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Annual Review of Microbiology 2013Plasmodium and Toxoplasma are genera of apicomplexan parasites that infect millions of people each year. The former causes malaria, and the latter causes neurotropic... (Review)
Review
Plasmodium and Toxoplasma are genera of apicomplexan parasites that infect millions of people each year. The former causes malaria, and the latter causes neurotropic infections associated with a weakened or developing immune system. These parasites harbor a peculiar organelle, the apicoplast. The apicoplast is the product of an ancient endosymbiosis between a heterotrophic and a photosynthetic protist. We explore the cellular and molecular mechanisms that enabled a stable union of two previously independent organisms. These include the exchange of metabolites, transfer of genes, transport of proteins, and overall coordination of biogenesis and proliferation. These mechanisms are still active today and can be exploited to treat parasite infection. They were shaped by the dramatic changes that occurred in the evolution of the phylum Apicomplexa--including the gain and loss of photosynthesis, adaptation to symbiosis and parasitism, and the explosion of animal diversity-that ultimately provided an aquatic alga access to every biotope on this planet.
Topics: Animals; Apicomplexa; Apicoplasts; Biological Evolution; Humans; Parasites; Protozoan Infections; Rhodophyta
PubMed: 23808340
DOI: 10.1146/annurev-micro-092412-155741 -
Frontiers in Immunology 2018Extracellular vesicles (EVs) are small membrane-surrounded structures released by different kinds of cells (normal, diseased, and transformed cells) and that contain... (Review)
Review
Extracellular vesicles (EVs) are small membrane-surrounded structures released by different kinds of cells (normal, diseased, and transformed cells) and that contain large amounts of important substances (such as lipids, proteins, metabolites, DNA, RNA, and non-coding RNA (ncRNA), including miRNA, lncRNA, tRNA, rRNA, snoRNA, and scaRNA) in an evolutionarily conserved manner. EVs, including exosomes, play a role in the transmission of information, and substances between cells that is increasingly being recognized as important. In some infectious diseases such as parasitic diseases, EVs have emerged as a ubiquitous mechanism for mediating communication during host-parasite interactions. EVs can enable multiple modes to transfer virulence factors and effector molecules from parasites to hosts, thereby regulating host gene expression, and immune responses and, consequently, mediating the pathogenic process, which has made us rethink our understanding of the host-parasite interface. Thus, here, we review the present findings regarding EVs (especially exosomes) and recognize the role of EVs in host-parasite interactions. We hope that a better understanding of the mechanisms of parasite-derived EVs may provide new insights for further diagnostic biomarker, vaccine, and therapeutic development.
Topics: Animals; Antiprotozoal Agents; Biomarkers; Exosomes; Host-Parasite Interactions; Humans; Parasites; Parasitic Diseases; Protozoan Vaccines; Virulence Factors
PubMed: 30697211
DOI: 10.3389/fimmu.2018.03066 -
Methods in Molecular Biology (Clifton,... 2022The pathogenesis of malaria is largely attributable to the parasite's ability to modulate its cytoadhesion phenotype. This relates to the multigenic families comprising...
The pathogenesis of malaria is largely attributable to the parasite's ability to modulate its cytoadhesion phenotype. This relates to the multigenic families comprising dozens to hundreds of members, whose expression, often mutually exclusive, allows the parasite to vary its adhesive properties and antigenic appearance. This phenomenon is mainly described for the variant surface antigens that the parasite expresses on the infected erythrocyte. In order to decipher these gene expression spectra and identify potential antigenic candidates and/or targets of therapeutic interest, the analysis of the transcriptomes of the parasites directly isolated from patients with well-defined clinical presentation is important. RNA stabilization is an absolute prerequisite for a precise and accurate transcriptome profiling. Immediate stabilization of RNA of biological samples is therefore necessary to prevent degradation by ribonucleases (RNase) or cellular changes. This chapter described methodology for preserving parasite RNA samples from malaria patients in the field for transcriptome studies.
Topics: Animals; Antigens; Erythrocytes; Malaria; Malaria, Falciparum; Parasites; Plasmodium falciparum; RNA
PubMed: 35881335
DOI: 10.1007/978-1-0716-2189-9_3 -
Conservation Biology : the Journal of... Aug 2016Parasitic species, which depend directly on host species for their survival, represent a major regulatory force in ecosystems and a significant component of Earth's...
Parasitic species, which depend directly on host species for their survival, represent a major regulatory force in ecosystems and a significant component of Earth's biodiversity. Yet the negative impacts of parasites observed at the host level have motivated a conservation paradigm of eradication, moving us farther from attainment of taxonomically unbiased conservation goals. Despite a growing body of literature highlighting the importance of parasite-inclusive conservation, most parasite species remain understudied, underfunded, and underappreciated. We argue the protection of parasitic biodiversity requires a paradigm shift in the perception and valuation of their role as consumer species, similar to that of apex predators in the mid-20th century. Beyond recognizing parasites as vital trophic regulators, existing tools available to conservation practitioners should explicitly account for the unique threats facing dependent species. We built upon concepts from epidemiology and economics (e.g., host-density threshold and cost-benefit analysis) to devise novel metrics of margin of error and minimum investment for parasite conservation. We define margin of error as the risk of accidental host extinction from misestimating equilibrium population sizes and predicted oscillations, while minimum investment represents the cost associated with conserving the additional hosts required to maintain viable parasite populations. This framework will aid in the identification of readily conserved parasites that present minimal health risks. To establish parasite conservation, we propose an extension of population viability analysis for host-parasite assemblages to assess extinction risk. In the direst cases, ex situ breeding programs for parasites should be evaluated to maximize success without undermining host protection. Though parasitic species pose a considerable conservation challenge, adaptations to conservation tools will help protect parasite biodiversity in the face of an uncertain environmental future.
Topics: Animals; Biodiversity; Conservation of Natural Resources; Ecosystem; Host-Parasite Interactions; Parasites
PubMed: 26400623
DOI: 10.1111/cobi.12634 -
Trends in Parasitology Aug 2018Biological invasions have the potential to influence parasite dynamics by altering ecological interactions. Similarly, parasitism can influence invasion by aiding or... (Review)
Review
Biological invasions have the potential to influence parasite dynamics by altering ecological interactions. Similarly, parasitism can influence invasion by aiding or limiting expansion. While many parasite-invasion relationships have been evaluated, many have not been described. Here, we present a conceptual framework of potential interactions, and introduce two new concepts. The first, disease facilitation, nested within the parasite spillback hypothesis, is when invasive species facilitate parasite transmission through habitat alteration or physical transfer. The second, suppressive spillover, is when the deleterious effects of parasitic infection limit the expansion of an introduced species (and hence invasion success). Taken together, the proposed framework may aide in our understanding of ecological drivers of invasion and parasite ecology and can be used to improve mitigation strategies.
Topics: Animals; Ecosystem; Host-Parasite Interactions; Introduced Species; Parasites
PubMed: 29935995
DOI: 10.1016/j.pt.2018.05.008 -
Trends in Parasitology Dec 2018In this era of unprecedented growth in aquaculture and trade, aquatic parasite cultures are essential to better understand emerging diseases and their implications for... (Review)
Review
In this era of unprecedented growth in aquaculture and trade, aquatic parasite cultures are essential to better understand emerging diseases and their implications for human and animal health. Yet culturing parasites presents multiple challenges, arising from their complex, often multihost life cycles, multiple developmental stages, variable generation times and reproductive modes. Furthermore, the essential environmental requirements of most parasites remain enigmatic. Despite these inherent difficulties, in vivo and in vitro cultures are being developed for a small but growing number of aquatic pathogens. Expanding this resource will facilitate diagnostic capabilities and treatment trials, thus supporting the growth of sustainable aquatic commodities and communities.
Topics: Animals; Aquatic Organisms; Culture Techniques; Humans; Life Cycle Stages; Parasites
PubMed: 30473011
DOI: 10.1016/j.pt.2018.09.007 -
RNA Biology Mar 2013miRNAs, a subclass of small regulatory RNAs, are present from ancient unicellular protozoans to parasitic helminths and parasitic arthropods. The miRNA-silencing... (Review)
Review
miRNAs, a subclass of small regulatory RNAs, are present from ancient unicellular protozoans to parasitic helminths and parasitic arthropods. The miRNA-silencing mechanism appears, however, to be absent in a number of protozoan parasites. Protozoan miRNAs and components of their silencing machinery possess features different from other eukaryotes, providing some clues on the evolution of the RNA-induced silencing machinery. miRNA functions possibly associate with neoblast biology, development, physiology, infection and immunity of parasites. Parasite infection can alter host miRNA expression that can favor both parasite clearance and infection. miRNA pathways are, thus, a potential target for the therapeutic control of parasitic diseases.
Topics: Animals; Antiparasitic Agents; Evolution, Molecular; Gene Expression Regulation; Humans; MicroRNAs; Parasites; Parasitic Diseases; RNA Interference; RNA, Helminth; RNA, Protozoan; RNA, Small Nucleolar; Signal Transduction
PubMed: 23392243
DOI: 10.4161/rna.23716 -
Parasitology Research Jan 2022Hosts represent discrete habitats that contain finite parasite communities, and individual hosts can be used as replicates in parasitism studies, such as investigations... (Review)
Review
Hosts represent discrete habitats that contain finite parasite communities, and individual hosts can be used as replicates in parasitism studies, such as investigations of the processes that mediate the formation of parasite communities. However, within a single host population, there may be singularities among individuals that affect parasite contact rates. Accordingly, the goals of the present study were to document the parasites associated with the small treefrog Scinax fuscovarius, to verify possible variation and co-occurrences in parasite infracommunities, and to assess the effects of host characteristics (size and sex) on infracommunity structure. Treefrog specimens (n = 75) were collected from the Bodoquena Mountains in Mato Grosso do Sul, Brazil. After collection, the specimens were transported to the laboratory, and examined for parasitic. The parasites found were removed, fixed, and identified. Patterns in parasite infracommunity organization were analyzed using the checkerboard score index, which was calculated using a presence-absence matrix. The matrix was randomized under the null hypothesis that the infracommunities independently represent the component community. Forty-two (56%) of the individuals harbored at least one parasite, and a total of 500 metazoan parasites were recovered, with a particularly rich composite community of 18 taxa, including 13 nematodes, two trematodes, one cestode, one oligochaete, and one mite larvae. The parasite species were randomly distributed among the infracommunities, with no evidence of co-occurrence, segregation, or aggregation. However, both body size and sex influenced infection, with larger hosts harboring more parasites and parasites were more abundant in male specimens and more species rich in female specimens. These results suggest that the parasite infracommunities of S. fuscovarius are shaped by both random factors and individual host characteristics.
Topics: Animals; Anura; Brazil; Ecosystem; Female; Humans; Male; Nematoda; Parasites
PubMed: 34820717
DOI: 10.1007/s00436-021-07378-3 -
Trends in Parasitology May 2021Biological interactions are key drivers of ecological and evolutionary processes. The complexity of such interactions hinders our understanding of ecological systems and... (Review)
Review
Biological interactions are key drivers of ecological and evolutionary processes. The complexity of such interactions hinders our understanding of ecological systems and our ability to make effective predictions in changing environments. However, network analysis allows us to better tackle the complexity of ecosystems because it extracts the properties of an ecological system according to the number and distribution of links among interacting entities. The number of studies using network analysis to solve ecological and evolutionary questions in parasitology has increased over the past decade. Here, we synthesise the contribution of network analysis toward disentangling host-parasite processes. Furthermore, we identify current trends in mainstream ecology and novel applications of network analysis that present opportunities for research on host-parasite interactions.
Topics: Animals; Host-Parasite Interactions; Models, Biological; Parasitology; Social Network Analysis
PubMed: 33558197
DOI: 10.1016/j.pt.2021.01.005 -
Open Biology Jun 2022MicroRNAs (miRNAs) are a group of small non-coding RNAs present in a wide diversity of organisms. MiRNAs regulate gene expression at a post-transcriptional level through... (Review)
Review
MicroRNAs (miRNAs) are a group of small non-coding RNAs present in a wide diversity of organisms. MiRNAs regulate gene expression at a post-transcriptional level through their interaction with the 3' untranslated regions of target mRNAs, inducing translational inhibition or mRNA destabilization and degradation. Thus, miRNAs regulate key biological processes, such as cell death, signal transduction, development, cellular proliferation and differentiation. The dysregulation of miRNAs biogenesis and function is related to the pathogenesis of diseases, including parasite infection. Moreover, during host-parasite interactions, parasites and host miRNAs determine the probability of infection and progression of the disease. The present review is focused on the possible role of miRNAs in the pathogenesis of diseases of clinical interest caused by parasitic protists. In addition, the potential role of miRNAs as targets for the design of drugs and diagnostic and prognostic markers of parasitic diseases is also discussed.
Topics: 3' Untranslated Regions; Animals; Gene Expression Regulation; Host-Parasite Interactions; MicroRNAs; Parasites
PubMed: 35702995
DOI: 10.1098/rsob.210395