Host immune status affects maturation time in two nematode species – but not as predicted by a simple life-history model

Parasitology ◽  
2003 ◽  
Vol 127 (5) ◽  
pp. 507-512 ◽  
Author(s):  
M. A. GUINNEE ◽  
A. W. GEMMILL ◽  
B. H. K. CHAN ◽  
M. E. VINEY ◽  
A. F. READ
Keyword(s):  
Immune Responses ◽  
Nematode Species ◽  
Parasitic Nematodes ◽  
Nippostrongylus Brasiliensis ◽  
Short Term ◽  
Maturation Time ◽  
Nematode Parasites ◽  
Nude Rats ◽  
Immune Mediated ◽  
Fitness Benefits

In theory, the age at which maturation occurs in parasitic nematodes is inversely related to pre-maturational mortality rate, and cross-species data on mammalian nematodes are consistent with this prediction. Immunity is a major source of parasite mortality and parasites stand to gain sizeable fitness benefits through short-term adjustments of maturation time in response to variation in immune-mediated mortality. The effects of thymus-dependent immune responses on maturation in the nematode parasites Strongyloides ratti and Nippostrongylus brasiliensis were investigated using congenitally thymus-deficient (nude) rats. As compared with worms in normal rats, reproductive maturity of parasites (presence of eggs in utero) in nude rats occurred later in S. ratti but earlier in N. brasiliensis. Immune-mediated differences in maturation time were not associated with differences in worm length. Thymus-dependent immunity had no effect on pre-maturational mortality. Results are discussed in relation to theoretical expectations and possible explanations for the observed patterns in parasite maturation.

Nutritional control of gastrointestinal parasitism in lactating rats

2005 ◽  
Vol 2005 ◽  
pp. 11-11 ◽  
Author(s):  
J.G.M. Houdijk ◽  
N.S. Jessop ◽  
D.P. Knox ◽  
I. Kyriazakis
Keyword(s):  
Immune Responses ◽  
Indirect Evidence ◽  
Host Protein ◽  
Nippostrongylus Brasiliensis ◽  
Host Immune Responses ◽  
Protein Nutrition ◽  
Intestinal Nematode ◽  
Nematode Parasites ◽  
Periparturient Period ◽  
Protein Supply

Small ruminant studies have shown that a reduction in protein scarcity, through either an increase in protein supply or reduction in protein demand, results in reduced nematode egg excretion and worm burdens during the periparturient period (Houdijk and Athanasiadou, 2003). Whilst this reduced degree of parasitism indirectly suggests that such nutritional effects are mediated through changes in host immune responses, there is only limited direct evidence for this. A rodent model may be used for directly assessing immune responses that underlie nutritional control of nematode parasites. There is indirect evidence that lactating rats undergo a breakdown of immunity to the intestinal nematode Nippostrongylus brasiliensis (Houdijk et al., 2003). Provided that this breakdown is sensitive to protein nutrition, this model may be used for elucidating interactions between nutrition and immunity to parasites. Therefore, we assessed whether breakdown of immunity to N. brasiliensis in the lactating rat is sensitive to host protein nutrition.

scholarly journals Molecular Diversity of Nematode Parasites in Afrotropical Reed Frogs (Hyperolius spp.)

Diversity ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 265
Author(s):  
Ulrich Sinsch ◽  
J. Maximilian Dehling ◽  
Patrick Scheid ◽  
Carsten Balczun
Keyword(s):  
Dna Sequences ◽  
Nematode Species ◽  
Sub Saharan Africa ◽  
Parasitic Nematodes ◽  
Marker Genes ◽  
Nematode Parasites ◽  
Diversity Assessment ◽  
Wide Range ◽  
Nematode Diversity ◽  
Sub Saharan

The diversity of nematodes infecting amphibians is understudied in tropical Africa and unknown in Rwanda. Diversity assessment is hampered by the fact that species descriptions refer mostly to morphological features that are unlinked to DNA sequences of marker genes available in public databases. In this paper, we explore the abundance and diversity of parasitic nematodes in reed frogs Hyperolius kivuensis (n = 115), H. parallelus (n = 45) and H. viridiflavus (n = 100) collected in Rwanda. Five nematode species were identified morphologically as Orneoascaris chrysanthemoides, O. schoutedeni, Gendria leberrei, Aplectana chamaeleonis and Rhabdias collaris. Corresponding DNA sequences of 18S and COI genes were determined and subsequently deposited in GenBank. Aplectana chamaeleonis showed the highest prevalence (8.7%), but O. chrysanthemoides the highest mean intensity of infection (6.0) and largest number (24) of individuals in H. kivuensis. To the best of our knowledge, all amphibian hosts are new records for these nematode species, which are known to infect a wide range of amphibian and reptile species. Our findings suggest that nematode diversity is probably lower than previously assumed due to low host specificity. As morphological species identification is often challenging, our data facilitate molecular identification of adult and specifically larval nematodes found in amphibians of Sub-Saharan Africa.

NEMATODE PARASITES OF WATERLEAF (Talinum triangulare) IN OBIO-AKPOR AND IKWERRE LOCAL GOVERNMENT AREAS OF RIVERS STATE, NIGERIA

2021 ◽  
Vol 5 (1) ◽  
pp. 140-150
Author(s):  
Adebowale Adegboyega Tanimola ◽  
A. O. Asimiea ◽  
G. Uwaoma
Keyword(s):  
Local Government ◽  
Sampling Technique ◽  
Nematode Species ◽  
Diversity Indices ◽  
Parasitic Nematodes ◽  
Plant Parasitic Nematodes ◽  
Nematode Parasites ◽  
Rivers State ◽  
Talinum Triangulare ◽  
Plant Parasitic

Waterleaf, Talinum triangulare is cultivated in home gardens and fields to improve nutritional quality for the family and a source of livelihood for farmers. However, the role of T. triangulare is often counteracted by plant-parasitic nematodes (PPNs). Effective management of PPNs will depend on the identification and determination of their population and distribution. A survey was conducted in two Local Government Areas (LGAs), Ikwerre and Obio-Akpor of Rivers State to identify plant-parasitic nematodes associated with waterleaf. Multistage random sampling technique was employed in the collection of 60 bulked soil and root samples across six waterleaf monoculture farming communities. The nematodes were extracted, identified and their population determined using standard procedures. Occurrences, relative importance values (RIV) and diversity indices were determined. Other data were analysed using descriptive statistics and analysis of variance. Six plant-parasitic nematodes genera were encountered in this study, Helicotylenchus, Pratylenchus, Paratylenchus, Meloidogyne, Scutellonema and Tylenchulus. Pratylenchus and Helicotylenchus were the most frequently occurring nematode pest genera with equal relative frequency of occurrence of 38.89%. Pratylenchus species with RIV of 61.34% was the most important nematode pest associated with waterleaf across the six farm communities. The dominance index of 0.71 for the nematode genera showed that some nematode species dominated others. Alakahia farms had the highest population of plant-parasitic nematodes (2,780) across the six farm communities, whereas Omagwa farms had the lowest (250). The study showed that nematode pests are associated with waterleaf and could be contributing to yield losses in this crop

Molecular diagnosis of parasitic nematodes

Parasitology ◽  
1999 ◽  
Vol 117 (7) ◽  
pp. 87-96 ◽  
Author(s):  
J. B. McKEAND
Keyword(s):  
Developmental Stages ◽  
Nematode Species ◽  
Parasitic Nematodes ◽  
Morphological Identification ◽  
Past Infection ◽  
Essential Requirement ◽  
Prevalence Studies ◽  
Nematode Parasites ◽  
Highly Sensitive ◽  
Immunological Assays

There is an essential requirement for highly sensitive tools that will differentiate nematode parasites of animals and plants to the species level. For studying host range, genetic variation, virulence and resistance, the availability of well defined populations is vital. Many nematode species cannot be identified with certainty using traditional morphological or morphometric techniques. This is particularly the case for the more accessible developmental stages that, depending on the particular group concerned, live as eggs and larvae in the environment or as micro-filariae that circulate in the blood or inhabit the skin. Morphological identification of these stages requires specialized expertise and is extremely time consuming. Immunological assays have their place in nematode identification but they do not discriminate between current and previous infections, an essential requirement in many epidemiological and prevalence studies. In addition to being highly sensitive, DNA-based methods of detection define present over past infection and are not dependent on the parasite stage. Many types of methodology are available for the detection and definition of nematode DNA. This paper reviews these methods citing examples that have been used with success in the laboratory as well as the field.

scholarly journals In silico analyses of neuropeptide-like protein (NLP) profiles in parasitic nematodes

2021 ◽  
Author(s):  
Fiona M McKay ◽  
Ciaran J McCoy ◽  
Nikki J Marks ◽  
Aaron G Maule ◽  
Louise E Atkinson ◽  
...  
Keyword(s):  
Drug Targets ◽  
Anthelmintic Resistance ◽  
Physiological Activity ◽  
Nematode Species ◽  
Nematode Parasite ◽  
Parasitic Nematodes ◽  
Global Food Security ◽  
Nematode Parasites ◽  
Parasite Infections ◽  
Novel Drug

Nematode parasite infections cause disease in humans and animals and threaten global food security by reducing productivity in livestock and crop farming. The escalation of anthelmintic resistance in economically important nematode parasites underscores the need for the identification of novel drug targets in these worms. Nematode neuropeptide signalling is an attractive system for potential chemotherapeutic exploitation, with neuropeptide G-protein coupled receptors (NP-GPCRs) representing the leading target candidates therein. In order to successfully validate NP-GPCRs as targets for parasite control it is necessary to characterise their function and importance to nematode biology. This can be aided through identifying receptor activating ligand(s) in a process known as receptor deorphanisation. Such efforts first require the identification of all neuropeptide ligands within parasites. Here we comb the genomes of nine therapeutically relevant pathogenic nematode species to comprehensively characterise the nematode parasite neuropeptide-like protein (NLP) complements, and details the discovery of several previously unreported, yet conserved, neuropeptides and neuropeptide-encoding genes. We identify the neuropeptides that are most highly conserved in all parasites examined, and characterise their physiological activity on the reproductive musculature of the parasite, Ascaris suum. These data suggest conserved neuropeptide functions in both free living and parasitic nematodes, and support the potential for exploitation of the neuropeptide signalling system as an anthelmintic target.

Rapid changes in the surface of parasitic nematodes during transition from pre- to post-parasitic forms

Parasitology ◽  
1993 ◽  
Vol 107 (1) ◽  
pp. 107-117 ◽  
Author(s):  
L. Proudfoot ◽  
J. R. Kusel ◽  
H. V. Smith ◽  
W. Harnett ◽  
M. J. Worms ◽  
...  
Keyword(s):  
Trichinella Spiralis ◽  
Lateral Diffusion ◽  
Nematode Species ◽  
Oral Route ◽  
Culture Conditions ◽  
Parasitic Nematodes ◽  
Surface Coat ◽  
Nippostrongylus Brasiliensis ◽  
Dauer Larva

SummaryAll mammalian-parasitic stages of a range of nematode species investigated (Brugia pahangi, Acanthocheilonema viteae, Strongyloides ratti, Nippostrongylus brasiliensis, Trichinella spiralisandOstertagia ostertagi) labelled in a surface-restricted manner with the fluorescent lipid analogues 5-N-(octadecanoyl)aminofluorescein (AF18) or nitrobenzoxadiazole-cholesterol (NBD-chol), but failed to bind other similar probes. In contrast, the surfaces of the ‘pre-parasitic’ infective stages of these species had affinity for neither AF18 nor NBD-chol. This exclusion of lipid analogues changed rapidly upon exposure of the larvae to tissue culture conditions which mimic the mammalian tissue environment (e.g. RPMI 1640/37°C) such that the above probes could then insert into the surface layer of the larvae. The dauer larva ofCaenorhabditis elegansalso excluded the probes, but became permissive to labelling upon stimulation to emerge from the dauer state. The time taken for the surface transformation to occur ranged from less than 10 min in the vector-borne parasites to approximately 5 h in those which enter by the oral route, with direct skin-penetrators occupying an intermediate position. In all cases, the alteration proceeded too rapidly for it to have been associated with a moult. Fluorescence Recovery After Photobleaching (FRAP) studies ofA. viteaelarvae showed that approximately 50% of the AF18 probe was free to diffuse within the plane of the surface immediately after transformation. This is only a transitory state because AF18 was found to be highly restricted in its lateral diffusion on the surface of adult parasites. In the larvae ofS. ratti, the change in affinity for AF18 was accompanied by the rapid shedding of an otherwise stable surface coat of polyanionic material, here visualized by labelling with fluorescein-conjugated cationized ferritin. Incubation of larvae in lipid-rich host serum during the induction of transformation inhibited subsequent labelling with AF 18. This possibly reflects competition for insertion sites and anin vivopropensity towards the acquisition of host lipid by invading parasites.

scholarly journals Sheep nemabiome diversity and its response to anthelmintic treatment in Swedish sheep herds

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Peter Halvarsson ◽  
Johan Höglund
Keyword(s):  
Species Richness ◽  
Diversity Index ◽  
Nematode Species ◽  
Abundant Species ◽  
Anthelmintic Treatment ◽  
Host Age ◽  
Larval Culture ◽  
Nematode Parasites ◽  
South Central ◽  
Nematode Diversity

Abstract Background A novel way to study the species composition and diversity of nematode parasites in livestock is to perform deep sequencing on composite samples containing a mixture of different species. Herein we describe for the first time the nematode community structures (nemabiomes) inhabiting Swedish sheep and how these are/were affected by host age and recent anthelmintic treatments. Methods A total of 158 fecal samples were collected (n = 35 in 2007 and n = 123 in 2013–2016) and cultured from groups of sheep on 61 commercial farms in the south-central part of the country where most animals are grazed. Among the samples, 2 × 44 (56%) were paired collections from the same groups pre- and post-treatment with anthelmintics such as macrocyclic lactones, benzimidazoles or levamisole. Samples were analyzed for their nemabiome using the PacBio platform followed by bioinformatic sequence analysis with SCATA. Species richness and diversity were calculated and analyzed in R. Results Nematode ITS2 sequences were found in all larval culture samples except two, even though the fecal egg counts were below the McMaster threshold in 20 samples. Sequencing yielded, on average, 1008 sequences per sample. In total, 16 operational taxonomical units (OTU), all with ≥ 98 % identity to sequences in the NCBI database, were recognized. The OTUs found represented nematode species of which ten are commonly associated with sheep. Multiple species were identified in all pre-anthelmintic treatment larval culture samples. No effects on nematode diversity were found in relation to host age. On the other hand, recent anthelmintic treatment lowered species richness, especially after use of ivermectin and albendazole. Interestingly, despite zero egg counts after use of levamisole, these samples still contained nematode DNA and especially H. contortus. Conclusions Our findings provide evidence that nemabiome analysis combined with diversity index analysis provides an objective methodology in the study of the efficacy of anthelmintic treatment as both high and low abundant species were detected.

scholarly journals Susceptible trichostrongyloid species mask presence of benzimidazole-resistant Haemonchus contortus in cattle

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Khalid M. Mohammedsalih ◽  
Jürgen Krücken ◽  
Ahmed Bashar ◽  
Fathel-Rahman Juma ◽  
Abdalhakaim A. H. Abdalmalaik ◽  
...  
Keyword(s):  
Haemonchus Contortus ◽  
Epidemiological Data ◽  
Nematode Species ◽  
Parasitic Nematodes ◽  
Molecular Approaches ◽  
Tubulin Genes ◽  
Faecal Egg Count ◽  
Third Stage ◽  
Before And After ◽  
Β Tubulin

Abstract Background Benzimidazole (BZ) anthelmintics are widely used to control infections with parasitic nematodes, but BZ resistance is an emerging threat among several nematode species infecting humans and animals. In Sudan, BZ-resistant Haemonchus contortus populations were recently reported in goats in South Darfur State. The objective of this study was to collect data regarding the situation of BZ resistance in cattle parasitic nematodes in South Darfur using phenotypic and molecular approaches, besides providing some epidemiological data on nematodes in cattle. Methods The faecal egg count reduction test and the egg hatch test (EHT) were used to evaluate benzimidazole efficacy in cattle nematodes in five South Darfur study areas: Beleil, Kass, Nyala, Rehed Al-Birdi and Tulus. Genomic DNA was extracted from pools of third-stage larvae (L3) (n = 40) during trials, before and after treatment, and pools of adult male Haemonchus spp. (n = 18) from abattoirs. The polymorphisms F167Y, E198A and F200Y in isotype 1 β-tubulin genes of H. contortus and H. placei were analysed using Sanger and pyrosequencing. Results Prevalence of gastro-intestinal helminths in cattle was 71% (313/443). Reduced albendazole faecal egg count reduction efficacy was detected in three study areas: Nyala (93.7%), Rehed Al-Birdi (89.7%) and Tulus (88.2%). In the EHT, EC50 values of these study areas ranged between 0.032 and 0.037 µg/ml thiabendazole. Genus-specific PCRs detected the genera Haemonchus, Trichostrongylus and Cooperia in L3 samples collected after albendazole treatment. Sanger sequencing followed by pyrosequencing assays did not detect elevated frequencies of known BZ resistance-associated alleles in codon F167Y, E198A and F200Y in isotype 1 β-tubulin gene of H. placei (≤ 11.38%). However, polymorphisms were detected in H. contortus and in samples with mixed infections with H. contortus and H. placei at codon 198, including E198L (16/58), E198V (2/58) and potentially E198Stop (1/58). All pooled L3 samples post-albendazole treatment (n = 13) were identified as H. contortus with an E198L substitution at codon 198. Conclusions To the knowledge of the authors, this is the first report of reduced albendazole efficacy in cattle in Sudan and is the first study describing an E198L substitution in phenotypically BZ-resistant nematodes collected from cattle.

scholarly journals Description of Mesocriconema ericaceum n. sp. (Nematoda: Criconematidae) and notes on other nematode species discovered in an ericaceous heath bald community in Great Smoky Mountains National Park, USA

Nematology ◽  
2016 ◽  
Vol 18 (8) ◽  
pp. 879-903 ◽  
Author(s):  
Thomas O. Powers ◽  
Peter Mullin ◽  
Rebecca Higgins ◽  
Timothy Harris ◽  
Kirsten S. Powers
Keyword(s):  
New Species ◽  
National Park ◽  
Gulf Coast ◽  
Nematode Species ◽  
Coi Gene ◽  
Parasitic Nematodes ◽  
Soil Nematode ◽  
Coastal Forests ◽  
Great Smoky Mountains ◽  
Smoky Mountains

A new species of Mesocriconema and a unique assemblage of plant-parasitic nematodes was discovered in a heath bald atop Brushy Mountain in Great Smoky Mountains National Park. Mesocriconema ericaceum n. sp., a species with males, superficially resembles M. xenoplax. DNA barcoding with the mitochondrial COI gene provided evidence of the new species as a distinct lineage. SEM revealed significant variability in arrangement of labial submedian lobes, plates, and anterior and posterior annuli. Three other nematodes in the family Criconematidae were characterised from the heath bald. Ogma seymouri, when analysed by statistical parsimony, established connections with isolates from north-eastern Atlantic coastal and north-western Pacific coastal wet forests. Criconema loofi has a southern Gulf Coast distribution associated with boggy soils. Criconema cf. acriculum is known from northern coastal forests of California. Understanding linkages between these species and their distribution may lead to the broader development of a terrestrial soil nematode biogeography.

scholarly journals Prospects of Using High-Throughput Proteomics to Underpin the Discovery of Animal Host–Nematode Interactions

Pathogens ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 825
Author(s):  
Tao Wang ◽  
Robin Gasser
Keyword(s):  
Mass Spectrometry ◽  
High Throughput ◽  
Anthelmintic Resistance ◽  
Nematode Species ◽  
Economic Losses ◽  
Future Research ◽  
Parasitic Nematodes ◽  
Public Health Burden ◽  
Host Parasite Interactions ◽  
Host Parasite

Parasitic nematodes impose a significant public health burden, and cause major economic losses to agriculture worldwide. Due to the widespread of anthelmintic resistance and lack of effective vaccines for most nematode species, there is an urgent need to discover novel therapeutic and vaccine targets, informed through an understanding of host–parasite interactions. Proteomics, underpinned by genomics, enables the global characterisation proteins expressed in a particular cell type, tissue and organism, and provides a key to insights at the host–parasite interface using advanced high-throughput mass spectrometry-based proteomic technologies. Here, we (i) review current mass-spectrometry-based proteomic methods, with an emphasis on a high-throughput ‘bottom-up’ approach; (ii) summarise recent progress in the proteomics of parasitic nematodes of animals, with a focus on molecules inferred to be involved in host–parasite interactions; and (iii) discuss future research directions that could enhance our knowledge and understanding of the molecular interplay between nematodes and host animals, in order to work toward new, improved methods for the treatment, diagnosis and control of nematodiases.

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