(International journal for parasitology[TA]) articles in PubMed
- Erratum to "Profiling the anti-protozoal activity of anti-cancer HDAC inhibitors against Plasmodium and Trypanosoma parasites" [Int. J. Parasitol. Drugs Drug Res. 5 (2015) 117-126]. [PUBLISHED ERRATUM]
- Int J Parasitol Drugs Drug Resist 2016 May 30IJ
- Polymorphism in ion channel genes of Dirofilaria immitis: Relevant knowledge for future anthelmintic drug design. [Journal Article]
- Int J Parasitol Drugs Drug Resist 2016 Jul 1IJ
- Dirofilaria immitis, a filarial parasite, causes cardiopulmonary dirofilariasis in dogs, cats and wild canids. The macrocyclic lactone (ML) class of drugs has been used to prevent heartworm infection...
Dirofilaria immitis, a filarial parasite, causes cardiopulmonary dirofilariasis in dogs, cats and wild canids. The macrocyclic lactone (ML) class of drugs has been used to prevent heartworm infection. There is confirmed ML resistance in D. immitis and thus there is an urgent need to find new anthelmintics that could prevent and/or control the disease. Targeting ion channels of D. immitis for drug design has obvious advantages. These channels, present in the nematode nervous system, control movement, feeding, mating and respond to environmental cues which are necessary for survival of the parasite. Any new drug that targets these ion channels is likely to have a motility phenotype and should act to clear the worms from the host. Many of the successful anthelmintics in the past have targeted these ion channels and receptors. Knowledge about genetic variability of the ion channel and receptor genes should be useful information for drug design as receptor polymorphism may affect responses to a drug. Such information may also be useful for anticipation of possible resistance development. A total of 224 ion channel genes/subunits have been identified in the genome of D. immitis. Whole genome sequencing data of parasites from eight different geographical locations, four from ML-susceptible populations and the other four from ML-loss of efficacy (LOE) populations, were used for polymorphism analysis. We identified 1762 single nucleotide polymorphic (SNP) sites (1508 intronic and 126 exonic) in these 224 ion channel genes/subunits with an overall polymorphic rate of 0.18%. Of the SNPs found in the exon regions, 129 of them caused a non-synonymous type of polymorphism. Fourteen of the exonic SNPs caused a change in predicted secondary structure. A few of the SNPs identified may have an effect on gene expression, function of the protein and resistance selection processes.
- Parasites and invasions: changes in gastrointestinal helminth assemblages in invasive and native rodents in Senegal. [Journal Article]
- Int J Parasitol 2016 Sep 23IJ
- Understanding why some exotic species become widespread and abundant in their colonized range is a fundamental issue that still needs to be addressed. Among many hypotheses, newly established host po...
Understanding why some exotic species become widespread and abundant in their colonized range is a fundamental issue that still needs to be addressed. Among many hypotheses, newly established host populations may benefit from a parasite loss ("enemy release" hypothesis) through impoverishment of their original parasite communities or reduced infection levels. Moreover, the fitness of competing native hosts may be negatively affected by the acquisition of exotic taxa from invaders ("parasite spillover") and/or by an increased transmission risk of native parasites due to their amplification by invaders ("parasite spillback"). We focused on gastrointestinal helminth (GIH) communities to determine whether these predictions could explain the ongoing invasion success of the commensal house mouse (Mus musculus domesticus) and black rat (Rattus rattus), as well as the associated decrease in native Mastomys spp., in Senegal. For both invasive species, our results were consistent with the predictions of the enemy release hypothesis. A decrease in overall GIH prevalence and infracommunity species richness was observed along the invasion gradients as well as lower specific prevalence/abundance (Aspiculuris tetraptera in M. m. domesticus, Hymenolepis diminuta in R. rattus) on the invasion fronts. Conversely, we did not find strong evidence of GIH spillover or spillback in invasion fronts, where native and invasive rodents co-occurred. Further experimental research is needed to determine whether and how the loss of GIHs and reduced infection levels along invasion routes may result in any advantageous effects on invader fitness and competitive advantage.
- Severe malaria: what's new on the pathogenesis front? [Review]
- Int J Parasitol 2016 Sep 23IJ
- Plasmodium falciparum causes the most severe and fatal form of malaria in humans with over half a million deaths each year. Cerebral malaria (CM), a complex neurological syndrome of severe falciparum...
Plasmodium falciparum causes the most severe and fatal form of malaria in humans with over half a million deaths each year. Cerebral malaria (CM), a complex neurological syndrome of severe falciparum malaria, is often fatal and represents a major public health burden. Despite vigorous efforts, the pathophysiology of CM remains to be elucidated, thereby hindering the development of adjunctive therapies. In recent years, multidisciplinary and collaborative approaches have led to groundbreaking progress both in the laboratory and in the field. Here we review the latest breakthroughs in severe malaria pathogenesis, with a specific focus on new pathogenetic mechanisms leading to CM. The most recent findings point towards specific parasite phenotypes targeting brain microvasculature, endothelial dysfunction and subsequent oedema-induced brain swelling.
- The life cycle of the reptile-inhabiting nematode Abbreviata hastaspicula (Spirurida: Physalopteridae: Physalopterinae) in Australia. [Journal Article]
- Int J Parasitol Parasites Wildl 2016; 5(3):258-62IJ
- This study elucidates the life-cycle of the reptile inhabiting nematode Abbreviata hastaspicula (Spirurida: Physalopteridae: Physalopterinae) in Australia. Eight Varanus gouldii (Lacertilia: Varanida...
This study elucidates the life-cycle of the reptile inhabiting nematode Abbreviata hastaspicula (Spirurida: Physalopteridae: Physalopterinae) in Australia. Eight Varanus gouldii (Lacertilia: Varanidae), and two Christinus marmoratus (Reptilia: Gekkonidae) lizards were captured in the wild. Two V. gouldii were used as controls and no experimental procedures were carried out on them. Another six V. gouldii (final host) and the two C. marmoratus (paratenic host) were treated with oral anthelmintics to remove all parasitic worms and were fed with infected live arthropods containing third stage larvae of Abbreviata hastaspicula. Faeces of V. gouldii were examined under the microscope weekly to determine whether the third stage larvae had developed into adults. Two months later, a total of 30 larvae and adults of A. hastaspicula were found in the stomachs of four experimentally-infected V. gouldii lizards. No cysts or larva were found in the C. marmoratus. This is the first study to demonstrate the life-cycle of this genus of nematode in their definitive reptile hosts.
- Versatile glycoside hydrolase family 18 chitinases for fungi ingestion and reproduction in the pinewood nematode Bursaphelenchus xylophilus. [Journal Article]
- Int J Parasitol 2016 Sep 15IJ
- The glycoside hydrolase family 18 (GH18) of chitinases is a gene family widely expressed in archaes, prokaryotes and eukaryotes, and hydrolyzes the β-1,4-linkages in chitin. The pinewood nematode Bur...
The glycoside hydrolase family 18 (GH18) of chitinases is a gene family widely expressed in archaes, prokaryotes and eukaryotes, and hydrolyzes the β-1,4-linkages in chitin. The pinewood nematode Bursaphelenchus xylophilus is one of the organisms that produces GH18 chitinases. Notably, B. xylophilus has a higher number of GH18 chitinases compared with the obligate plant-parasitic nematodes Meloidogyne incognita and Meloidogyne hapla. In this study, seven GH18 chitinases were identified and cloned from B. xylophilus based on genomic analyses. The deduced amino acid sequences of all these genes contained an N-terminal signal peptide and a GH18 catalytic domain. Phylogenetic analysis showed that the origin of B. xylophilus GH18 chitinases was independent of those from fungi and bacteria. Real-time quantitative reverse transcription PCR analysis indicated that GH18 chitinase genes had discrete expression patterns, representing almost all the life stages of B. xylophilus. In situ hybridisation showed that the mRNA of GH18 chitinase genes of B. xylophilus were detected mainly in the spermatheca, esophageal gland cells, seminal vesicle and eggs. RNA interference (RNAi) results revealed different roles of GH18 chitinase genes in B. xylophilus. Bx-chi-1, Bx-chi-2 and Bx-chi-7 were associated with reproduction, fungal cell-wall degradation and egg hatching, respectively. Bx-chi-5 and Bx-chi-6 may be involved in sperm metabolism. In conclusion, this study demonstrates that GH18 chitinases have multiple functions in the life cycle of B. xylophilus.
- Metabolic profiling and in vitro assessment of anthelmintic fractions of Picria fel-terrae Lour. [Journal Article]
- Int J Parasitol Drugs Drug Resist 2016 Aug 26; 6(3):171-178IJ
- Anthelmintic resistance is widespread in gastrointestinal nematode populations, such that there is a consistent need to search for new anthelmintics. However, the cost of screening for new compounds ...
Anthelmintic resistance is widespread in gastrointestinal nematode populations, such that there is a consistent need to search for new anthelmintics. However, the cost of screening for new compounds is high and has a very low success rate. Using the knowledge of traditional healers from Borneo Rainforests (Sarawak, Malaysia), we have previously shown that some traditional medicinal plants are a rich source of potential new anthelmintic drug candidates. In this study, Picria fel-terrae Lour. plant extract, which has previously shown promising anthelmintic activities, was fractionated via the use of a solid phase extraction cartridge and each isolated fraction was then tested on free-living nematode Caenorhabditis elegans and the parasitic nematode Haemonchus contortus. We found that a single fraction was enriched for nematocidal activity, killing ≥90% of C. elegans adults and inhibiting the motility of exsheathed L3 of H. contortus, while having minimal cytotoxic activity in mammalian cell culture. Metabolic profiling and chemometric analysis of the effective fraction indicated medium chained fatty acids and phenolic acids were highly represented.
- Assessing anti-T. cruzi candidates in vitro for sterile cidality. [Journal Article]
- Int J Parasitol Drugs Drug Resist 2016 Aug 26; 6(3):165-170IJ
- Total clearance of the T. cruzi infection - referred to herein as "sterile cure" - seems to be a critical prerequisite for new drug candidates for Chagas disease, ensuring long-term beneficial effect...
Total clearance of the T. cruzi infection - referred to herein as "sterile cure" - seems to be a critical prerequisite for new drug candidates for Chagas disease, ensuring long-term beneficial effects for patients in the chronic indeterminate stage. This requirement is notably supported by the recent findings of clinical studies involving posaconazole and fosravuconazole, where the majority of patients treated eventually relapsed after an apparent clearance of parasitaemia at the end of treatment. We have adapted an in vitro system to predict the ability of a compound to deliver sterile cure. It relies on mouse peritoneal macrophages as host cells for Trypanosoma cruzi amastigotes. The macrophages do not proliferate, allowing for long-term testing and wash-out experiments. Giemsa staining followed by microscopy provides a highly sensitive and specific tool to quantify the numbers of infected host cells. Combining macrophages as host cells and Giemsa staining as the read-out, we demonstrate that posaconazole and other CYP51 inhibitors are unable to achieve complete clearance of an established T. cruzi infection in vitro in spite of the fact that these compounds are active at significantly lower concentrations than the reference drugs benznidazole and nifurtimox. Indeed, a few macrophages remained infected after 96 h of drug incubation in the presence of CYP51 inhibitors-albeit at a very low parasite load. These residual T. cruzi amastigotes were shown to be viable and infective, as demonstrated by wash-out experiments. We advocate characterizing any new anti-T. cruzi early stage candidates for sterile cidality early in the discovery cascade, as a surrogate for delivery of sterile cure in vivo.
- Intestinal parasites of Tolypeutes matacus, the most frequently consumed armadillo in the Chaco region. [Journal Article]
- Int J Parasitol Parasites Wildl 2016; 5(3):254-7IJ
- The southern three-banded armadillo Tolypeutes matacus (Desmarest, 1804) is distributed from eastern Bolivia, south-west Brazil, the Gran Chaco of Paraguay and Argentina, and lives in areas with dry ...
The southern three-banded armadillo Tolypeutes matacus (Desmarest, 1804) is distributed from eastern Bolivia, south-west Brazil, the Gran Chaco of Paraguay and Argentina, and lives in areas with dry vegetation. This armadillo is one of the most frequently consumed species by people in this area. The objective of this work was test for zoonotic species among helminths in 12 intestinal tracts of T. matacus in a locality from the Argentinean Chaco (Chamical, La Rioja province). The parasites were studied with conventional parasite morphology and morphometrics, and prevalence, mean intensity and mean abundance were calculated for each species encountered. In the small intestine, seven species of nematodes and two species of cestodes were identified. In the large intestine, two species of nematodes were recorded. We did not find zoonotic species but have added new host records. This study in the Chaco region thus contributes to growing knowledge of the parasite fauna associated with armadillo species in this region.
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- Assessing myxozoan presence and diversity using environmental DNA. [Journal Article]
- Int J Parasitol 2016 Sep 10IJ
- Amplicon sequencing on a High Throughput Sequencing platform (custom barcoding) was used to detect and characterise myxosporean communities in environmental DNA samples from marine and freshwater env...
Amplicon sequencing on a High Throughput Sequencing platform (custom barcoding) was used to detect and characterise myxosporean communities in environmental DNA samples from marine and freshwater environments and in faeces of animals that may serve as hosts or whose prey may host myxosporean infections. A diversity of myxozoans in filtered water samples and in faeces of piscivores (otters and great cormorants) was detected, demonstrating the suitability of lineage-specific amplicons for characterising otherwise difficult to sample parasite communities. The importance of using this approach was highlighted by the lack of myxosporean detection using commonly employed, broadly targeted eukaryotic primers. These results suggest that, despite being frequently present in eDNA samples, myxozoans have been generally overlooked in "eukaryote-wide" surveys. Lineage-specific primers, in contrast, detected 107 operational taxonomic units that were assigned to both the "freshwater" and "marine" myxosporean lineages. Only 7% of these OTUs clustered with sequences in GenBank, providing evidence for substantial undescribed myxosporean diversity. Many new operational taxonomic units, including those found in otter faeces, clustered with a clade of myxosporeans previously characterised by sequences from invertebrate hosts and water samples only. Because myxozoan species identification is heavily reliant on molecular signatures, lineage-specific amplicon sequencing offers an effective and non-destructive means of improving our knowledge of myxozoan diversity. In addition, the analysis of myxozoan DNA in faeces of piscivores offers a potentially efficient method of sampling for diversity and revealing life cycles as piscivore activities may integrate myxozoan infections in fish over relatively broad spatial scales.