Search Results (108)

Background/Objectives: Malaria remains a major global health burden, increasingly complicated by resistance to artemisinin-based therapies. Because artemisinin activation depends on heme and porphyrin chemistry, we sought to exploit host red blood cell (RBC) heme metabolism as a therapeutic vulnerability. This study aims to develop and evaluate a host-directed “bait-and-kill” strategy that selectively sensitizes malaria-infected RBCs to artemisinin. Methods: We integrated quantitative proteomics, erythropoiesis transcriptomic analyses, flow cytometry, and in vitro malaria culture assays to characterize heme metabolism in mature RBCs and Plasmodium falciparum-infected RBCs (iRBCs). The heme precursor 5-aminolevulinic acid (ALA) was used to induce porphyrin accumulation, and dihydroartemisinin (DHA) was applied as the killing agent. Drug synergy, porphyrin accumulation, reactive oxygen species (ROS) induction, and parasite survival were assessed, including ring-stage survival assays using artemisinin-resistant clinical isolates. Results: Mature RBCs retain a truncated heme biosynthesis pathway capable of accumulating porphyrin intermediates, while uninfected RBCs are impermeable to ALA. In contrast, iRBCs exhibit increased membrane permeability, allowing selective ALA uptake and porphyrin accumulation. ALA alone did not induce cytotoxicity or ROS, whereas DHA induced ROS and parasite killing. The ALA + DHA combination resulted in synergistic parasite elimination, including complete clearance of artemisinin-resistant P. falciparum isolates from the Greater Mekong Subregion, with no recrudescence observed over three weeks of culture. Evidence supports a predominant role for host-derived heme metabolites in mediating this synergy. Conclusions: The bait-and-kill strategy selectively exploits host RBC heme metabolism to restore and enhance artemisinin efficacy while sparing uninfected cells. Using clinically safe compounds, this host-directed approach provides a promising, resistance-bypassing framework for malaria treatment and combination drug development. Full article

Malaria remains a major global health burden, and the emergence of resistance to blood stage antimalarials underscores the need for new interventions targeting earlier stages of the parasite’s life cycle. The pre-erythrocytic liver stage represents a critical bottleneck and an attractive target for chemotherapeutic and prophylactic interventions. In this study, we functionally characterized the putative E3 ubiquitin ligase Trophozoite Exported Protein 1 (TEX1; PBANKA_0102200) in Plasmodium berghei using gene knockout, tagging, and imaging approaches across the mosquito and liver stages. TEX1 knockout parasites (PbTEX1-KO) showed impaired development during mosquito-stage transitions, with significant reductions in ookinete formation, oocyst numbers, and sporozoites reaching the salivary glands. In hepatic stages, TEX1-KO parasites displayed reduced growth, abnormal nuclear division, and impaired liver stage maturation, ultimately leading to a dramatic decline in detached cell formation and blood stage infectivity. Endogenous C-terminal tagging of TEX1 with GFP and 3×HA revealed a discrete subnuclear localization pattern, indicating a critical role in DNA synthesis and/or mitotic regulation. Our findings reveal that TEX1 is required for nuclear replication and division and successful development in both the mosquito and liver stages of Plasmodium. Given its pivotal role and nuclear localization during hepatic schizogony, TEX1 represents a promising target for the development of liver stage antimalarial interventions. Full article

Background: Erythroblasts have recently been identified as host cells for malarial parasites, revealing a previously underappreciated host–parasite interaction. However, their extremely low abundance in peripheral blood has hindered progress, especially in elucidating the biological significance of parasitized erythroblasts (pEBs) in vivo. Methods: Here, we visualized pEBs in a murine model and established a method to increase their number in peripheral blood by immunizing mice with live Plasmodium yoelii 17XNL, followed by challenge with P. berghei ANKA. Results: Immunized mice were protected from cerebral malaria and survived longer, during which pEBs appeared in circulation and were detected using Giemsa-stained smears. All blood-stage parasite forms were identified within pEBs, including enucleating erythroblasts. Conclusions: This model enables in vivo/ex vivo analysis of pEB biology without bone marrow/spleen isolation, thus lowering technical/ethical barriers for the field. Full article

Background: Recurrent malaria refers to repeated episodes of the disease in the same individual. Plasmodium vivax is known for its ability to relapse due to dormant liver-stage hypnozoites and poses a particular risk to travelers returning from endemic areas. Prompt diagnosis and treatment are crucial to prevent recurrences. Case Presentation: We present the case of a 41-year-old man from Romania who developed Plasmodium vivax malaria after traveling through Southeast Asia without chemoprophylaxis. He presented with fever, chills, myalgia, headache, vomiting, and abdominal pain. Clinical findings included mild jaundice and slight neurological signs. Laboratory tests showed severe thrombocytopenia, elevated bilirubin, inflammatory markers, and borderline creatinine levels. Malaria was confirmed by a rapid diagnostic test and blood smear microscopy. The patient was treated with doxycycline and atovaquone–proguanil. He improved and was discharged, but experienced two relapses, both confirmed as Plasmodium vivax by RT-PCR. Despite receiving primaquine as radical cure after the first Plasmodium vivax malaria relapse, a second relapse occurred. Each episode was managed with blood-stage antimalarial therapy, leading to full clinical and biological recovery. Conclusions: Malaria rarely occurs in non-endemic areas; it should be considered in patients with compatible travel history and symptoms. Given the high relapse potential of Plasmodium vivax, accurate species identification is critical to guide appropriate long-term management. Full article

Carboxylesterases (CCEs) have been demonstrated to be involved in pyrethroid resistance in insect species. This study aims to investigate CCE-mediated resistance mechanisms in Anopheles sinensis, a major malaria vector. Through comparative transcriptomics of a deltamethrin-resistant strain (CQ-LR) versus susceptible strain (WX-LS) of An. sinensis, we identified differentially expressed CCE genes across five developmental stages, five tissues, and three time points post-blood-meal. Four candidate genes (AsAe9, AsAe10, AsAce2, AsUn5) showed significantly upregulated expression. Subsequent qRT-PCR validation across four field-derived resistant strains (WX-LR, AH-LR, YH-LR, CQ-LR) and the susceptible strain confirmed significant upregulation of AsAe9, AsAe10, AsAce1, AsAce2, and AsBe4 in more than two resistant populations. RNAi-based functional validation showed that silencing AsAe10 or AsBe4 in the WX-LR strain significantly decreased knockdown time and raised 24 h mortality upon diagnostic deltamethrin exposure, with AsAe10 silencing having the strongest effect. This study identifies CCE genes involved in deltamethrin resistance in An. sinensis, providing valuable insights into the resistance mechanisms of pyrethroid and a theoretical basis for mosquito resistance management. Full article

Malaria is a parasitic infectious disease that is endemic in many tropical countries. Even though several effective antimalarial agents have been implemented, treatment failure still occurs, and malaria continues to cause neurological complications and death, particularly in severe or drug-resistant cases. Hence, novel therapeutic agents with distinct mechanisms of action, as well as alternative chemical compounds that can overcome resistance, are still needed to improve malaria therapy. This study aimed to investigate the antimalarial activities of Brucea javanica, a tropical plant extracts against Plasmodium falciparum, the major species associated with severe malaria. In this study, malaria parasites were treated with plant extracts using single and co-incubation methods, along with artesunate and chloroquine, and their inhibitory effect on parasite development was determined by microscopy. The results show that all tested doses of the extracts that effectively inhibited malaria parasites did not cause hemolysis of red blood cells (RBCs). The root extract (RE) and fruit extract (FE) inhibited parasite growth at IC₅₀ values of 0.41 ± 1.14 µg/mL and 0.26 ± 1.15 µg/mL, respectively. These plant extracts significantly interrupted malaria development at the ring stage, as presented by a reduction in the conversion rate to trophozoites and schizonts. The defective parasites treated with plant extracts were characterized by nuclear clumping, leading to pyknotic cell death. Moreover, RE and FW extracts elicited an additive effect with artesunate and chloroquine, significantly reducing IC₉₀ levels for the inhibition of parasite development. In conclusion, B. javanica extracts inhibited the asexual blood-stage development of malaria parasites. They distinctively show the additive effects of ATS and CRQ, elucidating their potential for further studies on novel formulas of antimalarial drug regimens. Full article

Background and Objectives: To evaluate the mRNA vaccine platform for blood-stage Plasmodium parasites, we completed a proof-of-concept study using the P. yoelii mouse model of malaria and two mRNA-based vaccines. Both encoded PyMSP1₁₉ fused to PyMSP8 (PyMSP1/8). One was designed for secretion of the encoded protein (PyMSP1/8-sec); the other encoded membrane-bound antigen (PyMSP1/8-mem). Methods: Secretion of PyMSP1/8-sec and membrane localization of PyMSP1/8-mem were verified in mRNA-transfected cells. As recombinant PyMSP1/8 (rPyMSP1/8) is known to protect mice against lethal P. yoelii 17XL infection, we first compared immunogenicity and efficacy of the PyMSP1/8-sec mRNA vaccine versus the recombinant formulation in outbred mice. Animals were immunized three times followed by challenge with a lethal dose of P. yoelii 17XL-parasitized RBCs (pRBCs). Similar immunization and challenge experiments were conducted to compare PyMSP1/8-sec versus PyMSP1/8-mem mRNA vaccines. Results: Immunogenicity of the PyMSP1/8-sec mRNA vaccine was superior to the recombinant formulation, inducing higher antibody titers against both vaccine components. Following challenge with P. yoelii 17XL pRBCs, all PyMSP1/8-sec-immunized animals survived, with 50% of these showing no detectible pRBCs in circulation (<0.01%). In addition, mean peak parasitemia in PyMSP1/8-sec mRNA-immunized mice was significantly lower than that in the rPyMSP1/8 vaccine group. Both PyMSP1/8-sec and PyMSP1/8-mem were protective against P. yoelii 17XL challenge, with PyMSP1/8-mem immunization providing a significantly higher level of protection than PyMSP1/8-sec immunization considering the number of animals with no detectable pRBCs in circulation and the mean peak parasitemia in animals with detectable parasitemia. Conclusions: mRNA vaccines were highly immunogenic and potently protective against blood-stage malaria, outperforming a similar recombinant-based vaccine. The membrane-bound antigen was more effective at inducing protective antibody responses, highlighting the need to consider antigen localization for mRNA vaccine design. Full article

Background: Malaria remains a significant global health burden, particularly in sub-Saharan Africa, accounting for high rates of illness and death. The growing resistance to frontline antimalarial therapies underscores the urgent need for novel drug targets and therapeutics. Bromodomain-containing proteins, which regulate gene expression through chromatin remodeling, have gained attention as potential targets. Plasmodium falciparum bromodomain protein 1 (PfBDP1), a 55 kDa nuclear protein, plays a key role in recognizing acetylated lysine residues and facilitating transcription during parasite development. Methods: This study investigated ex vivo PfBDP1 gene mutations and identified potential small molecule inhibitors using computational approaches. Malaria-positive blood samples were collected. Genomic DNA was extracted, assessed for quality, and amplified using PfBDP1-specific primers. DNA sequencing and alignment were performed to determine single-nucleotide polymorphism (SNP). Structural modeling used the PfBDP1 crystal structure (PDB ID: 7M97), and active site identification was conducted using CASTp 3.0. Virtual screening and pharmacophore modeling were performed using Pharmit and AutoDock Vina, followed by ADME/toxicity evaluations with SwissADME, OSIRIS, and Discovery Studio. GROMACS was used for 100 ns molecular dynamics simulations. Results: The malaria prevalence rate stood at 12.24%, and the sample size was 165. Sequencing results revealed conserved PfBDP1 gene sequences compared to the 3D7 reference strain. Virtual screening identified nine lead compounds with binding affinities ranging from −9.8 to −10.7 kcal/mol. Of these, CHEMBL2216838 had a binding affinity of −9.9 kcal/mol, with post-screening predictions of favorable drug-likeness (8.60), a high drug score (0.78), superior pharmacokinetics, and a low toxicity profile compared to chloroquine. Molecular dynamics simulations confirmed its stable interaction within the PfBDP1 active site. Conclusions: Overall, this study makes a significant contribution to the ongoing search for novel antimalarial drug targets by providing both molecular and computational evidence for PfBDP1 as a promising therapeutic target. The prediction of CHEMBL2216838 as a lead compound with favorable binding affinity, drug-likeness, and safety profile, surpassing those of existing drugs like chloroquine, sets the stage for preclinical validation and further structure-based drug design efforts. These findings are supported by prior experimental evidence showing significant parasite inhibition and gene suppression capability of predicted hits. Full article

Malaria remains a significant global health challenge. Although the recent approval of the liver-stage vaccines RTS, S and R21 marks significant progress in malaria control, challenges remain in achieving long-lasting and broad protection. In this review, we provide an overview of the current landscape of malaria control, especially anti-malaria vaccine development. We first review the development of the RTS, S and R21 vaccines, highlighting their efficacy and limitations. We then examine other vaccines in development, including attenuated whole-sporozoite vaccines, as well as blood-stage-targeting vaccines and transmission-blocking vaccines targeting a variety of different immunogens. Additionally, we discuss emerging technologies, such as mRNA-based platforms, nanoparticle delivery systems, and novel adjuvants, assessing their potential to enhance the efficacy and mitigate the waning immunity concerns of most malaria vaccines. We believe that the identification of novel immunogen candidates, together with continued innovation in vaccine design and delivery, will enable us to win the fight against malaria in the future. Full article

In response to vaccination and/or infectious agents, the liver produces acute-phase proteins (APPs) driven by IL-6, which circulate in blood plasma as components of the humoral innate defense. This study investigates the liver of mice for possible effects of protective vaccination against primary blood-stage infections of Plasmodium chabaudi malaria on the expression of genes encoding APPs and IL-6 family members. Female Balb/c mice were vaccinated with a non-infectious vaccine prior to challenge with 10⁶ P. chabaudi-infected erythrocytes, resulting in about 80% survival of otherwise lethal infections. Gene expression microarrays were used to determine the relative transcript levels of genes in the livers of vaccinated and unvaccinated mice on days 0, 1, 4, 8, and 11 p.i. (post infectionem). Vaccination induced significant (p-value < 0.05) differences in the expression of malaria-responsive genes toward the end of crisis on day 11 p.i., when mice recovered from infections. These genes include Saa4, Apcs, Cp, and Crp, encoding APPs described to inhibitorily interact with parasitic blood stages; the genes F2, F7, F8, F9, F10, and F13b, and Plg, Plat, and Serpina5, encoding proteins balancing coagulation vs. fibrinolysis dysregulated by malaria, respectively; the genes Hc, C8a, C8b, C8g, and C9, encoding components of lytic complement membrane attack complex (MAC); and Cfh, Cfi, and C4bp, encoding complement-regulatory proteins. Vaccination accelerated, albeit differently, the malaria-induced activation of all three complement pathways, evidenced as higher transcript levels of C1qa, C1qb, C1qc, Fcna, Cfp, C3, Cfh, C8a, and C9 on day 4 p.i., C1ra, C1s, and C2 on day 1 p.i., and Serping1, encoding the multifunctional protease inhibitor C1INH, on day 0 p.i. Protective vaccination may also accelerate downregulation of the malaria-promoting lethality of IL-6 trans-signaling, which may contribute to an overall accelerated recovery of mice from otherwise lethal blood-stage malaria. Full article

Malaria remains a critical global health issue due to high mortality rates, drug resistance, and low treatment efficacy. The genetic variability of Plasmodium proteins complicates the development of long-lasting immunity, as it impedes the human immune system’s ability to sustain effective responses. T cells play a crucial role in combating malaria, but the parasite’s complex life cycle—spanning liver and blood stages—presents significant challenges in effectively activating and targeting these cells. Immunotherapy, which enhances the immune response and promotes durable T cell activity, offers a promising avenue for more effective and lasting malaria treatments. This review systematically analyzed 63 studies published in the last decade, focusing on the role of T cells in malaria. Among the studies, 87.2% targeted T cells as immunotherapy candidates, with CD4+ and CD8+ T cells each accounting for 47.6% of the studies. γδ T cells were the focus in 7.9% of cases, while 12.7% explored non-T cell contributions to enhancing T cell-mediated responses. The findings underscore the potential of T cells, particularly CD8+ T cells, in liver-stage defense and advocate for the exploration of advanced vaccine platforms and novel therapies, such as mRNA-based vectors and monoclonal antibodies. Full article

Malaria remains a global health concern, with 249 million cases and 608,000 deaths being reported by the WHO in 2022. Traditional diagnostic methods often struggle with inconsistent stain quality, lighting variations, and limited resources in endemic regions, making manual detection time-intensive and error-prone. This study introduces an automated system for analyzing Romanowsky-stained thick blood smears, focusing on image quality evaluation, leukocyte detection, and malaria parasite classification. Using a dataset of 1000 clinically diagnosed images, we applied feature extraction techniques, including histogram bins and texture analysis with the gray level co-occurrence matrix (GLCM), alongside support vector machines (SVMs), for image quality assessment. Leukocyte detection employed optimal thresholding segmentation utility (OTSU) thresholding, binary masking, and erosion, followed by the connected components algorithm. Parasite detection used high-intensity region selection and adaptive bounding boxes, followed by a custom convolutional neural network (CNN) for candidate identification. A second CNN classified parasites into trophozoites, schizonts, and gametocytes. The system achieved an F1-score of 95% for image quality evaluation, 88.92% for leukocyte detection, and 82.10% for parasite detection. The F1-score—a metric balancing precision (correctly identified positives) and recall (correctly detected instances out of actual positives)—is especially valuable for assessing models on imbalanced datasets. In parasite stage classification, CNN achieved F1-scores of 85% for trophozoites, 88% for schizonts, and 83% for gametocytes. This study introduces a robust and scalable automated system that addresses critical challenges in malaria diagnosis by integrating advanced image quality assessment and deep learning techniques for parasite detection and classification. This system’s adaptability to low-resource settings underscores its potential to improve malaria diagnostics globally. Full article

Malaria, a severe vector-borne disease, affects billions of people globally and claims over half a million lives annually. Climate change can impact lifespan and the development of vectors. There is a gap in organized, multidisciplined research on climate change’s impact on malaria incidence and transmission. This review assesses and summarizes research on the effects of change in climate on human health, specifically on malaria. Results suggest that higher temperatures accelerate larval development, promote reproduction, enhance blood feed frequency, increase digestion, shorten vector life cycles, and lower mortality rates. Rainfall provides aquatic stages, extends mosquitoes’ lifespans, and increases cases. Mosquito activity increases with high humidity, which facilitates malaria transmission. Flooding can lead to increased inhabitation development, vector population growth, and habitat diversion, increasing breeding sites and the number of cases. Droughts can increase vector range by creating new breeding grounds. Strong storms wash Anopheles’ eggs and reproduction habitat. It limits reproduction and affects disease outbreaks. The Indian Ocean Dipole (IOD) and El Nino Southern Oscillation (ENSO) indirectly alter malaria transmission. The study recommends strengthening collaboration between policymakers, researchers, and stakeholders to reduce malaria risks. It also suggests strengthening control mechanisms and improved early warnings. Full article

Reproducibly assessing malaria exposure is critical for force health protection for military service members deployed to malaria-endemic regions as well as for civilians making public health decisions and evaluating malaria eradication efforts. However, malaria disease surveillance is challenged by under-reporting, natural immunity, and chemoprophylaxis, which can mask malaria exposure and lead to an underestimation of malaria prevalence. In this study, we determined the feasibility of using a serosurveillance-based approach to measure Anopheles vector exposure, Plasmodium sporozoite exposure, and blood-stage parasitemia using a multiplex serological panel. We tested post-deployment samples obtained from U.S. service members returning from regions with malaria risk to assess the potential of this serosurveillance panel. The results identified that some service members had anti-CSP antibody levels comparable to those found in endemic populations, suggesting exposure to sporozoites while those individuals were on chemoprophylaxis. We also observed isolated cases of anti-MSP1 levels that were as high as those observed in endemic populations and in CHMI studies, suggesting possible cases of clinical or subclinical parasitemia. The study demonstrated the feasibility of implementing a multiplex serology approach for conducting serosurveillance for Anopheles vector exposure and Plasmodium parasite exposure in samples collected following military deployments and its potential to support public health policies. Full article

Background: The current economic and social crisis in Latin America has caused migration to the USA, bringing with it Public Health challenges due to the importation of various infectious diseases. Migrants, particularly those with chronic conditions, such as HIV infection and other sexually transmitted infections (STI), are at greater risk due to pharmacological interruption and access to medical care, so the timely detection of diseases acquired during their migration, such as malaria, is crucial to avoid health complications. Objective: To outline by a multidisciplinary approach (Infectology, Parasitology, Epidemiology, molecular Biology, Venereology, and Public Health) the diagnosis and management of a male case with malaria imported to Mexican territory, HIV chronic infection, and latent syphilis. Methods: A male migrant of Venezuelan nationality attended the Clínica Especializada Condesa Iztapalapa in Mexico City for health complications. A comprehensive analysis of laboratory and molecular tests was performed to confirm HIV infection. During the STI diagnostic algorithm, latent syphilis was detected and microscopic observation of blood smears revealed parasitic forms compatible with malaria. Standard and molecular tests were applied under the operational definition for malaria cases for identification, diagnosis, and treatment. Finally, study of clinical history and migration route by questioning for the investigation of the imported case was performed. Results: The immigrant was diagnosed with HIV chronic-stage infection with interrupted antiretroviral therapy (ART), latent syphilis, and malaria by Plasmodium vivax. The ART administered was chosen based on the possible drug interaction with antimalarials and genetic barrier to the HLA-B* allele. Finally, antimicrobial therapy against syphilis was penicillin. From the analysis of the migratory route, incubation time of imported malaria, and questioning, we speculated that the migrant acquired the P. vivax infection in Panama. Conclusions: This case highlights the complex health problems faced by migrants with HIV infection, particularly when they contract additional infections such as malaria during migration and highlights the need for comprehensive access to healthcare and ART, antimalarial and antimicrobial treatments to mitigate the health risks of this vulnerable population. Full article