Journal articles on the topic 'Parasites'
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1
WOOD, CHELSEA L., and KEVIN D. LAFFERTY. "How have fisheries affected parasite communities?" Parasitology 142, no. 1 (March 3, 2014): 134–44. http://dx.doi.org/10.1017/s003118201400002x.
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SUMMARYTo understand how fisheries affect parasites, we conducted a meta-analysis of studies that contrasted parasite assemblages in fished and unfished areas. Parasite diversity was lower in hosts from fished areas. Larger hosts had a greater abundance of parasites, suggesting that fishing might reduce the abundance of parasites by selectively removing the largest, most heavily parasitized individuals. After controlling for size, the effect of fishing on parasite abundance varied according to whether the host was fished and the parasite's life cycle. Parasites of unfished hosts were more likely to increase in abundance in response to fishing than were parasites of fished hosts, possibly due to compensatory increases in the abundance of unfished hosts. While complex life cycle parasites tended to decline in abundance in response to fishing, directly transmitted parasites tended to increase. Among complex life cycle parasites, those with fished hosts tended to decline in abundance in response to fishing, while those with unfished hosts tended to increase. However, among directly transmitted parasites, responses did not differ between parasites with and without fished hosts. This work suggests that parasite assemblages are likely to change substantially in composition in increasingly fished ecosystems, and that parasite life history and fishing status of the host are important in predicting the response of individual parasite species or groups to fishing.
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Farahani, Sajad. "Success of Infection by Parasites." Journal of Biomedical Research & Environmental Sciences 4, no. 7 (July 2023): 1153–55. http://dx.doi.org/10.37871/jbres1780.
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The success of infection by parasites during the host-parasite coevolution is related to increasing a parasite’s ability to alter intermediate host behaviour, resulting in higher fitness of parasites. The “increased host abilities’ hypothesis” posits that parasites manipulate the behavior of their intermediate hosts or improves its chances of intermediate host survival in order to enhance their transmission to the next host. Research shows that the transmission of the parasites to their definitive host is facilitated by non-host predator avoidance by the intermediate host, which would otherwise prevent completion of the parasite’s life cycle.
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Hart, B. L. "Behavioural defense against parasites: interaction with parasite invasiveness." Parasitology 109, S1 (1994): S139—S151. http://dx.doi.org/10.1017/s0031182000085140.
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SUMMARYBehavioural patterns involved in avoiding, repelling, or removing parasites allow mammalian hosts to defend themselves from an array of parasites that threaten the host's fitness in the natural world. Some examples of behavioural defenses and the presumed target parasites are: grooming to remove ticks, grouping to reduce attack rate of biting flies, fly repelling movements to reduce parasitic flies, and selective grazing to reduce intake of faecal-borne parasites. These behavioural defenses are discussed with regard to effectiveness in controlling the target parasites. Parasites have sometimes evolved behavioural strategies of evading, penetrating or disabling these behavioural defenses. These parasite behavioural strategies, though less studied, are discussed. Also discussed is the possibility that host behavioural patterns that may defend against one parasite may be exploited by a different type of parasite to facilitate its own transmission. The interplay between host defensive strategies, the cost versus the effectiveness of such strategies, and a parasite's evasion or exploitation of such strategies, may be useful in understanding some aspects of host-parasite dynamics in nature.
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Severins, Maite, Don Klinkenberg, and Hans Heesterbeek. "How selection forces dictate the variant surface antigens used by malaria parasites." Journal of The Royal Society Interface 9, no. 67 (July 6, 2011): 246–60. http://dx.doi.org/10.1098/rsif.2011.0239.
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Red blood cells infected by the malaria parasite Plasmodium falciparum express variant surface antigens (VSAs) that evade host immunity and allow the parasites to persist in the human population. There exist many different VSAs and the differential expression of these VSAs is associated with the virulence (damage to the host) of the parasites. The aim of this study is to unravel the differences in the effect key selection forces have on parasites expressing different VSAs such that we can better understand how VSAs enable the parasites to adapt to changes in their environment (like control measures) and how this may impact the virulence of the circulating parasites. To this end, we have built an individual-based model that captures the main selective forces on malaria parasites, namely parasite competition, host immunity, host death and mosquito abundance at both the within- and between-host levels. VSAs are defined by the net growth rates they infer to the parasites and the model keeps track of the expression of, and antibody build-up against, each VSA in all hosts. Our results show an ordered acquisition of VSA-specific antibodies with host age, which causes a dichotomy between the more virulent VSAs that reach high parasitaemias but are restricted to young relatively non-immune hosts, and less virulent VSAs that do not reach such high parasitaemias but can infect a wider range of hosts. The outcome of a change in the parasite's environment in terms of parasite virulence depends on the exact balance between the selection forces, which sets the limiting factor for parasite survival. Parasites will evolve towards expressing more virulent VSAs when the limiting factor for parasite survival is the within-host parasite growth and the parasites are able to minimize this limitation by expressing more virulent VSAs.
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Forbes, Mark R., André Morrill, and Jennifer Schellinck. "Host species exploitation and discrimination by animal parasites." Philosophical Transactions of the Royal Society B: Biological Sciences 372, no. 1719 (March 13, 2017): 20160090. http://dx.doi.org/10.1098/rstb.2016.0090.
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Parasite species often show differential fitness on different host species. We developed an equation-based model to explore conditions favouring host species exploitation and discrimination. In our model, diploid infective stages randomly encountered hosts of two species; the parasite's relative fitness in exploiting each host species, and its ability to discriminate between them, was determined by the parasite's genotype at two independent diallelic loci. Relative host species frequency determined allele frequencies at the exploitation locus, whereas differential fitness and combined host density determined frequency of discrimination alleles. The model predicts instances where populations contain mixes of discriminatory and non-discriminatory infective stages. Also, non-discriminatory parasites should evolve when differential fitness is low to moderate and when combined host densities are low, but not so low as to cause parasite extinction. A corollary is that parasite discrimination (and host-specificity) increases with higher combined host densities. Instances in nature where parasites fail to discriminate when differential fitness is extreme could be explained by one host species evolving resistance, following from earlier selection for parasite non-discrimination. Similar results overall were obtained for haploid extensions of the model. Our model emulates multi-host associations and has implications for understanding broadening of host species ranges by parasites. This article is part of the themed issue ‘Opening the black box: re-examining the ecology and evolution of parasite transmission’.
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Mathieu-Bégné, Eglantine, Simon Blanchet, Guillaume Mitta, Clément Le Potier, Géraldine Loot, and Olivier Rey. "Transcriptomic Adjustments in a Freshwater Ectoparasite Reveal the Role of Molecular Plasticity for Parasite Host Shift." Genes 13, no. 3 (March 16, 2022): 525. http://dx.doi.org/10.3390/genes13030525.
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A parasite’s lifestyle is characterized by a critical dependency on its host for feeding, shelter and/or reproduction. The ability of parasites to exploit new host species can reduce the risk associated with host dependency. The number of host species that can be infected by parasites strongly affects their ecological and evolutionary dynamics along with their pathogenic effects on host communities. However, little is known about the processes and the pathways permitting parasites to successfully infect alternative host species, a process known as host shift. Here, we tested whether molecular plasticity changes in gene expression and in molecular pathways could favor host shift in parasites. Focusing on an invasive parasite, Tracheliastes polycolpus, infecting freshwater fish, we conducted a transcriptomic study to compare gene expression in parasites infecting their main host species and two alternative host species. We found 120 significant differentially expressed genes (DEGs) between parasites infecting the different host species. A total of 90% of the DEGs were identified between parasites using the main host species and those using the two alternative host species. Only a few significant DEGs (seven) were identified when comparing parasites from the two alternative host species. Molecular pathways enriched in DEGs and associated with the use of alternative host species were related to cellular machinery, energetic metabolism, muscle activity and oxidative stress. This study strongly suggests that molecular plasticity is an important mechanism sustaining the parasite’s ability to infect alternative hosts.
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Duneau, David, and Dieter Ebert. "The role of moulting in parasite defence." Proceedings of the Royal Society B: Biological Sciences 279, no. 1740 (April 11, 2012): 3049–54. http://dx.doi.org/10.1098/rspb.2012.0407.
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Parasitic infections consist of a succession of steps during which hosts and parasites interact in specific manners. At each step, hosts can use diverse defence mechanisms to counteract the parasite's attempts to invade and exploit them. Of these steps, the penetration of parasites into the host is a key step for a successful infection and the epithelium is the first line of host defence. The shedding of this protective layer (moulting) is a crucial feature in the life cycle of several invertebrate and vertebrate taxa, and is generally considered to make hosts vulnerable to parasites and predators. Here, we used the crustacean Daphnia magna to test whether moulting influences the likelihood of infection by the castrating bacterium Pasteuria ramosa . This parasite is known to attach to the host cuticula before penetrating into its body. We found that the likelihood of successful parasite infection is greatly reduced if the host moults within 12 h after parasite exposure. Thus, moulting is beneficial for the host being exposed to this parasite. We further show that exposure to the parasite does not induce hosts to moult earlier. We discuss the implications of our findings for host and parasite evolution and epidemiology.
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Kelsen, Anne, Robyn S. Kent, Anne K. Snyder, Eddie Wehri, Stephen J. Bishop, Rachel V. Stadler, Cameron Powell, et al. "MyosinA is a druggable target in the widespread protozoan parasite Toxoplasma gondii." PLOS Biology 21, no. 5 (May 8, 2023): e3002110. http://dx.doi.org/10.1371/journal.pbio.3002110.
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Toxoplasma gondii is a widespread apicomplexan parasite that can cause severe disease in its human hosts. The ability of T. gondii and other apicomplexan parasites to invade into, egress from, and move between cells of the hosts they infect is critical to parasite virulence and disease progression. An unusual and highly conserved parasite myosin motor (TgMyoA) plays a central role in T. gondii motility. The goal of this work was to determine whether the parasite’s motility and lytic cycle can be disrupted through pharmacological inhibition of TgMyoA, as an approach to altering disease progression in vivo. To this end, we first sought to identify inhibitors of TgMyoA by screening a collection of 50,000 structurally diverse small molecules for inhibitors of the recombinant motor’s actin-activated ATPase activity. The top hit to emerge from the screen, KNX-002, inhibited TgMyoA with little to no effect on any of the vertebrate myosins tested. KNX-002 was also active against parasites, inhibiting parasite motility and growth in culture in a dose-dependent manner. We used chemical mutagenesis, selection in KNX-002, and targeted sequencing to identify a mutation in TgMyoA (T130A) that renders the recombinant motor less sensitive to compound. Compared to wild-type parasites, parasites expressing the T130A mutation showed reduced sensitivity to KNX-002 in motility and growth assays, confirming TgMyoA as a biologically relevant target of KNX-002. Finally, we present evidence that KNX-002 can slow disease progression in mice infected with wild-type parasites, but not parasites expressing the resistance-conferring TgMyoA T130A mutation. Taken together, these data demonstrate the specificity of KNX-002 for TgMyoA, both in vitro and in vivo, and validate TgMyoA as a druggable target in infections with T. gondii. Since TgMyoA is essential for virulence, conserved in apicomplexan parasites, and distinctly different from the myosins found in humans, pharmacological inhibition of MyoA offers a promising new approach to treating the devastating diseases caused by T. gondii and other apicomplexan parasites.
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Jürgens, Anna-Sophie, and Alexander G. Maier. "From circus acts to violent clowns: The parasite as performer." Journal of Science & Popular Culture 3, no. 1 (March 1, 2020): 39–56. http://dx.doi.org/10.1386/jspc_00011_1.
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Abstract With the growing awareness of the contribution of parasites to life, their influences on humans also become clearer. The parasite's footprints can be seen everywhere, in genetics, epidemiology, medicine, history and, as this article clarifies, parasites play a vivid part in our cultural imagination surrounding popular entertainment. Drawing and expanding on Michel Serres' and Enid Welsford's discussions of the parasite as a cultural force, this article explores the line of filiation and interplay between biological parasites, circus arts and their comic emblem, the clown, in different narratives and media. It documents not only fantasies of a collaborative relationship between flea performers and their 'masters', and of the relationship between clowns and parasites, both of which are mischievous 'characters', but also circus-related imaginaries of parasitic remote control.
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Coppens, Isabelle. "Metamorphoses of malaria: the role of autophagy in parasite differentiation." Essays in Biochemistry 51 (October 24, 2011): 127–36. http://dx.doi.org/10.1042/bse0510127.
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Several protozoan parasites undergo a complex life cycle that alternates between an invertebrate vector and a vertebrate host. Adaptations to these different environments by the parasites are achieved by drastic changes in their morphology and metabolism. The malaria parasites must be transmitted to a mammal from a mosquito as part of their life cycle. Upon entering the mammalian host, extracellular malaria sporozoites reach the liver and invade hepatocytes, wherein they meet the challenge of becoming replication-competent schizonts. During the process of conversion, the sporozoite selectively discards organelles that are unnecessary for the parasite growth in liver cells. Among the organelles that are cleared from the sporozoite are the micronemes, abundant secretory vesicles that facilitate the adhesion of the parasite to hepatocytes. Organelles specialized in sporozoite motility and structure, such as the inner membrane complex (a major component of the motile parasite's cytoskeleton), are also eliminated from converting parasites. The high degree of sophistication of the metamorphosis that occurs at the onset of the liver-form development cascade suggests that the observed changes must be multifactorial. Among the mechanisms implicated in the elimination of sporozoite organelles, the degradative process called autophagy contributes to the remodelling of the parasite interior and the production of replicative liver forms. In a broader context, the importance of the role played by autophagy during the differentiation of protozoan parasites that cycle between insects and vertebrates is nowadays clearly emerging. An exciting prospect derived from these observations is that the parasite proteins involved in the autophagic process may represent new targets for drug development.
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Hershenhorn, Joseph, Yaakov Goldwasser, Dina Plakhine, Geza Herzlinger, Shmuel Golan, Rinat Russo, and Yeshayahu Kleifeld. "Role of Pepper (Capsicum annuum) as a Trap and Catch Crop for Control of Orobanche aegyptiaca and O. cernua." Weed Science 44, no. 4 (December 1996): 948–51. http://dx.doi.org/10.1017/s0043174500094972.
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The response of pepper varieties to Egyptian broomrape and nodding broomrape was characterized in comparison with tomatoes grown in pots and in aqueous solution, according to two criteria: 1. germination of the parasite's seeds in the presence of the host roots; and 2. the number of parasites per host plant. More than 50% of Egyptian broomrape seeds germinated in the presence of all pepper variety roots except the sweet pepper Maor. However, only a few attached and developed. The two paprika varieties Lehava and Shani were hosts to more parasites than the sweet pepper varieties, and showed as many as 15 parasites per host plant. In contrast, tomato roots induced less then 10% seed germination but were highly susceptible to the parasite (30 parasites per host plant). Damage caused to pepper foliage and fruit was not significant, compared to the heavy damage caused to tomato. Pepper roots stimulated germination of 22 to 26% of nodding broomrape seeds but without the formation of parasitic attachments, whereas tomato roots stimulated germination of less than 10% of the seeds but the plants were then heavily damaged by the parasite. Interplanting of tomato with pepper in nutrient solution did not change the amount of Egyptian broomrape parasites on pepper, hut a fourfold increase in the number of nodding broomrape was observed on tomato roots, compared to the number of parasites on tomato roots when planted without pepper.
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POULIN, R. "Relative infection levels and taxonomic distances among the host species used by a parasite: insights into parasite specialization." Parasitology 130, no. 1 (December 13, 2004): 109–15. http://dx.doi.org/10.1017/s0031182004006304.
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Parasites often exploit more than one host species at any stage in their life-cycle, but the extent to which these host species are used varies greatly. Parasites typically achieve their highest prevalence, intensity and/or abundance in one host species (the principal host), whereas infection levels in auxiliary hosts range from relatively high to very low. The present study examines what influences the distribution of parasite individuals among their different host species, using metazoan parasites that use freshwater fish as their definitive or only host. Specifically, I test the hypothesis that differences in relative infection levels by a parasite among its auxiliary hosts are proportional to the taxonomic distance between the respective auxiliary hosts and the parasite's principal host. Taxonomic distance among hosts is a surrogate measure of their similarity in terms of ecology, physiology and immunology. Using data on 29 parasite species and 6 fish communities, for a total of 47 parasite-locality combinations, it was found that taxonomic distance between the auxiliary hosts and the principal host had no real influence on infection levels in auxiliary hosts, measured as either prevalence, intensity or abundance. The analysis revealed differences in the degree of specialization among major groups of parasites: in terms of abundance or intensity, auxiliary hosts were less important for cestodes than for nematodes and copepods. The lack of an effect of taxonomic distance may indicate that ecological similarity among host species, arising from convergence and not from relatedness, is more important than host phylogeny or taxonomy. Although the results are based on a limited number of parasite taxa, they suggest that parasites may be opportunistic in their colonization of new hosts, and not severely constrained by evolutionary baggage.
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Lehane, Adele M., Donelly A. van Schalkwyk, Stephanie G. Valderramos, David A. Fidock, and Kiaran Kirk. "Differential Drug Efflux or Accumulation Does Not Explain Variation in the Chloroquine Response of Plasmodium falciparum Strains Expressing the Same Isoform of Mutant PfCRT." Antimicrobial Agents and Chemotherapy 55, no. 5 (February 22, 2011): 2310–18. http://dx.doi.org/10.1128/aac.01167-10.
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ABSTRACTMutant forms of thePlasmodium falciparumchloroquine resistance transporter (PfCRT) mediate chloroquine resistance by effluxing the drug from the parasite's digestive vacuole, the acidic organelle in which chloroquine exerts its parasiticidal effect. However, different parasites bearing the same mutant form of PfCRT can vary substantially in their chloroquine susceptibility. Here, we have investigated the biochemical basis for the difference in chloroquine response among transfectant parasite lines having different genetic backgrounds but bearing the same mutant form of PfCRT. Despite showing significant differences in their chloroquine susceptibility, all lines with the mutant PfCRT showed a similar chloroquine-induced H+leak from the digestive vacuole, indicative of similar rates of PfCRT-mediated chloroquine efflux. Furthermore, all lines showed similarly reduced levels of drug accumulation. Factors other than chloroquine efflux and accumulation therefore influence the susceptibility to this drug in parasites expressing mutant PfCRT. Furthermore, in some but not all strains bearing mutant PfCRT, the 50% inhibitory concentration (IC50) for chloroquine and the degree of resistance compared to that of recombinant control parasites varied with the length of the parasite growth assays. In these parasites, the 50% inhibitory concentration for chloroquine measured in 72- or 96-h assays was significantly lower than that measured in 48-h assays. This highlights the importance of considering the first- and second-cycle activities of chloroquine in future studies of parasite susceptibility to this drug.
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Alyasiri, Ali Jawad, and Mohammed Qasim Waheeb. "Global overview of Leishmania virulence factors, and the role of GP63 in promastigotes." Science Archives 03, no. 02 (2022): 124–32. http://dx.doi.org/10.47587/sa.2022.3208.
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Protozoa parasites of the genus Leishmania have a great ability to avoid damage in the hostile environments they encounter throughout their life cycle within the host’s body. Parasites have developed many virulence factors to ensure their persistence and replication within the host, and the first role of these factors is to attenuate the host’s defenses against them through innate and adaptive immunity, as evidence indicates that the determinants of parasite virulence are responsible for evading the host’s defenses, allowing these organisms to survive on Alive in the host’s hostile immune environment. Understanding the molecular details of how these pathogens persist with impunity under extreme conditions is beginning to begin. The fact that Leishmania parasites have adapted not only to survive but are likely to reproduce is due to the protection afforded by specialized molecules on the parasite’s cell surface. Although recent years have seen clear and significant progress in the research on Leishmania in different directions, many issues have yet to be clarified. The surface of all parasites, especially protozoa, usually undergoes pronounced changes during their life cycle. It is of particular interest in the case of protozoan parasites of the genus Leishmania whose surface is exposed to different and hostile environments within vertebrate and invertebrate organisms. Because of the importance that the cell surface of pathogenic parasites plays in their interaction with the host for survival, some efforts have been devoted to their characterization. This review aims to give an overview of the main virulence factors that contribute to parasite survival and survival. We have attempted to provide a brief picture of the factors that influence the interaction of the parasite in its host, further highlighting GP63 as a critical virulence factor affecting macrophage physiology as well as the functioning of the immune system.
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Prior, Kimberley F., Benita Middleton, Alíz T. Y. Owolabi, Mary L. Westwood, Jacob Holland, Aidan J. O'Donnell, Michael J. Blackman, Debra J. Skene, and Sarah E. Reece. "Synchrony between daily rhythms of malaria parasites and hosts is driven by an essential amino acid." Wellcome Open Research 6 (October 20, 2021): 186. http://dx.doi.org/10.12688/wellcomeopenres.16894.2.
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Background: Rapid asexual replication of blood stage malaria parasites is responsible for the severity of disease symptoms and fuels the production of transmission forms. Here, we demonstrate that a Plasmodium chabaudi’s schedule for asexual replication can be orchestrated by isoleucine, a metabolite provided to the parasite in a periodic manner due to the host’s rhythmic intake of food. Methods: We infect female C57BL/6 and Per1/2-null mice which have a disrupted canonical (transcription translation feedback loop, TTFL) clock with 1×105 red blood cells containing P. chabaudi (DK genotype). We perturb the timing of rhythms in asexual replication and host feeding-fasting cycles to identify nutrients with rhythms that match all combinations of host and parasite rhythms. We then test whether perturbing the availability of the best candidate nutrient in vitro changes the schedule for asexual development. Results: Our large-scale metabolomics experiment and follow up experiments reveal that only one metabolite - the amino acid isoleucine – fits criteria for a time-of-day cue used by parasites to set the schedule for replication. The response to isoleucine is a parasite strategy rather than solely the consequences of a constraint imposed by host rhythms, because unlike when parasites are deprived of other essential nutrients, they suffer no apparent costs from isoleucine withdrawal. Conclusions: Overall, our data suggest parasites can use the daily rhythmicity of blood-isoleucine concentration to synchronise asexual development with the availability of isoleucine, and potentially other resources, that arrive in the blood in a periodic manner due to the host’s daily feeding-fasting cycle. Identifying both how and why parasites keep time opens avenues for interventions; interfering with the parasite’s time-keeping mechanism may stall replication, increasing the efficacy of drugs and immune responses, and could also prevent parasites from entering dormancy to tolerate drugs.
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Prior, Kimberley F., Benita Middleton, Alíz T. Y. Owolabi, Mary L. Westwood, Jacob Holland, Aidan J. O'Donnell, Michael J. Blackman, Debra J. Skene, and Sarah E. Reece. "Synchrony between daily rhythms of malaria parasites and hosts is driven by an essential amino acid." Wellcome Open Research 6 (July 22, 2021): 186. http://dx.doi.org/10.12688/wellcomeopenres.16894.1.
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Background: Rapid asexual replication of blood stage malaria parasites is responsible for the severity of disease symptoms and fuels the production of transmission forms. Here, we demonstrate that the Plasmodium chabaudi’s schedule for asexual replication can be orchestrated by isoleucine, a metabolite provided to the parasite in periodic manner due to the host’s rhythmic intake of food. Methods: We infect female C57BL/6 and Per1/2-null TTFL clock-disrupted mice with 1×105 red blood cells containing P. chabaudi (DK genotype). We perturb the timing of rhythms in asexual replication and host feeding-fasting cycles to identify nutrients with rhythms that match all combinations of host and parasite rhythms. We then test whether perturbing the availability of the best candidate nutrient in vitro elicits changes their schedule for asexual development. Results: Our large-scale metabolomics experiment and follow up experiments reveal that only one metabolite - the amino acid isoleucine – fits criteria for a time-of-day cue used by parasites to set the schedule for replication. The response to isoleucine is a parasite strategy rather than solely the consequences of a constraint imposed by host rhythms, because unlike when parasites are deprived of other essential nutrients, they suffer no apparent costs from isoleucine withdrawal. Conclusions: Overall, our data suggest parasites can use the daily rhythmicity of blood-isoleucine concentration to synchronise asexual development with the availability of isoleucine, and potentially other resources, that arrive in the blood in a periodic manner due to the host’s daily feeding-fasting cycle. Identifying both how and why parasites keep time opens avenues for interventions; interfering with the parasite’s time-keeping mechanism may stall replication, increasing the efficacy of drugs and immune responses, and could also prevent parasites from entering dormancy to tolerate drugs.
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McRobert, Louisa, Peter Preiser, Sarah Sharp, William Jarra, Mallika Kaviratne, Martin C. Taylor, Laurent Renia, and Colin J. Sutherland. "Distinct Trafficking and Localization of STEVOR Proteins in Three Stages of the Plasmodium falciparum Life Cycle." Infection and Immunity 72, no. 11 (November 2004): 6597–602. http://dx.doi.org/10.1128/iai.72.11.6597-6602.2004.
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ABSTRACT The genome of Plasmodium falciparum harbors three extensive multigene families, var, rif, and stevor (for subtelomeric variable open reading frame), located mainly in the subtelomeric regions of the parasite's 14 chromosomes. STEVOR variants are known to be expressed in asexual parasites, but no function has as yet been ascribed to this protein family. We have examined the expression of STEVOR proteins in intraerythrocytic sexual stages, gametocytes, and extracellular sporozoites isolated from infected Anopheles mosquitoes. In gametocytes, stevor transcripts appear transiently early in development but STEVOR proteins persist for several days and are transported out of the parasite, travel through the host cell cytoplasm, and localize to the erythrocyte plasma membrane. In contrast to asexual parasites, gametocytes move STEVOR to the periphery via a trafficking pathway independent of Maurer's clefts. In sporozoites, STEVOR appear dispersed throughout the cytoplasm in vesicle-like structures. The pattern of STEVOR localization we have observed in gametocytes and sporozoites differs significantly from that in asexual parasite stages. STEVOR variants are therefore likely to perform different functions in each stage of the parasites life cycle in which they occur.
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Ellis, Vincenzo A., Michael D. Collins, Matthew C. I. Medeiros, Eloisa H. R. Sari, Elyse D. Coffey, Rebecca C. Dickerson, Camile Lugarini, et al. "Local host specialization, host-switching, and dispersal shape the regional distributions of avian haemosporidian parasites." Proceedings of the National Academy of Sciences 112, no. 36 (August 24, 2015): 11294–99. http://dx.doi.org/10.1073/pnas.1515309112.
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The drivers of regional parasite distributions are poorly understood, especially in comparison with those of free-living species. For vector-transmitted parasites, in particular, distributions might be influenced by host-switching and by parasite dispersal with primary hosts and vectors. We surveyed haemosporidian blood parasites (Plasmodium and Haemoproteus) of small land birds in eastern North America to characterize a regional parasite community. Distributions of parasite populations generally reflected distributions of their hosts across the region. However, when the interdependence between hosts and parasites was controlled statistically, local host assemblages were related to regional climatic gradients, but parasite assemblages were not. Moreover, because parasite assemblage similarity does not decrease with distance when controlling for host assemblages and climate, parasites evidently disperse readily within the distributions of their hosts. The degree of specialization on hosts varied in some parasite lineages over short periods and small geographic distances independently of the diversity of available hosts and potentially competing parasite lineages. Nonrandom spatial turnover was apparent in parasite lineages infecting one host species that was well-sampled within a single year across its range, plausibly reflecting localized adaptations of hosts and parasites. Overall, populations of avian hosts generally determine the geographic distributions of haemosporidian parasites. However, parasites are not dispersal-limited within their host distributions, and they may switch hosts readily.
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Frasse, Philip, Daniel Goldberg, and Audrey Odom John. "#23: Investigation of Phosphomannomutase as an Antimalarial Drug Target." Journal of the Pediatric Infectious Diseases Society 10, Supplement_2 (June 1, 2021): S10. http://dx.doi.org/10.1093/jpids/piab031.019.
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Abstract Background Malaria continues to pose an enormous economic and global health threat, killing over 200,000 people annually, primarily children under the age of 5. With the constant barrier of antimalarial resistance and the rise of delayed clearance by artemisinin, it is especially important to identify drug/target pairs that rapidly kill parasites. We study targetable metabolic pathways in the malaria parasite, Plasmodium falciparum, to guide such future drug development against this disease. In recent years, we have discovered that a large family of hydrolases, the Haloacid Dehalogenase (HAD) Superfamily of proteins, are implicated in regulating a variety of P. falciparum metabolic pathways, which can lead to dramatic changes in central carbon metabolism and drug resistance. We now turn our attention to a related HAD protein, the putative phosphomannomutase in these parasites, HAD5, responsible for the interconversion of mannose-6-phosphate and mannose-1-phosphate. This is an essential process for all stages of the parasite, and thus has potential as a broad antimalarial target. We examined the role of HAD5 in these parasites, and its potential to be chemically inhibited. Methods Recombinant protein was generated and purified for enzymatic assays to determine HAD5 activity and test inhibitor potency against HAD5 compared to recombinant human orthologs, PMM1 and PMM2. In parallel, CRISPR/Cas9 was used to generate inducible knockdown parasite strains to demonstrate this gene’s essentiality and its role in parasite biology. Parasite growth was measured by flow cytometry and light microscopy. Immunofluorescence analysis (IFA) was used to track the parasite development on a molecular scale. Results Inhibition of HAD5 was achieved in biochemical assays, with an IC50 of 68µM in our most potent compound, representing roughly 10-fold increased potency against the parasite protein compared to human orthologs. In culture, knockdown of HAD5 leads to interrupted egress from and reinvasion into red blood cells, culminating in parasite death. In IFA-visualized parasites, reinvasion-facilitating proteins were no longer anchored to parasite surfaces, accounting for the inhibition of the parasite life cycle. Conclusion In the search for new antimalarial targets, identifying proteins that are essential across multiple parasite life-stages while being distinct from human orthologs is necessary to block parasite transmission, cure symptomatic infection, and minimize off-target effects. HAD5 is an essential protein in malaria parasites that is expressed throughout the parasite’s life cycle, and can be specifically targeted by inhibitors, giving it promise as a future drug target.
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Grüter, Christoph, Evelien Jongepier, and Susanne Foitzik. "Insect societies fight back: the evolution of defensive traits against social parasites." Philosophical Transactions of the Royal Society B: Biological Sciences 373, no. 1751 (June 4, 2018): 20170200. http://dx.doi.org/10.1098/rstb.2017.0200.
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Insect societies face many social parasites that exploit their altruistic behaviours or their resources. Due to the fitness costs these social parasites incur, hosts have evolved various behavioural, chemical, architectural and morphological defence traits. Similar to bacteria infecting multicellular hosts, social parasites have to successfully go through several steps to exploit their hosts. Here, we review how social insects try to interrupt this sequence of events. They can avoid parasite contact by choosing to nest in parasite-free locales or evade attacks by adapting their colony structure. Once social parasites attack, hosts attempt to detect them, which can be facilitated by adjustments in colony odour. If social parasites enter the nest, hosts can either aggressively defend their colony or take their young and flee. Nest structures are often shaped to prevent social parasite invasion or to safeguard host resources. Finally, if social parasites successfully establish themselves in host nests, hosts can rebel by killing the parasite brood or by reproducing in the parasites' presence. Hosts of social parasites can therefore develop multiple traits, leading to the evolution of complex defence portfolios of co-dependent traits. Social parasites can respond to these multi-level defences with counter-adaptations, potentially leading to geographical mosaics of coevolution. This article is part of the Theo Murphy meeting issue ‘Evolution of pathogen and parasite avoidance behaviours’.
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Hernandez-Caballero, Irene, Luz Garcia-Longoria, Ivan Gomez-Mestre, and Alfonso Marzal. "The Adaptive Host Manipulation Hypothesis: Parasites Modify the Behaviour, Morphology, and Physiology of Amphibians." Diversity 14, no. 9 (September 8, 2022): 739. http://dx.doi.org/10.3390/d14090739.
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Parasites have evolved different strategies to increase their transmission from one host to another. The Adaptive Host Manipulation hypothesis states that parasites induce modifications of host phenotypes that could maximise parasite fitness. There are numerous examples of parasite manipulation across a wide range of host and parasite taxa. However, the number of studies exploring the manipulative effects of parasites on amphibians is still scarce. Herein, we extensively review the current knowledge on phenotypic alterations in amphibians following parasite infection. Outcomes from different studies show that parasites may manipulate amphibian behaviours to favour their transmission among conspecifics or to enhance the predation of infected amphibians by a suitable definite host. In addition, parasites also modify the limb morphology and impair locomotor activity of infected toads, frogs, and salamanders, hence facilitating their ingestion by a final host and completing the parasite life cycle. Additionally, parasites may alter host physiology to enhance pathogen proliferation, survival, and transmission. We examined the intrinsic (hosts traits) and extrinsic (natural and anthropogenic events) factors that may determine the outcome of infection, where human-induced changes of environmental conditions are the most harmful stressors that enhance amphibian exposure and susceptibility to parasites.
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Enslow, Chelsea, Rachel Vallender, Emily Rondel, and Nicola Koper. "Host dispersal and landscape conversion are associated with the composition of haemosporidian parasites of the golden-winged warbler." Parasitology 147, no. 1 (September 18, 2019): 96–107. http://dx.doi.org/10.1017/s0031182019001240.
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AbstractUnderstanding factors that influence the spatial and temporal distributions of blood parasites is important to help predict how host species and their parasites may respond to global change. Factors that may influence parasite distributions are land cover and host dispersal patterns, which may result in exposure of a host to novel parasites, or escape from parasites of their origin. We screened golden-winged warblers from across the United States and Canada for blood parasites, and investigated whether land-use patterns or host dispersal affected the prevalence and composition of haemosporidian assemblages. Parasite prevalence varied strongly with study area, and areas with high agricultural cover had a significantly higher prevalence of Leucocytozoon and Parahaemoproteus parasites. Lineages of Parahaemoproteus and Leucocytozoon were genetically differentiated among study areas, and prevalence and composition of parasite assemblages indicated an increase in parasite prevalence and accumulation of unique parasite lineages from the southeast to the northwest. This matches the historical range expansion and natal dispersal patterns of golden-winged warblers, and suggests that golden-winged warblers may have been sensitive to novel parasites as they dispersed. The high prevalence and diversity of parasite lineages in the north-west extent of their breeding range (Manitoba) indicates that this population may face unique pressures.
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Tang, Qing, Nicole Andenmatten, Miryam A. Hortua Triana, Bin Deng, Markus Meissner, Silvia N. J. Moreno, Bryan A. Ballif, and Gary E. Ward. "Calcium-dependent phosphorylation alters class XIVa myosin function in the protozoan parasite Toxoplasma gondii." Molecular Biology of the Cell 25, no. 17 (September 2014): 2579–91. http://dx.doi.org/10.1091/mbc.e13-11-0648.
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Class XIVa myosins comprise a unique group of myosin motor proteins found in apicomplexan parasites, including those that cause malaria and toxoplasmosis. The founding member of the class XIVa family, Toxoplasma gondii myosin A (TgMyoA), is a monomeric unconventional myosin that functions at the parasite periphery to control gliding motility, host cell invasion, and host cell egress. How the motor activity of TgMyoA is regulated during these critical steps in the parasite's lytic cycle is unknown. We show here that a small-molecule enhancer of T. gondii motility and invasion (compound 130038) causes an increase in parasite intracellular calcium levels, leading to a calcium-dependent increase in TgMyoA phosphorylation. Mutation of the major sites of phosphorylation altered parasite motile behavior upon compound 130038 treatment, and parasites expressing a nonphosphorylatable mutant myosin egressed from host cells more slowly in response to treatment with calcium ionophore. These data demonstrate that TgMyoA undergoes calcium-dependent phosphorylation, which modulates myosin-driven processes in this important human pathogen.
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SEARLE, C. L., J. H. OCHS, C. E. CÁCERES, S. L. CHIANG, N. M. GERARDO, S. R. HALL, and M. A. DUFFY. "Plasticity, not genetic variation, drives infection success of a fungal parasite." Parasitology 142, no. 6 (February 25, 2015): 839–48. http://dx.doi.org/10.1017/s0031182015000013.
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SUMMARYHosts strongly influence parasite fitness. However, it is challenging to disentangle host effects on genetic vs plasticity-driven traits of parasites, since parasites can evolve quickly. It remains especially difficult to determine the causes and magnitude of parasite plasticity. In successive generations, parasites may respond plastically to better infect their current type of host, or hosts may produce generally ‘good’ or ‘bad’ quality parasites. Here, we characterized parasite plasticity by taking advantage of a system in which the parasite (the yeast Metschnikowia bicuspidata, which infects Daphnia) has no detectable heritable variation, preventing rapid evolution. In experimental infection assays, we found an effect of rearing host genotype on parasite infectivity, where host genotypes produced overall high or low quality parasite spores. Additionally, these plastically induced differences were gained or lost in just a single host generation. Together, these results demonstrate phenotypic plasticity in infectivity driven by the within-host rearing environment. Such plasticity is rarely investigated in parasites, but could shape epidemiologically important traits.
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MUÑOZ, G., A. S. GRUTTER, and T. H. CRIBB. "Endoparasite communities of five fish species (Labridae: Cheilininae) from Lizard Island: how important is the ecology and phylogeny of the hosts?" Parasitology 132, no. 3 (December 7, 2005): 363–74. http://dx.doi.org/10.1017/s0031182005009133.
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The parasite community of animals is generally influenced by host physiology, ecology, and phylogeny. Therefore, sympatric and phylogenetically related hosts with similar ecologies should have similar parasite communities. To test this hypothesis we surveyed the endoparasites of 5 closely related cheilinine fishes (Labridae) from the Great Barrier Reef. They were Cheilinus chlorourus, C. trilobatus, C. fasciatus, Epibulus insidiator and Oxycheilinus diagramma. We examined the relationship between parasitological variables (richness, abundance and diversity) and host characteristics (body weight, diet and phylogeny). The 5 fishes had 31 parasite species with 9–18 parasite species per fish species. Cestode larvae (mostly Tetraphyllidea) were the most abundant and prevalent parasites followed by nematodes and digeneans. Parasites, body size and diet of hosts differed between fish species. In general, body weight, diet and host phylogeny each explained some of the variation in richness and composition of parasites among the fishes. The 2 most closely related species, Cheilinus chlorourus and C. trilobatus, had broadly similar parasites but the other fish species differed significantly in all variables. However, there was no all-encompassing pattern. This may be because different lineages of parasites may react differently to ecological variables. We also argue that adult parasites may respond principally to host diet. In contrast, larval parasite composition may respond both to host diet and predator-prey interactions because this is the path by which many parasites complete their life-cycles. Finally, variation in parasite phylogeny and parasite life-cycles among hosts likely increase the complexity of the system making it difficult to find all-encompassing patterns between host characteristics and parasites, particularly when all the species in rich parasite communities are considered.
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Ezenwa, Vanessa O., Elizabeth A. Archie, Meggan E. Craft, Dana M. Hawley, Lynn B. Martin, Janice Moore, and Lauren White. "Host behaviour–parasite feedback: an essential link between animal behaviour and disease ecology." Proceedings of the Royal Society B: Biological Sciences 283, no. 1828 (April 13, 2016): 20153078. http://dx.doi.org/10.1098/rspb.2015.3078.
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Animal behaviour and the ecology and evolution of parasites are inextricably linked. For this reason, animal behaviourists and disease ecologists have been interested in the intersection of their respective fields for decades. Despite this interest, most research at the behaviour–disease interface focuses either on how host behaviour affects parasites or how parasites affect behaviour, with little overlap between the two. Yet, the majority of interactions between hosts and parasites are probably reciprocal, such that host behaviour feeds back on parasites and vice versa. Explicitly considering these feedbacks is essential for understanding the complex connections between animal behaviour and parasite ecology and evolution. To illustrate this point, we discuss how host behaviour–parasite feedbacks might operate and explore the consequences of feedback for studies of animal behaviour and parasites. For example, ignoring the feedback of host social structure on parasite dynamics can limit the accuracy of predictions about parasite spread. Likewise, considering feedback in studies of parasites and animal personalities may provide unique insight about the maintenance of variation in personality types. Finally, applying the feedback concept to links between host behaviour and beneficial, rather than pathogenic, microbes may shed new light on transitions between mutualism and parasitism. More generally, accounting for host behaviour–parasite feedbacks can help identify critical gaps in our understanding of how key host behaviours and parasite traits evolve and are maintained.
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Kumar, Krishna, Yael Hacham, and Rachel Amir. "The Effect of 10 Crop Plants That Served as Hosts on the Primary Metabolic Profile of the Parasitic Plant Phelipanche aegyptiaca." Metabolites 12, no. 12 (November 29, 2022): 1195. http://dx.doi.org/10.3390/metabo12121195.
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Phelipanche aegyptiaca Pers. is a holoparasitic plant that parasitizes various types of host plants. Its penetration into host roots causes a massive reduction in the yield of many crop plants worldwide. The nature of the compounds taken by the parasite from its host is still under debate in the scientific literature. To gain more knowledge about the effect of the hosts on the parasite’s primary metabolic profile, GC-MS analyses were conducted on the parasites that developed on 10 hosts from four plant families. There are three hosts from each family: Brassicaceae, Apiaceae and Solanaceae and one host from Fabaceae. The results showed significant differences in the metabolic profiles of P. aegyptiaca collected from the different hosts, indicating that the parasites rely strongly on the host’s metabolites. Generally, we found that the parasites that developed on Brassicaceae and Fabaceae accumulated more amino acids than those developed on Apiaceae and Solanaceae that accumulated more sugars and organic acids. The contents of amino acids correlated positively with the total soluble proteins. However, the aromatic amino acid, tyrosine, correlated negatively with the accumulation of the total phenolic compounds. This study contributes to our knowledge of the metabolic relationship between host and parasite.
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Fahrurrozi, Ashari, Linayati Linayati, and Wijianto Wijianto. "Prevalence and Degree of Endoparasite Infection in Kuniran Fish (Upeneus spp.) in Pekalongan Regency." Berkala Perikanan Terubuk 51, no. 1 (February 28, 2023): 1736. http://dx.doi.org/10.31258/terubuk.51.1.1736-1741.
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Pekalongan Regency is one of the coastal areas producing consumption fish with one species of kuniran fish (Upeneus spp). However, its production is decreasing due to growth disturbance, one of which is caused by parasitic infection. Information regarding the existence of parasites in kuniran fish is still limited. The research was conducted at the Pekalongan University Biology Laboratory from November 7 to November 30, 2022. This research aimed to discover the types of parasites that infect kuniran fish in Pekalongan Regency. The parasite's prevalence rate and degree of infection were also analyzed descriptively. The research was carried out using a sample of 36 fish. Fish were grouped into three groups, namely group I (23.3 ±1.2 cm), group II (18.5 ±0.9 cm), and group III (14.3 ±0.4 cm). The parasite results obtained from the endoparasite group, namely the Procamallanus sp. and Camallanus sp. with the highest parasite prevalence value found in group III with a size of 14.3 ± 0.4 cm both Procamallanus sp. value of 33.3% and Camallanus sp. with a discount of 50%. In addition, the degree of infection in both parasites and fish groups showed a low category.
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STUMBO, ANTHONY D., and ROBERT POULIN. "Possible mechanism of host manipulation resulting from a diel behaviour pattern of eye-dwelling parasites?" Parasitology 143, no. 10 (May 24, 2016): 1261–67. http://dx.doi.org/10.1017/s0031182016000810.
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SUMMARYParasitic infection often results in alterations to the host's phenotype, and may modify selection pressures for host populations. Elucidating the mechanisms underlying these changes is essential to understand the evolution of host–parasite interactions. A variety of mechanisms may result in changes in the host's behavioural phenotype, ranging from simple by-products of infection to chemicals directly released by the parasite to alter behaviour. Another possibility may involve parasites freely moving to certain sites within tissues, at specific times of the day to induce behavioural changes in the host. We tested the hypothesis that parasites shift to certain sites within the host by quantifying the location and activity of the trematode Tylodelphys sp., whose mobile metacercarial stages remain unencysted in the eyes of the second intermediate fish host, the common bully (Gobiomorphus cotidianus). This parasite's definitive host is a piscivorous bird feeding exclusively during daytime. Ocular obstruction and metacercarial activity were assessed within the sedated host's eye at three time points 24 h−1 period, using video captured via an ophthalmoscope. Although observed metacercarial activity did not change between time periods, ocular obstruction was significantly reduced at night. Increased visual obstruction specifically during the foraging time of the parasite's definitive host strongly suggests that the parasite's activity pattern is adaptive.
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VAN DER VEEN, I. T., and J. KURTZ. "To avoid or eliminate: cestode infections in copepods." Parasitology 124, no. 4 (April 2002): 465–74. http://dx.doi.org/10.1017/s0031182001001275.
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The outcome of a parasite infection is the result of the interaction between the host and the parasite. In the system we studied, there are 3 critical stages for the outcome of infection of the (intermediate) host, the copepod Macrocyclops albidus, with the cestode Schistocephalus solidus. During the establishment phase of the parasite, the host may firstly avoid ingesting the parasite and, secondly, may prevent the parasite from entering the body cavity and, thirdly, during the growth phase of the parasite, the host's immune system may eliminate the parasite from the body cavity. We were able to study the growth phase separately from the establishment phase. The establishment phase was influenced by characteristics of the host as well as characteristics of the parasites. Small copepods and males performed poorly; they were more often infected and had a lower survival. Parasites from different sib-groups differed in infectivity. During the growth phase some disappearance of parasites was observed. However, this could not be related to any of the studied characteristics of the host, and the sib-groups of parasites did not seem to differ in their likelihood to disappear. Instead, we suggest that disappearance of parasites, once they have entered the body cavity, may be due to intrinsic mortality of the parasites, independent of the host or the sib-group that the parasites belong to. This indicates that the crucial interactions between host and parasite determining the outcome of infection takes place in the short time-period between ingestion and penetration of the gut-wall.
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Cohen, Joel E., Robert Poulin, and Clément Lagrue. "Linking parasite populations in hosts to parasite populations in space through Taylor's law and the negative binomial distribution." Proceedings of the National Academy of Sciences 114, no. 1 (December 19, 2016): E47—E56. http://dx.doi.org/10.1073/pnas.1618803114.
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The spatial distribution of individuals of any species is a basic concern of ecology. The spatial distribution of parasites matters to control and conservation of parasites that affect human and nonhuman populations. This paper develops a quantitative theory to predict the spatial distribution of parasites based on the distribution of parasites in hosts and the spatial distribution of hosts. Four models are tested against observations of metazoan hosts and their parasites in littoral zones of four lakes in Otago, New Zealand. These models differ in two dichotomous assumptions, constituting a 2 × 2 theoretical design. One assumption specifies whether the variance function of the number of parasites per host individual is described by Taylor's law (TL) or the negative binomial distribution (NBD). The other assumption specifies whether the numbers of parasite individuals within each host in a square meter of habitat are independent or perfectly correlated among host individuals. We find empirically that the variance–mean relationship of the numbers of parasites per square meter is very well described by TL but is not well described by NBD. Two models that posit perfect correlation of the parasite loads of hosts in a square meter of habitat approximate observations much better than two models that posit independence of parasite loads of hosts in a square meter, regardless of whether the variance–mean relationship of parasites per host individual obeys TL or NBD. We infer that high local interhost correlations in parasite load strongly influence the spatial distribution of parasites. Local hotspots could influence control and conservation of parasites.
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Rumondang, J. P. Batubara, K. Laila, D. Gustira, and I. Mulyani. "Identification of Ectoparasites that Infect Mangrove Crabs (Scylla Serrata) in Asahan District, Indonesia." IOP Conference Series: Earth and Environmental Science 1118, no. 1 (December 1, 2022): 012007. http://dx.doi.org/10.1088/1755-1315/1118/1/012007.
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Abstract The purpose of this study was to determine the type and level of prevalence and intensity of ectoparasites that infect mud crabs (Scylla serrata) in Asahan district. The method of data collection was carried out by field observation methods carried out in the sea silos, Pematang Baru, and Sei Kepayang areas. The crab samples observed were live crabs, the number of mud crabs taken for the sample was 10% of each population. Furthermore, in the carapace, the type of parasite that attacks is Trichodina sp with a prevalence rate of 38%. This parasite infected 5 of the 13 samples. Then the types of parasites Carchesium sp and Poecilasmatidae each with a prevalence rate of 31% these two types of parasites infect 4 samples of crabs found at the foot of theroad, this type of parasite infects 4 out of 13 samples. Then the types of parasites Carchesium sp and Poecilasmatidae each with a prevalence rate of 31% these two types of parasites infect 4 samples of crabs found at the foot of theroad, this type of parasite infects 4 out of 13 samples. Then the types of parasites Carchesium sp and Poecilasmatidae sp each with a prevalence rate of 31% these two types of parasites infect 4 samples of crabs found at the foot of theroad, this type of parasite infects 4 out of 13 samples. The crabs that attack the sea silos are Octolasmis sp, Ichtyopthyrius multifilis, Trichodina sp, Zoothamnium sp. The parasites that attack the new ponds are Octolasmis sp, Carchesium sp, Zoothamnium sp, and the parasites that attack Sei Kepayang are Octolasmis sp, Carchesium sp, Poecilasmatidae sp, Trichodina sp. The intensity of the parasites found was classified as moderate but for the parasite Octolasmis sp.
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PAGENKOPP LOHAN, KATRINA M., KRISTINA M. HILL-SPANIK, MARK E. TORCHIN, LEOPOLDINA AGUIRRE-MACEDO, ROBERT C. FLEISCHER, and GREGORY M. RUIZ. "Richness and distribution of tropical oyster parasites in two oceans." Parasitology 143, no. 9 (June 6, 2016): 1119–32. http://dx.doi.org/10.1017/s0031182015001900.
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SUMMARYParasites can exert strong effects on population to ecosystem level processes, but data on parasites are limited for many global regions, especially tropical marine systems. Characterizing parasite diversity and distributions are the first steps towards understanding the potential impacts of parasites. The Panama Canal serves as an interesting location to examine tropical parasite diversity and distribution, as it is a conduit between two oceans and a hub for international trade. We examined metazoan and protistan parasites associated with ten oyster species collected from both Panamanian coasts, including the Panama Canal and Bocas del Toro. We found multiple metazoan taxa (pea crabs, Stylochus spp., Urastoma cyrinae). Our molecular screening for protistan parasites detected four species of Perkinsus (Perkinsus marinus, Perkinsus chesapeaki, Perkinsus olseni, Perkinsus beihaiensis) and several haplosporidians, including two genera (Minchinia, Haplosporidium). Species richness was higher for the protistan parasites than for the metazoans, with haplosporidian richness being higher than Perkinsus richness. Perkinsus species were the most frequently detected and most geographically widespread among parasite groups. Parasite richness and overlap differed between regions, locations and oyster hosts. These results have important implications for tropical parasite richness and the dispersal of parasites due to shipping associated with the Panama Canal.
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Tomlinson, S., L. C. Pontes de Carvalho, F. Vandekerckhove, and V. Nussenzweig. "Role of sialic acid in the resistance of Trypanosoma cruzi trypomastigotes to complement." Journal of Immunology 153, no. 7 (October 1, 1994): 3141–47. http://dx.doi.org/10.4049/jimmunol.153.7.3141.
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Abstract Trypomastigotes of Trypanosoma cruzi, mammalian infective forms of the parasite, express an unusual cell surface trans-sialidase. This enzyme enables the parasite to rapidly sialylate its surface when supplied with alpha(2,3)-linked sialic acid from glycoconjugates in serum or on cell surfaces. Here we used a novel fluorescence-based, trypomastigote lysis assay to evaluate the role of sialic acid on the parasite's plasma membrane in providing protection against the complement cascade. Trypomastigotes were desialylated, and sialic acid removal was confirmed by a chemical assay and also by flow cytometry with the use of a mAb that recognizes a T. cruzi-sialylated epitope. Compared with sialylated trypomastigotes, which were completely refractory to lysis by human serum, only about 5% of the desialylated trypomastigotes were lysed by complement. However, further analysis revealed that the desialylated parasites had been resialylated during exposure to serum complement. Next we incubated desialylated trypomastigotes with samples of desialylated human serum. Although the sialidase-treated serum retained its full hemolytic activity, lysis of trypomastigotes increased only from 5 to 24%. This increase correlated with an enhanced deposition of complement protein C3 on the parasite surface. The ratio of C3b to lytically inactive iC3b was increased for desialylated, compared with sialylated, parasites. We conclude that although parasite sialic acid promotes C3b cleavage into iC3b, this mechanism alone does not account for the robust resistance of these parasites to complement lysis.
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Conrad, Sean M., Dalit Strauss-Ayali, Ann E. Field, Matthias Mack, and David M. Mosser. "Leishmania-Derived Murine Monocyte Chemoattractant Protein 1 Enhances the Recruitment of a Restrictive Population of CC Chemokine Receptor 2-Positive Macrophages." Infection and Immunity 75, no. 2 (November 6, 2006): 653–65. http://dx.doi.org/10.1128/iai.01314-06.
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ABSTRACT Transgenic Leishmania parasites that encode the murine chemokine monocyte chemoattractant protein 1 (MCP-1) were generated. These parasites transcribed MCP-1 mRNA and secreted MCP-1 protein. Infection of BALB/c, C57BL/6, or MCP-1 knockout (KO) mice with these parasites resulted in minimal lesion development with fewer parasites in the infected foot, lymph node, and spleen compared to wild-type-infected mice. In contrast, transgenic parasites caused substantial lesions with relatively high numbers of parasites in CC chemokine receptor 2 (CCR2) KO mice, indicating that the parasites are viable and healthy and that the lack of lesion development is CCR2 dependent. Prior infection of mice with transgenic parasites offered no protection to subsequent wild-type L. major challenge, suggesting that the transgenic parasites are controlled by an early innate immune response. Consistent with innate immunity, flow cytometry of cells from the ears of mice infected with transgenic parasites revealed an increase in the number of CCR2-positive macrophages by day 7 postinfection. The enumeration of transgenic parasites in ear lesions demonstrated a significant reduction in parasite numbers, which coincided with the increased CCR2-positive macrophage migration. CCR2-positive macrophages isolated from ears of mice infected with transgenic parasites contained virtually no parasites. In vitro studies revealed that optimal parasite killing required the recruitment of CCR2-positive macrophages, followed by stimulation with a combination of both MCP-1 and gamma interferon (IFN-γ). This work suggests that the parasite-derived MCP-1 can recruit a restrictive population of CCR2-positive macrophages into lesions that can be optimally stimulated by MCP-1 and IFN-γ to efficiently kill Leishmania parasites.
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Taraschewski, H. "Hosts and parasites as aliens." Journal of Helminthology 80, no. 2 (June 2006): 99–128. http://dx.doi.org/10.1079/joh2006364.
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AbstractOver the past decades, various free-living animals (hosts) and their parasites have invaded recipient areas in which they had not previously occurred, thus gaining the status of aliens or exotics. In general this happened to a low extent for hundreds of years. With variable frequency, invasions have been followed by the dispersal and establishment of non-indigenous species, whether host or parasite. In the literature thus far, colonizations by both hosts and parasites have not been treated and reviewed together, although both are usually interwoven in various ways. As to those factors permitting invasive success and colonization strength, various hypotheses have been put forward depending on the scientific background of respective authors and on the conspicuousness of certain invasions. Researchers who have tried to analyse characteristic developmental patterns, the speed of dispersal or the degree of genetic divergence in populations of alien species have come to different conclusions. Among parasitologists, the applied aspects of parasite invasions, such as the negative effects on economically important hosts, have long been at the centre of interest. In this contribution, invasions by hosts as well as parasites are considered comparatively, revealing many similarities and a few differences. Two helminths, the liver fluke,Fasciola hepatica,of cattle and sheep and the swimbladder nematode,Anguillicola crassus,of eels are shown to be useful as model parasites for the study of animal invasions and environmental global change. Introductions ofF. hepaticahave been associated with imports of cattle or other grazing animals. In various target areas, susceptible lymnaeid snails serving as intermediate hosts were either naturally present and/or were introduced from the donor continent of the parasite (Europe) and/or from other regions which were not within the original range of the parasite, partly reflecting progressive stages of a global biota change. In several introduced areas,F. hepaticaco-occurs with native or exotic populations of the congenericF. gigantica, with thus far unknown implications. Over the fluke's extended range, in addition to domestic stock animals, wild native or naturalized mammals can also serve as final hosts. Indigenous and displaced populations ofF. hepatica, however, have not yet been studied comparatively from an evolutionary perspective.A. crassus, from the Far East, has invaded three continents, without the previous naturalization of its natural hostAnguilla japonica, by switching to the respective indigenous eel species. Local entomostrac crustaceans serve as susceptible intermediate hosts. The novel final hosts turned out to be naive in respect to the introduced nematode with far reaching consequences for the parasite's morphology (size), abundance and pathogenicity. Comparative infection experiments with Japanese and European eels yielded many differences in the hosts' immune defence, mirroring coevolution versus an abrupt host switch associated with the introduction of the helminth. In other associations of native hosts and invasive parasites, the elevated pathogenicity of the parasite seems to result from other deficiencies such as a lack of anti-parasitic behaviour of the naïve host compared to the donor host which displays distinct behavioural patterns, keeping the abundance of the parasite low. From the small amount of available literature, it can be concluded that the adaptation of certain populations of the novel host to the alien parasite takes several decades to a century or more. Summarizing all we know about hosts and parasites as aliens, tentative patterns and principles can be figured out, but individual case studies teach us that generalizations should be avoided.
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Zheng, Yadong, Xuepeng Cai, and Janette E. Bradley. "microRNAs in parasites and parasite infection." RNA Biology 10, no. 3 (March 2013): 371–79. http://dx.doi.org/10.4161/rna.23716.
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Kim, Ju Yeong, Myung-Hee Yi, and Tai-Soon Yong. "Allergen-like Molecules from Parasites." Current Protein & Peptide Science 21, no. 2 (March 10, 2020): 186–202. http://dx.doi.org/10.2174/1389203720666190708154300.
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Parasite infections modulate immunologic responses, and the loss of parasite infections in the last two to three decades might explain the increased prevalence of allergic diseases in developed countries. However, parasites can enhance allergic responses. Parasites contain or release allergen-like molecules that induce the specific immunoglobulin, IgE, and trigger type-2 immune responses. Some parasites and their proteins, such as Anisakis and Echinococcus granulosus allergens, act as typical allergens. A number of IgE-binding proteins of various helminthic parasites are cross-reactive to other environmental allergens, which cause allergic symptoms or hamper accurate diagnosis of allergic diseases. The cross-reactivity is based on the fact that parasite proteins are structurally homologous to common environmental allergens. In addition, IgE-binding proteins of parasites might be useful for developing vaccines to prevent host re-infection. This review discusses the functions of the IgE-biding proteins of parasites.
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Omeji, S., S. G. Solomon, and E. S. Idoga. "A Comparative Study of the Common Protozoan Parasites ofClarias gariepinusfrom the Wild and Cultured Environments in Benue State, Nigeria." Journal of Parasitology Research 2011 (2011): 1–8. http://dx.doi.org/10.1155/2011/916489.
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A total of one hundred and twentyClarias gariepinuscomprising 30 dead and 30 live fishes were examined for protozoan parasites infestation, sixty each from the wild and a pond (cultured environment) over a period of six months.Ichthyophthirius multifiliiswas the most common protozoan parasites found inC. gariepinusfrom the wild (River Benue) and cultured (pond) environments. These protozoan parasites constitute 37.08% of the total parasites encountered for fishes in the pond and 42.51% of fishes in the wild. Among the body parts of the sampled fishes from the pond, the gills had the highest parasite load (38.86%). Also, the gills had the highest parasite load (40.54%) among the body parts of the fishes sampled from the wild. Fishes not infested with any protozoan parasites from the pond constituted 36.70% of the total fish sampled. On the other hand, fishes not infested with any protozoan parasites from the wild constituted 31.65% of the total fish sampled. Female fishes had more protozoan parasites than the male fishes. Bigger fishes of total length (25–48 cm) had more parasite load than the smaller ones (19–24 cm). Also, fishes between 150–750 g had more parasite load than the smaller ones of less than 150 g. Protozoan parasite load of fish from the cultured environment (pond) did not differ significantly (P<0.05) from those from River Benue (wild).
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Kalanon, Ming, and Geoffrey I. McFadden. "Malaria, Plasmodium falciparum and its apicoplast." Biochemical Society Transactions 38, no. 3 (May 24, 2010): 775–82. http://dx.doi.org/10.1042/bst0380775.
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Malaria, which is caused by species of the parasite genus Plasmodium, remains a major global health problem. A vestigial plastid homologous with the chloroplasts of plants and algae was discovered in malaria and related parasites from the phylum Apicomplexa and has radically changed our view of the evolutionary origins of these disease-causing protists. We now recognize that this large group of parasites had a photosynthetic ancestry and were converted into parasitism early in the evolution of animals. Apicomplexans have probably been parasitizing the animal kingdom for more than 500 million years. The relic plastid persists in most apicomplexans and is an essential component. Perturbation of apicoplast function or inheritance results in parasite death, making the organelle a promising target for chemotherapy. Plastids, including those of malaria parasites, are essentially reduced endosymbiotic bacteria living inside a eukaryotic host. This means that plastids have bacterial-type metabolic pathways and housekeeping processes, all of which are vulnerable to antibacterial compounds. Indeed, many antibacterials kill malaria parasites by blocking essential processes in the plastid. Furthermore, a range of herbicides that target plastid metabolism of undesired plants are also parasiticidal, making them potential new leads for antimalarial drugs. In the present review, we examine the evolutionary origins of the malaria parasite's plastid by endosymbiosis and outline the recent findings on how the organelle imports nuclear-encoded proteins through a set of translocation machineries in the membranes that bound the organelle.
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PERKINS, S. L., E. S. MARTINSEN, and B. G. FALK. "Do molecules matter more than morphology? Promises and pitfalls in parasites." Parasitology 138, no. 13 (June 9, 2011): 1664–74. http://dx.doi.org/10.1017/s0031182011000679.
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SUMMARYSystematics involves resolving both the taxonomy and phylogenetic placement of organisms. We review the advantages and disadvantages of the two kinds of information commonly used for such inferences – morphological and molecular data – as applied to the systematics of metazoan parasites generally, with special attention to the malaria parasites. The problems that potentially confound the use of morphology in parasites include challenges to consistent specimen preservation, plasticity of features depending on hosts or other environmental factors, and morphological convergence. Molecular characters such as DNA sequences present an alternative data source and are particularly useful when not all the parasite's life stages are present or when parasitaemia is low. Nonetheless, molecular data can bring challenges that include troublesome DNA isolation, paralogous gene copies, difficulty in developing molecular markers, and preferential amplification in mixed species infections. Given the differential benefits and shortcomings of both molecular and morphological characters, both should be implemented in parasite taxonomy and phylogenetics.
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Lester, R. J. G., and R. McVinish. "Does moving up a food chain increase aggregation in parasites?" Journal of The Royal Society Interface 13, no. 118 (May 2016): 20160102. http://dx.doi.org/10.1098/rsif.2016.0102.
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General laws in ecological parasitology are scarce. Here, we evaluate data on numbers of fish parasites published by over 200 authors to determine whether acquiring parasites via prey is associated with an increase in parasite aggregation. Parasite species were grouped taxonomically to produce 20 or more data points per group as far as possible. Most parasites that remained at one trophic level were less aggregated than those that had passed up a food chain. We use a stochastic model to show that high parasite aggregation in predators can be solely the result of the accumulation of parasites in their prey. The model is further developed to show that a change in the predators feeding behaviour with age may further increase parasite aggregation.
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Anshary, Hilal, Karmila Azra, Ika, Nila Sukarni, Hendrawani, Rosmaniar, and Sriwulan. "Occurrence of ectoparasites on Nile Tilapia (Oreochromis niloticus) from South Sulawesi Lakes, and Aquaculture facility." IOP Conference Series: Earth and Environmental Science 1119, no. 1 (December 1, 2022): 012013. http://dx.doi.org/10.1088/1755-1315/1119/1/012013.
Full textAbstract:
Abstract Nile tilapia, whether cultivated or living in the wild, is susceptible to various parasite’ infection. A parasitology investigation was conducted to identify parasites of Nile tilapia in Lakes and from aquaculture facilities. The fish examined from aquaculture facility in Bantaeng has a total length of 15 to 20 cm (n= 30) and the hybrid-tilapia from a mini hatchery consist of three groups of fish size. Fish from Towuti Lake range from 7.0 to 21.8 cm in total length (n= 35), and the fish from Tempe Lake range from 10 to 16 cm in total length (n= 40). Parasites found from Nile tilapia in Tempe Lake were monogenean: Cichlidogyrus spp. and Scutogyrus longicornis, and Crustacea; Argulus indicus. Parasites found from Aquaculture facility in Bantaeng were Trichodina magna, Gyrodactylus cichlidarum, Cichlidogyrus spp. and S. longicornis. Trichodinids from Nile tilapia in Towuti Lake were Paratrichodina sp., T. heterodentata, Trichodinella sp., and Tripartiella sp. Parasites found from red hybrid tilapia were Trichodina spp., Cichlidogyrus spp., and G. cichlidarum. The prevalence and mean intensity of the parasite’s infection were discussed. In this study, we present for the first time the presence of some genera of Trichodinids in Nile tilapia in Towuti Lake.
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Lafferty, Kevin D. "Biodiversity loss decreases parasite diversity: theory and patterns." Philosophical Transactions of the Royal Society B: Biological Sciences 367, no. 1604 (October 19, 2012): 2814–27. http://dx.doi.org/10.1098/rstb.2012.0110.
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Past models have suggested host–parasite coextinction could lead to linear, or concave down relationships between free-living species richness and parasite richness. I explored several models for the relationship between parasite richness and biodiversity loss. Life cycle complexity, low generality of parasites and sensitivity of hosts reduced the robustness of parasite species to the loss of free-living species diversity. Food-web complexity and the ordering of extinctions altered these relationships in unpredictable ways. Each disassembly of a food web resulted in a unique relationship between parasite richness and the richness of free-living species, because the extinction trajectory of parasites was sensitive to the order of extinctions of free-living species. However, the average of many disassemblies tended to approximate an analytical model. Parasites of specialist hosts and hosts higher on food chains were more likely to go extinct in food-web models. Furthermore, correlated extinctions between hosts and parasites (e.g. if parasites share a host with a specialist predator) led to steeper declines in parasite richness with biodiversity loss. In empirical food webs with random removals of free-living species, the relationship between free-living species richness and parasite richness was, on average, quasi-linear, suggesting biodiversity loss reduces parasite diversity more than previously thought.
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Penley, McKenna J., and Levi T. Morran. "Host mating system and coevolutionary dynamics shape the evolution of parasite avoidance in Caenorhabditis elegans host populations." Parasitology 145, no. 6 (June 28, 2017): 724–30. http://dx.doi.org/10.1017/s0031182017000804.
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AbstractHosts exhibit a variety of defence mechanisms against parasites, including avoidance. Both host–parasite coevolutionary dynamics and the host mating system can alter the evolutionary trajectories of populations. Does the nature of host–parasite interactions and the host mating system affect the mechanisms that evolve to confer host defence? In a previous experimental evolution study, mixed mating and obligately outcrossing Caenorhabditis elegans host populations adapted to either coevolving or static Serratia marcescens parasite populations. Here, we assessed parasite avoidance as a mechanism underlying host adaptation. We measured host feeding preference for the coevolved and static parasites vs preference for Escherichia coli, to assess the evolution of avoidance behaviour within our experiment. We found that mixed mating host populations evolved a preference for E. coli relative to the static parasite strain; therefore, the hosts evolved parasite avoidance as a defence. However, mixed mating hosts did not exhibit E. coli preference when exposed to coevolved parasites, so avoidance cannot account for host adaptation to coevolving parasites. Further, the obligately outcrossing host populations did not exhibit parasite avoidance in the presence of either static or coevolved parasites. Therefore, both the nature of host–parasite interactions and the host mating system shaped the evolution of host defence.
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O'Donnell, Aidan J., Kimberley F. Prior, and Sarah E. Reece. "Host circadian clocks do not set the schedule for the within-host replication of malaria parasites." Proceedings of the Royal Society B: Biological Sciences 287, no. 1932 (August 12, 2020): 20200347. http://dx.doi.org/10.1098/rspb.2020.0347.
Full textAbstract:
Circadian clocks coordinate organisms' activities with daily cycles in their environment. Parasites are subject to daily rhythms in the within-host environment, resulting from clock-control of host activities, including immune responses. Parasites also exhibit rhythms in their activities: the timing of within-host replication by malaria parasites is coordinated to host feeding rhythms. Precisely which host feeding-related rhythm(s) parasites align with and how this is achieved are unknown. Understanding rhythmic replication in malaria parasites matters because it underpins disease symptoms and fuels transmission investment. We test if rhythmicity in parasite replication is coordinated with the host's feeding-related rhythms and/or rhythms driven by the host's canonical circadian clock. We find that parasite rhythms coordinate with the time of day that hosts feed in both wild-type and clock-mutant hosts, whereas parasite rhythms become dampened in clock-mutant hosts that eat continuously. Our results hold whether infections are initiated with synchronous or with desynchronized parasites. We conclude that malaria parasite replication is coordinated to rhythmic host processes that are independent of the core-clock proteins PERIOD 1 and 2; most likely, a periodic nutrient made available when the host digests food. Thus, novel interventions could disrupt parasite rhythms to reduce their fitness, without interference by host clock-controlled homeostasis.
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Zarlenga, Dante S. "Vaccinating against zoonotic parasitic diseases: myth or reality?" Animal Health Research Reviews 5, no. 2 (December 2004): 219–22. http://dx.doi.org/10.1079/ahr200471.
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AbstractThe largely unanticipated difficulties of parasite vaccine development have led us to a renewed awareness of the survival strategies evolutionarily embedded within parasites over hundreds of millions of years. We have grown to appreciate that efforts to disrupt parasite–host relationships are substantially compounded by our incomplete understanding of the complex immune responses that occur in the naturally infected host. Given the inability to transfer laboratory successes to field trials, research is leading us to conclude that genetically defined animal models may not be good predictors of the unique and disparate protective immune responses one can expect from the genetically heterogeneous populations of animals that represent the parasite's natural environment. This is further compounded by the abundance of mechanisms parasites have created for themselves to defend against immune intervention. Thus, in the never-ending saga of vaccine development, it is only appropriate that pitfalls and advancements be critiqued as they apply across parasite groups, with a look towards promising technologies that may propel this field to the level of scientific achievement once envisaged.
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Onyekwelu, K. C., and A. A. Eze. "Host immune response, nutrition, and metabolism in <i>Schistosoma</i> parasite-host interactions." Nigerian Journal of Parasitology 45, no. 1 (March 28, 2024): 248–55. http://dx.doi.org/10.4314/njpar.v45i1.26.
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Human schistosomiasis, a neglected tropical disease affecting millions of people, mainly in sub-Saharan Africa, is caused by a parasitic worm of the Schistosoma genus that resides in the veins of its host for many years. In parasite-host interactions, there is competition for survival between the parasite and its host because the parasite depends completely on the host for the maintenance of homeostasis. The host must protect itself from the harm caused by parasites in the process of obtaining food and shelter by attacking parasites with a strong immune defence system. Parasites have evolved strategies to survive in these unfavourable conditions created by the host. In this review, we examined the host immune response in Schistosoma parasite infection, the immune evasion mechanisms of Schistosoma parasites, nutrients, and the metabolic dependency of the parasite on the host.
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Anglade, T., and H. S. Randhawa. "Gaining insights into the ecological role of the New Zealand sole (Peltorhamphus novaezeelandiae) through parasites." Journal of Helminthology 92, no. 2 (April 20, 2017): 187–96. http://dx.doi.org/10.1017/s0022149x17000323.
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AbstractDespite the fact that tapeworms comprise the bulk of parasite communities of sharks in marine ecosystems, little is known about their life cycles and, more specifically, about the potential intermediate hosts they utilize as transmission routes. In the absence of morphological features required for specific identification of larval tapeworms from potential intermediate hosts, recent molecular advances have contributed to linking larval and adult parasites and, in some instances, uncovering unknown trophic links. Host–parasite checklists are often the first source of information consulted to assess the diversity and host specificity of parasites, and provide insights into parasite identification. However, these host–parasite checklists are only useful if they encompass the full spectrum of associations between hosts and parasites. A checklist of New Zealand fishes and their parasites has been published, but recent parasitological examinations of commercial fish species reveal that the checklist appears to be far from complete. We focused our current study on a comprehensive survey of macroparasites of a commercial species, the New Zealand sole (Peltorhamphus novaezeelandiae) off the coast of Otago, New Zealand. Specifically, we were expecting to recover marine tapeworms using sharks as their definitive hosts that are generally underreported in parasite surveys. The parasites recovered included tapeworms, flukes, round worms and thorny-headed worms. Surprisingly, a large proportion of the non-tapeworm parasites we recovered were not previously reported from this fish species. A discussion on the potential ecological roles played by this fish species in the transmission of parasites is included.
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Legas, Mohammed Seid. "THE ECOLOGICAL HOSTS SHIFT OF PARASITES AND THE OUTBREAK OF EMERGING INFECTIOUS DISEASES: A REVIEW." International Journal of Research -GRANTHAALAYAH 5, no. 8 (August 31, 2017): 104–8. http://dx.doi.org/10.29121/granthaalayah.v5.i8.2017.2189.
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Parasites are organisms which metabolically depend upon their hosts. To understand the ecological host shift of a parasite, it is important to look the host-parasite associations with respect to ecological change and factors that generate, maintain, and constrain the associations with implications for a wide range of ecological issues, including the dynamics of emerging infectious diseases. Although, the ecological significance of parasites is almost overlooked for several years by ecologists, considerable efforts are being made to understand their functional importance in ecosystems. Parasites play vital role in the trophic cascades of the food web. Environmental change caused by anthropogenic activities result host shift of specialist parasites and this shift of specialized parasites can rapidly to new hosts via ecological fitting play an important role in the ecology and evolution of host-parasite associations. This condition is the primary cause for the Emerging Infectious Diseases when parasite species begin infecting and causing disease in host species with which they have no previous history of association. Therefore, understanding the host parasites interaction and distribution of known and potential pathogens is a vital precondition for optimizing their positive, while minimizing their negative effects on conservation, restoration and sustained development programs.