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PLoS Neglected Tropical Diseases Aug 2018We briefly review cysteine proteases (orthologs of mammalian cathepsins B, L, F, and C) that are expressed in flatworm and nematode parasites. Emphasis is placed on... (Review)
Review
We briefly review cysteine proteases (orthologs of mammalian cathepsins B, L, F, and C) that are expressed in flatworm and nematode parasites. Emphasis is placed on enzyme activities that have been functionally characterized, are associated with the parasite gut, and putatively contribute to degrading host proteins to absorbable nutrients [1-4]. Often, gut proteases are expressed as multigene families, as is the case with Fasciola [5] and Haemonchus [6], presumably expanding the range of substrates that can be degraded, not least during parasite migration through host tissues [5]. The application of the free-living planarian and Caenorhabditis elegans as investigative models for parasite cysteine proteases is discussed. Finally, because of their central nutritive contribution, targeting the component gut proteases with small-molecule chemical inhibitors and understanding their utility as vaccine candidates are active areas of research [7].
Topics: Animals; Cysteine Proteases; Digestion; Helminths; Parasites
PubMed: 30138310
DOI: 10.1371/journal.pntd.0005840 -
Bulletin of the World Health... 1975The currently available preparations used as antigen in the serological investigation of parasitic diseases are ill-defined heterogeneous mixtures, and there is an...
The currently available preparations used as antigen in the serological investigation of parasitic diseases are ill-defined heterogeneous mixtures, and there is an evident need for better characterized reagents. Antigens of different parasite species (schistosomes, filariae, trypanosomes, and plasmodia) are discussed and parasite sources enumerated. Modern methods for the preparation of antigenic extracts and their fractionation are described, together with certain guidelines as to their biochemical characterization and their immunological activity. In order to implement this endeavour and to make better use of serological techniques in parasitic diseases, proposals are made concerning collaborative research and field application among a number of laboratories on schistosome, onchocercal, trypanosome, and plasmodial antigens.
Topics: Antigens; Humans; Parasites; Parasitic Diseases
PubMed: 1084794
DOI: No ID Found -
Microbiology Spectrum Aug 2016This chapter aims to provide some key points for researchers interested in the study of ancient gastrointestinal parasites. These few pages are dedicated to my colleague... (Review)
Review
This chapter aims to provide some key points for researchers interested in the study of ancient gastrointestinal parasites. These few pages are dedicated to my colleague and friend, Prof. Adauto Araújo (1951-2015), who participated in the writing of this chapter. His huge efforts in paleoparasitology contributed to the development and promotion of the discipline during more than 30 years.
Topics: Animals; Archaeology; Fossils; History, 15th Century; History, 16th Century; History, 17th Century; History, 18th Century; History, 19th Century; History, 20th Century; History, 21st Century; History, Ancient; History, Medieval; Humans; Intestinal Diseases, Parasitic; Paleopathology; Parasites; Parasitology
PubMed: 27726811
DOI: 10.1128/microbiolspec.PoH-0013-2015 -
Tropical Medicine & International... Jun 2012To review methods for the statistical analysis of parasite and other skewed count data. (Review)
Review
OBJECTIVE
To review methods for the statistical analysis of parasite and other skewed count data.
METHODS
Statistical methods for skewed count data are described and compared, with reference to a 10-year period of Tropical Medicine and International Health (TMIH). Two parasitological datasets are used for illustration.
RESULTS
The review of TMIH found 90 articles, of which 89 used descriptive methods and 60 used inferential analysis. A lack of clarity is noted in identifying the measures of location, in particular the Williams and geometric means. The different measures are compared, emphasising the legitimacy of the arithmetic mean for the skewed data. In the published articles, the t test and related methods were often used on untransformed data, which is likely to be invalid. Several approaches to inferential analysis are described, emphasising (1) non-parametric methods, while noting that they are not simply comparisons of medians, and (2) generalised linear modelling, in particular with the negative binomial distribution. Additional methods, such as the bootstrap, with potential for greater use are described.
CONCLUSIONS
Clarity is recommended when describing transformations and measures of location. It is suggested that non-parametric methods and generalised linear models are likely to be sufficient for most analyses.
Topics: Animals; Humans; Linear Models; Parasite Load; Parasites; Parasitology; Research Design
PubMed: 22943299
DOI: 10.1111/j.1365-3156.2012.02987.x -
Frontiers in Cellular and Infection... 2020Extracellular vesicles (EVs) are membranous structures formed during biological processes in living organisms. For protozoan parasites, secretion of EVs can occur... (Review)
Review
Extracellular vesicles (EVs) are membranous structures formed during biological processes in living organisms. For protozoan parasites, secretion of EVs can occur directly from the parasite organellar compartments and through parasite-infected or antigen-stimulated host cells in response to and physiological stressors. These secreted EVs characteristically reflect the biochemical features of their parasitic origin and activating stimuli. Here, we review the species-specific morphology and integrity of parasitic protozoan EVs in concurrence with the origin, functions, and internalization process by recipient cells. The activating stimuli for the secretion of EVs in pathogenic protozoa are discoursed alongside their biomolecules and specific immune cell responses to protozoan parasite-derived EVs. We also present some insights on the intricate functions of EVs in the context of protozoan parasitism.
Topics: Animals; Exosomes; Extracellular Vesicles; Host-Parasite Interactions; Parasites; Protozoan Proteins
PubMed: 32923407
DOI: 10.3389/fcimb.2020.00371 -
Parasitology Dec 2022Given the abundance, heterogeneity and ubiquity of parasitic organisms, understanding how they influence biodiversity, evolution, health and ecosystem functionality is... (Review)
Review
Given the abundance, heterogeneity and ubiquity of parasitic organisms, understanding how they influence biodiversity, evolution, health and ecosystem functionality is crucial, especially currently when anthropogenic pressures are altering host–parasite balances. This review describes the features, roles and impacts of metazoan parasites of fish occurring in transitional waters (TW). These aquatic ecosystems are highly productive and widespread around the globe and represent most favourable theatres for parasitism given the availability of hosts (invertebrates, fishes and birds) and an increased probability of parasite transmission, especially of those having complex life cycles. Fascinating examples of how parasitism can influence different hierarchical levels of biological systems, from host individuals and populations to entire aquatic communities, through effects on food webs come from this kind of ecosystem. Edible fish of commercial value found in TW can harbour some parasite species, significantly reducing host health, marketability and food safety, with possible economic and public health consequences. Many TW are historically exploited by humans as sources of relevant ecosystem services, including fisheries and aquaculture, and they are highly vulnerable ecosystems. Alteration of TW can be revealed through the study of parasite communities, contributing, as bioindicators, for assessing environmental changes, health and restoration. Fish parasites can provide much information about TW, but this potential appears to be not fully exploited. More studies are necessary to quantify the ecological, economic and medical impacts fish parasites can have on these important ecosystems.
Topics: Humans; Animals; Parasites; Ecosystem; Host-Parasite Interactions; Fishes; Fisheries; Fish Diseases
PubMed: 35946119
DOI: 10.1017/S0031182022001068 -
Trends in Parasitology May 2019Malaria infection is often accompanied by periodic fevers, triggered by synchronous cycles of parasite replication within the host. The degree of synchrony in parasite... (Review)
Review
Malaria infection is often accompanied by periodic fevers, triggered by synchronous cycles of parasite replication within the host. The degree of synchrony in parasite development influences the efficacy of drugs and immune defenses and is therefore relevant to host health and infectiousness. Synchrony is thought to vary over the course of infection and across different host-parasite genotype or species combinations, but the evolutionary significance - if any - of this diversity remains elusive. Standardized methods are lacking, but the most common metric for quantifying synchrony is the percentage of parasites in a particular developmental stage. We use a heuristic model to show that this metric is often unacceptably biased. Methodological challenges must be addressed to characterize diverse patterns of synchrony and their consequences for disease severity and spread.
Topics: Humans; Life Cycle Stages; Malaria; Parasitology; Plasmodium
PubMed: 30952484
DOI: 10.1016/j.pt.2019.03.002 -
The Journal of Biological Chemistry Mar 2023Parasitic diseases result in considerable human morbidity and mortality. The continuous emergence and spread of new drug-resistant parasite strains is an obstacle to... (Review)
Review
Parasitic diseases result in considerable human morbidity and mortality. The continuous emergence and spread of new drug-resistant parasite strains is an obstacle to controlling and eliminating many parasitic diseases. Aminoacyl-tRNA synthetases (aaRSs) are ubiquitous enzymes essential for protein synthesis. The design and development of diverse small molecule, drug-like inhibitors against parasite-encoded and expressed aaRSs have validated this enzyme family as druggable. In this work, we have compiled the progress to date towards establishing the druggability of aaRSs in terms of their biochemical characterization, validation as targets, inhibitor development, and structural interpretation from parasites responsible for malaria (Plasmodium), lymphatic filariasis (Brugia,Wuchereria bancrofti), giardiasis (Giardia), toxoplasmosis (Toxoplasma gondii), leishmaniasis (Leishmania), cryptosporidiosis (Cryptosporidium), and trypanosomiasis (Trypanosoma). This work thus provides a robust framework for the systematic dissection of aaRSs from these pathogens and will facilitate the cross-usage of potential inhibitors to jump-start anti-parasite drug development.
Topics: Animals; Humans; Amino Acyl-tRNA Synthetases; Cryptosporidiosis; Cryptosporidium; Drug Development; Eukaryota; Parasites; RNA, Transfer; Parasitic Diseases
PubMed: 36596362
DOI: 10.1016/j.jbc.2022.102860 -
Journal of Visualized Experiments : JoVE Jan 2022Micro-CT scanning has become an established tool in investigating plant structure and function. Its non-destructive nature, combined with the possibility of...
Micro-CT scanning has become an established tool in investigating plant structure and function. Its non-destructive nature, combined with the possibility of three-dimensional visualization and virtual sectioning, has allowed novel and increasingly detailed analysis of complex plant organs. Interactions among plants, including between parasitic plants and their hosts, can also be explored. However, sample preparation before scanning becomes crucial due to the interaction between these plants, which often differ in tissue organization and composition. Furthermore, the broad diversity of parasitic flowering plants, ranging from highly reduced vegetative bodies to trees, herbs, and shrubs, must be considered during the sampling, treatment, and preparation of parasite-host material. Here two different approaches are described for introducing contrast solutions into the parasite and/or host plants, focusing on analyzing the haustorium. This organ promotes connection and communication between the two plants. Following a simple approach, details of haustorium tissue organization can be explored three-dimensionally, as shown here for euphytoid, vine, and mistletoe parasitic species. Selecting specific contrasting agents and application approaches also allow detailed observation of endoparasite spread within the host body and detection of direct vessel-to-vessel connection between parasite and host, as shown here for an obligate root parasite. Thus, the protocol discussed here can be applied to the broad diversity of parasitic flowering plants to advance the understanding of their development, structure, and functioning.
Topics: Animals; Host-Parasite Interactions; Parasites; Plants; Trees; X-Ray Microtomography
PubMed: 35098949
DOI: 10.3791/63423 -
Trends in Parasitology Oct 2015Nucleic acid extraction and sequencing of genes from organisms within environmental samples encompasses a variety of techniques collectively referred to as environmental... (Review)
Review
Nucleic acid extraction and sequencing of genes from organisms within environmental samples encompasses a variety of techniques collectively referred to as environmental DNA or 'eDNA'. The key advantages of eDNA analysis include the detection of cryptic or otherwise elusive organisms, large-scale sampling with fewer biases than specimen-based methods, and generation of data for molecular systematics. These are particularly relevant for parasitology because parasites can be difficult to locate and are morphologically intractable and genetically divergent. However, parasites have rarely been the focus of eDNA studies. Focusing on eukaryote parasites, we review the increasing diversity of the 'eDNA toolbox'. Combining eDNA methods with complementary tools offers much potential to understand parasite communities, disease risk, and parasite roles in broader ecosystem processes such as food web structuring and community assembly.
Topics: Animals; DNA; Ecosystem; Environmental Monitoring; Parasites; Parasitology
PubMed: 26433253
DOI: 10.1016/j.pt.2015.06.013