Molecular characterization of freshwater snails in the genus Bulinus: a role for barcodes?

<p>Abstract</p> <p>Background</p> <p>Reliable and consistent methods are required for the identification and classification of freshwater snails belonging to the genus <it>Bulinus </it>(Gastropoda, Planorbidae) which act as intermediate hosts for schistosomes of both medical and veterinary importance. The current project worked towards two main objectives, the development of a cost effective, simple screening method for the routine identification of <it>Bulinus </it>isolates and the use of resultant sequencing data to produce a model of relationships within the group.</p> <p>Results</p> <p>Phylogenetic analysis of the DNA sequence for a large section (1009 bp) of the mitochondrial gene cytochrome oxidase subunit 1 (<it>cox1</it>) for isolates of <it>Bulinus </it>demonstrated superior resolution over that employing the second internal transcribed spacer <it>(its2</it>) of the ribosomal gene complex. Removal of transitional substitutions within <it>cox1 </it>because of saturation effects still allowed identification of snails at species group level. Within groups, some species could be identified with ease but there were regions where the high degree of molecular diversity meant that clear identification of species was problematic, this was particularly so within the <it>B. africanus </it>group.</p> <p>Conclusion</p> <p>The sequence diversity within <it>cox1 </it>is such that a barcoding approach may offer the best method for characterization of populations and species within the genus from different geographical locations. The study has confirmed the definition of some accepted species within the species groups but additionally has revealed some unrecognized isolates which underlines the need to use molecular markers in addition to more traditional methods of identification. A barcoding approach based on part of the <it>cox1 </it>gene as defined by the Folmer primers is proposed.</p

Molecular characterization of host-parasite cell signalling in 'Schistosoma mansoni' during early development

During infection of their human definitive host, schistosomes transform rapidly from free-swimming infective cercariae in freshwater to endoparasitic schistosomules. The 'somules' next migrate within the skin to access the vasculature and are surrounded by host molecules that might activate intracellular pathways that influence somule survival, development and/or behaviour. However, such 'transactivation' by host factors in schistosomes is not well defined. In the present study, we have characterized and functionally localized the dynamics of protein kinase C (PKC) and extracellular signal-regulated kinase (ERK) activation during early somule development in vitro and demonstrate activation of these protein kinases by human epidermal growth factor, insulin, and insulin-like growth factor I, particularly at the parasite surface. Further, we provide evidence that support the existence of specialized signalling domains called lipid rafts in schistosomes and propose that correct signalling to ERK requires proper raft organization. Finally, we show that modulation of PKC and ERK activities in somules affects motility and reduces somule survival. Thus, PKC and ERK are important mediators of host-ligand regulated transactivation events in schistosomes, and represent potential targets for anti-schistosome therapy aimed at reducing parasite survival in the human host

Sensory protein kinase signalling in ' Schistosoma mansoni ' Cercariae : host location and invasion

Schistosoma mansoni cercariae display specific behavioural responses to abiotic/biotic stimuli enabling them to locate and infect the definitive human host. Here we report the effect of such stimulants on signalling pathways of cercariae in relation to host finding and invasion. Cercariae exposed to various light/temperature regimes displayed modulated protein kinase C (PKC), extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (p38 MAPK) activities, with distinct responses at 37°C and intense light/dark, when compared to 24°C under normal light. Kinase activities were localized to regions including the oral sensory papillae, acetabular ducts, tegument, acetabular glands, and nervous system. Furthermore, linoleic acid (LA) modulated PKC and ERK activities concurrent with the temporal release of acetabular gland components. Attenuation of PKC, ERK and p38 MAPK activities significantly reduced gland component release, particularly in response to LA, demonstrating the importance of these signalling pathways to host penetration mechanisms

Genomic evidence of contemporary hybridization between Schistosoma species

This work was supported by the Wellcome Trust (grant number 206194); the Biotechnology and Biological Sciences Research Council, the Department for International Development, the Economic & Social Research Council, the Medical Research Council, the Natural Environment Research Council and the Defence Science & Technology Laboratory, under the Zoonoses and Emerging Livestock Systems (ZELS) programme (grant number BB/L018985/1 to JPW and MS and grant number BB/S013822/1 to JPW, MS and NDD). FA, AE and MR received funding from the Wellcome Trust (grant number 104958/Z/14/Z).Hybridization between different species of parasites is increasingly being recognised as a major public and veterinary health concern at the interface of infectious diseases biology, evolution, epidemiology and ultimately control. Recent research has revealed that viable hybrids and introgressed lineages between Schistosoma spp. are prevalent across Africa and beyond, including those with zoonotic potential. However, it remains unclear whether these hybrid lineages represent recent hybridization events, suggesting hybridization is ongoing, and/or whether they represent introgressed lineages derived from ancient hybridization events. In human schistosomiasis, investigation is hampered by the inaccessibility of adult-stage worms due to their intravascular location, an issue which can be circumvented by post-mortem of livestock at abattoirs for Schistosoma spp. of known zoonotic potential. To characterise the composition of naturally-occurring schistosome hybrids, we performed whole-genome sequencing of 21 natural livestock infective schistosome isolates. To facilitate this, we also assembled a de novo chromosomal-scale draft assembly of Schistosoma curassoni. Genomic analyses identified isolates of S. bovis, S. curassoni and hybrids between the two species, all of which were early generation hybrids with multiple generations found within the same host. These results show that hybridization is an ongoing process within natural populations with the potential to further challenge elimination efforts against schistosomiasis.Publisher PDFPeer reviewe

Chlorination of Schistosoma mansoni cercariae.

BACKGROUND: Schistosomiasis is a water-based disease acquired through contact with cercaria-infested water. Communities living in endemic regions often rely on parasite-contaminated freshwater bodies for their daily water contact activities, resulting in recurring schistosomiasis infection. In such instances, water treatment can provide safe water on a household or community scale. However, to-date there are no water treatment guidelines that provide information on how to treat water containing schistosome cercariae. Here, we rigorously test the effectiveness of chlorine against Schistosoma mansoni cercariae. METHOD: S. mansoni cercariae were chlorinated using sodium hypochlorite under lab and field condition. The water pH was controlled at 6.5, 7.0 or 7.5, the water temperature at 20°C or 27°C, and the chlorine dose at 1, 2 or 3 mg/l. Experiments were conducted up to contact times of 45 minutes. 100 cercariae were used per experiment, thereby achieving up to 2-log10 inactivations of cercariae. Experiments were replicated under field conditions at Lake Victoria, Tanzania. CONCLUSION: A CT (residual chlorine concentration x chlorine contact time) value of 26±4 mg·min/l is required to achieve a 2-log10 inactivation of S. mansoni cercariae under the most conservative condition tested (pH 7.5, 20°C). Field and lab-cultivated cercariae show similar chlorine sensitivities. A CT value of 30 mg·min/l is therefore recommended to disinfect cercaria-infested water, though safety factors may be required, depending on water quality and operating conditions. This CT value can be achieved with a chlorine residual of 1 mg/l after a contact time of 30 minutes, for example. This recommendation can be used to provide safe water for household and recreational water activities in communities that lack safe alternative water sources

Parameters for effective sand filtration of <i>Schistosoma mansoni</i> cercariae from water

Abstract Schistosomiasis is a water-based neglected tropical disease that is prevalent in over 78 countries. It affects communities that are reliant on freshwater bodies contaminated with Schistosome cercariae for their daily water activities. Whilst treatment with the drug praziquantel is relatively effective, it does not prevent reinfection. One option for reducing schistosomiasis infection is providing at-risk communities with treated water, thereby reducing contact with cercaria-infested water for activities such as bathing or doing laundry. This study aims to establish design guidance for sand filtration to remove schistosome cercariae from water. Four sand filters were tested, varying from 300 to 2000 μm in sand grain size. Each filter was tested with a sand depth of 20 cm, which was increased until no cercariae were detected in the effluent. The required filter depth to remove 100% of cercariae ranged between 40 and 70 cm depending on sand grain size. Cercaria removal was more effective in filters with smaller sand grain size and larger filter depth. These results are valid for intermittent flow, for up to six cycle flushes. While more rigorous testing is needed, these initial results suggest that sand filters can be an effective way to treat cercaria-contaminated water in low-income settings.</jats:p

The potential for production of high quality bio-coal from early harvested Miscanthus by hydrothermal carbonisation

To meet combustion quality requirements, Miscanthus is conventionally harvested in late winter/early spring after senescence due to a lowering of fuel nitrogen, chlorine and ash content. This can overcome combustion issues such as slagging, fouling and corrosion however there is a significant reduction in dry matter yields compared to early harvesting in the autumn. In this study, Miscanthus × giganteus harvested conventionally (after senescence) and early (green) have been pre-treated by hydrothermal carbonisation (HTC) at 200 °C and 250 °C. HTC at 200 °C improves the grindability of the biomass but results in limited energy densification. HTC at 250 °C results in increased energy densification producing a bio-coal with a HHV ranging from 27 to 28 MJ/kg for early and 25 to 26 MJ/kg for conventional harvesting; the Hardgrove Grindability Index (HGI) increases from 0 to 150. At higher HTC temperatures, the combustion profile of the bio-coal exhibits a ‘coal like’ single stage combustion profile. HTC results in a significant reduction in alkali metal content, increases safe combustion temperatures and reduces the theoretical propensity of the derived fuel to slag, foul and corrode. The results indicate that HTC can valorise both conventional and early harvested Miscanthus without producing any adverse effect on the yields and quality of the bio-coal. The challenges associated with early harvesting of Miscanthus appear to be largely overcome by HTC resulting in increased yields of up to 40% per hectare due to reduction in dry matter loss

How many metazoan species live in the world’s largest mineral exploration region?

The global surge in demand for metals such as cobalt and nickel has created unprecedented interest in deep-sea habitats with mineral resources. The largest area of activity is a 6 million km2 region known as the Clarion-Clipperton Zone (CCZ) in the central and eastern Pacific, regulated by the International Seabed Authority (ISA). Baseline biodiversity knowledge of the region is crucial to effective management of environmental impact from potential deep-sea mining activities, but until recently this has been almost completely lacking. The rapid growth in taxonomic outputs and data availability for the region over the last decade has allowed us to conduct the first comprehensive synthesis of CCZ benthic metazoan biodiversity for all faunal size classes. Here we present the CCZ Checklist, a biodiversity inventory of benthic metazoa vital to future assessments of environmental impacts. An estimated 92% of species identified from the CCZ are new to science (436 named species from a total of 5,578 recorded). This is likely to be an overestimate owing to synonyms in the data but is supported by analysis of recent taxonomic studies suggesting that 88% of species sampled in the region are undescribed. Species richness estimators place total CCZ metazoan benthic diversity at 6,233 (+/−82 SE) species for Chao1, and 7,620 (+/−132 SE) species for Chao2, most likely representing lower bounds of diversity in the region. Although uncertainty in estimates is high, regional syntheses become increasingly possible as comparable datasets accumulate. These will be vital to understanding ecological processes and risks of biodiversity loss

Chromosome-level genome of Schistosoma haematobium underpins genome-wide explorations of molecular variation.

Urogenital schistosomiasis is caused by the blood fluke Schistosoma haematobium and is one of the most neglected tropical diseases worldwide, afflicting \u3e 100 million people. It is characterised by granulomata, fibrosis and calcification in urogenital tissues, and can lead to increased susceptibility to HIV/AIDS and squamous cell carcinoma of the bladder. To complement available treatment programs and break the transmission of disease, sound knowledge and understanding of the biology and ecology of S. haematobium is required. Hybridisation/introgression events and molecular variation among members of the S. haematobium-group might effect important biological and/or disease traits as well as the morbidity of disease and the effectiveness of control programs including mass drug administration. Here we report the first chromosome-contiguous genome for a well-defined laboratory line of this blood fluke. An exploration of this genome using transcriptomic data for all key developmental stages allowed us to refine gene models (including non-coding elements) and annotations, discover \u27new\u27 genes and transcription profiles for these stages, likely linked to development and/or pathogenesis. Molecular variation within S. haematobium among some geographical locations in Africa revealed unique genomic \u27signatures\u27 that matched species other than S. haematobium, indicating the occurrence of introgression events. The present reference genome (designated Shae.V3) and the findings from this study solidly underpin future functional genomic and molecular investigations of S. haematobium and accelerate systematic, large-scale population genomics investigations, with a focus on improved and sustained control of urogenital schistosomiasis

Cross-reactivity of glycan-reactive HIV-1 broadly neutralizing antibodies with parasite glycans

The HIV-1 Envelope glycoprotein (Env) is the sole target for broadly neutralizing antibodies (bnAbs). Env is heavily glycosylated with host-derived N-glycans, and many bnAbs bind to, or are dependent upon, Env glycans for neutralization. Although glycan-binding bnAbs are frequently detected in HIV-infected individuals, attempts to elicit them have been unsuccessful because of the poor immunogenicity of Env N-glycans. Here, we report cross-reactivity of glycan-binding bnAbs with self- and non-self N-glycans and glycoprotein antigens from different life-stages of Schistosoma mansoni. Using the IAVI Protocol C HIV infection cohort, we examine the relationship between S. mansoni seropositivity and development of bnAbs targeting glycan-dependent epitopes. We show that the unmutated common ancestor of the N332/V3-specific bnAb lineage PCDN76, isolated from an HIV-infected donor with S. mansoni seropositivity, binds to S. mansoni cercariae while lacking reactivity to gp120. Overall, these results present a strategy for elicitation of glycan-reactive bnAbs which could be exploited in HIV-1 vaccine development.This project has received funding from the European Union’s Horizon 2020 Research and Innovation program under grant agreement 681137 (to K.J.D. and I.H.), the Medical Research Council (MRC) (to K.J.D. [MR/K024426/1]), The Rosetrees Trust (to K.J.D. [M686]) and Fondation Dormeur, Vaduz (to K.J.D). This research was funded or supported by the National Institute for Health Research Biomedical Research Centre based at Guy’s and St Thomas’ NHS Foundation Trust and King’s College London and/or the NIHR Clinical Research Facility. The views expressed are those of the authors and not necessarily those of the National Health Service (NHS), the National Institute for Health Research (NIHR), or the Department of Health. N.R. acknowledges funding from Ministry of Science and Education grants CTQ2017-90039-R, RTC-2017-6126-1, and CTQ2011-27874 (fellowship to K.B.) and the Maria de Maeztu Units of Excellence Program from the Spanish State Research Agency (grant MDM-2017-0720). F.A. was funded by the Wellcome Trust (104958/Z/14/Z). J.A. was supported by the Spanish Ministry of Science, Innovation and Universities through the grant PID2019-109395GB-I00. J.A. and S.M. acknowledge support of BBSRC (grant BB/P010660/1). T.H. and S.W. were funded by Biotechnology and Biological Sciences Research Council (BBSRC) Norwich Research Park Doctoral Training Grant BB/M011216/1. IAVI’s work is made possible by generous support from many donors, including the Bill & Melinda Gates Foundation, the Ministry of Foreign Affairs of Denmark, Irish Aid, the Ministry of Finance of Japan in partnership with The World Bank, the Ministry of Foreign Affairs of the Netherlands, the Norwegian Agency for Development Cooperation, the United Kingdom Department for International Development (DFID), and the United States Agency for International Development. The full list of IAVI donors is available at www.iavi.org. Brendan McAtarsney and Jonathan Hare from the IAVI Human Immunology Lab (HIL) for coordinating the samples transfers and shipments. Monica Agromayor and the KCL Nikon Centre for assistance and advice on confocal microscopy. NMRI strain Schistosoma mansoni-infected Biomphalaria glabrata snails were provided by the NIAID Schistosomiasis Resource Center, Rockville, USA.Peer reviewe