vaccines

2026-04-15 | In-silico design of a multi-epitope vaccine candidate against Strongyloides stercoralis.

BACKGROUND: Strongyloides stercoralis is a soil-transmitted helminth causing strongyloidiasis, mainly affecting impoverished populations in tropical and subtropical regions. Despite its high global prevalence, affecting an estimated 613.9 million people, it remains neglected in public health initiatives. Current treatments, including albendazole and ivermectin, show variable efficacy and face potential resistance, making vaccine development critical for long-term control and achieving WHO targets. METHODS: We employed an immunoinformatics approach to design a multi-epitope vaccine candidate by combining B-cell and T-cell epitopes from key L3-stage proteins involved in S. stercoralis infection. In addition, interactions with TLR4 were implemented to assess the vaccine’s ability to elicit an innate immune response. RESULTS: The selected proteins exhibited strong conservation, suggesting potential cross-protection across Strongyloides strains. The vaccine candidate was predicted to be antigenic, non-allergenic, and immunogenic, with immune simulation demonstrating robust activation of humoral and cellular immune responses. Extensive HLA coverage analysis indicated broad population applicability. Additionally, protein–protein docking and normal-mode analyses indicated efficient binding and stable interaction of the vaccine candidate with TLR4. CONCLUSION: This study provides a promising approach to designing multi-epitope vaccines against S. stercoralis designed through integrative immunoinformatics. Overall, the designed vaccine candidate demonstrated immunogenicity and safety features that warrant further experimental validation in vitro and in vivo. These findings lay important groundwork for future vaccine development aimed at improving the prevention and control of strongyloidiasis globally.

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2024-02-14 | Generation of IgG antibodies against Strongyloides stercoralis in mice via immunization with recombinant antigens A133 and Ss-IR.

Strongyloidiasis, caused by the nematode Strongyloides stercoralis, remains a threat to global public health, and a vaccine would be useful to control the disease, especially in developing countries. This study aimed to evaluate the efficacy of recombinant proteins, A133 and Ss-IR, as potential vaccine candidates against strongyloidiasis by investigating the humoral and cellular immune responses in immunized mice. Respective antigens were adjuvanted with Complete Freund's Adjuvant (prime) and Incomplete Freund's Adjuvant (boost) and administered intraperitoneally (prime) and subcutaneously (boost) to female BALB/c mice. For antigen-only doses, only antigens were injected without adjuvants. Altogether, 1 prime dose, 4 booster doses, and 2 antigen-only doses were administered successively. ELISAs were conducted to assess the antibody responses, along with flow cytometry and cytokine ELISA to elucidate the cellular immune responses. Results showed that A133 and Ss-IR induced the production of IgG1 and IgG2a, with A133 generating more robust IgG2a responses than Ss-IR. Flow cytometry findings indicated that effector CD8+T-cells and memory B-cells activity were upregulated significantly for A133 only, whereas cytokine ELISA demonstrated that a Th1/Th2/Th17 mixed cell responses were triggered upon vaccination with either antigen. This preliminary study illustrated the good potential of recombinant A133 and Ss-IR as vaccine candidates against S. stercoralis. It provided information on the probable immune mechanism involved in host defence and the elicitation of protection against S. stercoralis.

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2023-07-18 | [Bioinformatics analysis and prokaryotic expression of Strongyloides stercoralis serine protease inhibitor 1].

To predict the structure and antigenic epitope of the Strongyloides stercoralis serine protease inhibitor 1 (Ss-SRPN-1) protein using bioinformatics tools, and to construct prokaryotic expression plasmids for expression of recombinant Ss-SRPN-1 protein, so as to provide the basis for unraveling the function of the Ss-SRPN-1 protein. The amino acid sequence of the Ss-SRPN-1 protein was downloaded from the NCBI database, and the physicochemical properties, structure and antigenic epitopes of the Ss-SRPN-1 protein were predicted using bioinformatics tools, including ExPASy, SWISS-MODEL and Protean. Primers were designed according to the nucleotide sequences of Ss-SRPN-1, and the Ss-SRPN-1 gene was amplified, cloned and sequenced with genomic DNA extracted from the infective third-stage larvae of S. stercoralis as a template. The Ss-SRPN-1 protein sequence was cloned into the pET28a (+) expression vector and transformed into Escherichia coli BL21 (DE) cells for induction of the recombinant Ss-SRPN-1 protein expression. The recombinant Ss-SRPN-1 protein was then purified and identified using Western blotting and mass spectrometry. Bioinformatics analysis showed that the Ss-SRPN-1 protein, which was composed of 372 amino acids and had a molecular formula of C1948H3046N488O575S16, was a stable hydrophilic protein, and the subcellular localization of the protein was predicted to be extracellular. The Ss-SRPN-1 protein was predicted to contain 11 dominant B-cell antigenic epitopes and 20 T-cell antigenic epitopes. The Ss-SRPN-1 gene with a length of 1 119 bp was successfully amplified, and the recombinant plasmid pET28a (+)/Ss-SRPN-1 was constructed and transformed into E. coli BL21(DE) cells. The expressed recombinant Ss-SRPN-1 protein had a molecular weight of approximately 43 kDa, and was characterized as a Ss-SRPN-1 protein. The recombinant Ss-SRPN-1 protein has been expressed successfully, and this recombinant protein may be a potential vaccine candidate against strongyloidiasis. ［摘要］ 目的 采用生物信息学方法预测粪类圆线虫丝氨酸蛋白酶抑制剂1 (Strongyloides stercoralis serine protease inhibitor 1, Ss-SRPN-1) 蛋白结构和抗原表位, 构建原核表达载体并进行重组蛋白表达, 为阐明Ss-SRPN-1蛋白功能奠定基 础。方法 自NCBI数据库中获取Ss-SRPN-1氨基酸序列, 使用ExPASY、SWISS-MODEL和Protean等生物信息学软件对 Ss-SRPN-1蛋白的理化性质、结构和抗原表位等进行预测。根据Ss-SRPN-1核苷酸序列设计引物, 以粪类圆线虫感染性 三期幼虫DNA为模板, 对Ss-SRPN-1 基因进行扩增、克隆和测序。将重组质粒pET28a (+)/Ss-SRPN-1转入大肠埃希菌 BL21 (DE) 中诱导重组Ss-SRPN-1蛋白表达, 纯化重组蛋白并进行Western blotting及质谱鉴定。结果 生物信息学分析 显示, Ss-SRPN-1蛋白由372个氨基酸组成, 分子式为C1948H3046N488O575S16, 是一种稳定的亲水性蛋白, 预测其亚细胞定位在 细胞外; 预测该蛋白存在11个优势B细胞抗原表位、20个T细胞表位。成功扩增长度为1 119 bp的Ss-SRPN-1 基因, 构建 了重组质粒pET28a (+)/Ss-SRPN-1并转化至大肠埃希菌BL21 (DE) 进行表达, 表达的重组Ss-SRPN-1 蛋白分子量约 43 kDa, 鉴定结果显示该重组蛋白为Ss-SRPN-1蛋白。结论 成功表达了重组Ss-SRPN-1蛋白, 预测该蛋白可作为一种 潜在的粪类圆线虫病疫苗候选分子。.

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2017-12-19 | Venestatin, a Ca++-binding protein from the parasitic nematode Strongyloides venezuelensis, is involved in the larval migration process.

The secretory EF-hand Ca++-binding proteins act as calcium signaling molecules for control of cell functions, but those proteins from parasitic helminths are poorly understood. Here, we have identified and characterized an EF-hand Ca++-binding protein from the rodent nematode, Strongyloides venezuelensis, termed 'venestatin', which is highly conserved in Strongyloides spp. Canonical two EF-hand domains and a signal peptide are present in venestatin. A gel mobility shift assay and Ruthenium red staining indicated that the recombinant venestatin possesses binding ability with Ca++ ions. Endogenous venestatin was seemingly localized in the hypodermis and gut of the worms and was found in the excretory-secretory products. Quantitative reverse transcription-PCR data showed that venestatin-specific transcript was upregulated in the parasitic stages of S. venezuelensis, and the upregulation occurred promptly after larval invasion through the host's skin, but not in the case of in vitro incubation. Immunization of mice with recombinant venestatin caused a 55% reduction in larval migration to the lungs, and lung hemorrhaging was mild compared with non-immunized groups, suggesting that anti-venestatin sera may interfere with larval migration from skin to lung. Our results suggest that venestatin is secreted from the hypodermis and gut of S. venezuelensis, and has pivotal roles in larval migration.

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2016-10-19 | Current progress toward vaccine and passive immunization approaches for Strongyloides spp.

Strongyloides stercoralis is a helminth parasite that can infect millions of people worldwide, particularly in tropical, subtropical and temperate regions with poor sanitation. Several aspects of epidemiology, biology and host-parasite interactions of S. stercoralis have been studied, and substantial knowledge has been acquired; however, very few studies on immunotherapeutic control strategies to prevent infection and disease in humans have been conducted. Therefore, this article reviews the current progress and targets toward vaccine and passive immunization approaches for Strongyloides spp.

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small molecules

2026-08-31 | Clinical and Epidemiologic Features of Pediatric Strongyloidiasis in Spain: A Multicenter Registry.

Data about pediatric strongyloidiasis are scarce in our setting. We conducted a retrospective multicenter registry of cases of pediatric strongyloidiasis in Spain. Among 138 cases, 76% were travelers/migrants. Overall, 32% were symptomatic, and 35% had eosinophilia (higher in symptomatic patients, P < 0.05). Confirmed diagnosis occurred in 10% (stool polymerase chain reaction), while 90% were probable (serology). Ivermectin was the first therapy (98%). Adequate follow-up after treatment was achieved in only 36%. One-fourth of cases were authochthonous, so screening should not be limited to migrant children. Mild eosinophilia could help to detect asymptomatic cases.

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2026-08-25 | Severe ARDS caused by Strongyloides stercoralis hyperinfection in a patient with Sjögren's syndrome: a case report.

Strongyloides stercoralis (S. stercoralis) is a neglected tropical disease that can be fatal in immunocompromised hosts. Diagnosis is challenging due to nonspecific clinical manifestations and low sensitivity of conventional stool examination. Patients with autoimmune diseases receiving long-term glucocorticoid therapy are at high risk of hyperinfection syndrome, which can rapidly progress to acute respiratory distress syndrome (ARDS). A 65-year-old man with an 8-year history of Sjögren's syndrome and chronic interstitial lung disease, who had been on long-term oral methylprednisolone, tripterygium glycosides, and hydroxychloroquine, presented with abdominal pain and vomiting. He rapidly developed severe ARDS requiring invasive mechanical ventilation. Laboratory tests showed persistent eosinopenia (0.01 × 109/L) and lymphopenia. Bronchoalveolar lavage fluid was subjected to metagenomic capture sequencing (MetaCAP), which revealed S. stercoralis [16,030 reads per million (RPM)] and cytomegalovirus (14,397RPM). Sputum smear microscopy showed motile S. stercoralis larvae, confirming the diagnosis. The patient was treated with albendazole (0.4 g via nasogastric tube twice daily) combined with ivermectin (12 mg via nasogastric tube once daily) for strongyloidiasis, together with ganciclovir for cytomegalovirus. Because of severe ARDS and possible autoimmune flare, methylprednisolone (80 mg intravenously every 12 h followed by tapering) was cautiously administered under effective anti-infective coverage. Two days after treatment, the oxygenation index improved from 77 mmHg to 214 mmHg. One week later, repeat MetaCAP showed a marked reduction of S. stercoralis reads to 69RPM and cytomegalovirus 9 RPM. The patient was successfully extubated and discharged after consolidation therapy. At nine-month follow-up he remained well. This case demonstrates that S. stercoralis hyperinfection can occur without eosinophilia in immunocompromised patients with autoimmune diseases and can rapidly progress to ARDS. MetaCAP of bronchoalveolar lavage fluid enables rapid and sensitive diagnosis. Short-term glucocorticoid therapy to control ARDS and autoimmune disease activity is feasible and safe provided that effective anti-infective treatment is in place.

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2026-08-19 | Intestinal Histomorphometric Alterations During Experimental Strongyloidiasis in Mice Treated with Rosmarinus officinalis Essential Oil.

Strongyloidiasis is an intestinal helminthiasis that can induce structural alterations in the intestinal mucosa during infection. The present study evaluated histomorphometric alterations of the small intestine in mice experimentally infected with Strongyloides venezuelensis and treated with Rosmarinus officinalis essential oil. Infected animals were treated orally with R. officinalis essential oil (200 or 400 mg/kg), ivermectin or control treatments. Histomorphometric parameters of the small intestine were evaluated, including villus height, epithelial height, crypt depth, muscular layer thickness, brush border height and goblet cell counts. Parasitological parameters were also assessed to characterize the infection model. Histomorphometric analysis demonstrated that treatment with essential oil at 200 mg/kg was associated with recovery of villus and epithelial height, increased brush border and goblet cell numbers, as well as attenuation of muscular layer hypertrophy, suggesting preservation of mucosal structure during infection. The 400 mg/kg dose, although associated with greater reduction in parasite burden, was accompanied by increased crypt depth, indicating more intense proliferative remodeling of the intestinal mucosa. Ivermectin promoted the greatest reduction in parasite burden with marked elimination of eggs and females. These findings indicate that R. officinalis essential oil modulates intestinal mucosal architecture during experimental strongyloidiasis and highlight its potential influence on host intestinal responses during infection.

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2026-08-13 | Recent advances in Strongyloides screening, diagnostics, therapeutics, and management.

Strongyloidiasis affects an estimated 30-100 million people globally and can have life-threatening consequences in immunocompromised hosts, yet it remains underdiagnosed due to limited access and performance of available diagnostics. Novel assays and anthelmintics may reshape screening, diagnosis, treatment, and prevention for at-risk populations. Advances in molecular diagnostics coupled with robust stool extraction methods have supplanted traditional parasitologic methods in settings where nucleic acid amplification is feasible. Transition from standard immunoglobulin G (IgG)-based immunoassays to the new IgG- and IgG4-based rapid diagnostic tests using recombinant Strongyloides stercoralis nematode immunodominant E antigen (NIE) and/or S. stercoralis immunoreactive antigen (SsIR) has facilitated serologic screening at the point of care. The World Health Organization now conditionally recommends community-wide ivermectin mass drug administration in highly endemic settings. Regarding new treatment options, moxidectin is noninferior to ivermectin with 93-94% cure rates and a longer half-life, while emodepside shows 80-90% predicted cure rates in early trials and offers a mechanistically distinct option. Understanding of immunosuppressed populations at risk for hyperinfection has expanded, prompting updated screening recommendations. Serologic and molecular tools are improving screening and diagnosis, and moxidectin and emodepside may broaden treatment options, but data in severe disease and special populations remain limited. Priorities include harmonized screening algorithms and prospective studies in high-risk groups.

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2026-08-09 | Phenotypic and genotypic characterization of human-derived Strongyloides stercoralis based on cox 1 gene.

Strongyloidiasis is a neglected tropical disease caused by the roundworm Strongyloides stercoralis. The prevalence of strongyloidiasis is higher in tropical and sub-tropical areas, there have been reports of infection in temperate regions. India is an endemic region for strongyloidiasis, however, there is extreme scarcity of molecular data related to S. stercoralis from this region. A cross sectional study was conducted in Varanasi, Uttar Pradesh, from July 2023 to January 2025. A total of 800 stool samples from patients were screened based on microscopy and confirmed through culture and molecular aspects. Conventional PCR targeting 18S rRNA and mitochondrial cytochrome c oxidase subunit 1 (cox1) gene for S. stercoralis detection was performed and positive S. stercoralis isolates underwent sequencing, phylogenetic analysis and subsequent haplotype mapping. This study identified S. stercoralis infection in 1.1% (9/800) in human stool samples via microscopy, culture and phylogenetic analysis. Clustering of Indian isolates with Asian lineages based on cox 1 sequencing revealed its potential role as biomarker. Haplotype mapping and codon-based analysis showed five novel haplotypes (Hd = 0.6667) including three novel haplotypes, under purifying selection and transition-biased substitutions. This study inclusively underscores the importance of integrating molecular/genetic data into epidemiological frameworks to predictive public health action. By utilizing mitochondrial cox 1 gene for phylogenetic insights and haplotype mapping, the study revealed Indian isolates clustered strongly with Asian lineages.

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cell therapies

2026-04-14 | CD160-competent ILC2 are crucial for the ejection of intestinal helminths by the innate immune system.

1.6 billion people are currently infected with parasitic worms. Group 2 innate lymphoid cells (ILC2) play a central role in promoting the protective type 2 immunity against these parasites. Here we show that a subpopulation of intestinal ILC2 express the immune checkpoint molecule CD160 in mice infected with the parasitic nematode Strongyloides ratti. CD160+ ILC2 represented a distinct ST2-IL-17RB+Ki-67+ subset that expanded in vivo during S. ratti infection. By contrast, CD160- ILC2 were ST2+IL-17RB-Ki-67- and represented the dominant producers of type 2 cytokines. Upon in vitro stimulation, sorted CD160+ ILC2 progressively lost CD160 expression and acquired cytokine-producing capacity. While CD160-competent RAG KO mice efficiently controlled S. ratti infection with less than 1% of the infective dose remaining by day 10 post-infection, CD160-deficient RAG KO mice failed to expand intestinal ILC2, failed to activate mucosal mast cells and retained high intestinal worm burden for nearly 100 days. Adoptive transfer of CD160-competent ILC2 into S. ratti-infected CD160-deficient RAG KO mice partially restored mast cell activation and reduced intestinal worm burden by 50%. Collectively, these findings identify CD160 expression as a critical checkpoint in the development and expansion of fully functional ILC2 required for effective immunity against intestinal helminth infection.

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2025-10-31 | Fecal microbiota transplantation as salvage therapy for disseminated strongyloidiasis in an immunosuppressed patient: a case report.

Disseminated strongyloidiasis carries high mortality in immunosuppressed populations. We report a case of refractory Strongyloides stercoralis-induced severe diarrhea and sepsis successfully treated with fecal microbiota transplantation (FMT). A 68-year-old male with nephrotic syndrome on long-term glucocorticoids developed hyperinfection syndrome manifesting as septic shock, multiorgan dysfunction, and intractable diarrhea (>30 episodes/day). Conventional therapies including antiparasitics (albendazole), antibiotics, and probiotics failed. FMT achieved rapid symptom resolution and microbiota restoration. This case highlights FMT's potential in modulating gut-parasite interactions and suggests its role as adjunctive therapy for parasitic hyperinfection syndromes.

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2014-10-03 | Foxp3⁺ regulatory T cells delay expulsion of intestinal nematodes by suppression of IL-9-driven mast cell activation in BALB/c but not in C57BL/6 mice.

Accumulating evidence suggests that IL-9-mediated immunity plays a fundamental role in control of intestinal nematode infection. Here we report a different impact of Foxp3⁺ regulatory T cells (Treg) in nematode-induced evasion of IL-9-mediated immunity in BALB/c and C57BL/6 mice. Infection with Strongyloides ratti induced Treg expansion with similar kinetics and phenotype in both strains. Strikingly, Treg depletion reduced parasite burden selectively in BALB/c but not in C57BL/6 mice. Treg function was apparent in both strains as Treg depletion increased nematode-specific humoral and cellular Th2 response in BALB/c and C57BL/6 mice to the same extent. Improved resistance in Treg-depleted BALB/c mice was accompanied by increased production of IL-9 and accelerated degranulation of mast cells. In contrast, IL-9 production was not significantly elevated and kinetics of mast cell degranulation were unaffected by Treg depletion in C57BL/6 mice. By in vivo neutralization, we demonstrate that increased IL-9 production during the first days of infection caused accelerated mast cell degranulation and rapid expulsion of S. ratti adults from the small intestine of Treg-depleted BALB/c mice. In genetically mast cell-deficient (Cpa3-Cre) BALB/c mice, Treg depletion still resulted in increased IL-9 production but resistance to S. ratti infection was lost, suggesting that IL-9-driven mast cell activation mediated accelerated expulsion of S. ratti in Treg-depleted BALB/c mice. This IL-9-driven mast cell degranulation is a central mechanism of S. ratti expulsion in both, BALB/c and C57BL/6 mice, because IL-9 injection reduced and IL-9 neutralization increased parasite burden in the presence of Treg in both strains. Therefore our results suggest that Foxp3⁺ Treg suppress sufficient IL-9 production for subsequent mast cell degranulation during S. ratti infection in a non-redundant manner in BALB/c mice, whereas additional regulatory pathways are functional in Treg-depleted C57BL/6 mice.

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2014-02-20 | Human and mouse macrophages collaborate with neutrophils to kill larval Strongyloides stercoralis.

Macrophages are multifunctional cells that are active in TH1- and TH2-mediated responses. In this study, we demonstrate that human and mouse macrophages collaborate with neutrophils and complement to kill the parasite Strongyloides stercoralis in vitro. Infection of mice with worms resulted in the induction of alternatively activated macrophages (AAM) within the peritoneal cavity. These cells killed the worms in vivo and collaborated with neutrophils and complement during the in vitro killing process. AAM generated in vitro killed larvae more rapidly than naive macrophages, which killed larvae after a longer time period. In contrast, classically activated macrophages were unable to kill larvae either in vitro or in vivo. This study adds macrophages to the armamentarium of immune components that function in elimination of parasitic helminths and demonstrate a novel function by which AAM control large extracellular parasites.

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2011-06-16 | Strongyloides ratti infection induces expansion of Foxp3+ regulatory T cells that interfere with immune response and parasite clearance in BALB/c mice.

To escape expulsion by their host's immune system, pathogenic nematodes exploit regulatory pathways that are intrinsic parts of the mammalian immune system, such as regulatory T cells (Tregs). Using depletion of Treg mice, we showed that Foxp3(+) Treg numbers increased rapidly during infection with the nematode Strongyloides ratti. Transient depletion of Tregs during the first days of infection led to dramatically reduced worm burden and larval output, without aggravation of immune pathology. The transient absence of Tregs during primary infection did not interfere with the generation of protective memory. Depletion of Tregs at later time points of infection (i.e., day 4) did not improve resistance, suggesting that Tregs exert their counterregulatory function during the priming of S. ratti-specific immune responses. Improved resistance upon early Treg depletion was accompanied by accelerated and prolonged mast cell activation and increased production of types 1 and 2 cytokines. In contrast, the blockade of the regulatory receptor CTLA-4 specifically increased nematode-specific type 2 cytokine production. Despite this improved immune response, resistance to the infection was only marginally improved. Taken together, we provide evidence that Treg expansion during S. ratti infection suppresses the protective immune response to this pathogenic nematode and, thus, represents a mechanism of immune evasion.

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antibodies

2025-03-12 | Myeloid-derived IL-33 drives γδ T cell-dependent resistance against cutaneous infection by Strongyloides ratti.

Interleukin 33 (IL-33) is a pleiotropic cytokine released from diverse cell types that regulate both pro- and anti-inflammatory responses during pathogen infection. However, it remains unclear whether IL-33 controls key aspects of cutaneous immunity against skin-penetrating parasites. In this study, mice percutaneously infected with the parasitic helminth Strongyloides ratti were investigated to understand mechanisms of anamnestic immunity at the skin barrier. Surprisingly, mice lacking the Type 2 transcription factor STAT6 (signal transducer and activator of transcription 6) had no defects in secondary resistance to infection, whereas IL-33 gene deficiency or local blockade of IL-33 receptor (ST2) signaling abrogated host resistance. Depletion of CD4+ T cells or type 2 innate lymphoid cells had only a moderate impact on protection, but the loss of γδ T cells completely ablated cutaneous immunity against rechallenge. We identified a CD62Lhi IL-33 receptor (ST2)-expressing γδ T cell population that accumulated in the skin of protected mice that was dependent upon IL-33 expression in myeloid lineage antigen-presenting cells. This work suggests a previously unrecognized mechanism wherein noncanonical type 2 immunity operates through myeloid antigen-presenting cells and skin γδ T cells to adaptively repel skin-penetrating helminth larvae.

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2021-01-28 | Broad specificity of immune helminth scFv library to identify monoclonal antibodies targeting Strongyloides

Abstract Antibodies have different chemical properties capable of targeting a diverse nature of antigens. Traditionally, immune antibody libraries are perceived to be disease-specific with a skewed repertoire. The complexity during the generation of a combinatorial antibody library allows for a skewed but diverse repertoire to be generated. Strongyloides stercoralis is a parasite that causes strongyloidiasis, a potentially life-threatening disease with a complex diagnosis that impedes effective control and treatment of the disease. This study describes the isolation of monoclonal antibodies against S. stercoralis NIE recombinant protein using an immune antibody phage display library derived from lymphatic filaria-infected individuals. The isolated antibody clones showed both lambda and kappa light chains gene usage, with diverse amino acid distributions. Structural analysis showed that electropositivity and the interface area could determine the binding affinity of the clones with NIE. The successful identification of S. stercoralis antibodies from the filarial immune library highlights the breadth of antibody gene diversification in an immune antibody library that can be applied for closely related infections.

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2019-05-14 | Detection of immune complexes and evaluation of alcoholic individuals' serological profile in the diagnosis of strongyloidiasis.

Strongyloidiasis is a human parasitosis that is considered a public health problem. Early diagnosis of this infection is extremely important in immunocompromised patients (i.e. subjects with alcoholism). This study aimed to evaluate anti-Strongyloides immunoglobulin G (IgG) and immunoglobulin A (IgA), assess levels of circulating immune complexes (IC) and determine IgG avidity in serum samples from alcoholic and nonalcoholic individuals. A total of 140 blood samples were collected from male individuals (70 alcoholic and 70 nonalcoholic subjects). Serum was obtained and analysed by enzyme-linked immunosorbent assay for IgG, IgA, IC detection and avidity determination. Anti-Strongyloides IgG was detected in 55.7% of alcoholic subjects and 32.8% nonalcoholics, while IC levels showed frequencies of 38.6% and 17.1% in these groups, respectively. Anti-Strongyloides IgA was lower among alcoholics (4.3%) than nonalcoholics (34.3%). Spearman's correlation coefficient reported a positive correlation between IgG, IC and IgA in alcoholic individuals and no correlation in nonalcoholics. The median avidity index was higher in alcoholics (83.8%) than nonalcoholic subjects (73.2%). In conclusion, this study shows that alcoholic subjects produced specific antibodies against S. stercoralis regardless of the possible immunosuppression caused by chronic alcoholism. Considering that alcoholics are more susceptible to the severe forms of strongyloidiasis, the implementation of immunological methods as a complementary approach to parasitological diagnostics (i.e. detection of IgG, IC and antibody avidity) appears to be an alternative method for early diagnosis in these individuals.

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2017-11-15 | P20 Latent helminth disease as a cause of eosinophilia in respiratory patients

Introduction

Within the UK, eosinophilia is most commonly associated with allergy and respiratory diseases such as asthma. Increasingly raised blood eosinophil counts are seen as a biomarker of heightened Th2 inflammation indicating a need to prescribe steroids in airways diseases. New treatments for severe Th2-high asthma aim to inhibit the eosinophilic pathway to reduce pathological inflammation. However by inhibiting this pathway we risk suppressing the body’s natural defences against parasitic helminth disease – in patients with asymptomatic latent Strongyloides stercoralis there is the risk of catastrophic hyper-infection. Our particular patient cohort in East London is a diverse international community who travel frequently. We therefore sought to evaluate the prevalence of asymptomatic helminth disease in respiratory, and particularly asthma patients, within our Trust, which includes a severe asthma service where we prescribe biologics that inhibit the Th2 pathway.

Methods

We prospectively tested eosinophilic patients reviewed in respiratory clinic for helminth infection using serological screening as part of a Service Evaluation. Inclusion criteria were an eosinophilia (≥0.3) or those being considered for treatment with Mepoluzimab. Patients were tested for strongyloidiasis, filariasis and schistosomiasis depending on travel history. Patients symptomatic of helminth infection (e.g., diarrhoea) were excluded from this evaluation.

Results

We tested 80 patients, 32 from severe asthma clinic, 42 from the general asthma clinic and 6 from other clinics. From these 16 (20%) had positive parasite serology: 14 of these were for Strongyloides stercoralis and 1 each for filarial and schistosomal. All the positives had asthma and 4 were from the severe asthma service. The average IgE was 433 and the average eosinophil count was 0.7. There was no statistical difference between the eosinophil counts, or total IgEs, between the positive and negative groups.

Conclusion

There is a high prevalence of asymptomatic parasitic infection within our cohort, suggesting local patients who have an eosinophilia should be screened for helminth disease even in the presence of another cause eosinophilia. Furthermore, we recommend all patients being assessed for a biologic that would inhibit Th2 responses, such as Mepoluzimab, should be screened for latent Stronglyloides stercoralis infection given the danger of hyper-infection upon immunosuppression.

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2017-07-14 | A Rare Case of Strongyloides Hyperinfection from Hypogammaglobulinemia

Strongyloides infection can range from asymptomatic eosinophilia to disseminated disease. Common in tropical and subtropical nations, it can lead to hyperinfection, an autoinfection increasing parasitic burden in immunocompromised. Cell-mediated immunity is important in combating parasite infection. We present a case of Strongyloides hyperinfection in hypogammaglobulinemia which was refractory to conventional treatment but responded to immunoglobulin administration with complete resolution indicating role of humoral immunity also.

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other

2026-06-03 | Molecular characterisation of extracellular vesicles released by Strongyloides stercoralis infective larvae isolated from a clinical sample

Abstract Background Extracellular vesicles (EVs) represent a key mechanism of host–pathogen crosstalk. Numerous helminth parasites have already been reported to shed EV-like structures carrying biomolecules, including small RNAs (sRNAs), with functional effects on target cells. However, the ability of Strongyloides stercoralis to release EVs has yet to be demonstrated. Methods and results Following the isolation of S. stercoralis infective larvae (iL3s) from faecal samples obtained from a patient with strongyloidiasis, we showed that iL3s maintained in vitro for up to 48 h release EV-like structures. Transmission electron microscopy and nanoparticle tracking analysis highlighted vesicular structures enclosed by a bilayer and with a diameter of 120 nm in range. Small RNA sequencing identified multiple EV-associated sRNA types, including miRNAs, only partly overlapping with the previously described somatic miRNome. Comparative analyses revealed that several EV-associated miRNAs were conserved amongst Strongyloides spp., whereas others appeared specific to S. stercoralis. Prediction analyses indicated that miRNAs and other sRNAs may target human genes associated with the regulation of gene expression and immune response, supporting a potential role in host–parasite interaction. Conclusions These findings provide the first experimental evidence that S. stercoralis iL3s release EVs carrying regulatory sRNAs and suggest that EV-mediated RNA delivery may represent an additional tool for host–pathogen interaction. More in-depth investigations of these EVs may provide novel insights into the pathophysiology of strongyloidiasis as well as novel targets for clinical applications. Graphical Abstract

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2024-06-05 | The generation of stable transgenic lines in the human-infective nematode Strongyloides stercoralis.

The skin-penetrating gastrointestinal parasitic nematode Strongyloides stercoralis causes strongyloidiasis, which is a neglected tropical disease that is associated with severe chronic illness and fatalities. Unlike other human-infective nematodes, S. stercoralis cycles through a single free-living generation and thus serves as a genetically tractable model organism for understanding the mechanisms that enable parasitism. Techniques such as CRISPR/Cas9-mediated mutagenesis and transgenesis are now routinely performed in S. stercoralis by introducing exogenous DNA into free-living adults and then screening their F1 progeny for transgenic or mutant larvae. However, transgenesis in S. stercoralis has been severely hindered by the inability to establish stable transgenic lines that can be propagated for multiple generations through a host; to date, studies of transgenic S. stercoralis have been limited to heterogeneous populations of transgenic F1 larvae. Here, we develop an efficient pipeline for the generation of stable transgenic lines in S. stercoralis. We also show that this approach can be used to efficiently generate stable transgenic lines in the rat-infective nematode Strongyloides ratti. The ability to generate stable transgenic lines circumvents the limitations of working with heterogeneous F1 populations, such as variable transgene expression and the inability to generate transgenics of all life stages. Our transgenesis approach will enable novel lines of inquiry into parasite biology, such as transgene-based comparisons between free-living and parasitic generations.

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2019-03-29 | RNAi-mediated knockdown of daf-12 in the model parasitic nematode Strongyloides ratti

The gene daf-12 has long shown to be involved in the dauer pathway in Caenorhabditis elegans (C. elegans). Due to the similarities of the dauer larvae of C. elegans and infective larvae of certain parasitic nematodes such as Strongyloides spp., this gene has also been suspected to be involved in the development of infective larvae. Previous research has shown that the application of dafachronic acid, the steroid hormone ligand of DAF-12 in C. elegans, affects the development of infective larvae and metabolism in Strongyloides. However, a lack of tools for either forward or reverse genetics within Strongyloides has limited studies of gene function within these important parasites. After determining whether Strongyloides had the requisite proteins for RNAi, we developed and report here the first successful RNAi by soaking protocol for Strongyloides ratti (S. ratti) and use this protocol to study the functions of daf-12 within S. ratti. Suppression of daf-12 in S. ratti severely impairs the formation of infective larvae of the direct cycle and redirects development towards the non-infective (non-dauer) free-living life cycle. Further, daf-12(RNAi) S. ratti produce slightly but significantly fewer offspring and these offspring are developmentally delayed or incapable of completing their development to infective larvae (L3i). Whilst the successful daf-12(RNAi) L3i are still able to infect a new host, the resulting infection is less productive and shorter lived. Further, daf-12 knockdown affects metabolism in S. ratti resulting in a shift from aerobic towards anaerobic fat metabolism. Finally, daf-12(RNAi) S. ratti have reduced tolerance of temperature stress.

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2012-12-17 | Transposon-mediated chromosomal integration of transgenes in the parasitic nematode Strongyloides ratti and establishment of stable transgenic lines.

Genetic transformation is a potential tool for analyzing gene function and thereby identifying new drug and vaccine targets in parasitic nematodes, which adversely affect more than one billion people. We have previously developed a robust system for transgenesis in Strongyloides spp. using gonadal microinjection for gene transfer. In this system, transgenes are expressed in promoter-regulated fashion in the F1 but are silenced in subsequent generations, presumably because of their location in repetitive episomal arrays. To counteract this silencing, we explored transposon-mediated chromosomal integration of transgenes in S. ratti. To this end, we constructed a donor vector encoding green fluorescent protein (GFP) under the control of the Ss-act-2 promoter with flanking inverted tandem repeats specific for the piggyBac transposon. In three experiments, free-living Strongyloides ratti females were transformed with this donor vector and a helper plasmid encoding the piggyBac transposase. A mean of 7.9% of F1 larvae were GFP-positive. We inoculated rats with GFP-positive F1 infective larvae, and 0.5% of 6014 F2 individuals resulting from this host passage were GFP-positive. We cultured GFP-positive F2 individuals to produce GFP-positive F3 L3i for additional rounds of host and culture passage. Mean GFP expression frequencies in subsequent generations were 15.6% in the F3, 99.0% in the F4, 82.4% in the F5 and 98.7% in the F6. The resulting transgenic lines now have virtually uniform GFP expression among all progeny after at least 10 generations of passage. Chromosomal integration of the reporter transgenes was confirmed by Southern blotting and splinkerette PCR, which revealed the transgene flanked by S. ratti genomic sequences corresponding to five discrete integration sites. BLAST searches of flanking sequences against the S. ratti genome revealed integrations in five contigs. This result provides the basis for two powerful functional genomic tools in S. ratti: heritable transgenesis and insertional mutagenesis.

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2011-12-02 | In silico secretome analysis approach for next generation sequencing transcriptomic data

Excretory/secretory proteins (ESPs) play a major role in parasitic infection as they are present at the host-parasite interface and regulate host immune system. In case of parasitic helminths, transcriptomics has been used extensively to understand the molecular basis of parasitism and for developing novel therapeutic strategies against parasitic infections. However, none of transcriptomic studies have extensively covered ES protein prediction for identifying novel therapeutic targets, especially as parasites adopt non-classical secretion pathways. We developed a semi-automated computational approach for prediction and annotation of ES proteins using transcriptomic data from next generation sequencing platforms. For the prediction of non-classically secreted proteins, we have used an improved computational strategy, together with homology matching to a dataset of experimentally determined parasitic helminth ES proteins. We applied this protocol to analyse 454 short reads of parasitic nematode, Strongyloides ratti. From 296231 reads, we derived 28901 contigs, which were translated into 20877 proteins. Based on our improved ES protein prediction pipeline, we identified 2572 ES proteins, of which 407 (1.9%) proteins have classical N-terminal signal peptides, 923 (4.4%) were computationally identified as non-classically secreted while 1516 (7.26%) were identified by homology to experimentally identified parasitic helminth ES proteins. Out of 2572 ES proteins, 2310 (89.8%) ES proteins had homologues in the free-living nematode Caenorhabditis elegans and 2220 (86.3%) in parasitic nematodes. We could functionally annotate 1591 (61.8%) ES proteins with protein families and domains and establish pathway associations for 691 (26.8%) proteins. In addition, we have identified 19 representative ES proteins, which have no homologues in the host organism but homologous to lethal RNAi phenotypes in C. elegans, as potential therapeutic targets. We report a comprehensive approach using freely available computational tools for the secretome analysis of NGS data. This approach has been applied to S. ratti 454 transcriptomic data for in silico excretory/secretory proteins prediction and analysis, providing a foundation for developing new therapeutic solutions for parasitic infections.

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