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1
Damian, Raymond T. "Immunological aspects of host-schistosome relationships". Memórias do Instituto Oswaldo Cruz 82, suppl 4 (1987): 13–16. http://dx.doi.org/10.1590/s0074-02761987000800004.
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Bhopale, Mahendra. "Experimental Hookworm Infection in Laboratory animals: Parasite behavior, Immune response and Chemotherapeutic Studies". Biotechnology and Bioprocessing 2, n.º 5 (24 de junio de 2021): 01–03. http://dx.doi.org/10.31579/2766-2314/040.
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Hookworm disease is known to be caused allergic manifestation and severe anemic pathogenicity in man and canine hosts. Attempts have been made to establish laboratory models of Necator americaus, Ancylostoma duodenale, and Ancylostoma ceylanicum, together with canine parasite, Ancylostoma caninum. The studies include pathophysiological aspects of the host-parasite relationship, and develop to establish patent infection. Immunological approach to selecting antigen for diagnosis and protective immunity purpose using larval and adult worm antigens and their secretions became the focus with the subsequent discovery of cloning in vaccine development as main research interest. Chemotherapy of newer drug screening in laboratory models ultimately selected to use for preventive chemotherapy in hookworm endemic areas using recommended drugs.
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Duff, Gordon W. y Joost J. Oppenheim. "Comparative aspects of host-parasite and host-tumor relationships". Cytokine 4, n.º 5 (septiembre de 1992): 331–39. http://dx.doi.org/10.1016/1043-4666(92)90075-3.
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Czerwaty, Katarzyna, Katarzyna Piszczatowska, Jacek Brzost, Nils Ludwig, Mirosław J. Szczepański y Karolina Dżaman. "Immunological Aspects of Chronic Rhinosinusitis". Diagnostics 12, n.º 10 (29 de septiembre de 2022): 2361. http://dx.doi.org/10.3390/diagnostics12102361.
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Chronic rhinosinusitis (CRS) is related to persistent inflammation with a dysfunctional relationship between environmental agents and the host immune system. Disturbances in the functioning of the sinus mucosa lead to common clinical symptoms. The major processes involved in the pathogenesis of CRS include airway epithelial dysfunctions that are influenced by external and host-derived factors which activate multiple immunological mechanisms. The molecular bases for CRS remain unclear, although some factors commonly correspond to the disease: bacterial, fungal and viral infections, comorbidity diseases, genetic dysfunctions, and immunodeficiency. Additionally, air pollution leads increased severity of symptoms. CRS is a heterogeneous group of sinus diseases with different clinical courses and response to treatment. Immunological pathways vary depending on the endotype or genotype of the patient. The recent knowledge expansion into mechanisms underlying the pathogenesis of CRS is leading to a steadily increasing significance of precision medicine in the treatment of CRS. The purpose of this review is to summarize the current state of knowledge regarding the immunological aspects of CRS, which are essential for ensuring more effective treatment strategies.
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Schmid-Hempel, Paul. "Immune defence, parasite evasion strategies and their relevance for ‘macroscopic phenomena’ such as virulence". Philosophical Transactions of the Royal Society B: Biological Sciences 364, n.º 1513 (17 de octubre de 2008): 85–98. http://dx.doi.org/10.1098/rstb.2008.0157.
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The discussion of host–parasite interactions, and of parasite virulence more specifically, has so far, with a few exceptions, not focused much attention on the accumulating evidence that immune evasion by parasites is not only almost universal but also often linked to pathogenesis, i.e. the appearance of virulence. Now, the immune evasion hypothesis offers a deeper insight into the evolution of virulence than previous hypotheses. Sensitivity analysis for parasite fitness and life-history theory shows promise to generate a more general evolutionary theory of virulence by including a major element, immune evasion to prevent parasite clearance from the host. Also, the study of dose–response relationships and multiple infections should be particularly illuminating to understand the evolution of virulence. Taking into account immune evasion brings immunological processes to the core of understanding the evolution of parasite virulence and for a range of related issues such as dose, host specificity or immunopathology. The aim of this review is to highlight the mechanism underlying immune evasion and to discuss possible consequences for the evolutionary ecology analysis of host–parasite interactions.
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Anversa, Laís, Monique Gomes Salles Tiburcio, Virgínia Bodelão Richini-Pereira y Luis Eduardo Ramirez. "Human leishmaniasis in Brazil: A general review". Revista da Associação Médica Brasileira 64, n.º 3 (marzo de 2018): 281–89. http://dx.doi.org/10.1590/1806-9282.64.03.281.
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Summary Leishmaniasis is a disease with ample clinical spectrum and epidemiological diversity and is considered a major public health problem. This article presents an overview of the transmission cycles, host-parasite interactions, clinical, histological and immunological aspects, diagnosis and treatment of various forms of the human disease.
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Dajčman, Urban, Miguel A. Carretero, Rodrigo Megía-Palma, Ana Perera, Rok Kostanjšek y Anamarija Žagar. "Shared haemogregarine infections in competing lacertids". Parasitology 149, n.º 2 (28 de septiembre de 2021): 193–202. http://dx.doi.org/10.1017/s0031182021001645.
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AbstractIn parasite–host interactions host species may differ in their ability to fight parasitic infections, while other ecological interactions, including competition, may differentially alter their physiological state, making them even more susceptible to parasites. In this study, we analyse the haemogregarine blood parasites infecting two competing lizard species, Iberolacerta horvathi and Podarcis muralis, and explore host–parasite relationships under different host competition scenarios. Both species were infected with haemogregarine parasites belonging to the genus Karyolysus. Using the 18S rRNA gene, six new Karyolysus haplotypes were identified clustering with other Central and Eastern European samples, and widely shared between both lizard hosts. Haemogregarine infections were detected at all sampled sites with over 50% of individuals parasitized. Overall, I. horvathi was more frequently and also more intensely parasitized than P. muralis, with higher infection rates observed in syntopy. Males of both species tended to be more frequently infected and showed a higher infection intensity than conspecific females. The results suggest that parasitisation by haemogregarines may be relevant in the dynamics of the competitive relationship between these lizard species. More studies, including immunological response analysis, and the identification of the vectors are needed to better understand host–parasite relationships and competition.
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MEDLEY, G. F. "The epidemiological consequences of optimisation of the individual host immune response". Parasitology 125, n.º 7 (octubre de 2002): S61—S70. http://dx.doi.org/10.1017/s0031182002002354.
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We present a simple unscaled, quantitative framework that addresses the optimum use of resources throughout a host's lifetime based on continuous exposure to parasites (rather than evolutionary, genetically explicit trade-offs). The principal assumptions are that a host's investment of resources in growth increases its survival and reproduction, and that increasing parasite burden reduces survival. The host reproductive value is maximised for a given combination of rates of parasite exposure, host resource acquisition and pathogenicity, which results in an optimum parasite burden (for the host). Generally, results indicate that the optimum resource allocation is to tolerate some parasite infection. The lower the resource acquisition, the lower the proportion of resources that should be devoted to immunity, i.e. the higher the optimum parasite burden. Increases in pathogenicity result in reduced optimum parasite burdens, whereas increases in exposure result in increasing optimum parasite burdens. Simultaneous variation in resource acquisition, pathogenicity and exposure within a community of hosts results in overdispersed parasite burdens, with the degree of heterogeneity decreasing as mean burden increases. The relationships between host condition and parasite burden are complicated, and could potentially confound data analysis. Finally, the value of this approach for explaining epidemiological patterns, immunological processes and the possibilities for further work are discussed.
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KOPRIVNIKAR, J. y H. S. RANDHAWA. "Benefits of fidelity: does host specialization impact nematode parasite life history and fecundity?" Parasitology 140, n.º 5 (24 de enero de 2013): 587–97. http://dx.doi.org/10.1017/s0031182012002132.
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SUMMARYThe range of hosts used by a parasite is influenced by macro-evolutionary processes (host switching, host–parasite co-evolution), as well as ‘encounter filters’ and ‘compatibility filters’ at the micro-evolutionary level driven by host/parasite ecology and physiology. Host specialization is hypothesized to result in trade-offs with aspects of parasite life history (e.g. reproductive output), but these have not been well studied. We used previously published data to create models examining general relationships among host specificity and important aspects of life history and reproduction for nematodes parasitizing animals. Our results indicate no general trade-off between host specificity and the average pre-patent period (time to first reproduction), female size, egg size, or fecundity of these nematodes. However, female size was positively related to egg size, fecundity, and pre-patent period. Host compatibility may thus not be the primary determinant of specificity in these parasitic nematodes if there are few apparent trade-offs with reproduction, but rather, the encounter opportunities for new host species at the micro-evolutionary level, and other processes at the macro-evolutionary level (i.e. phylogeny). Because host specificity is recognized as a key factor determining the spread of parasitic diseases understanding factors limiting host use are essential to predict future changes in parasite range and occurrence.
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Robinson, M., F. Wahid, J. M. Behnke y F. S. Gilbert. "Immunological relationships during primary infection with Heligmosomoides polygyrus (Nematospiroides dubius): dose-dependent expulsion of adult worms". Parasitology 98, n.º 1 (febrero de 1989): 115–24. http://dx.doi.org/10.1017/s0031182000059758.
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SummaryThe survival of Heligmosomoides polygyrus was monitored during primary infections in female C57Bl10, NIH and BALB/c mice at low and high intensities of infection. Survivorship curves were fitted for each data set and analysed. C57Bl10 mice, given either low or high intensities of infection, harboured parasites for 28–37 weeks, heavier infections surviving marginally but significantly longer. Essentially the survivorship curves of H. polygyrus in C57Bl10 mice could be accounted for by senility, the increased probability of worms with a longer life-span occurring at high infection intensities and, possibly, by a contribution from host-protective immune mechanisms in the terminal stages of infection. The pattern of survivorship was different in NIH and BALB/c mice. NIH mice showed weak but significant density-dependent suppression of parasite loss and infections in this strain did not exceed 27·5 weeks in duration. Primary infections in BALB/c mice were briefer still and showed marked dependence on parasite density. Thus low-level infections lasted 10–15 weeks whereas heavier infections survived for 21–34 weeks. The data suggested that both strains developed host-protective responses to adult H. polygyrus and that parasite survival was curtailed earlier than would be expected if senility alone was involved. The hybrid strains (C57Bl10 × NIH)F1 and (B10G × NIH)F1 both expelled H. polygyrus in a dose-dependent manner, worm loss commencing within 10 weeks of infection. In some experiments worm loss was clearly evident by weeks 4 and 6. These hybrid strains showed gene complementation in that adult worms were cleared considerably earlier than in parental strains.
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Su, XQ y RWG White. "Frequency Distribution and Host-Parasite Relationships of Zschokkella Leptatherinae (Myxozoa: Myxiidae), a Parasite of Atherinid Fishes". Australian Journal of Zoology 44, n.º 1 (1996): 97. http://dx.doi.org/10.1071/zo9960097.
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The frequency distribution and aspects of host-parasite relationship of the myxosporean Zschokkella leptatherinae Su and White (1995) in the hepatic ducts and gall bladder of two atherinid fishes, Atherinosoma microstoma (Gunther) and Leptatherina presbyteroides (Richardson), were studied from January 1990 to June 1992. In both fish species, the distribution of Z. leptatherinae fitted the log-normal model. The prevalence and intensity of infection did not vary seasonally. The infection of the parasite occurred more frequently in larger hosts in both fish species but no relationship existed either between the intensity of parasite infection and the size of fish or between the prevalence of parasite infection and sex of fish.
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Melo, Francisco Tiago de Vasconcelos, Rogério Antonio Ribeiro Rodrigues, Elane Guerreiro Giese, Scott Lyell Gardner y Jeannie Nascimento dos Santos. "Histopathologic aspects in Plagioscion squamosissimus (HECKEL, 1940) induced by Neoechinorhynchus veropesoi, metacestodes and anisakidae juveniles". Revista Brasileira de Parasitologia Veterinária 23, n.º 2 (junio de 2014): 224–30. http://dx.doi.org/10.1590/s1984-29612014048.
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Plagioscion squamosissimus (Heckel 1840), a fish endemic to the Amazon Basin and commonly known as the “silver croaker”, plays an important role in the ecology and economy of Pará State, Brazil. Knowledge of host-parasite relationships is important to understanding the role of parasites in the control of natural host populations. This work describes histopathological aspects caused by several common intestinal parasites found during a helminthological survey of fish in northern Brazil. We observed a high prevalence of helminth infection, especially by J3 nematode juveniles of the family Anisakidae and metacestodes of the family Protocephalidae (both with 100% prevalence). An external capsule surrounded each juvenile with numerous juveniles inside sac-like structures formed of connective tissue. Inflammation was observed to be caused by infection of metacestodes, reaching the intestinal muscularis mucosa. Neoechinorhynchus veropesoi (38% prevalence) was found in the small intestine of P. squamosissimus, invading the mucosa, submucosa, and internal muscularis of the intestine causing intense inflammation. Histopathology of host-parasite relationships in fish has been rare, and the pathology of parasites in P. squamosissimus is described herein.
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Velavan, TP y Olusola Ojurongbe. "Regulatory T Cells and Parasites". Journal of Biomedicine and Biotechnology 2011 (2011): 1–8. http://dx.doi.org/10.1155/2011/520940.
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Human host encounters a wide array of parasites; however, the crucial aspect is the failure of the host immune system to clear these parasites despite antigen recognition. In the recent past, a new immunological concept has emerged, which provides a framework to better understand several aspects of host susceptibility to parasitic infection. It is widely believed that parasites are able to modulate the magnitude of effector responses by inducing regulatory T cell (Tregs) population and several studies have investigated whether this cell population plays a role in balancing protective immunity and pathogenesis during parasite infection. This review discusses the several mechanism of Treg-mediated immunosuppression in the human host and focuses on the functional role of Tregs and regulatory gene polymorphisms in infectious diseases.
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Zhang, Wenbao, Hao Wen, Jun Li, Renyong Lin y Donald P. McManus. "Immunology and Immunodiagnosis of Cystic Echinococcosis: An Update". Clinical and Developmental Immunology 2012 (2012): 1–10. http://dx.doi.org/10.1155/2012/101895.
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Cystic echinococcosis (CE) is a cosmopolitan zoonosis caused by the larval cystic stage of the dog tapewormEchinococcus granulosus. This complex multicellular pathogen produces various antigens which modulate the host immune response and promote parasite survival and development. The recent application of modern molecular and immunological approaches has revealed novel insights on the nature of the immune responses generated during the course of a hydatid infection, although many aspects of theEchinococcus-host interplay remain unexplored. This paper summarizes recent developments in our understanding of the immunology and diagnosis of echinococcosis, indicates areas where information is lacking, and suggests possible new strategies to improve serodiagnosis for practical application.
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Darlan, Dewi Masyithah, Muhammad Fakhrur Rozi y Hemma Yulfi. "Overview of Immunological Responses and Immunomodulation Properties of Trichuris sp.: Prospects for Better Understanding Human Trichuriasis". Life 11, n.º 3 (27 de febrero de 2021): 188. http://dx.doi.org/10.3390/life11030188.
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Trichuris sp. infection has appeared as a pathological burden in the population, but the immunomodulation features could result in an opportunity to discover novel treatments for diseases with prominent inflammatory responses. Regarding the immunological aspects, the innate immune responses against Trichuris sp. are also responsible for determining subsequent immune responses, including the activation of innate lymphoid cell type 2 (ILC2s), and encouraging the immune cell polarization of the resistant host phenotype. Nevertheless, this parasite can establish a supportive niche for worm survival and finally avoid host immune interference. Trichuris sp. could skew antigen recognition and immune cell activation and proliferation through the generation of specific substances, called excretory/secretory (ESPs) and soluble products (SPs), which mainly mediate its immunomodulation properties. Through this review, we elaborate and discuss innate–adaptive immune responses and immunomodulation aspects, as well as the clinical implications for managing inflammatory-based diseases, such as inflammatory bowel diseases, allergic, sepsis, and other autoimmune diseases.
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Tate, Ann T. y Andrea L. Graham. "Dissecting the contributions of time and microbe density to variation in immune gene expression". Proceedings of the Royal Society B: Biological Sciences 284, n.º 1859 (26 de julio de 2017): 20170727. http://dx.doi.org/10.1098/rspb.2017.0727.
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Widespread differential expression of immunological genes is a hallmark of the response to infection in almost all surveyed taxa. However, several challenges remain in the attempt to connect differences in gene expression with functional outcomes like parasite killing and host survival. For example, temporal gene expression patterns are not always monotonic (unidirectional slope), yielding results that qualitatively depend on the time point selected for analysis. They may also be correlated to microbe density, confounding the strength of an immune response and resistance to parasites. In this study, we analyse these relationships in an mRNA-seq time series of Tribolium castaneum infected with Bacillus thuringiensis . Our results suggest that many extracellular immunological components with known roles in immunity, like antimicrobial peptides and recognition proteins, are highly correlated to microbe load. On the other hand, intracellular components of immunological signalling pathways overwhelmingly show non-monotonic temporal patterns of gene expression, despite the underlying assumption of monotonicity in most ecological and comparative transcriptomics studies that rely on cross-sectional analyses. Our results raise a host of new questions, including to what extent variation in host resistance, infection tolerance and immunopathology can be explained by variation in the slope or sensitivity of these newly characterized patterns.
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Bouzid, Maha, Paul R. Hunter, Rachel M. Chalmers y Kevin M. Tyler. "Cryptosporidium Pathogenicity and Virulence". Clinical Microbiology Reviews 26, n.º 1 (enero de 2013): 115–34. http://dx.doi.org/10.1128/cmr.00076-12.
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SUMMARYCryptosporidiumis a protozoan parasite of medical and veterinary importance that causes gastroenteritis in a variety of vertebrate hosts. Several studies have reported different degrees of pathogenicity and virulence amongCryptosporidiumspecies and isolates of the same species as well as evidence of variation in host susceptibility to infection. The identification and validation ofCryptosporidiumvirulence factors have been hindered by the renowned difficulties pertaining to thein vitroculture and genetic manipulation of this parasite. Nevertheless, substantial progress has been made in identifying putative virulence factors forCryptosporidium. This progress has been accelerated since the publication of theCryptosporidium parvumandC. hominisgenomes, with the characterization of over 25 putative virulence factors identified by using a variety of immunological and molecular techniques and which are proposed to be involved in aspects of host-pathogen interactions from adhesion and locomotion to invasion and proliferation. Progress has also been made in the contribution of host factors that are associated with variations in both the severity and risk of infection. Here we provide a review comprised of the current state of knowledge onCryptosporidiuminfectivity, pathogenesis, and transmissibility in light of our contemporary understanding of microbial virulence.
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Ezenwa, Vanessa O. y Matthew H. Snider. "Reciprocal relationships between behaviour and parasites suggest that negative feedback may drive flexibility in male reproductive behaviour". Proceedings of the Royal Society B: Biological Sciences 283, n.º 1831 (25 de mayo de 2016): 20160423. http://dx.doi.org/10.1098/rspb.2016.0423.
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Parasites are ubiquitous components of the environment that contribute to behavioural and life-history variation among hosts. Although it is well known that host behaviour can affect parasite infection risk and that parasites can alter host behaviour, the potential for dynamic feedback between these processes is poorly characterized. Using Grant's gazelle ( Nanger granti ) as a model, we tested for reciprocal effects of behaviour on parasites and parasites on behaviour to understand whether behaviour–parasite feedback could play a role in maintaining variation in male reproductive behaviour. Adult male gazelles either defend territories to attract mates or reside in bachelor groups. Territoriality is highly variable both within- and between-individuals, suggesting that territory maintenance is costly. Using a combination of longitudinal and experimental studies, we found that individual males transition frequently between territorial and bachelor reproductive status, and that elevated parasite burdens are a cost of territoriality. Moreover, among territorial males, parasites suppress aspects of behaviour related to territory maintenance and defence. These results suggest that territorial behaviour promotes the accumulation of parasites in males, and these parasites dampen the very behaviours required for territory maintenance. Our findings suggest that reciprocal feedback between host behaviour and parasitism could be a mechanism maintaining variation in male reproductive behaviour in the system.
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Gomez, Lourdes M., Victor A. Meszaros, Wendy C. Turner y C. Brandon Ogbunugafor. "The Epidemiological Signature of Pathogen Populations That Vary in the Relationship between Free-Living Parasite Survival and Virulence". Viruses 12, n.º 9 (22 de septiembre de 2020): 1055. http://dx.doi.org/10.3390/v12091055.
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The relationship between parasite virulence and transmission is a pillar of evolutionary theory that has implications for public health. Part of this canon involves the idea that virulence and free-living survival (a key component of transmission) may have different relationships in different host–parasite systems. Most examinations of the evolution of virulence-transmission relationships—Theoretical or empirical in nature—Tend to focus on the evolution of virulence, with transmission being a secondary consideration. Even within transmission studies, the focus on free-living survival is a smaller subset, though recent studies have examined its importance in the ecology of infectious diseases. Few studies have examined the epidemic-scale consequences of variation in survival across different virulence–survival relationships. In this study, we utilize a mathematical model motivated by aspects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) natural history to investigate how evolutionary changes in survival may influence several aspects of disease dynamics at the epidemiological scale. Across virulence–survival relationships (where these traits are either positively or negatively correlated), we found that small changes (5% above and below the nominal value) in survival can have a meaningful effect on certain outbreak features, including R0, and on the size of the infectious peak in the population. These results highlight the importance of properly understanding the mechanistic relationship between virulence and parasite survival, as the evolution of increased survival across different relationships with virulence may have considerably different epidemiological signatures.
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HIGÓN, MELISSA, GRAEME COWAN, NORMAN NAUSCH, DAVID CAVANAGH, ANA OLEAGA, RAFAEL TOLEDO, J. RUSSELL STOTHARD et al. "Screening trematodes for novel intervention targets: a proteomic and immunological comparison of Schistosoma haematobium, Schistosoma bovis and Echinostoma caproni". Parasitology 138, n.º 12 (10 de junio de 2011): 1607–19. http://dx.doi.org/10.1017/s0031182011000412.
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SUMMARYWith the current paucity of vaccine targets for parasitic diseases, particularly those in childhood, the aim of this study was to compare protein expression and immune cross-reactivity between the trematodes Schistosoma haematobium, S. bovis and Echinostoma caproni in the hope of identifying novel intervention targets. Native adult parasite proteins were separated by 2-dimensional gel electrophoresis and identified through electrospray ionisation tandem mass spectrometry to produce a reference gel. Proteins from differential gel electrophoresis analyses of the three parasite proteomes were compared and screened against sera from hamsters infected with S. haematobium and E. caproni following 2-dimensional Western blotting. Differential protein expression between the three species was observed with circa 5% of proteins from S. haematobium showing expression up-regulation compared to the other two species. There was 91% similarity between the proteomes of the two Schistosoma species and 81% and 78·6% similarity between S. haematobium and S. bovis versus E. caproni, respectively. Although there were some common cross-species antigens, species-species targets were revealed which, despite evolutionary homology, could be due to phenotypic plasticity arising from different host-parasite relationships. Nevertheless, this approach helps to identify novel intervention targets which could be used as broad-spectrum candidates for future use in human and veterinary vaccines.
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Zainab A. Makawi, Hind D Hadi y Azhar Ali. "Revision of some species of the genus Cryptosporidium (Tyzzer, 1907) (Eucoccidiorida, cryptosporidiidae) in cattle in Iraq". GSC Biological and Pharmaceutical Sciences 14, n.º 1 (30 de enero de 2021): 116–20. http://dx.doi.org/10.30574/gscbps.2021.14.1.0003.
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Cryptosporidium is a protozoan parasite of medical and veterinary significance that causes gastroenteritis in a number of vertebrate hosts. Several studies have recorded different degrees of pathogenicity and virulence among Cryptosporidium species and isolates of the same species as well as evidence of variation in host susceptibility to infection. Nevertheless, important progress has been made in determining Cryptosporidium's putative virulence factors. Since the publication of C parvum and C. Hominis this development has been accelerated genomes, identified by a range of immunological and molecular techniques with the characterization of over 25 putative virulence factors, which are proposed to be involved in aspects of host-pathogen interactions from adhesion and locomotion to invasion and proliferation. There has also been improvement in the contribution of host variables correlated with differences in both the severity and risk of infection. In view of our current understanding of microbial virulence, we present a summary of the current state of information on Cryptosporidium infectivity, pathogenesis, and transmissibility here.
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Stear, M. J., D. Singleton y L. Matthews. "An evolutionary perspective on gastrointestinal nematodes of sheep". Journal of Helminthology 85, n.º 2 (19 de abril de 2011): 113–20. http://dx.doi.org/10.1017/s0022149x11000058.
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AbstractThe purpose of this paper was to discuss from an evolutionary perspective the interaction between domestic sheep (Ovis aries)and their gastrointestinal nematodes. Although evolution is the central theme of biology, there has been little attempt to consider how evolutionary forces have shaped and continue to shape the relationships between domestic animals and their parasite community. Mathematical modelling of the host–parasite relationship indicated that the system is remarkably robust to perturbations in its parameters. This robustness may be a consequence of the long coevolution of host and parasites. Although nematodes can potentially evolve faster than the host, coevolution is not dominated by the parasite and there are several examples where breeds of cattle or sheep have evolved high levels of resistance to disease. Coevolution is a more equal partnership between host and nematode than is commonly assumed. Coevolution between parasites and the host immune system is often described as an arms race where both host immune response genes and parasite proteins evolve rapidly in response to each other. However, initial results indicate that nematode antigens are not evolving rapidly; the arms race between the immune system and nematodes, if it exists, is happening very slowly. Fisher's fundamental theorem of natural selection states that genes with positive effects on fitness will be fixed by natural selection. Consequently, heritable variation in fitness traits is expected to be low. Contrary to this argument, there is considerable genetic variation in resistance to nematode infection. In particular, the heritabilities of nematode-specific IgA and IgE activity are moderate to high. The reasons for this apparent violation of the fundamental theorem of natural selection are not clear but several possible explanations are explored. Faecal nematode egg counts increase at the beginning of the grazing season – a phenomenon known as the periparturient rise. This increase benefits host and parasite and appears to be a consequence of coevolution. In conclusion, an evolutionary perspective can shed light on many aspects of the host–parasite relationship in domestic animals.
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Florentino, P. T. V., F. Real, A. Bonfim-Melo, C. M. Orikaza, E. R. Ferreira, C. C. Pessoa, B. R. Lima, G. R. S. Sasso y R. A. Mortara. "An Historical Perspective on How Advances in Microscopic Imaging Contributed to Understanding theLeishmaniaSpp. andTrypanosoma cruziHost-Parasite Relationship". BioMed Research International 2014 (2014): 1–16. http://dx.doi.org/10.1155/2014/565291.
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The literature has identified complex aspects of intracellular host-parasite relationships, which require systematic, nonreductionist approaches and spatial/temporal information. Increasing and integrating temporal and spatial dimensions in host cell imaging have contributed to elucidating several conceptual gaps in the biology of intracellular parasites. To access and investigate complex and emergent dynamic events, it is mandatory to follow them in the context of living cells and organs, constructing scientific images with integrated high quality spatiotemporal data. This review discusses examples of how advances in microscopy have challenged established conceptual models of the intracellular life cycles ofLeishmaniaspp. andTrypanosoma cruziprotozoan parasites.
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Duaso, Juan, Erika Yanez, Christian Castillo, Norbel Galanti, Gonzalo Cabrera, Gabriela Corral, Juan Diego Maya, Inés Zulantay, Werner Apt y Ulrike Kemmerling. "Reorganization of Extracellular Matrix in Placentas from Women with Asymptomatic Chagas Disease: Mechanism of Parasite Invasion or Local Placental Defense?" Journal of Tropical Medicine 2012 (2012): 1–8. http://dx.doi.org/10.1155/2012/758357.
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Chagas disease, produced by the protozoanTrypanosoma cruzi(T. cruzi), is one of the most frequent endemic diseases in Latin America. In spite the fact that in the past few yearsT. cruzicongenital transmission has become of epidemiological importance, studies about this mechanism of infection are scarce. In order to explore some morphological aspects of this infection in the placenta, we analyzed placentas fromT. cruzi-infected mothers by immunohistochemical and histochemical methods. Infection in mothers, newborns, and placentas was confirmed by PCR and by immunofluorescence in the placenta.T. cruzi-infected placentas present destruction of the syncytiotrophoblast and villous stroma, selective disorganization of the basal lamina, and disorganization of collagen I in villous stroma. Our results suggest that the parasite induces reorganization of this tissue component and in this way may regulate both inflammatory and immune responses in the host. Changes in the ECM of placental tissues, together with the immunological status of mother and fetus, and parasite load may determine the probability of congenital transmission ofT. cruzi.
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VELASQUEZ, LEONARDO G., MARIANA K. GALUPPO, ELOIZA DE REZENDE, WESLEY N. BRANDÃO, JEAN PIERRE PERON, SILVIA R. B. ULIANA, MARIA IRMA DUARTE y BEATRIZ S. STOLF. "Distinct courses of infection withLeishmania(L.)amazonensisare observed in BALB/c, BALB/c nude and C57BL/6 mice". Parasitology 143, n.º 6 (19 de febrero de 2016): 692–703. http://dx.doi.org/10.1017/s003118201600024x.
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SUMMARYLeishmania(L.)amazonensis[L.(L.)amazonensis] is widely distributed in Brazil and its symptomatic infections usually lead to few localized lesions and sometimes to diffuse cutaneous form, with nodules throughout the body, anergy to parasite antigens and poor therapeutic response. The variability of these manifestations draws attention to the need for studies on the pathophysiology of infection by this species. In this study, we analysed the course and immunological aspects ofL.(L.)amazonensisinfection in BALB/c and C57BL/6 strains, both susceptible, but displaying different clinical courses, and athymic BALB/c nude, to illustrate the role of T cell dependent responses. We analysed footpad thickness and parasite burden byin vivoimaging. Furthermore, we evaluated the cellular profile and cytokine production in lymph nodes and the inflammatory infiltrates of lesions. Nude mice showed delayed lesion development and less inflammatory cells in lesions, but higher parasite burden than BALB/c and C57BL/6. BALB/c and C57BL/6 mice had similar parasite burdens, lesion sizes and infiltrates until 6 weeks after infection, and after that C57BL/6 mice controlled the infection. Small differences in parasite numbers were observed in C57BL/6 macrophagesin vitro, indicating thatin vivomilieu accounts for most differences in infection. We believe our results shed light on the role of host immune system in the course ofL.(L.)amazonensisinfection by comparing three mouse strains that differ in parasitaemia and inflammatory cells.
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P., Ma y Gonzalez-Lanza, Ma C. "Goussia carpelli (Protozoa, Apicomplexa) in cyprinid fish of the Duero basin (NW Spain). Aspects of host-parasite relationships". Journal of Applied Ichthyology 2, n.º 3 (julio de 1986): 125–30. http://dx.doi.org/10.1111/j.1439-0426.1986.tb00439.x.
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Gabriel, Áurea Martins, Adan Galué-Parra, Washington Luiz Assunção Pereira, Ketil Winther Pedersen y Edilene Oliveira da Silva. "Leishmania 360°: Guidelines for Exosomal Research". Microorganisms 9, n.º 10 (2 de octubre de 2021): 2081. http://dx.doi.org/10.3390/microorganisms9102081.
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Leishmania parasites are a group of kinetoplastid pathogens that cause a variety of clinical disorders while maintaining cell communication by secreting extracellular vesicles. Emerging technologies have been adapted for the study of Leishmania-host cell interactions, to enable the broad-scale analysis of the extracellular vesicles of this parasite. Leishmania extracellular vesicles (LEVs) are spheroidal nanoparticles of polydispersed suspensions surrounded by a layer of lipid membrane. Although LEVs have attracted increasing attention from researchers, many aspects of their biology remain unclear, including their bioavailability and function in the complex molecular mechanisms of pathogenesis. Given the importance of LEVs in the parasite-host interaction, and in the parasite-parasite relationships that have emerged during the evolutionary history of these organisms, the present review provides an overview of the available data on Leishmania, and formulates guidelines for LEV research. We conclude by reporting direct methods for the isolation of specific LEVs from the culture supernatant of the promastigotes and amastigotes that are suitable for a range of different downstream applications, which increases the compatibility and reproducibility of the approach for the establishment of optimal and comparable isolation conditions and the complete characterization of the LEV, as well as the critical immunomodulatory events triggered by this important group of parasites.
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Pittman, Kelly J. y Laura J. Knoll. "Long-Term Relationships: the Complicated Interplay between the Host and the Developmental Stages of Toxoplasma gondii during Acute and Chronic Infections". Microbiology and Molecular Biology Reviews 79, n.º 4 (2 de septiembre de 2015): 387–401. http://dx.doi.org/10.1128/mmbr.00027-15.
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SUMMARYToxoplasma gondiirepresents one of the most common parasitic infections in the world. The asexual cycle can occur within any warm-blooded animal, but the sexual cycle is restricted to the feline intestinal epithelium.T. gondiiis acquired through consumption of tissue cysts in undercooked meat as well as food and water contaminated with oocysts. Once ingested, it differentiates into a rapidly replicating asexual form and disseminates throughout the body during acute infection. After stimulation of the host immune response,T. gondiidifferentiates into a slow-growing, asexual cyst form that is the hallmark of chronic infection. One-third of the human population is chronically infected withT. gondiicysts, which can reactivate and are especially dangerous to individuals with reduced immune surveillance. Serious complications can also occur in healthy individuals if infected with certainT. gondiistrains or if infection is acquired congenitally. No drugs are available to clear the cyst form during the chronic stages of infection. This therapeutic gap is due in part to an incomplete understanding of both host and pathogen responses during the progression ofT. gondiiinfection. While many individual aspects ofT. gondiiinfection are well understood, viewing the interconnections between host and parasite during acute and chronic infection may lead to better approaches for future treatment. The aim of this review is to provide an overview of what is known and unknown about the complex relationship between the host and parasite during the progression ofT. gondiiinfection, with the ultimate goal of bridging these events.
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Vijay, Sonam, Manmeet Rawat y Arun Sharma. "Mass Spectrometry Based Proteomic Analysis of Salivary Glands of Urban Malaria VectorAnopheles stephensi". BioMed Research International 2014 (2014): 1–12. http://dx.doi.org/10.1155/2014/686319.
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Salivary gland proteins ofAnophelesmosquitoes offer attractive targets to understand interactions with sporozoites, blood feeding behavior, homeostasis, and immunological evaluation of malaria vectors and parasite interactions. To date limited studies have been carried out to elucidate salivary proteins ofAn. stephensisalivary glands. The aim of the present study was to provide detailed analytical attributives of functional salivary gland proteins of urban malaria vectorAn. stephensi. A proteomic approach combining one-dimensional electrophoresis (1DE), ion trap liquid chromatography mass spectrometry (LC/MS/MS), and computational bioinformatic analysis was adopted to provide the first direct insight into identification and functional characterization of known salivary proteins and novel salivary proteins ofAn. stephensi. Computational studies by online servers, namely, MASCOT and OMSSA algorithms, identified a total of 36 known salivary proteins and 123 novel proteins analysed by LC/MS/MS. This first report describes a baseline proteomic catalogue of 159 salivary proteins belonging to various categories of signal transduction, regulation of blood coagulation cascade, and various immune and energy pathways ofAn. stephensisialotranscriptome by mass spectrometry. Our results may serve as basis to provide a putative functional role of proteins in concept of blood feeding, biting behavior, and other aspects of vector-parasite host interactions for parasite development in anopheline mosquitoes.
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Hoberg, Eric P. "Evolution and historical biogeography of a parasite–host assemblage: Alcataenia spp. (Cyclophyllidea: Dilepididae) in Alcidae (Charadriiformes)". Canadian Journal of Zoology 64, n.º 11 (1 de noviembre de 1986): 2576–89. http://dx.doi.org/10.1139/z86-378.
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The methodology of phylogenetic systematics was used to develop hypotheses for the evolution of eight species of Alcataenia, a group of host-specific cestodes of the Alcidae and, to a lesser extent, the Laridae (Charadriiformes). Concurrently, aspects of the early biogeography of alcids were reevaluated making it possible to study the historical and distributional relationships of parasites and hosts. The most parsimonious hypothesis for the phylogeny of Alcataenia suggested that sequential colonization or host switching with limited coevolution (coaccommodation) by parasites best explained the distributional patterns exhibited by Alcataenia spp. Morphological evolution of specific species of Alcataenia accompanied host switching, but was limited subsequent to the initial event of colonization. Thus evolution of these parasites following colonization lagged behind continuing diversification of the host group. Although alcids are an ancient group, as indicated by palaeontological and phylogenetic data, their cestode fauna is apparently not. It is postulated that Alcataenia spp. were acquired by their characteristic hosts in the late Pliocene and early Pleistocene, following diversification of the Alcidae at the generic level during the Miocene. Host distributions of respective Alcataenia spp. are more narrow than expected, considering the relatively young age of this assemblage. The current paradigm linking pronounced host specificity with coevolution of hosts and parasites in assemblages of great evolutionary age is not supported.
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Behnke, J. M., Diane J. Williams, J. Hannah y D. I. Pritchard. "Immunological relationships during primary infection with Heligmosomoides polygyrus (Nematospiroides dubius): the capacity of adult worms to survive following transplantation to recipient mice". Parasitology 95, n.º 3 (diciembre de 1987): 569–81. http://dx.doi.org/10.1017/s0031182000057991.
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SUMMARYChronic primary infections with Heligmosomoides polygyrus (Nematospiroides dubius) are still relatively poorly documented, particularly in relation to the role of host resistance in limiting worm survival. In the present work the duration of infection with H. polygyrus was studied in CFLP mice given doses of infective larvae ranging from 50 to 500 L3. The least heavily infected (50 L3) group ceased egg production earliest (week 36) whereas eggs were still detected in the faeces of mice given 500 larvae in week 42. At autopsy (week 42) mice given 50 larvae had virtually lost their entire worm burden with 5 out of 11 mice still harbouring a single worm each. However, all the mice in the group given 500 larvae were still infected, the highest worm burden being 93. The concentration of serum IgGl and specific antibody was highest in mice given 500 larvae, but sera taken from mice with declining worm burdens 19–38 weeks post-infection did not contain detectable host-protective antibody. During the course of infection in CFLP mice, H, polygyrus sustained irreversible changes in its capacity for subsequent survival. Thus, adult worms transferred to naive mice 2, 7, 14, 30 or 36 weeks post-infection did not live longer than worms of a comparable age in the respective donor group. In contrast, primary infection worms taken from jirds in which expulsion is usually completed by 6 weeks post-infection, re-established in mice and survived considerably longer than in the group of donor jirds. These results were discussed in relation to the possible interactions between parasite senility and immunomodulation, and host resistance in limiting primary infections with H. polygyrus in mice and jirds.
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INNES, E. A. y A. N. VERMEULEN. "Vaccination as a control strategy against the coccidial parasitesEimeria,ToxoplasmaandNeospora". Parasitology 133, S2 (octubre de 2006): S145—S168. http://dx.doi.org/10.1017/s0031182006001855.
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The protozoan parasitesEimeriaspp.Toxoplasma gondiiandNeospora caninumare significant causes of disease in livestock worldwide andT. gondiiis also an important human pathogen. Drugs have been used with varying success to help control aspects of these diseases and commercial vaccines are available for all three groups of parasites. However, there are issues with increasing development of resistance to many of the anti-coccidial drugs used to help control avian eimeriosis and public concerns about the use of drugs in food animals. In addition there are no drugs available that can act against the tissue cyst stage of eitherT. gondiiorN. caninumand thus cure animals or people of infection. All three groups of parasites multiply within the cells of their host species and therefore cell mediated immune mechanisms are thought to be an important component of host protective immunity. Successful vaccination strategies for bothEimeriaandToxoplasmahave relied on using a live vaccination approach using attenuated parasites which allows correct processing and presentation of antigen to the host immune system to stimulate appropriate cell mediated immune responses. However, live vaccines can have problems with safety, short shelf-life and large-scale production; therefore there is continued interest in devising new vaccines using defined recombinant antigens. The major challenges in devising novel vaccines are to select relevant antigens and then present them to the immune system in an appropriate manner to enable the induction of protective immune responses. With all three groups of parasites, vaccine preparations comprising antigens from the different life cycle stages may also be advantageous. In the case ofEimeriaparasites there are also problems with strain-specific immunity therefore a cocktail of antigens from different parasite strains may be required. Improving our knowledge of the different parasite transmission routes, host-parasite relationships, disease pathogenesis and determining the various roles of the host immune response being at times host-protective, parasite protective and in causing immunopathology will help to tailor a vaccination strategy against a particular disease target. This paper discusses current vaccination strategies to help combat infections withEimeria,ToxoplasmaandNeosporaand recent research looking towards developing new vaccine targets and approaches.
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Ji, Jian y Hao Qu. "Cross-regulatory Circuit Between AHR and Microbiota". Current Drug Metabolism 20, n.º 1 (11 de marzo de 2019): 4–8. http://dx.doi.org/10.2174/1389200219666180129151150.
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Background: The gut microbes have a close symbiotic relationship with their host. Interactions between host and the microbiota affect the nutritional, immunological, and physiological status of the host. The Aryl Hydrocarbon Receptor (AHR) is a ligand activated transcription factor that mediates the toxicity of xenobiotics. Recently, the relationship between the gut microbiota and AHR has attracted the attention of many researchers. Methods: We undertook a structured search of bibliographic databases for peer-reviewed research literature. Results: We found and reviewed 49 peer-reviewed papers dealing with the major aspects related to the crosstalk between AHR and microbiota. The AHR influences the intestinal microbiota population and mediates host-microbe homeostasis. Interestingly, the gut microbiota also produces ligands of AHR from bacterial metabolism and thereby activates the AHR signaling pathway. </P><P> Concusion: This review presents current knowledge of the cross-regulatory circuit between the AHR and intestinal microbiota. The findings of this review confirm the importance of AHR-microbiota interactions in health and disease.
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Wysmołek, Magdalena Elżbieta, Ewa Długosz y Marcin Wiśniewski. "The Immunological Role of Vascular and Lymphatic Endothelial Cells in Filarial Infections". Animals 12, n.º 4 (10 de febrero de 2022): 426. http://dx.doi.org/10.3390/ani12040426.
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The embryonic stage of filarial nematodes, or microfilariae (Mf), shows daily and seasonal periodicity that requires their migration through blood vessels into the lungs, where they are sequestered when not circulating in the peripheral blood. Therefore, Mf and the host endothelium are likely in a permanent state of hide and seek. Interestingly, filarial nematodes co-cultured in media with a murine endothelial cell line survive eight times longer than those cultured in media alone. This suggests that the endothelium is an important element of the immune response in filarial nematodes, perversely promoting their survival in the host. In this review, we will focus on potential pathways involved in the relationship between filarial nematodes and the host endothelium, including the role of endothelial ICAM/VCAM/PECAM adhesion molecules, surface markers involved in the passage of Mf through host tissue, anti-thrombolic effects caused by the presence of filarial nematodes (including plasmins), endothelial cell proliferation (VEGF), and other aspects of the immune activation of the endothelium. The aim of this review is to merge the knowledge about the cross-talk between Mf of different filarial nematode species and endothelial cells (EC), thus allowing a better understanding of the mechanism of these parasitic infections.
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Vanalli, Chiara, Lorenzo Mari, Lorenzo Righetto, Renato Casagrandi, Marino Gatto y Isabella M. Cattadori. "Within-host mechanisms of immune regulation explain the contrasting dynamics of two helminth species in both single and dual infections". PLOS Computational Biology 16, n.º 11 (23 de noviembre de 2020): e1008438. http://dx.doi.org/10.1371/journal.pcbi.1008438.
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Variation in the intensity and duration of infections is often driven by variation in the network and strength of host immune responses. While many of the immune mechanisms and components are known for parasitic helminths, how these relationships change from single to multiple infections and impact helminth dynamics remains largely unclear. Here, we used laboratory data from a rabbit-helminth system and developed a within-host model of infection to investigate different scenarios of immune regulation in rabbits infected with one or two helminth species. Model selection suggests that the immunological pathways activated against Trichostrongylus retortaeformis and Graphidium strigosum are similar. However, differences in the strength of these immune signals lead to the contrasting dynamics of infections, where the first parasite is rapidly cleared and the latter persists with high intensities. In addition to the reactions identified in single infections, rabbits with both helminths also activate new pathways that asymmetrically affect the dynamics of the two species. These new signals alter the intensities but not the general trend of the infections. The type of interactions described can be expected in many other host-helminth systems. Our immune framework is flexible enough to capture different mechanisms and their complexity, and provides essential insights to the understanding of multi-helminth infections.
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Widmer, Giovanni, David Carmena, Martin Kváč, Rachel M. Chalmers, Jessica C. Kissinger, Lihua Xiao, Adam Sateriale et al. "Update on Cryptosporidium spp.: highlights from the Seventh International Giardia and Cryptosporidium Conference". Parasite 27 (2020): 14. http://dx.doi.org/10.1051/parasite/2020011.
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While cryptosporidiosis is recognized as being among the most common causes of human parasitic diarrhea in the world, there is currently limited knowledge on Cryptosporidium infection mechanisms, incomplete codification of diagnostic methods, and a need for additional therapeutic options. In response, the Seventh International Giardia and Cryptosporidium Conference (IGCC 2019) was hosted from 23 to 26 June 2019, at the Rouen Normandy University, France. This trusted event brought together an international delegation of researchers to synthesize recent advances and identify key research questions and knowledge gaps. The program of the interdisciplinary conference included all aspects of host-parasite relationships from basic research to applications to human and veterinary medicine, and environmental issues associated with waterborne parasites and their epidemiological consequences. In relation to Cryptosporidium and cryptosporidiosis, the primary research areas for which novel findings and the most impressive communications were presented and discussed included: Cryptosporidium in environmental waters, seafood, and fresh produce; Animal epidemiology; Human cryptosporidiosis and epidemiology; Genomes and genomic evolution encompassing: Comparative genomics of Cryptosporidium spp., Genomic insights into biology, Acquiring and utilizing genome sequences, Genetic manipulation; Host-parasite interaction (immunology, microbiome); and Diagnosis and treatment. High quality presentations discussed at the conference reflected decisive progress and identified new opportunities that will engage investigators and funding agencies to spur future research in a “one health” approach to improve basic knowledge and the clinical and public health management of zoonotic cryptosporidiosis.
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GOWER, C. M., A. F. GABRIELLI, M. SACKO, R. DEMBELÉ, R. GOLAN, A. M. EMERY, D. ROLLINSON y J. P. WEBSTER. "Population genetics of Schistosoma haematobium: development of novel microsatellite markers and their application to schistosomiasis control in Mali". Parasitology 138, n.º 8 (17 de junio de 2011): 978–94. http://dx.doi.org/10.1017/s0031182011000722.
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SUMMARYThe recent implementation of mass drug administration (MDA) for control of uro-genital schistosomiasis has identified an urgent need for molecular markers to both directly monitor the impact of MDA, for example to distinguish re-infections from uncleared infections, as well as understand aspects of parasite reproduction and gene flow which might predict evolutionary change, such as the development and spread of drug resistance. We report the development of a novel microsatellite tool-kit allowing, for the first time, robust genetic analysis of individual S. haematobium larvae collected directly from infected human hosts. We genotyped the parasite populations of 47 children from 2 schools in the Ségou region of Mali, the first microsatellite study of this highly neglected parasite. There was only limited evidence of population subdivision between individual children or between the two schools, suggesting that few barriers to gene flow exist in this population. Complex relationships between parasite reproductive success, infection intensity and host age and gender were identified. Older children and boys harboured more diverse infections, as measured by the number of unique adult genotypes present. Individual parasite genotypes had variable reproductive success both across hosts, a pre-requisite for evolutionary selection, and, phenotypically, in hosts of different ages and genders. These data serve as a baseline against which to measure the effect of treatment on parasite population genetics in this region of Mali, and the tools developed are suitable to further investigate this important pathogen, and its close relatives, throughout their range.
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Mariano, M. "The experimental granuloma: a hypothesis to explain the persistence of the lesion". Revista do Instituto de Medicina Tropical de São Paulo 37, n.º 2 (abril de 1995): 161–76. http://dx.doi.org/10.1590/s0036-46651995000200012.
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Granulomatous inflammation is the morphological substrate of a variety of important infectious diseases such as tuberculosis, leprosy, schistosomiasis and others. Nevertheless, although many aspects of this special type of inflammation are known, fundamental questions concerning granuloma formation, persistence, fate and significance for host-parasite relationships still remain to be elucidated. In this brief review, the basic and more relevant literature related to experimental investigations on granuloma physiopathology is presented. Based on recent investigations performed in our laboratory showing that MDF (Macrophage Deactivating Fator) secreted by epithelioid cells and characterized as the calcium-binding protein protein MRP-14 deactivates activated macrophages, a hypothesis to explain the persistence of granulomatous inflammation is put forward
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Buret, André G., Simone M. Cacciò, Loïc Favennec y Staffan Svärd. "Update on Giardia: Highlights from the seventh International Giardia and Cryptosporidium Conference". Parasite 27 (2020): 49. http://dx.doi.org/10.1051/parasite/2020047.
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Although Giardia duodenalis is recognized as one of the leading causes of parasitic human diarrhea in the world, knowledge of the mechanisms of infection is limited, as the pathophysiological consequences of infection remain incompletely elucidated. Similarly, the reason for and consequences of the very specific genome-organization in this parasite with 2 active nuclei is only partially known. Consistent with its tradition, the 7th International Giardia and Cryptosporidium Conference (IGCC 2019) was held from June 23 to 26, 2019, at the Faculty of Medicine and Pharmacy of the University of Rouen-Normandie, France, to discuss current research perspectives in the field. This renowned event brought together an international delegation of researchers to present and debate recent advances and identify the main research themes and knowledge gaps. The program for this interdisciplinary conference included all aspects of host-parasite relationships, from basic research to applications in human and veterinary medicine, as well as the environmental issues raised by water-borne parasites and their epidemiological consequences. With regard to Giardia and giardiasis, the main areas of research for which new findings and the most impressive communications were presented and discussed included: parasite ecology and epidemiology of giardiasis, Giardia-host interactions, and cell biology of Giardia, genomes and genomic evolution. The high-quality presentations discussed at the Conference noted breakthroughs and identified new opportunities that will inspire researchers and funding agencies to stimulate future research in a “one health” approach to improve basic knowledge and clinical and public health management of zoonotic giardiasis.
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Binimelis-Salazar, Josefa, Angélica Casanova-Katny, Norbert Arnold, Celia A. Lima, Heraldo V. Norambuena, Gerardo González-Rocha y Götz Palfner. "Diversity and Host Relationships of the Mycoparasite Sepedonium (Hypocreales, Ascomycota) in Temperate Central Chile". Microorganisms 9, n.º 11 (30 de octubre de 2021): 2261. http://dx.doi.org/10.3390/microorganisms9112261.
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We present the first major survey of regional diversity, distribution and host-association of Sepedonium. Whereas the rather scarce worldwide records of this mycoparasitic fungus suggested no specific distribution pattern of most species before, we provide new evidence of endemic and specific host-parasite guilds of Sepedonium in Southern South America, including the description of a new species. The corresponding inventory was performed in temperate central Chile. The regional landscape, a mosaic of exotic timber plantations and remnants of native Nothofagus forests, facilitates a unique combination of endemic and adventitious Boletales hosts. During a two-year survey, 35 Sepedonium strains were isolated and cultured from infected basidiomata of allochthonous Chalciporus piperatus, Paxillus involutus, Rhizopogon spp. and Suillus spp., as well as from the native Boletus loyita, B. loyo, B. putidus and Gastroboletus valdivianus. Taxonomic diagnosis included morphology of conidia and conidiophores, sequences of ITS, RPB2 and EF1 molecular markers and characteristics of in vitro cultures. Phylogenetic reconstructions were performed using Bayesian methods. Four Sepedonium species could be identified and characterized, viz.: S. ampullosporum, S. chrysospermum, S. laevigatum and the newly described species S. loyorum. The most frequent species on introduced Boletales was S. ampullosporum, followed by S. chrysospermum and S. laevigatum. S. loyorum sp. nov. was found exclusively on native boletacean hosts, separated from its closest relative S. chalcipori by micromorphological and molecular attributes. Species descriptions and identification keys are provided. Ecological and biogeographical aspects of endemic and allochthonous symbiotic units consisting of mycoparasite, ectomycorrhizal fungal host and respective mycorrhizal tree are discussed.
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Gasan, Thomas A., Marije E. Kuipers, Grisial H. Roberts, Gilda Padalino, Josephine E. Forde-Thomas, Shona Wilson, Jakub Wawrzyniak, Edridah M. Tukahebwa, Karl F. Hoffmann y Iain W. Chalmers. "Schistosoma mansoni Larval Extracellular Vesicle protein 1 (SmLEV1) is an immunogenic antigen found in EVs released from pre-acetabular glands of invading cercariae". PLOS Neglected Tropical Diseases 15, n.º 11 (18 de noviembre de 2021): e0009981. http://dx.doi.org/10.1371/journal.pntd.0009981.
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Extracellular Vesicles (EVs) are an integral component of cellular/organismal communication and have been found in the excreted/secreted (ES) products of both protozoan and metazoan parasites. Within the blood fluke schistosomes, EVs have been isolated from egg, schistosomula, and adult lifecycle stages. However, the role(s) that EVs have in shaping aspects of parasite biology and/or manipulating host interactions is poorly defined. Herein, we characterise the most abundant EV-enriched protein in Schistosoma mansoni tissue-migrating schistosomula (Schistosoma mansoni Larval Extracellular Vesicle protein 1 (SmLEV1)). Comparative sequence analysis demonstrates that lev1 orthologs are found in all published Schistosoma genomes, yet homologs are not found outside of the Schistosomatidae. Lifecycle expression analyses collectively reveal that smlev1 transcription peaks in cercariae, is male biased in adults, and is processed by alternative splicing in intra-mammalian lifecycle stages. Immunohistochemistry of cercariae using a polyclonal anti-recombinant SmLEV1 antiserum localises this protein to the pre-acetabular gland, with some disperse localisation to the surface of the parasite. S. mansoni—infected Ugandan fishermen exhibit a strong IgG1 response against SmLEV1 (dropping significantly after praziquantel treatment), with 11% of the cohort exhibiting an IgE response and minimal levels of detectable antigen-specific IgG4. Furthermore, mice vaccinated with rSmLEV1 show a slightly reduced parasite burden upon challenge infection and significantly reduced granuloma volumes, compared with control animals. Collectively, these results describe SmLEV1 as a Schistosomatidae-specific, EV-enriched immunogen. Further investigations are now necessary to uncover the full extent of SmLEV1’s role in shaping schistosome EV function and definitive host relationships.
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Barreto-Lima, A. F., G. M. Toledo y L. A. Anjos. "The nematode community in the Atlantic rainforest lizard Enyalius perditus Jackson, from south-eastern Brazil". Journal of Helminthology 86, n.º 4 (11 de octubre de 2011): 395–400. http://dx.doi.org/10.1017/s0022149x11000599.
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AbstractStudies focusing on communities of helminths from Brazilian lizards are increasing, but there are many blanks in the knowledge of parasitic fauna of wild fauna. This lack of knowledge hampers understanding of ecological and parasitological aspects of involved species. Moreover, the majority of research has focused on parasitic fauna of lizards from families Tropiduridae and Scincidae. Only a few studies have looked at lizards from the family Leiosauridae, including some species of Enyalius. This study presents data on the gastrointestinal parasite fauna of Enyalius perditus and their relationships with ecological aspects of hosts in a disturbed Atlantic rainforest area in the state of Minas Gerais, south-eastern Brazil. Two nematode species, Oswaldocruzia burseyi [(Molineidae) and Strongyluris oscari (Heterakidae) were found. Nematode species showed an aggregated distribution in this host population, with O. burseyi being more aggregated than S. oscari. The present study extends the range of occurrence of O. burseyi to the Brazilian continental area.
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Gomes Pereira, Sandra. "Aspects of the development of new anti-Leishmania drugs: from control of neglected infections to parasite-host interactions and drug-resistant parasites". FarmaJournal 5, n.º 1 (14 de enero de 2020): 105–6. http://dx.doi.org/10.14201/fj202051105106.
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Leishmaniasis is a neglected disease caused by parasites of the genus Leishmania. The disease leads to different clinical manifestations determined by parasite features like heterogeneity in the virulence of distinct species-zymodemes and host parameters such as genetic characteristics and immunological status.Visceral leishmaniasis (VL) is the most severe disease form and is potentially fatal if untreated. Drugs in use against VL present several drawbacks including high toxicity, relevant contraindications and complicated administration regimens. In addition, 90% of world´s VL cases are concentrated in poorest locations like the Indian sub-continent where a number of factors contribute to an ineffective disease control including access to medicines and its relatively expensive price and the development of resistant Leishmania strains, not only to the classical antimonials drugs but also to miltefosine, the only oral drug available.Therefore, the development of new drugs against VL is urgent and must have in consideration several aspects in order to achieve and be effective to most of the disease cases. Indeed, treatment outcomes vary substantially between different geographic regions and depend on the drug(s) used, drug exposure, severity of disease, host immunity, and the presence of coinfections. So, in order to improve the drug discovery process for anti-leishmanials the drug screening should involve recent clinical isolates of the L. donovani complex, with different susceptibility profiles to existing drugs and from different geographical origin.Both synthetic and natural product libraries might be screened, but evaluation of drugs already in use by developing new formulations or even drug repurposing might also contribute to a faster identification of new candidates. Additional short-term approaches might be combinatory therapies, some of which have proven to be useful mainly in coinfections with HIV.Other important issue is the establishment of standard techniques for the selection of ’hit compounds‘ and the criteria established by the Global Health Innovative Technology Fund represent an interesting approach: a given hit should present a 50% effective concentration (EC50 value) lower than 10?M against intracellular amastigotes of Leishmania sp. and for the in vivo model of VL (i.e. mouse or hamster infected with L. infantum or L. donovani), treatment schemes should result in 70% reduction of liver parasite load after up to 5 doses of 50mg/kg, orally, one or two times a day.In the last decades, technology advances have allowed the establishment of High-throughput screening (HTS), a potential efficient way of identifying active compounds able to eliminate the parasite without affecting the host. However, the lack of central database capable of concentrating positive and negative results from different research groups and compounds tested also contributes to delaying the identification of potential candidates against Leishmania protozoa. Also by applying bioinformatic tools such as a systematic in silico chemogenomics strategy in combination with the classical approach, its expected to identify new antiparasitic compounds that will be available for application in the pharmaceutical industry and further research lines.A relevant portion of drug prospection for neglected diseases relies on academic and research institution but dealing with diseases of such relevance worldwide must require the incorporation of Government and private funding for basic and clinical research projects through direct investments and incentives to both academia and the private sector.
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Maslov, Dmitri A., Fred R. Opperdoes, Alexei Y. Kostygov, Hassan Hashimi, Julius Lukeš y Vyacheslav Yurchenko. "Recent advances in trypanosomatid research: genome organization, expression, metabolism, taxonomy and evolution". Parasitology 146, n.º 1 (14 de junio de 2018): 1–27. http://dx.doi.org/10.1017/s0031182018000951.
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AbstractUnicellular flagellates of the family Trypanosomatidae are obligatory parasites of invertebrates, vertebrates and plants. Dixenous species are aetiological agents of a number of diseases in humans, domestic animals and plants. Their monoxenous relatives are restricted to insects. Because of the high biological diversity, adaptability to dramatically different environmental conditions, and omnipresence, these protists have major impact on all biotic communities that still needs to be fully elucidated. In addition, as these organisms represent a highly divergent evolutionary lineage, they are strikingly different from the common ‘model system’ eukaryotes, such as some mammals, plants or fungi. A number of excellent reviews, published over the past decade, were dedicated to specialized topics from the areas of trypanosomatid molecular and cell biology, biochemistry, host–parasite relationships or other aspects of these fascinating organisms. However, there is a need for a more comprehensive review that summarizing recent advances in the studies of trypanosomatids in the last 30 years, a task, which we tried to accomplish with the current paper.
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Loria-Cervera, Elsy Nalleli y Fernando Jose Andrade-Narvaez. "ANIMAL MODELS FOR THE STUDY OF LEISHMANIASIS IMMUNOLOGY". Revista do Instituto de Medicina Tropical de São Paulo 56, n.º 1 (enero de 2014): 1–11. http://dx.doi.org/10.1590/s0036-46652014000100001.
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Leishmaniasis remains a major public health problem worldwide and is classified as Category I by the TDR/WHO, mainly due to the absence of control. Many experimental models like rodents, dogs and monkeys have been developed, each with specific features, in order to characterize the immune response to Leishmania species, but none reproduces the pathology observed in human disease. Conflicting data may arise in part because different parasite strains or species are being examined, different tissue targets (mice footpad, ear, or base of tail) are being infected, and different numbers (“low” 1×102 and “high” 1×106) of metacyclic promastigotes have been inoculated. Recently, new approaches have been proposed to provide more meaningful data regarding the host response and pathogenesis that parallels human disease. The use of sand fly saliva and low numbers of parasites in experimental infections has led to mimic natural transmission and find new molecules and immune mechanisms which should be considered when designing vaccines and control strategies. Moreover, the use of wild rodents as experimental models has been proposed as a good alternative for studying the host-pathogen relationships and for testing candidate vaccines. To date, using natural reservoirs to study Leishmania infection has been challenging because immunologic reagents for use in wild rodents are lacking. This review discusses the principal immunological findings against Leishmania infection in different animal models highlighting the importance of using experimental conditions similar to natural transmission and reservoir species as experimental models to study the immunopathology of the disease.
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Kayano, Ana Carolina A. V., João Conrado K. Dos-Santos, Marcele F. Bastos, Leonardo J. Carvalho, Júlio Aliberti y Fabio T. M. Costa. "Pathophysiological Mechanisms in Gaseous Therapies for Severe Malaria". Infection and Immunity 84, n.º 4 (1 de febrero de 2016): 874–82. http://dx.doi.org/10.1128/iai.01404-15.
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Over 200 million people worldwide suffer from malaria every year, a disease that causes 584,000 deaths annually. In recent years, significant improvements have been achieved on the treatment of severe malaria, with intravenous artesunate proving superior to quinine. However, mortality remains high, at 8% in children and 15% in adults in clinical trials, and even worse in the case of cerebral malaria (18% and 30%, respectively). Moreover, some individuals who do not succumb to severe malaria present long-term cognitive deficits. These observations indicate that strategies focused only on parasite killing fail to prevent neurological complications and deaths associated with severe malaria, possibly because clinical complications are associated in part with a cerebrovascular dysfunction. Consequently, different adjunctive therapies aimed at modulating malaria pathophysiological processes are currently being tested. However, none of these therapies has shown unequivocal evidence in improving patient clinical status. Recently, key studies have shown that gaseous therapies based mainly on nitric oxide (NO), carbon monoxide (CO), and hyperbaric (pressurized) oxygen (HBO) alter vascular endothelium dysfunction and modulate the host immune response to infection. Considering gaseous administration as a promising adjunctive treatment against severe malaria cases, we review here the pathophysiological mechanisms and the immunological aspects of such therapies.
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McHugh, S. M., Patricia S. Coulson y R. A. Wilson. "The relationship between pathology and resistance to reinfection with Schistosoma mansoni in mice: a causal mechanism of resistance in chronic infections". Parasitology 94, n.º 1 (febrero de 1987): 81–91. http://dx.doi.org/10.1017/s0031182000053476.
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SUMMARYThe development of resistance in mice to reinfection with Schistosoma mansoni was recorded during an early chronic infection, and compared with hepatic portal pathological and vascular changes. The latter were assessed using a microsphere injection technique. The degree of acquired resistance was directly dependent on the patent worm burden and the time post-infection. Strong correlations were noted between the development of resistance and the appearance of parasite eggs in the lungs and spleens of infected hosts. Weaker associations were present between resistance and other aspects of the disease pathology, such as portal hypertension and organ weights. The appearance of injected microspheres in the lungs and spleens correlated well with the appearance of eggs in those organs and with the development of resistance. The levels of resistance had risen and microspheres were detected in the lungs, before the development of major extra-hepatic, porta-systemic collateral vessels. It is concluded that intra-hepatic vascular alterations may be a causal factor in the development of resistance, preventing the sequestration of migrating schistosomula in the liver. It is estimated that as much as 70–75% of the recorded resistance can be attributed to this immunologically non-specific mechanism.
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Summers, Kelly L. "A Structural Chemistry Perspective on the Antimalarial Properties of Thiosemicarbazone Metal Complexes". Mini-Reviews in Medicinal Chemistry 19, n.º 7 (28 de marzo de 2019): 569–90. http://dx.doi.org/10.2174/1389557518666181015152657.
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Malaria is a potentially life-threatening disease, affecting approx. 214 million people worldwide. Malaria is caused by a protozoan, Plasmodium falciparum, which is transmitted through the Anopheles mosquito. Malaria treatment is becoming more challenging due to rising resistance against the antimalarial drug, chloroquine. Novel compounds that target aspects of parasite development are being explored in attempts to overcome this wide-spread problem. Anti-malarial drugs target specific aspects of parasite growth and development within the human host. One of the most effective targets is the inhibition of hematin formation, either through inhibition of cysteine proteases or through iron chelation. Metal-thiosemicarbazone (TSC) complexes have been tested for antimalarial efficacy against drug-sensitive and drug-resistant strains of P. falciparum. An array of TSC complexes with numerous transition metals, including ruthenium, palladium, and gold has displayed antiplasmodial activity. Au(I)- and Pd(II)-TSC complexes displayed the greatest potency; 4-amino-7-chloroquine moieties were also found to improve antiplasmodial activity of TSCs. Although promising metal-TSC drug candidates have been tested against laboratory strains of P. falciparum, problems arise when attempting to compare between studies. Future work should strive to completely characterize synthesized metal-TSC structures and assess antiplasmodial potency against several drug-sensitive and drugresistant strains. Future studies need to precisely determine IC50 values for antimalarial drugs, chloroquine and ferroquine, to establish accurate standard values. This will make future comparisons across studies more feasible and potentially help reveal structure-function relationships. Investigations that attempt to link drug structures or properties to antiplasmodial mechanism(s) of action will aid in the design of antimalarial drugs that may combat rising drug resistance.
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KNOWLES, LACEY L. y PAVEL B. KLIMOV. "Estimating phylogenetic relationships despite discordant gene trees across loci: the species tree of a diverse species group of feather mites (Acari: Proctophyllodidae)". Parasitology 138, n.º 13 (20 de abril de 2011): 1750–59. http://dx.doi.org/10.1017/s003118201100031x.
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SUMMARYWith the increased availability of multilocus sequence data, the lack of concordance of gene trees estimated for independent loci has focused attention on both the biological processes producing the discord and the methodologies used to estimate phylogenetic relationships. What has emerged is a suite of new analytical tools for phylogenetic inference – species tree approaches. In contrast to traditional phylogenetic methods that are stymied by the idiosyncrasies of gene trees, approaches for estimating species trees explicitly take into account the cause of discord among loci and, in the process, provides a direct estimate of phylogenetic history (i.e. the history of species divergence, not divergence of specific loci). We illustrate the utility of species tree estimates with an analysis of a diverse group of feather mites, the pinnatus species group (genus Proctophyllodes). Discord among four sequenced nuclear loci is consistent with theoretical expectations, given the short time separating speciation events (as evident by short internodes relative to terminal branch lengths in the trees). Nevertheless, many of the relationships are well resolved in a Bayesian estimate of the species tree; the analysis also highlights ambiguous aspects of the phylogeny that require additional loci. The broad utility of species tree approaches is discussed, and specifically, their application to groups with high speciation rates – a history of diversification with particular prevalence in host/parasite systems where species interactions can drive rapid diversification.
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Feitelson, Mark A., Alla Arzumanyan, Ira Spector y Arvin Medhat. "Hepatitis B x (HBx) as a Component of a Functional Cure for Chronic Hepatitis B". Biomedicines 10, n.º 9 (7 de septiembre de 2022): 2210. http://dx.doi.org/10.3390/biomedicines10092210.
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Patients who are carriers of the hepatitis B virus (HBV) are at high risk of chronic liver disease (CLD) which proceeds from hepatitis, to fibrosis, cirrhosis and to hepatocellular carcinoma (HCC). The hepatitis B-encoded X antigen, HBx, promotes virus gene expression and replication, protects infected hepatocytes from immunological destruction, and promotes the development of CLD and HCC. For virus replication, HBx regulates covalently closed circular (ccc) HBV DNA transcription, while for CLD, HBx triggers cellular oxidative stress, in part, by triggering mitochondrial damage that stimulates innate immunity. Constitutive activation of NF-κB by HBx transcriptionally activates pro-inflammatory genes, resulting in hepatocellular destruction, regeneration, and increased integration of the HBx gene into the host genome. NF-κB is also hepatoprotective, which sustains the survival of infected cells. Multiple therapeutic approaches include direct-acting anti-viral compounds and immune-stimulating drugs, but functional cures were not achieved, in part, because none were yet devised to target HBx. In addition, many patients with cirrhosis or HCC have little or no virus replication, but continue to express HBx from integrated templates, suggesting that HBx contributes to the pathogenesis of CLD. Blocking HBx activity will, therefore, impact multiple aspects of the host–virus relationship that are relevant to achieving a functional cure.