Biology subjects

Hoffmann, K. F.

Publications and source records attributed to Hoffmann, K. F..

11 recordsLinked to original sources

bioRxiv2026

The histone code of love: epigenetics of maturation of gonads in the human blood fluke Schistosoma mansoni

Schistosoma mansoni is a parasitic flatworm that has two, genetically determined, sexes. We used aggregated data of 8 posttranslational histone modifications (ChIP-Seq), chromatin accessibility (ATAC-Seq), transcription (RNA-Seq) and genome feature annotations to decipher the histone code of genes involved in the differentiation of schistosome gonads (i.e. female ovaries and male testes). We show schistosome gonads express at least two classes of protein coding genes: H3K4me3-positive genes that display canonical features of eukaryotic protein-coding genes such as peaks of H3K4me3 at the transcription start sites (TSS) and increases in histone acetylation marks towards the transcription end site (TES), but also a non-canonical H3K9/27me3 plateau just upstream of the TSS. H3K4me3 enrichment at the TSS is highly predictive for transcription strength in these genes compared to a second class of protein coding genes (H3K4me3-negative genes) that do not display this pattern and is characterised by absence of the investigated histone marks at TSS and TES. This is indicative of the existence of hitherto unknown, potentially schistosome-specific histone marks in these genes. The absence of H3K4me3 at the TSS is not associated with inducible or stable gene expression in the gonads. Instead, gene ontology analysis indicates that H3K4me3-positive genes are related to functions which typically govern processes such as metabolism or signal transduction while H3K4me3-negative genes are dedicated to cell communication or immune responses. Second, individual histone modifications and their combinations are associated with functional features of the schistosome genome, known as "chromatin colours". In H3K4me3-positive genes, there is clear co-linearity of 3 colours, which strongly suggests a functional role for histone modifications in the control of transcription pre-initiation, promotor release, and transcription termination. Third, there are striking chromatin structure changes during maturation of the gonads in all genomic features including protein-coding and non-protein coding genes as well as repetitive sequences. The nature of these changes is different in both sexes. H3K36me3 and H3K9me3, as well as H3K23ac and H3K9ac show the strongest variations. Last, we show that pharmacological inhibition of histone demethylation activity by IOX1 leads to a concentration-dependent separation ("divorce") of schistosome couples confirming the importance of H3K36/H3K9 methylation for pairing maintenance and indicating histone demethylases as a potential drug target family. Collectively, our findings offer unprecedented insights into histone codes and chromatin dynamics governing the reproductive development of S. mansoni gonads.

developmental biology↗

bioRxiv2026

In vitro sexual dimorphism establishment in schistosomes

Schistosomes are parasitic flatworms that cause Schistosomiasis, a major Neglected Tropical Disease (NTD) that affects more than 250 million people worldwide. With two morphologically distinct sexes, a heterogametic female (ZW) and a homogametic male (ZZ), schistosomes are an exception among flatworms, which are largely hermaphroditic. Sexual dimorphism in schistosomes only becomes apparent by adulthood within the mammalian host. The cellular and molecular mechanisms underlying the sexual differentiation of these parasites are poorly understood, partly due to intrinsic challenges in assessing parasite development in vivo. Therefore, robust and reproducible approaches for maintaining and developing parasites in vitro are needed to overcome these difficulties. However, to date, only a few studies have focused on protocols that allow cultured parasites to reach sexual dimorphic stages, and none have been reproduced, limiting the ability to understand the unique sexual biology of this major human parasite. Here, we refine a protocol for long-term culture of newly transformed cercariae that developed in vitro into sexually dimorphic forms. We assessed the effect of two different sera, Foetal Bovine Serum (FBS) and Human Serum (HS), added to the culture medium supplemented with human red blood cells. We found that in contrast to FBS-cultured worms, HS-cultured parasites digested red blood cells, a crucial step for long term parasite development. Additionally, while most FBS-cultured parasites did not progress beyond an early liver stage, sexual dimorphism was clearly established in the HS-cultured worms, albeit delayed compared to in vivo development. Moreover, EdU pulse experiments revealed a continuous proliferation of cells over time in HS-cultured parasites, while a significantly lower number of proliferating cells were detected in FBS-cultured worms. This protocol paves the way to study parasite development in vitro, positively impacting the principles of the 3Rs (Replacement, Reduction and Refinement) for animal research, and allowing for in-depth studies of sexual dimorphism establishment as well as in vitro screening for novel control strategies across the life cycle of these major human parasites.

developmental biology↗

bioRxiv2025

Use of a cytochrome P450 humanised mouse model to refine schistosomiasis drug discovery.

Control of schistosomiasis, a neglected tropical disease caused by infection with Schistosoma spp., remains reliant on a single chemotherapy, praziquantel (PZQ). This strategy presents a risk to global health should PZQ-resistant schistosomes establish in endemic areas and justifies the search for new drugs. However, species-specific metabolic differences between humans and preclinical models hinder the optimisation of next-generation anti-schistosomal therapeutics. Here, to bypass these species-specific limitations, we exploited a humanised mouse model, 8HUM, engineered to express the principal human Phase I cytochrome P450 enzymes (CYP1A1/2, CYP2C9, CYP2D6, CYP3A4/7) as well as the transcription factors constitutive androstane receptor (CAR) and pregnane X receptor (PXR) in place of 35 murine orthologues. We characterised S. mansoni development, immunopathology, hepatic transcriptomic responses, intestinal microbiome changes and PZQ metabolism as well as PZQ efficacy in 8HUM versus wild-type (WT) mice. 8HUM mice supported normal S. mansoni maturation, infection-associated microbiome dysbiosis, Th2-dominant immune responses and characteristic hepatic pathology. PZQ intrinsic clearance in 8HUM hepatic microsomes mirrored human levels and was >10-fold lower than that found for WT microsomes. Oral dosing revealed human-like PZQ exposures of (R)-PZQ and 4OH-PZQ in 8HUM mice at 25 mg/kg bodyweight and >90% reductions in worm burdens at 100 mg/kg bodyweight (equivalent to that seen in WT mice administered PZQ at 400 mg/kg bodyweight). Our results revealed that 8HUM mice recapitulate key features of murine schistosomiasis while exhibiting human-relevant drug metabolism. These findings establish 8HUM as a refined translational platform for anti-schistosomal drug development, improving predictive accuracy and accelerating therapeutic discovery. One Sentence SummaryA cytochrome P450 humanised mouse model is used to study Schistosoma mansoni development, schistosomiasis, drug metabolism and drug efficacy.

pharmacology and toxicology↗

bioRxiv2024

2,3-bis (phenylamino) quinoxaline - containing compounds display potent activity against Methicillin-resistant Staphylococcus aureus, Enterococcus faecalis and their biofilms

Antimicrobial resistance remains a global challenge threatening the ability to control diseases caused by bacterial infections. Here, we explored the antimicrobial activity of 2,3-N,N-diphenyl quinoxaline derivatives against representative Gram-positive, Gram-negative and Mycobacterium species. Two quinoxaline derivatives (compounds 25 and 31) demonstrated particularly potent activity against most Staphylococcus aureus, Enterococcus faecium and Enterococcus faecalis strains tested (MIC values between 0.25 to 1 mg/l). These compounds also demonstrated potent antibacterial activity against methicillin-resistant S. aureus (MRSA) and vancomycin-resistant E. faecium/E. faecalis (VRE) strains. Against an extensive panel of clinically relevant isolates, they further showed comparable or better activity to four currently used antibiotics (vancomycin, teicoplanin, daptomycin and linezolid). Finally, they performed better in preventing S. aureus and E. faecalis biofilm formation when compared to several other antibiotics. In conclusion, these two quinoxaline derivatives have promising activities that could be further explored as part of efforts to identify urgently needed new antibacterial agents.

microbiology↗

bioRxiv2022

Targeted insertion of reporter transgene into a gene safe harbor in human blood fluke, Schistosoma mansoni

The identification and characterization of genomic safe harbor sites (GSH) aims to facilitate consistent transgene activity without disruption to the host cell genome. We combined genome annotation and chromatin structure analysis by computational approach to predict the location of four GSHs in the human blood fluke, Schistosoma mansoni, a major infectious pathogen of the tropics. Introduction of a transgene into the egg of the parasite was accomplished using CRISPR/Cas-assisted homology-directed repair and overlapping guide RNAs. Gene editing efficiencies of 24% and transgene-encoded fluorescence of 75% of gene-edited schistosome eggs were observed. These outcomes advance functional genomics for schistosomes by providing a tractable path towards transgenic helminths using homology directed repair-catalyzed transgene insertion. This approach should be adaptable to helminths generally. MotivationFunctional genomics methods are needed in the arena of the Neglected Tropical Diseases, especially for helminth parasites, to facilitate basic and transformational studies to improve global public health. Gain-of-function phenotypes would be valuable in this context. Hence, the motivation for this investigation was to identify a genome safe harbor (GSH) site in the chromosomes of the human blood fluke, Schistosoma mansoni and, in a pilot approach, and to develop methods for transgene insertion and methods to characterize transgene performance following homology directed insertion at the schistosome GSH. The progress reported here can be expected to advance functional genomics for species of the Platyhelminthes - including model, free living species of planarians, and should be adaptable to helminths generally.

molecular biology↗

bioRxiv2021

Schistosoma mansoni α-N-acetylgalactosaminidase (SmNAGAL) regulates coordinated parasite movement and egg production

-galactosidase (-GAL) and -N-acetylgalactosaminidase (-NAGAL) are two glycosyl hydrolases responsible for maintaining cellular homeostasis by regulating glycan substrates on proteins and lipids. Mutations in the human genes encoding either enzyme lead to neurological and neuromuscular impairments seen in both Fabry- and Schindler/Kanzaki-diseases. Here, we investigate whether the parasitic blood fluke Schistosoma mansoni, responsible for the neglected tropical disease schistosomiasis, also contains functionally important -GAL and -NAGAL proteins. As infection, parasite maturation and host interactions are all governed by carefully-regulated glycosylation processes, inhibiting S. mansonis -GAL and -NAGAL activities could lead to the development of novel chemotherapeutics. Sequence and phylogenetic analyses of putative -GAL/-NAGAL protein types showed Smp_089290 to be the only S. mansoni protein to contain the functional amino acid residues necessary for -GAL/-NAGAL substrate cleavage. Both -GAL and -NAGAL enzymatic activities were higher in females compared to males (p<0.05; -NAGAL > -GAL), which was consistent with smp_089290s female biased expression. Spatial localisation of smp_089290 revealed accumulation in parenchymal cells, neuronal cells, and the vitellaria and mature vitellocytes of the adult schistosome. siRNA-mediated knockdown (>90%) of smp_089290 in adult worms significantly inhibited -NAGAL activity when compared to control worms (siLuc treated males, p<0.01; siLuc treated females, p<0.05). No significant reductions in -GAL activities were observed in the same extracts. Despite this, decreases in -NAGAL activities correlated with a significant inhibition in adult worm motility as well as in egg production. Programmed CRISPR/Cas9 editing of smp_089290 in adult worms confirmed the egg reduction phenotype. Based on these results, Smp_089290 was determined to act predominantly as an -NAGAL (hereafter termed SmNAGAL) in schistosome parasites where it participates in coordinating movement and oviposition processes. Pharmacological inhibition of SmNAGAL may lead to the development of a novel anthelmintic class of compounds. Author summarySchistosomiasis is a parasitic disease caused by infection with blood flukes, which leads to acute and chronic pathology in millions of infected individuals located in deprived tropical and subtropical regions. Elucidating the function of schistosome genes has provided a clearer view on their roles in various molecular pathways, which are critical to successful parasitism. This information is invaluable when progressing novel drug and vaccine candidates. Here, we add to the existing knowledge of the Schistosoma mansoni parasitic glycan processing and modification machinery by functionally characterising a glycosyl hydrolase (S. mansoni -N-acetylgalactosaminidase, SmNAGAL). We demonstrate that this protein is enzymatically active and important in coordinating parasite movement in adult male and female schistosomes. Additionally, we provide evidence that this protein regulates pathways associated with egg production in female schistosomes, which is responsible for inducing pathological reactions. Developing drugs that inhibit SmNAGAL enzymatic activity could provide a novel approach for controlling schistosomiasis.

molecular biology↗

bioRxiv2020

The anti-mycobacterial activity of Artemisia annua L is based on deoxyartemisinin and artemisinic acid

The discovery of antimalarial artemisinin from Artemisia annua L. is an example of how Traditional Chinese Medicine (TCM) may be exploited to meet a recognized need. In this study, we systemically investigated A. annua L. for its antimicrobial activity and assessed it as a source of bioactive natural products for anti-mycobacterial activity. We used a silica gel column to perform antimicrobial activity-guided purification of the A. annua leaf, whose identity was confirmed by rbcL DNA barcoding, and used UHPLC-HRMS and NMR to elucidate the structure of purified active compounds. The antimicrobial activity of crude extracts, isolated compounds and the control artemisinin (Apollo Scientific Ltd) was assessed against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), Mycobacterium smegmatis strains by serial micro dilution method (31.25-1000 g/mL). The isolated compounds were tested for synergistic effects against mycobacterium. Bioactive compounds were purified and identified as deoxyartemisinin and artemisinic acid. Artemisinic acid (MIC 250 g/mL) was more effective in comparison to deoxyartemisinin (MIC 500 g/mL) and artemisinin (MIC 1000 g/mL) against M. smegmatis. We used a molecular docking approach to investigate the interactions between selected anti-mycobacterial compounds and proteins involved in vital physiological functions in M. tuberculosis, namely MtPks13, MtPknB, MtPanK, MtKasA, MtInhA and MtDprE1 and found artemisinic acid showed docking scores superior to the control inhibiters for MtKasA, suggesting it to be a potential nick for further in vitro biological evaluation and anti-TB drug design.

pharmacology and toxicology↗

bioRxiv2020

Schistosoma mansoni lysine specific demethylase 1 (SmLSD1) is a druggable target involved in parasite survival, oviposition and stem cell proliferation.

Schistosomiasis is a chronically-debilitating neglected tropical disease (NTD) that predominantly affects people living in resource-poor communities of tropical and subtropical countries. Schistosoma mansoni, one of three species responsible for most human infections, undergoes strict developmental regulation of gene expression that is carefully controlled by both genetic- and epigenetic- processes. As inhibition of S. mansoni epigenetic machinery components has been shown to impair key transitions throughout the parasites digenetic lifecycle, this knowledge is currently fuelling the search for new epi-drug - based anthelmintics. In this study, the anti-schistosomal activity of 39 re-purposed Homo sapiens Lysine Specific Demethylase 1 (HsLSD1) inhibitors was investigated on key life cycle stages associated with both definitive (schistosomula, juvenile worms, sexually-mature adults) and intermediate host (miracidia) infection. The most active compound (compound 33; e.g. schistosomula phenotype EC50 = 4.370 {micro}M; adult worm motility EC50 = 2.137 {micro}M) was subsequently used to provide further insight into the critical role of S. mansoni lysine specific demethylase 1 (SmLSD1) in adult worm oviposition and stem cell proliferation. Here, compound 33 treatment of adult schistosomes led to significant defects in egg production, intra-egg vitellocyte/ovum packaging and gonadal/neoblast stem cell proliferation. A greater abundance of H3K4me2 marks accompanied these phenotypes and supported specific inhibition of SmLSD1 in adult schistosomes by compound 33. In silico screening indicated that compound 33 likely inhibits SmLSD1 activity by covalently reacting with the FAD cofactor. This work suggests that evaluation of HsLSD1 - targeting epi-drugs could have utility in the search for next-generation anti-schistosomals. The ability of compound 33 to inhibit parasite survival, oviposition, H3K4me2 demethylation and stem cell proliferation warrants further investigations of this compound and its epigenetic target. This data further highlights the importance of histone methylation in S. mansoni lifecycle transitions. Author summaryAffecting over 200 million people, schistosomiasis is a chronic disease caused by the parasitic worm Schistosoma mansoni. The frontline drug for schistosomiasis treatment is praziquantel. Owing to the concern surrounding praziquantel insensitivity or resistance developing, current research is directed towards the identification of novel drugs. We have focused our search for compounds that affect essential aspects of schistosome biology including parasite movement, fertility, cell proliferation and survival. Since all of these functions are potentially influenced by epigenetic regulation of gene expression, we investigated the activity of compounds that alter histone methylation status. In this report, we show that S. mansoni Lysine Specific Demethylase 1 (SmLSD1), a histone demethylase, is critical to miracidia-to-sporocyst transitioning, adult worm motility, egg production and parasite survival. Inhibition of SmLSD1 with compounds developed to inhibit the human paralog show promising potential as novel anti-schistosomal agents.

microbiology↗

bioRxiv2020

Quorum sensing N-Acyl homoserine lactones are a new class of anti-schistosomal.

BackgroundSchistosomiasis is a prevalent neglected tropical disease that affects approximately 300 million people worldwide. Its treatment is through a single class chemotherapy, praziquantel. Concerns surrounding the emergence of praziquantel insensitivity have led to a need for developing novel anthelmintics. Methodology/Principle findingsThrough evaluating and screening fourteen compounds (initially developed for anti-cancer and anti-viral projects) against Schistosoma mansoni, one of three species responsible for most cases of human schistosomiasis, a racemic N-acyl homoserine (1) demonstrated good efficacy against all intra mammalian lifecycle stages including schistosomula (EC50 = 4.7 {micro}M), juvenile worms (EC50 = 4.3 {micro}M) and adult worms (EC50 = 8.3 {micro}M). To begin exploring structural activity relationships, a further 8 analogues of this compound were generated, including individual (R)- and (S)- enantiomers. Upon anti-schistosomal screening of these analogues, the (R)- enantiomer retained activity, whereas the (S)- lost activity. Furthermore, modification of the lactone ring to a thiolactone ring (3) improved potency against schistosomula (EC50 = 2.1 {micro}M), juvenile worms (EC50 = 0.5 {micro}M) and adult worms (EC50 = 4.8 {micro}M). As the active racemic parent compound is structurally similar to quorum sensing signaling peptides used by bacteria, further evaluation of its effect (along with its stereoisomers and the thiolactone analogues) against Gram+ (Staphylococcus aureus) and Gram- (Escherichia coli) species was conducted. While some activity was observed against both Gram+ and Gram- bacteria species for the racemic compound 1 (MIC 125 mg/L), the (R) stereoisomer had better activity (125 mg/L) than the (S) (>125mg/L). However, the greatest antimicrobial activity (MIC 31.25 mg/L against S. aureus) was observed for the thiolactone containing analogue (3). Conclusion/SignificanceTo the best of our knowledge, this is the first demonstration that N-Acyl homoserines exhibit anthelmintic activities. Furthermore, their additional action on Gram+ bacteria opens a new avenue for exploring these molecules more broadly as part of future anti-infective initiatives. Author SummarySchistosomiasis, caused by infection with blood fluke schistosomes, is a neglected tropical disease that negatively impacts the lives of approximately 300 million people worldwide. In the absence of a vaccine, it is currently controlled by a single drug, Praziquantel (PZQ). Although incredibly valuable in controlling disease burden, PZQ-mediated chemotherapy is ineffective against juvenile worms and may not be sustainable should resistance develop. The need to identify an alternative or combinatorial drug is, therefore, a priority in contributing to the control of this parasitic disease into the 21st century. In this study, we have identified a new class of anthelmintic, N-acyl homoserine lactones, which are normally used by bacteria for quorum sensing and population density control. The tested N-acyl homoserine lactones were active against all intra-human schistosome lifecycle stages, in particular, when a thiolactone modification to the core N-acyl homoserine ring was made. Interestingly, these N-acyl homoserine lactones also displayed antimicrobial activities against Gram+ Staphylococcus aureus. By demonstrating broad activities against schistosomes and bacteria exemplars, this study identified a potential route for the further development of a new anti-infective class.

zoology↗

bioRxiv2019

The repositioning of epigenetic probes/inhibitors identifies new anti-schistosomal lead compounds and chemotherapeutic targets

BackgroundPraziquantel represents the frontline chemotherapy used to treat schistosomiasis, a neglected tropical disease (NTD) caused by infection with macro-parasitic blood fluke schistosomes. While this drug is safe, its inability to kill all schistosome lifecycle stages within the human host often requires repeat treatments. This limitation, amongst others, has led to the search for novel anti-schistosome replacement or combinatorial chemotherapies. Here, we describe a repositioning strategy to assess the anthelmintic activity of epigenetic probes/inhibitors obtained from the Structural Genomics Consortium.\n\nMethodology/Principle findingsThirty-seven epigenetic probes/inhibitors targeting histone readers, writers and erasers were initially screened against Schistosoma mansoni schistosomula using the high-throughput Roboworm platform. At 10 {micro}M, 14 of these 37 compounds (38%) negatively affected schistosomula motility and phenotype after 72 hours of continuous co-incubation. Subsequent dose-response titrations against schistosomula and adult worms revealed epigenetic probes targeting one reader (NVS-CECR2-1), one writer (LLY-507 and BAY-598) and one eraser (GSK-J4) to be particularly active. As LLY-507/BAY-598 (SMYD2 histone methyltransferase inhibitors) and GSK-J4 (a JMJD3 histone demethylase inhibitor) regulate an epigenetic process (protein methylation) known to be critical for schistosome development, further characterisation of these compounds/putative targets was performed. RNA interference (RNAi) of one putative LLY-507/BAY-598 S. mansoni target (Smp_000700) in adult worms replicated the compound-mediated motility and egg production defects. Furthermore, H3K36me2, a known product catalysed by SMYD2 activity, was also reduced by LLY-507 (25%), BAY-598 (23%) and siSmp_000700 (15%) treatment of adult worms. Oviposition and packaging of vitelline cells into in vitro laid eggs was also significantly affected by GSK-J4 (putative cell permeable prodrug inhibitor of Smp_034000), but not by the related structural analogue GSK-J1 (non-permeable inhibitor).\n\nConclusion/SignificanceCollectively, these results provide further support for the development of next-generation drugs targeting schistosome epigenetic pathway components. In particular, the progression of histone methylation/demethylation modulators presents a tractable strategy for anti-schistosomal control.\n\nAuthor SummaryHuman schistosomiasis is caused by infection with parasitic blood fluke worms. Global control of this NTD is currently facilitated by administration of a single drug, praziquantel (PZQ). This mono-chemotherapeutic strategy of schistosomiasis control presents challenges as PZQ is not active against all human-dwelling schistosome lifecycle stages and the evolution of PZQ resistant parasites remains a theat. Therefore, new drugs to be used in combination with or in replacement of PZQ are urgently needed. Here, continuing our studies on Schistosoma mansoni epigenetic processes, we performed anthelmintic screening of 37 epigenetic probes/epigenetic inhibitors obtained from the Structural Genomics Consortium (SGC). The results of these studies highlighted that schistosome methylation/demethylation processes are acutely vulnerable. In particular, compounds affecting schistosome SMYD (LLY-507, BAY-598) or JMJD (GSK-J4) homologues are especially active on schistosomula and adult worms during in vitro phenotypic drug screens. The active epigenetic probes identified here as well as their corresponding S. mansoni protein targets offers new starting points for the development of next-generation anti-schistosomals.

zoology↗

bioRxiv2018

Functional genomics and programmed genome editing of omega-1 of the blood fluke Schistosoma mansoni

CRISPR/Cas9 based genome editing has yet been reported in parasitic or indeed any species of the phylum Platyhelminthes. We tested this approach by targeting omega-1 ({omega}1) of Schistosoma mansoni as a proof of principle. This secreted ribonuclease is crucial for Th2 priming and granuloma formation, providing informative immuno-pathological readouts for programmed genome editing. Schistosome eggs were either exposed to Cas9 complexed with a synthetic guide RNA (sgRNA) complementary to exon 6 of {omega}1 by electroporation or transduced with pseudotyped lentivirus encoding Cas9 and the sgRNA. Some eggs were also transduced with a single stranded oligodeoxynucleotide donor transgene that encoded six stop codons, flanked by 50 nt-long 5-and 3-microhomology arms matching the predicted Cas9-catalyzed double stranded break (DSB) within {omega}1. CRISPResso analysis of amplicons spanning the DSB revealed [~]4.5% of the reads were mutated by insertions, deletions and/or substitutions, with an efficiency for homology directed repair of 0.19% insertion of the donor transgene. Transcripts encoding {omega}1 were reduced >80% and lysates of {omega}1-edited eggs displayed diminished ribonuclease activity indicative that programmed editing mutated the {omega}1 gene. Whereas lysates of wild type eggs polarized Th2 cytokine responses including IL-4 and IL-5 in human macrophage/T cell co-cultures, diminished levels of the cytokines followed the exposure to lysates of {omega}1-mutated schistosome eggs. Following injection of schistosome eggs into the tail vein of mice, the volume of pulmonary granulomas surrounding {omega}1-mutated eggs was 18-fold smaller than wild type eggs. Programmed genome editing was active in schistosomes, Cas9-catalyzed chromosomal breakage was repaired by homology directed repair and/or non-homologous end joining, and mutation of {omega}1 impeded the capacity of schistosome eggs both to drive Th2 polarization and to provoke formation of pulmonary circumoval granulomas. Knock-out of {omega}1 and the impaired immunological phenotype showcase the novel application of programmed gene editing in and functional genomics for schistosomes.

molecular biology↗