Explore the vast range of titles available.

Schistosoma japonicum is a parasitic flatworm that causes human schistosomiasis, which is a significant cause of morbidity in China and the Philippines. Here we present a draft genomic sequence for the worm. The genome provides a global insight into the molecular architecture and host interaction of this complex metazoan pathogen, revealing that it can exploit host nutrients, neuroendocrine hormones and signalling pathways for growth, development and maturation. Having a complex nervous system and a well-developed sensory system, S .  japonicum can accept stimulation of the corresponding ligands as a physiological response to different environments, such as fresh water or the tissues of its intermediate and mammalian hosts. Numerous proteases, including cercarial elastase, are implicated in mammalian skin penetration and haemoglobin degradation. The genomic information will serve as a valuable platform to facilitate development of new interventions for schistosomiasis control. Schistosome genomics Two international consortia this week report the whole genome sequences of the blood flukes Schistosoma mansoni and Schistosoma japonicum , two of the three major pathogens that cause schistosomiasis, also called bilharzia. Schistosomiasis is a 'neglected' tropical disease affecting more than 200 million people in 76 countries. Analyses of the new genome sequences provide insights into the molecular architecture and host interactions of these pathogens, as well as avenues for future development of targeted interventions for this disease. These are the first two flatworm genomes to be sequenced, so they offer new angles on the early events in animal evolution, in particular the determination of body pattern and the development of tissues into organs. Schistosoma mansoni and Schistosoma japonicum are the pathogenic agents that cause the tropical disease schistosomiasis. Here, and in an accompanying paper, the genomes of these two flatworms are sequenced and analysed. The results provide insights into the molecular architecture and host interactions of the flatworms, as well as avenues for future development of targeted interventions for schistosomiasis.

Schistosomiasis is an important neglected tropical disease necessitating focus. Cercarial proteases are essential for schistosome invasion. Leishmanolysin has been identified as the most predominant protease in Schistosoma japonicum (S. japonicum) cercariae, but the role and mechanism of leishmanolysin in host skin invasion by S. japonicum cercariae remain unclear. Our bioinformatic analysis revealed the classification of S. japonicum leishmanolysin within the M8 matrix metalloprotease family. We then expressed recombinant S. japonicum leishmanolysin-like peptidase isoform 1 (SjLLPi1) and verified its hydrolytic enzyme activity. Western blotting analysis confirmed high level of SjLLPi1 protein in S. japonicum cercariae. Immunofluorescence staining revealed SjLLPi1 is predominantly present in the acetabular glands and their ducts in the cercarial head. Infection of mice with anti-SjLLPi1 monoclonal antibody treated S. japonicum cercariae significantly reduced worm and egg burden in mice 42 days post-infection. Infection of mice with anti-SjLLPi1 monoclonal antibody treated S. japonicum cercariae also significantly reduced parasite number in mice 7 days post-infection. In addition, treatment of mouse macrophages with SjLLPi1 prompted notable macrophage activation and substantial parasiticidal NO release. Finally, mice infected with anti-SjLLPi1 monoclonal antibody treated cercariae demonstrated a marked reduction in skin-invading parasite numbers as early as 30 min post-infection. Our study indicates that SjLLPi1 aids S. japonicum cercariae penetration into the definitive host by hydrolyzing skin components, thereby facilitating parasite migration and transition to adult worms within the host. These results may provide valuable guidance for vaccine development and control strategy formulation against schistosome infection.

Schistosoma japonicum is a multi-host parasite, including asexual amplification in snail hosts and sexual reproduction in mammalian hosts. The genetic diversity of S. japonicum by host switching is less understood, which could help elucidate the genetic evolution of S. japonicum under host pressure and provide instruction for host sampling and the infection pattern to make S. japonicum infection models. Different developmental stages of S. japonicum were collected and genotyped with 24 microsatellite loci, including 345 cercariae from naturally infected snails and 472 and 540 adult worms from artificially infected mice and rabbits, separately. The genetic distribution of S. japonicum within and among hosts by different sampling was assessed, and the genetic diversity and population structure were calculated at different population levels during host switching. Seven cercariae were the minimum sample size to retrieve 85% of alleles for S. japonicum in each snail, and meanwhile, sampling parasites from 19 snails could recover 85% of the total Na of S. japonicum in all snails in this study. After infection in mice and rabbits, 8 worms per mouse and 76 worms per rabbit were the minimum samplings to retrieve 90% of alleles from each corresponding definitive host. Further, 16 mice and 2 rabbits were the least sampling size to recover 85% of the total Na of S. japonicum in all mice and rabbits, respectively. Although no significant difference was shown for S. japonicum between mice and rabbits at the suprapopulation level, it is clear that the genetic diversity of worms from 20 (or 40) mice was significantly higher than that from 1 (or 2) rabbits, especially when the host sampling was not sufficiently enough. The differentiation of worms at the infrapopulation level among mice is less than among rabbits. In addition, genetic differentiation was shown between cercaria and adult worms, which was considered to relate to allele loss after host switching. The population genetic diversity of S. japonicum differs in different developmental stages. Host species and sampling number significantly affect the distribution pattern of alleles and the genetic structure of S. japonicum at the suprapopulation level.

A ddPCR assay is presented to diagnose schistosomiasis japonica using feces, urine, saliva, and blood. The capability of the test to use noninvasive samples, its high sensitivity, and capacity to quantify infection intensity have public health implications for schistosomiasis control. Abstract Background Schistosomiasis japonica remains a major public health and socioeconomic concern in Southeast Asia. Sensitive and accurate diagnostics can play a pivotal role in achieving disease elimination goals. Methods We previously reported a novel droplet digital polymerase chain reaction (ddPCR) assay targeting the mitochondrial gene nad1 to diagnose schistosomiasis japonica. The tool identified both prepatent and patent infections using Schistosoma japonicum DNA isolated from serum, urine, salivary glands, and feces in a murine model. The assay was validated here using clinical samples collected from 412 subjects resident in an area moderately endemic for schistosomiasis in the Philippines. Results S. japonicum DNA present in human stool, serum, urine, and saliva was detected quantitatively with high sensitivity. The capability to diagnose cases of human schistosomiasis using noninvasively collected clinical samples, the higher level of sensitivity obtained compared with the microscopy-based Kato-Katz test, and the capacity to quantify infection intensity have important public health implications for schistosomiasis control and programs targeting other neglected tropical diseases. Conclusions This verified ddPCR method represents a valuable new tool for the diagnosis and surveillance of schistosomiasis, particularly in low-prevalence and low-intensity areas approaching elimination and in monitoring where disease emergence or re-emergence is a concern.

To achieve sustainable and integrated control of schistosomiasis, it necessitates the implementation of comprehensive strategies, where effective vaccines could play a pivotal role. The limited identification and validation of schistosome antigens hinders the progress of vaccine development for the disease. Schistosome cysteine proteinases are considered as important targets for novel anti-schistosomiasis immunoprophylaxis due to their primary role in nutrient absorption. Previous research on the Schistosoma japonicum degradome has identified a group of cathepsin L-like proteases (SjCLs) that are up-regulated in hepatic schistosomula and adult worms. In this study, five recombinant proteins representing the mature form of these SjCLs, designated as rSjCL1-5, were successfully produced. Mice immunized with the rSjCLs were subsequently challenged with cercariae to evaluate the immunoprotective efficacy of these proteins. The expression and localization of SjCL1 were analyzed by qRT-PCR, western blotting and immunofluorescence assays. Among these five rSjCLs, only the immunization with rSjCL1 conferred partial protection to the mice against S. japonicum infection, resulting in a reduction in worm burden by 34.9% ~ 38.0% and a decrease of egg burden by 46.2% ~ 48.3%. This immunization also effectively mitigated body weight loss and hepatomegaly in the challenged mice. SjCL1 was primarily localized along the intestinal intima of hepatic schistosomula, as well as male and female adults, and on the tegument of male adults. The mature form of SjCL1 was detected in the excretory/secretory products of the parasites. Hepatic schistosomulum treated with SjCL1 antibodies in vitro showed significant growth retardation, although remained viable and developed intestinal heme pigmentation, indicative of hemoglobin digestion. Our study revealed that SjCL1 is essential for normal parasite growth and shed new light for the development of schistosomiasis vaccines targeting cathepsins, which play a key role in the early intra-mammalian stages of schistosomes.

Schistosomiasis is a neglected tropical parasitic disease associated with severe pathology, mortality and economic loss worldwide. Programs for disease control may benefit from specific and sensitive diagnostic methods to detect Schistosoma trematodes in aquatic environments. Here we report the development of novel environmental DNA (eDNA) qPCR assays for the presence of the human-infecting species Schistosoma mansoni, S. haematobium and S. japonicum. We first tested the specificity of the assays across the three species using genomic DNA preparations which showed successful amplification of target sequences with no cross amplification between the three focal species. In addition, we evaluated the specificity of the assays using synthetic DNA of multiple Schistosoma species, and demonstrated a high overall specificity; however, S. japonicum and S. haematobium assays showed cross-species amplification with very closely-related species. We next tested the effectiveness of the S. mansoni assay using eDNA samples from aquaria containing infected host gastropods, with the target species revealed as present in all infected aquaria. Finally, we evaluated the effectiveness of the S. mansoni and S. haematobium assays using eDNA samples from eight discrete natural freshwater sites in Tanzania, and demonstrated strong correspondence between infection status established using eDNA and conventional assays of parasite prevalence in host snails. Collectively, our results suggest that eDNA monitoring is able to detect schistosomes in freshwater bodies, but refinement of the field sampling, storage and assay methods are likely to optimise its performance. We anticipate that environmental DNA-based approaches will help to inform epidemiological studies and contribute to efforts to control and eliminate schistosomiasis in endemic areas.

Schistosoma japonicum is a parasitic flatworm that causes human schistosomiasis, which is a significant cause of morbidity in China and the Philippines. A single draft genome was available for S. japonicum, yet this assembly is very fragmented and only covers 90% of the genome, which make it difficult to be applied as a reference in functional genome analysis and genes discovery. In this study, we present a high-quality assembly of the fluke S. japonicum genome by combining 20 G (~53X) long single molecule real time sequencing reads with 80 G (~ 213X) Illumina paired-end reads. This improved genome assembly is approximately 370.5 Mb, with contig and scaffold N50 length of 871.9 kb and 1.09 Mb, representing 142.4-fold and 6.2-fold improvement over the released WGS-based assembly, respectively. Additionally, our assembly captured 85.2% complete and 4.6% partial eukaryotic Benchmarking Universal Single-Copy Orthologs. Repetitive elements account for 46.80% of the genome, and 10,089 of the protein-coding genes were predicted from the improved genome, of which 96.5% have been functionally annotated. Lastly, using the improved assembly, we identified 20 significantly expanded gene families in S. japonicum, and those genes were primarily enriched in functions of proteolysis and protein glycosylation. Using the combination of PacBio and Illumina Sequencing technologies, we provided an improved high-quality genome of S. japonicum. This improved genome assembly, as well as the annotation, will be useful for the comparative genomics of the flukes and more importantly facilitate the molecular studies of this important parasite in the future.

Schistosomiasis affects more than 250 million people worldwide and is one of the neglected tropical diseases. Currently, the treatment of schistosomiasis relies on a single drug-praziquantel-which has led to increasing pressure from drug resistance. Therefore, there is an urgent need to find new treatments. The development of genome sequencing has provided valuable information for understanding the biology of schistosomes. In the genome of Schistosoma japonicum , approximately 11% of the protein-coding sequences are uncharacterized genes (UGs) annotated as “hypothetical protein” or “protein of unknown function.” These poorly understood genes have been unjustifiably neglected, although some may be essential for the survival of the parasites and serve as potential drug targets. In this study, we systematically mined the highly expressed UGs in both genders of this parasite throughout key developmental stages in their mammalian host, using our previously published S. japonicum genome and RNA-seq data. By employing in vitro RNA interference (RNAi), we screened 126 UGs that lack homologs in Homo sapiens and identified 8 that are essential for the parasite vitality. We further investigated two UGs, Sjc_0002003 and Sjc_0009272 , which resulted in the most severe phenotypes. Fluorescence in situ hybridization demonstrated that both genes were expressed throughout the body without sex bias. Silencing either Sjc_0002003 or Sjc_0009272 reduced the cell proliferation in the body. Furthermore, in vivo RNAi indicated both genes are required for the growth and survival of the parasites in the mammalian host. For Sjc_0002003 , we further characterize the underlying molecular cause of the observed phenotype. Through RNA-seq analysis and functional studies, we revealed that silencing Sjc_0002003 reduces the expression of a series of intestinal genes, including Sjc_0007312 (hypothetical protein), Sjc_0008276 (vha-17), Sjc_0002942 (PLA2G15), and Sjc_0003646 (SJCHGC09134 protein), leading to gut dilation. Our work highlights the importance of UGs in schistosomes as promising targets for drug development in the treatment of the schistosomiasis.

Novel tools for early diagnosis and monitoring of schistosomiasis are urgently needed. This study aimed to validate parasite-derived miRNAs as potential novel biomarkers for the detection of human Schistosoma japonicum infection. A total of 21 miRNAs were initially validated by real-time-polymerase chain reaction (RT-PCR) using serum samples of S. japonicum -infected BALB/c mice. Of these, 6 miRNAs were further validated with a human cohort of individuals from a schistosomiasis-endemic area of the Philippines. RT-PCR analysis showed that two parasite-derived miRNAs (sja-miR-2b-5p and sja-miR-2c-5p) could detect infected individuals with low infection intensity with moderate sensitivity/specificity values of 66%/68% and 55%/80%, respectively. Analysis of the combined data for the two parasite miRNAs revealed a specificity of 77.4% and a sensitivity of 60.0% with an area under the curve (AUC) value of 0.6906 ( P = 0.0069); however, a duplex RT-PCR targeting both sja-miR-2b-5p and sja-miR-2c-5p did not result in an increased diagnostic performance compared with the singleplex assays. Furthermore, the serum level of sja-miR-2c-5p correlated significantly with faecal egg counts, whereas the other five miRNAs did not. Targeting S. japonicum -derived miRNAs in serum resulted in a moderate diagnostic performance when applied to a low schistosome infection intensity setting.

Oncomelania hupensis robertsoni is the only intermediate host of Schistosoma japonicum in hilly regions of south-west China, which plays a key role during the transmission of Schistosomiasis. This study aimed to sequence the complete mitochondrial genome of Oncomelania hupensis robertsoni and analyze genetic differentiation of Oncomelania hupensis robertsoni. Samples were from 13 villages in Yunnan Province of China, with 30 Oncomelania hupensis snails per village, and the complete mitochondrial genome was sequenced. A comprehensive analysis of the genetic differentiation of Oncomelania hupensis robertsoni was conducted by constructing phylogenetic trees, calculating genetic distances, and analyzing identity. A total of 26 complete mitochondrial sequences were determined. The length of genome ranged from 15,181 to 15,187 bp, and the base composition of the genome was A+T (67.5%) and G+C content (32.5%). This genome encoded 37 genes, including 13 protein-coding genes, 2 rRNA genes, and 22 tRNA genes. The phylogenetic trees and identity analysis confirmed that Oncomelania hupensis robertsoni was subdivided into Oncomelania hupensis robertsoni Yunnan strain and Sichuan strain, with a genetic distance of 0.0834. Oncomelania hupensis robertsoni Yunnan strain was further subdivided into two sub-branches, corresponding to \"Yunnan North\" and \"Yunnan South\", with a genetic distance of 0.0216, and the samples exhibited over 97% identity. Oncomelania hupensis robertsoni is subdivided into Oncomelania hupensis robertsoni Yunnan strain and Sichuan strain. Oncomelania hupensis robertsoni Yunnan strain exhibits a higher level of genetic identity and clear north-south differentiation. This work reported the first mitochondrial genome of Oncomelania hupensis robertsoni Yunnan strain, which could be used as an important reference genome for Oncomelania hupensis, and also provide the important information for explaining the distribution pattern of Oncomelania hupensis robertsoni and control of Schistosoma japonicum.