging issues are: preprocessing, foreground extraction, clump erythrocyte segmentation and infected erythrocyte detection. The non-uniform illumination and other distortions of the acquired microscopic images are corrected by using median filtering technique. The foreground regions, i.e. erythrocyte regions are segmented from the other blood components in the smears by using Otsu’s thresholding along with morphological filtering. The clump erythrocytes are segmented based on the inherent geometrical property of the concavity point detection of the clump which is independent of any geometrical deformation or image acquisition errors. Further, the segmented erythrocytes are analysed to detect the infected erythrocytes using thresholding technique based on the “pseudo-valley” concept. The experimental analyses of the proposed method are carried out on three different sets of database. An accuracy of 97.95% was observed for the erythrocyte segmentation, with an improvement in accuracy of 8.76% and 0.87% as compared to classical watershed and marker controlled watershed segmentation technique respectively. Moreover, the infected erythrocyte was detected with an accuracy of 88.57%.

Malaria detection using deep residual networks with mobile microscopy

Automatic segmentation of erythrocytes in microscopic blood smear phone images is a critical step to visualize and identify malaria using machine learning technologies. However, it still remains a challenging problem due to the scarcity of experts, low image qualities, slow manual and inefficient quality of diagnosis. To handle these issues to some extent, we proposed an effective multi-magnification deep residual neural network (MM-ResNet), where we fully automatically classify the microscopic blood smear images as either infected/ non-infected at multiple magnifications. We have experimentally evaluated our approach by using it to train more efficient variants of different compact deep convolutional neural networks (CNN), evaluated on phone datasets. The MM-ResNet end-to-end framework shows similar or superior accuracy than the baseline architectures, as measured by GPU timings on the publicly available microscopic blood smear phone images. This approach is the first application of a MM-ResNet for malaria-infected erythrocyte identification in microscopic blood smear images.

Early Perturbations in Glucose Utilization in Malaria-Infected Murine Erythrocytes, Liver and Brain Observed by Metabolomics.

Investigation of glucose utilization during an infection is central to the study of energy metabolism. The heavy utilization of glucose by the malaria parasite, and the consequences of this process, have been investigated extensively. However, host glucose utilization during early infection has not been explored to date. In a first attempt, this article investigates the changes in the host glucose utilization in Balb/c mice infected with Plasmodium berghei ANKA using 13C-labeled glucose infusion followed by NMR spectroscopy. The results suggested significant alterations of liver, brain and red blood cell (RBC) glucose utilization during early infection when the parasitemia was <1%. At the pathway level, we observed a decrease in the shunt metabolite 2,3-bisphosphoglycerate in the RBCs. Glycolysis and pathways associated with it, along with fatty acid unsaturation, were altered in the liver. Significant changes were observed in the central carbon metabolic pathways in the brain. These results have implications in understanding the host physiology during early infection and pave the way for detailed flux analysis of the proposed perturbed pathways.

Development of a quantitative, portable, and automated fluorescent blue-ray device-based malaria diagnostic equipment with an on-disc SiO2 nanofiber filter

There is an urgent need to develop an automated malaria diagnostic system that can easily and rapidly detect malaria parasites and determine the proportion of malaria-infected erythrocytes in the clinical blood samples. In this study, we developed a quantitative, mobile, and fully automated malaria diagnostic system equipped with an on-disc SiO2 nanofiber filter and blue-ray devices. The filter removes the leukocytes and platelets from the blood samples, which interfere with the accurate detection of malaria by the blue-ray devices. We confirmed that the filter, which can be operated automatically by centrifugal force due to the rotation of the disc, achieved a high removal rate of leukocytes (99.7%) and platelets (90.2%) in just 30 s. The automated system exhibited a higher sensitivity (100%) and specificity (92.8%) for detecting Plasmodium falciparum from the blood of 274 asymptomatic individuals in Kenya when compared to the common rapid diagnosis test (sensitivity = 98.1% and specificity = 54.8%). This indicated that this system can be a potential alternative to conventional methods used at local health facilities, which lack basic infrastructure.

Biophysical and biomolecular interactions of malaria-infected erythrocytes in engineered human capillaries.

Microcirculatory obstruction is a hallmark of severe malaria, but mechanisms of parasite sequestration are only partially understood. Here, we developed a robust three-dimensional microvessel model that mimics the arteriole-capillary-venule (ACV) transition consisting of a narrow 5- to 10-μm-diameter capillary region flanked by arteriole- or venule-sized vessels. Using this platform, we investigated red blood cell (RBC) transit at the single cell and at physiological hematocrits. We showed normal RBCs deformed via in vivo-like stretching and tumbling with negligible interactions with the vessel wall. By comparison, Plasmodium falciparum-infected RBCs exhibited virtually no deformation and rapidly accumulated in the capillary-sized region. Comparison of wild-type parasites to those lacking either cytoadhesion ligands or membrane-stiffening knobs showed highly distinctive spatial and temporal kinetics of accumulation, linked to velocity transition in ACVs. Our findings shed light on mechanisms of microcirculatory obstruction in malaria and establish a new platform to study hematologic and microvascular diseases.

Light Emission in Betalains: From Fluorescent Flowers to Biotechnological Applications.

The discovery of visible fluorescence in the plant pigments betalains revealed the existence of fluorescent patterns in flowers of plants of the order Caryophyllales, where betalains substitute anthocyanins. The serendipitous initial discovery led to a systemized characterization of the role of different substructures on the photophysical phenomenon. Strong fluorescence is general to all members of the family of betaxanthins linked to the structural property that the betalamic acid moiety is connected to an amine group. This property has led to bioinspired tailor-made probes and to the development of novel biotechnological applications in screening techniques or microscopy labeling. Here, we comprehensively review the photophysics, photochemistry, and photobiology of betalain fluorescence and describe all current applications.

A High-Resolution Map of SBP1 Interactomes in Plasmodium falciparum-infected Erythrocytes.

SummaryThe pathogenesis of malaria parasites depends on host erythrocyte modifications that are facilitated by parasite proteins exported to the host cytoplasm. These exported proteins form a trafficking complex in the host cytoplasm that transports virulence determinants to the erythrocyte surface; this complex is thus essential for malaria virulence. Here, we report a comprehensive interaction network map of this complex. We developed authentic, unbiased, highly sensitive proteomic approaches to determine the proteins that interact with a core component of the complex, SBP1 (skeleton-binding protein 1). SBP1 interactomes revealed numerous exported proteins and potential interactors associated with SBP1 intracellular trafficking. We identified several host-parasite protein interactions and linked the exported protein MAL8P1.4 to Plasmodium falciparum virulence in infected erythrocytes. Our study highlights the complicated interplay between parasite and host proteins in the host cytoplasm and provides an interaction dataset connecting dozens of exported proteins required for P. falciparum virulence.

Cuckoo Search based Ensemble Classifier for Predictive Analysis of Malaria Infection Scope on thin Blood Smears

Classification of machine learning models had an ultimate achievement by means of supervised learning, but the “state of the art models” have not yet extensively applied the “biological image data”. To categorize the erythrocytes as malaria infested or not, we categorize erythrocytes thru ensemble classification method. With this regard, the script strived to prolong our former “decision tree based binary classifier” to accomplish the ensemble classification. Training data which is given clustered into diverse groups that are based on the variety perceived in all probable features projection. Every cluster is engaged to a greater extent to train single classifier. In this esteem, morphological features and entropy-based features are included. From legitimate pathology laboratories, the investigation carried on the real time inputs and combination of benchmark datasets composed as anonymous data. Unlike the existing methods, proposal of this document executed experiments on voluminous data that proliferate in size when compared to present benchmark datasets. With the statistical assessment the execution of proposal is evaluated by comparative analysis amid the two existing models “Malaria infected erythrocyte classification based on a hybrid classifier using microscopic images of thin blood smear (Hybrid Classification Approach)” and “Scale to Estimate Premature Malaria Parasites Scope (SEMPS)”and the proposed model “Cuckoo Search Based Ensemble Classifier (CSEC)”. As depicted by the experimental study the suggested model is surpassing the two existing models.

Malaria and Malnutrition: Kwashiorkor Associated with Low Levels of Parasitaemia.

Background The relationship between protein energy malnutrition (PEM) and malaria is controversial. While most studies demonstrate that PEM is associated with greater malaria morbidity, some indicate that PEM may in fact have a protective effect. PEM is differentiated into three subgroups: kwashiorkor (marked protein deficiency), marasmus (calorie deficiency), and kwashiorkor/marasmus. None of the studies concerning PEM and malaria seem to distinguish between these subgroups, and significant differences in susceptibility to malaria between these subgroups may have been overlooked. Plasmodium parasites and malaria infected erythrocytes are sensitive to oxidative stress. Since kwashiorkor patients seem to display an excess of prooxidants and as serum albumin is an important antioxidant, we hypothesized that patients with different forms of PEM might have different levels of malaria parasitaemia. Methods 72 PEM children older than 6 months admitted to Kwale Family Life Training Programme (Kenya) were included in the study. Results Mean parasitaemia was significantly lower in the kwashiorkor group than in the marasmus group (p < 0,001). There was no correlation between serum albumin and parasitaemia. Conclusion Our study suggests a protective effect of kwashiorkor against malaria, warranting further studies.