Immunoproteomic analysis of Schistosoma japonicum schistosomulum proteins recognized by immunoglobulin G in the sera of susceptible and non-susceptible hosts

Transmission-Blocking Vaccines against Schistosomiasis Japonica

Control of schistosomiasis japonica, endemic in Asia, including the Philippines, China, and Indonesia, is extremely challenging. Schistosoma japonicum is a highly pathogenic helminth parasite, with disease arising predominantly from an immune reaction to entrapped parasite eggs in tissues. Females of this species can generate 1000-2200 eggs per day, which is about 3- to 15-fold greater than the egg output of other schistosome species. Bovines (water buffalo and cattle) are the predominant definitive hosts and are estimated to generate up to 90% of parasite eggs released into the environment in rural endemic areas where these hosts and humans are present. Here, we highlight the necessity of developing veterinary transmission-blocking vaccines for bovines to better control the disease and review potential vaccine candidates. We also point out that the approach to producing efficacious transmission-blocking animal-based vaccines before moving on to human vaccines is crucial. This will result in effective and feasible public health outcomes in agreement with the One Health concept to achieve optimum health for people, animals, and the environment. Indeed, incorporating a veterinary-based transmission vaccine, coupled with interventions such as human mass drug administration, improved sanitation and hygiene, health education, and snail control, would be invaluable to eliminating zoonotic schistosomiasis.

Transcriptional profiling of Microtus fortis responses to S. japonicum: New sight into Mf-Hsp90α resistance mechanism

AIMS

Schistosomiasis is a parasitic disease with a chronic debilitating character caused by parasitic flatworms of the genus Schistosoma. The main disease-causing species of Schistosoma in China is S. japonicum. M fortis has been proved to be a nonpermissive host of S. japonicum. Mf-HSP90α (Microtus fortis heat shock protein 90alpha), the homologue of HSP90α, display anti-schistosome effect in vitro and in vivo. In the current study, in order to investigate the mechanism of anti-schistosome effect of Mf-HSP90α, we conducted RNA-Seq to obtain the transcriptome profile of M. fortis liver infected with S. japonicum at different time points.

METHODS AND RESULTS

By mapping the differential expressed genes (DEGs) to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG), we found that the JAK2/STAT1 pathway was highly enriched with an elevated level of IL-10 and HSP90α. We then checked the IL-10-JAK2/STAT1-HSP90α pathway, and found that this pathway was activated in the infected mice with S. japonicum. The expression of the molecules in this pathway was elevated on the 10^th day after infection and gradually decreased on the 20^th day.

CONCLUSIONS

The IL-10-JAK2/STAT1-HSP90α axis was associated with the anti-schistosome effect of Mf-HSP90α, and targeting IL-10-JAK2/STAT1-HSP90α axis might be a novel therapeutic strategy for developing resistance to S. japonicum infection.

The Potential Role of Schistosome-Associated Factors as Therapeutic Modulators of the Immune System

The parasites and eggs of helminths, including schistosomes, are associated with factors that can modulate the nature and outcomes of host immune responses, particularly enhancing type 2 immunity and impairing the effects of type 1 and type 17 immunity. The main species of schistosomes that cause infection in humans are capable of generating a microenvironment that allows survival of the parasite by evasion of the immune response. Schistosome infections are associated with beneficial effects on chronic immune disorders, including allergies, autoimmune diseases, and alloimmune responses. Recently, there has been increasing research interest in the role of schistosomes in immunoregulation during human infection, and the mechanisms underlying these roles continue to be investigated. Further studies may identify potential opportunities to develop new treatments for immune disease. In this review, we provide an update on the advances in our understanding of schistosome-associated modulation of the cells of the innate and adaptive immune systems as well as the potential role of schistosome-associated factors as therapeutic modulators of immune disorders, including allergies, autoimmune diseases, and transplant immunopathology. We also discuss potential opportunities for targeting schistosome-induced immunoregulation for future translation to the clinical setting.

Recent advances in Schistosoma mekongi ecology, transcriptomics and proteomics of relevance to snail control

Mekong schistosomiasis caused by Schistosoma mekongi is a public health problem that occurs along the border between southern Laos and northern Cambodia. Given its restricted distribution and low prevalence, eventual eradication via an effective control program can be expected to be successful. To achieve this goal detailed knowledge of its basic biology, molecular biology, biochemistry, and pathology is urgently required. In this regard, recent studies on transcriptome analysis of adult male and female S. mekongi worms, and proteome analysis of developmental stages have been reported and are discussed here. The biology, habitat, and distribution of the snail intermediate host Neotricula aperta, which are factors in disease transmission, are discussed in this review. These have initiated renewed interest in S. mekongi research and contributed promising data that will be utilized in the generation of effective control and prevention strategies.

A novel ex vivo immunoproteomic approach characterising Fasciola hepatica tegumental antigens identified using immune antibody from resistant sheep

A more thorough understanding of the immunological interactions between Fasciola spp. and their hosts is required if we are to develop new immunotherapies to control fasciolosis. Deeper knowledge of the antigens that are the target of the acquired immune responses of definitive hosts against both Fasciola hepatica and Fasciola gigantica will potentially identify candidate vaccine antigens. Indonesian Thin Tail sheep express a high level of acquired immunity to infection by F. gigantica within 4weeks of infection and antibodies in Indonesian Thin Tail sera can promote antibody-dependent cell-mediated cytotoxicity against the surface tegument of juvenile F. gigantica in vitro. Given the high protein sequence similarity between F. hepatica and F. gigantica, we hypothesised that antibody from F. gigantica-infected sheep could be used to identify the orthologous proteins in the tegument of F. hepatica. Purified IgG from the sera of F. gigantica-infected Indonesian Thin Tail sheep collected pre-infection and 4weeks p.i. were incubated with live adult F. hepatica ex vivo and the immunosloughate (immunoprecipitate) formed was isolated and analysed via liquid chromatography-electrospray ionisation-tandem mass spectrometry to identify proteins involved in the immune response. A total of 38 proteins were identified at a significantly higher abundance in the immunosloughate using week 4 IgG, including eight predicted membrane proteins, 20 secreted proteins, nine proteins predicted to be associated with either the lysosomes, the cytoplasm or the cytoskeleton and one protein with an unknown cellular localization. Three of the membrane proteins are transporters including a multidrug resistance protein, an amino acid permease and a glucose transporter. Interestingly, a total of 21 of the 38 proteins matched with proteins recently reported to be associated with the proposed small exosome-like extracellular vesicles of adult F. hepatica, suggesting that the Indonesian Thin Tail week 4 IgG is either recognising individual proteins released from extracellular vesicles or is immunoprecipitating intact exosome-like extracellular vesicles. Five extracellular vesicle membrane proteins were identified including two proteins predicted to be associated with vesicle transport/ exocytosis (VPS4, vacuolar protein sorting-associated protein 4b and the Niemann-Pick C1 protein). RNAseq analysis of the developmental transcription of the 38 immunosloughate proteins showed that the sequences are expressed over a wide abundance range with 21/38 transcripts expressed at a relatively high level from metacercariae to the adult life cycle stage. A notable feature of the immunosloughates was the absence of cytosolic proteins which have been reported to be secreted markers for damage to adult flukes incubated in vitro, suggesting that the proteins observed are not inadvertent contaminants leaking from damaged flukes ex vivo. The identification of tegument protein antigens shared between F. gigantica and F. hepatica is beneficial in terms of the possible development of a dual purpose vaccine effective against both fluke species.