-
Trends in Parasitology Feb 2012Malaria kills close to a million people every year, mostly children under the age of five. In the drive towards the development of an effective vaccine and new... (Review)
Review
Malaria kills close to a million people every year, mostly children under the age of five. In the drive towards the development of an effective vaccine and new chemotherapeutic targets for malaria, field-based studies on human malaria infection and laboratory-based studies using animal models of malaria offer complementary opportunities to further our understanding of the mechanisms behind malaria infection and pathology. We outline here the parallels between the Plasmodium chabaudi mouse model of malaria and human malaria. We will highlight the contribution of P. chabaudi to our understanding of malaria in particular, how the immune response in malaria infection is initiated and regulated, its role in pathology, and how immunological memory is maintained. We will also discuss areas where new tools have opened up potential areas of exploration using this invaluable model system.
Topics: Animals; Disease Models, Animal; Female; Host-Parasite Interactions; Humans; Immunologic Memory; Malaria; Mice; Plasmodium; Plasmodium chabaudi; Pregnancy
PubMed: 22100995
DOI: 10.1016/j.pt.2011.10.006 -
Current Opinion in Microbiology Dec 2011Protozoan parasites cause tremendous human suffering worldwide, but strategies for therapeutic intervention are limited. Recent studies illustrate that the paradigm of... (Review)
Review
Protozoan parasites cause tremendous human suffering worldwide, but strategies for therapeutic intervention are limited. Recent studies illustrate that the paradigm of microbes as social organisms can be brought to bear on questions about parasite biology, transmission and pathogenesis. This review discusses recent work demonstrating adaptation of social behaviors by parasitic protozoa that cause African sleeping sickness and malaria. The recognition of social behavior and cell-cell communication as a ubiquitous property of bacteria has transformed our view of microbiology, but protozoan parasites have not generally been considered in this context. Works discussed illustrate the potential for concepts of sociomicrobiology to provide insight into parasite biology and should stimulate new approaches for thinking about parasites and parasite-host interactions.
Topics: Cell Communication; Plasmodium; Trypanosoma brucei brucei
PubMed: 22020108
DOI: 10.1016/j.mib.2011.09.012 -
Genetics Aug 2019Understanding the relatedness of individuals within or between populations is a common goal in biology. Increasingly, relatedness features in genetic epidemiology...
Understanding the relatedness of individuals within or between populations is a common goal in biology. Increasingly, relatedness features in genetic epidemiology studies of pathogens. These studies are relatively new compared to those in humans and other organisms, but are important for designing interventions and understanding pathogen transmission. Only recently have researchers begun to routinely apply relatedness to apicomplexan eukaryotic malaria parasites, and to date have used a range of different approaches on an basis. Therefore, it remains unclear how to compare different studies and which measures to use. Here, we systematically compare measures based on identity-by-state (IBS) and identity-by-descent (IBD) using a globally diverse data set of malaria parasites, and , and provide marker requirements for estimates based on IBD. We formally show that the informativeness of polyallelic markers for relatedness inference is maximized when alleles are equifrequent. Estimates based on IBS are sensitive to allele frequencies, which vary across populations and by experimental design. For portability across studies, we thus recommend estimates based on IBD. To generate estimates with errors below an arbitrary threshold of 0.1, we recommend ∼100 polyallelic or 200 biallelic markers. Marker requirements are immediately applicable to haploid malaria parasites and other haploid eukaryotes. C.I.s facilitate comparison when different marker sets are used. This is the first attempt to provide rigorous analysis of the reliability of, and requirements for, relatedness inference in malaria genetic epidemiology. We hope it will provide a basis for statistically informed prospective study design and surveillance strategies.
Topics: Genome, Protozoan; Models, Genetic; Pedigree; Phylogeny; Plasmodium falciparum; Plasmodium vivax; Polymorphism, Single Nucleotide
PubMed: 31209105
DOI: 10.1534/genetics.119.302120 -
Current Opinion in Hematology May 2016Red cell receptors provide unique entry points for Plasmodium parasites to initiate blood-stage malaria infection. Parasites encode distinct ligands that bind... (Review)
Review
PURPOSE OF REVIEW
Red cell receptors provide unique entry points for Plasmodium parasites to initiate blood-stage malaria infection. Parasites encode distinct ligands that bind specifically to both highly abundant and low-copy receptors. Recent advances in the understanding of molecular and structural mechanisms of these interactions provide fundamental insights into receptor-ligand biology and molecular targets for intervention.
RECENT FINDINGS
The review focuses on the requirements for known interactions, insight derived from complex structures, and mechanisms of receptor/ligand engagement. Further, novel roles for established red cell membrane proteins, parasite ligands and associated interacting partners have recently been established in red cell invasion.
SUMMARY
The new knowledge underlines the intricacies involved in invasion by a eukaryotic parasite into a eukaryotic host cell demonstrated by expanded parasite ligand families, redundancy in red cell receptor engagement, multitiered temporal binding, and the breadth of receptors engaged.
Topics: Erythrocytes; Host-Parasite Interactions; Humans; Ligands; Malaria; Plasmodium; Receptors, Cell Surface
PubMed: 26766537
DOI: 10.1097/MOH.0000000000000219 -
Canadian Journal of Anaesthesia =... Mar 2015Malaria is a life-threatening infectious disease caused by the Plasmodium parasite. Increased global travel has resulted in an escalation in the number of imported cases... (Review)
Review
PURPOSE
Malaria is a life-threatening infectious disease caused by the Plasmodium parasite. Increased global travel has resulted in an escalation in the number of imported cases seen in developed countries. Patients with malaria may present for surgery in both endemic and non-endemic countries. This article reviews the perioperative considerations when managing patients with malaria.
SOURCE
A literature review of anesthesia, perioperative care, and malaria-related articles was performed using the MEDLINE(®), EMBASE™, and Web of Science databases to identify relevant articles published in English during 1945-2014. Of the 303 articles matching the search criteria, 265 were excluded based on title and abstract. Eleven of the remaining 38 articles were relevant to anesthesia/perioperative care, and 27 articles were identified as having direct relevance to critical care medicine.
PRINCIPAL FINDINGS
The majority of imported malaria cases are caused by the falciparum species, which is associated with the greatest degree of morbidity and mortality. Various organ systems may be impacted as a consequence of changes in the structure and function of parasitized erythrocytes. Preoperative assessment should focus on establishing the species of malaria, the severity of disease, assessing the degree of end-organ impairment, and initiating treatment of malaria prior to surgery. Intravenous artesunate is the treatment of choice for severe falciparum malaria. Quinine is a second-line agent but has a narrow therapeutic index and particularly hazardous side effects. Intraoperatively, attention should focus on fluid management, dynamics of cerebral blood flow, and avoidance of hypoglycemia. Postoperative care of severe cases should ideally take place in a critical care unit as there may be ongoing requirements for multi-organ support, including renal replacement therapy, ventilation, and/or inotropic support. The safety of neuraxial anesthesia has not been well studied in the setting of malaria.
CONCLUSIONS
Malaria remains one of the most devastating infectious diseases worldwide. Multiple organ systems can be impacted as a consequence of changes in structure and function of parasitized erythrocytes. Safe perioperative management requires a sound knowledge of all these potential system effects.
Topics: Antimalarials; Humans; Malaria; Perioperative Care; Plasmodium
PubMed: 25471683
DOI: 10.1007/s12630-014-0286-7 -
Trends in Parasitology Nov 2020Research on Plasmodium parasites has driven breakthroughs in reducing malaria morbidity and mortality. Experimental analysis of in vivo/ex vivo versus in vitro samples... (Review)
Review
Research on Plasmodium parasites has driven breakthroughs in reducing malaria morbidity and mortality. Experimental analysis of in vivo/ex vivo versus in vitro samples serve unique roles in Plasmodium research. However, these distinctly different environments lead to discordant biology between parasites in host circulation and those under laboratory cultivation. Here, we review how in vitro factors, such as nutrient levels and physical forces, differ from those in the human host and the resulting implications for parasite growth, survival, and virulence. Additionally, we discuss the current utility of direct-from-host methodologies, which avoid the potentially confounding effects of in vitro cultivation. Finally, we make the case for methodological improvements that will drive research progress of physiologically relevant phenotypes.
Topics: Animals; Cells, Cultured; Erythrocytes; Host-Parasite Interactions; Humans; In Vitro Techniques; Malaria; Plasmodium
PubMed: 32958385
DOI: 10.1016/j.pt.2020.08.008 -
Infection and Immunity Jul 2017Malaria vaccine development has been dominated by the subunit approach; however, many subunit vaccine candidates have had limited efficacy in settings of malaria... (Review)
Review
Malaria vaccine development has been dominated by the subunit approach; however, many subunit vaccine candidates have had limited efficacy in settings of malaria endemicity. As our search for an efficacious malaria vaccine continues, the development of a whole-organism vaccine is now receiving much scrutiny. One strategy currently being explored in the development of a whole-organism vaccine involves chemical attenuation of the malaria parasite. and chemical attenuation of both liver-stage and blood-stage parasites has been investigated. Here, we discuss both approaches of chemical attenuation in the development of a whole-organism vaccine against malaria.
Topics: Animals; Antimalarials; Malaria Vaccines; Plasmodium; Vaccines, Attenuated
PubMed: 28438976
DOI: 10.1128/IAI.00062-17 -
Cellular Microbiology May 2014Plasmodium spp. and Toxoplasma gondii are important human and veterinary pathogens. These parasites possess an unusual double membrane structure located directly below... (Review)
Review
Plasmodium spp. and Toxoplasma gondii are important human and veterinary pathogens. These parasites possess an unusual double membrane structure located directly below the plasma membrane named the inner membrane complex (IMC). First identified in early electron micrograph studies, huge advances in genetic manipulation of the Apicomplexa have allowed the visualization of a dynamic, highly structured cellular compartment with important roles in maintaining the structure and motility of these parasites. This review summarizes recent advances in the field and highlights the changes the IMC undergoes during the complex life cycles of the Apicomplexa.
Topics: Intracellular Membranes; Locomotion; Microscopy, Electron; Models, Biological; Plasmodium; Toxoplasma
PubMed: 24612102
DOI: 10.1111/cmi.12285 -
Frontiers in Cellular and Infection... 2021The control and elimination of malaria caused by both represent a great challenge due to the biological aspects of the species. Gametocytes are the forms responsible...
The control and elimination of malaria caused by both represent a great challenge due to the biological aspects of the species. Gametocytes are the forms responsible for the transmission of the parasite to the vector and the search for new strategies for blocking transmission are essential in a scenario of control and elimination The challenges in this search in regard to mainly stem from the lack of a long-term culture and the limitation of studies of gametocytes. This study evaluated the viability and infectivity of gametocytes in short-term culture. The samples enriched in gametocytes using Percoll (i), using magnetic-activated cell sorting (MACS) (ii), and using non-enriched samples (iii) were evaluated. After the procedures, gametocytes were cultured in IMDM medium for up to 48 h. Cultured gametocytes were viable and infectious for up to 48 h, however differences in viability and infectivity were observed in the samples after 12 h of culture in relation to 0 h. Percoll-enriched samples were shown to be viable in culture for longer intervals than those purified using MACS. Gametocyte viability after enrichment procedures and short-term culture may provide new avenues in the development of methods for evaluating TB.
Topics: Humans; Malaria; Malaria, Vivax; Plasmodium falciparum; Plasmodium vivax
PubMed: 34141630
DOI: 10.3389/fcimb.2021.676276 -
Molecular and Biochemical Parasitology Mar 2011Malaria is caused by protozoan parasites of the genus Plasmodium and involves infection of multiple hosts and cell types during the course of an infection. To complete... (Review)
Review
Malaria is caused by protozoan parasites of the genus Plasmodium and involves infection of multiple hosts and cell types during the course of an infection. To complete its complex life cycle the parasite requires strict control of gene regulation for survival and successful propagation. Thus far, the Apicomplexan AP2 (ApiAP2) family of DNA-binding proteins is the sole family of proteins to have surfaced as candidate transcription factors in all apicomplexan species. Work from several laboratories is beginning to shed light on how the ApiAP2 proteins from Plasmodium spp. contribute to the regulation of gene expression at various stages of parasite development. Here we highlight recent progress toward understanding the role of Plasmodium ApiAP2 proteins in DNA related regulatory processes including transcriptional regulation and gene silencing.
Topics: Apicomplexa; Gene Expression Regulation, Developmental; Plasmodium; Transcription Factor AP-2
PubMed: 21126543
DOI: 10.1016/j.molbiopara.2010.11.014