Immunoprotection of recombinant Eg.P29 against Echinococcus granulosus in sheep

Synthetic rEg.P29 Peptides Induce Protective Immune Responses Against Echinococcus granulosus in Mice

Background:Echinococcus granulosus represents a significant threat to animal husbandry and human health, but its consequences are often underestimated. Vaccination can prevent E. granulosus infection. We investigated the immune protective effect induced by the recombinant protein P29 of E. granulosus (rEg.P29) peptide vaccine. Methods: The CD4+ T-, CD8+ T-, Treg-, and CD8+CD107a+ T-cell proportions in the spleen and peripheral blood of infected mice were analyzed using flow cytometry. Additionally, we measured the proportions of IFN-γ and IL-2 secreted by memory T cells, CD19+CD138-B cells, CD19+CD138+ plasmablasts, CD19-CD138+ plasma cells, and CD19+IgD-IgG+ and CD19+IgD-IgA+ memory B cells. Results: No significant differences were noted in CD4+ T-, CD8+ T-, and CD8+CD107a+ Treg-cell percentages among the experimental groups. However, IFN-γ, IL-2, and TNF-α levels and vaccine-specific antibody concentrations in the plasma were significantly elevated in the rEg.P29T+B + CpG + infection and rEg.P29 + CpG + infection groups compared to those in the PBS + infection and CpG + infection groups. Similarly, CD19-CD138+ plasma cell and CD19+IgD-IgG+ and CD19+IgD-IgA+ memory B-cell populations, along with specific antibodies, were significantly higher in these groups. Especially, the average cyst burden in the rEg.P29T+B + CpG + infection and rEg.P29 + CpG + infection groups was significantly reduced compared to that in the PBS + infection and CpG + infection groups. Conclusions: Synthetic peptide vaccines targeting rEg.P29 can effectively inhibit cysts, offering a novel strategy for the development of vaccines against E. granulosus. These findings provide a foundation for further research on the immunogenicity and protective efficacy of rEg.P29-based vaccines.

Preliminary In silico Analysis of Echinococcus granulosus Calreticulin for Enhanced Vaccine Design against Cystic Echinococcosis

BACKGROUND

A neglected zoonosis, Cystic Echinococcosis (CE), is most common in developing nations worldwide. Vaccination is, therefore, helpful in preventing this disease.

OBJECTIVE

Predicting the main biochemical properties of E. granulosus Calreticulin (CRT) and its possible B-cell and T-cell-binding epitopes as a valuable candidate for immunization was the goal of the current study.

METHODS

Predictions were made to determine biochemical, antigenic, structural, and subcellular characteristics, along with the immunogenic epitopes, using several online servers.

RESULTS

The extracellular 48.15 KDa protein exhibited no allergenicity, while possessing hydrophilicity (GRAVY: -0.785), stability (instability: 33.88), tolerance to a wide range of temperatures (aliphatic: 62.45), and 59 post-translational modification sites. The secondary structure mostly comprised random coils and extended strands. The 3D model was generated using the Robetta server (confidence: 0.72), and was rehashed and confirmed subsequently. Common B-cell epitopes were discovered by three servers and screened for antigenic, allergenic, and solubility traits. Moreover, MHC-associated epitopes for mice and humans were predicted in E. granulosus CRT with subsequent screening.

CONCLUSION

This work offers a foundation for further investigation in order to design an effective vaccination against CE. Further empirical research on the examined protein solely or in combination with other antigens is needed.

Designing multi-epitope vaccines against Echinococcus granulosus: an in-silico study using immuno-informatics

Cystic echinococcosis (CE) is a worldwide zoonotic public health issue. The reasons for this include a lack of specific therapy options, increasing antiparasitic drug resistance, a lack of control strategies, and the absence of an approved vaccine. The aim of the current study is to develop a multiepitope vaccine against CE by in-silico identification and using different Antigen B subunits. The five Echinococcus granulosus antigen B (EgAgB) subunits were examined for eminent antigenic epitopes, and then the best B-cell and Major Histocompatibility Complex MHC-binding epitopes were predicted. Most significant epitopes were combined to create an effective multi-epitope vaccine, which was then validated by testing its secondary and tertiary structures, physicochemical properties, and molecular dynamics (MD) modelling. A multi-epitope vaccine construct of 483 amino acid sequences was designed. It contains B-cell, Helper T Lymphocyte (HTL), and Cytotoxic T Lymphocyte (CTL) epitopes as well as the appropriate adjuvant and linker molecules. The resultant vaccinal construct had a GDT-HA value of 0.9725, RMSD of 0.299, MolProbity of 1.891, Clash score of 13.1, Poor rotamers of 0.9, and qualifying features with Rama favoured of 89.9. It was also highly immunogenic and less allergic. The majority of the amino acids were positioned in the Ramachandran plot's favourable area, and during the molecular dynamic simulation at 100 ns, no notable structural abnormalities were noticed. The resultant construct was significantly expressed and received good endorsement in the pIB2-SEC13-mEGFP expressional vector. In conclusion, the current in-silico multi-epitope vaccine may be evaluated in-vitro, in-vivo, and in clinical trials as an immunogenic vaccine model. It can also play a vital role in preventing this zoonotic parasite infection.

Optimizing sheep B-cell epitopes in Echinococcus granulosus recombinant antigen P29 for vaccine development

Background

Echinococcus granulosus is a widespread zoonotic parasitic disease, significantly impacting human health and livestock development; however, no vaccine is currently available for humans. Our preliminary studies indicate that recombinant antigen P29 (rEg.P29) is a promising candidate for vaccine.

Methods

Sheep were immunized with rEg.P29, and venous blood was collected at various time points. Serum was isolated, and the presence of specific antibodies was detected using ELISA. We designed and synthesized a total of 45 B cell monopeptides covering rEg.P29 using the overlap method. ELISA was employed to assess the serum antibodies of the immunized sheep for recognition of these overlapping peptides, leading to the preliminary identification of B cell epitopes. Utilizing these identified epitopes, new single peptides were designed, synthesized, and used to optimize and confirm B-cell epitopes.

Results

rEg.P29 effectively induces a sustained antibody response in sheep, particularly characterized by high and stable levels of IgG. Eight B-cell epitopes of were identified, which were mainly distributed in three regions of rEg.P29. Finally, three B cell epitopes were identified and optimized: rEg.P2971-90, rEg.P29151-175, and rEg.P29211-235. These optimized epitopes were well recognized by antibodies in sheep and mice, and the efficacy of these three epitopes significantly increased when they were linked in tandem.

Conclusion

Three B-cell epitopes were identified and optimized, and the efficacy of these epitopes was significantly enhanced by tandem connection, which indicated the feasibility of tandem peptide vaccine research. This laid a solid foundation for the development of epitope peptide vaccine for Echinococcus granulosus.

Enhancing the therapeutic potential of P29 protein-targeted monoclonal antibodies in the management of alveolar echinococcosis through CDC-mediated mechanisms

Alveolar echinococcosis (AE) is a highly lethal helminth infection. Current chemotherapeutic strategies for AE primarily involve the use of benzimidazoles (BZs) such as mebendazole (MDZ) and albendazole (ABZ), which exhibit limited efficacy. In a previous study, the vaccine of recombinant Echinococcus granulosus P29 (rEgP29) showed significant immunoprotection against E. granulosus in both mice and sheep. In the current study, we utilized hybridoma technology to generate five monoclonal antibodies (mAbs) against P29, among which 4G10F4 mAb exhibited the highest antigen-specific binding capacity. This mAb was selected for further investigation of anti-AE therapy, both in vivo and in vitro. In vitro, 4G10F4 inhibited a noteworthy inhibition of E. multilocularis protoscoleces and primary cells viability through complement-dependent cytotoxicity (CDC) mechanism. In vivo, two experiments were conducted. In the first experiment, mice were intraperitoneally injected with Em protoscoleces, and subsequently treated with 4G10F4 mAb (2.5/5/10 mg/kg) at 12 weeks postinfection once per week for 8 times via tail vein injection. Mice that were treated with 4G10F4 mAb only in dosage of 5mg/kg exhibited a significant lower mean parasite burden (0.89±0.97 g) compared to isotype mAb treated control mice (2.21±1.30 g). In the second experiment, mice were infected through hepatic portal vein and treated with 4G10F4 mAb (5mg/kg) at one week after surgery once per week for 8 times. The numbers of hepatic metacestode lesions of the 4G10F4 treatment group were significantly lower in comparison to the isotype control group. Pathological analysis revealed severe disruption of the inner structure of the metacestode in both experiments, particularly affecting the germinal and laminated layers, resulting in the transformation into infertile vesicles after treatment with 4G10F4. In addition, the safety of 4G10F4 for AE treatment was confirmed through assessment of mouse weight and evaluation of liver and kidney function. This study presents antigen-specific monoclonal antibody immunotherapy as a promising therapeutic approach against E. multilocularis induced AE.

Immunoprotective effect and mechanism of rEg.P29 against CD4 + T cell-deficient mice with Echinococcus multilocularis infection

Alveolar echinococcosis (AE) is a zoonotic parasitic disease caused by infection with the larval stage of Echinococcus multilocularis and a major challenge to human public health. Vaccines are the most effective way to prevent and control infectious diseases. We previously revealed that the Echinocuccus granulosus recombinant protein P29 is a good vaccine candidate against E. granulosus. However, the protective and immunological mechanism of rEg.P29 against E. multilocularis remain unclear. In this study, CD4 + T cell-deficient mice are transferred with spleen CD4 + T cells isolated from wild-type mice and subjected to rEg.P29 immunization, and then these immunized mice are infected with E. multilocularis. The cyst inhibition rate is calculated by weighing the body and cyst weights. The level of antibody is detected by ELISA. Flow cytometry is used to detect the level of IFN-γ production by CD4 + T and CD8 + T cells. The cytokines in culture supernatant are detected by ELISA. The expressions of CD44 and CD62L on memory T cells are determined by flow cytometry. The results show the cyst inhibition rate is 41.52% after adoptive transfer of CD4 + T cells. Furthermore, the levels of IgG, IgM, IgA and IgE in serum are significantly increased compared with those in the PBS group. The IFN-γ-secretion by CD8 + T cells and the level of IFN-γ in culture supernatant are obviously increased; and the number of CD4 + T cells is increased, but the number of IFN-γ producing CD4 + T cells has no significant difference compared with PBS group. In addition, the number of CD44 +CD62L ‒CD8 + memory T cells in the spleen is significantly increased, while the number of CD44 ‒CD62L + CD8 + memory T cells is not significantly altered. Collectively, rEg.P29 can alleviate E. multilocularis infection by inducing humoral immune responses and CD8 + T cell responses.

Recombinant antigen P29 of Echinococcus granulosus induces Th1, Tc1, and Th17 cell immune responses in sheep

Echinococcosis is a common human and animal parasitic disease that seriously endangers human health and animal husbandry. Although studies have been conducted on vaccines for echinococcosis, to date, there is no human vaccine available for use. One of the main reasons for this is the lack of in-depth research on basic immunization with vaccines. Our previous results confirmed that recombinant antigen P29 (rEg.P29) induced more than 90% immune protection in both mice and sheep, but data on its induction of sheep-associated cellular immune responses are lacking. In this study, we investigated the changes in CD4+ T cells, CD8+ T cells, and antigen-specific cytokines IFN-γ, IL-4, and IL-17A after rEg.P29 immunization using enzyme-linked immunospot assay (ELISPOT), enzyme-linked immunosorbent assay (ELISA), and flow cytometry to investigate the cellular immune response induced by rEg.P29 in sheep. It was found that rEg.P29 immunization did not affect the percentage of CD4+ and CD8+ T cells in peripheral blood mononuclear cells (PBMCs), and was able to stimulate the proliferation of CD4+ and CD8+ T cells after immunization in vitro. Importantly, the results of both ELISPOT and ELISA showed that rEg.P29 can induce the production of the specific cytokines IFN-γ and IL-17A, and flow cytometry verified that rEg.P29 can induce the expression of IFN-γ in CD4+ and CD8+ T cells and IL-17A in CD4+ T cells; however, no IL-4 expression was observed. These results indicate that rEg.P29 can induce Th1, Th17, and Tc1 cellular immune responses in sheep against echinococcosis infection, providing theoretical support for the translation of rEg.P29 vaccine applications.

Changes in intestinal flora of mice induced by rEg.P29 epitope peptide vaccines

OBJECTIVE

Cystic echinococcosis (CE), a zoonotic parasitic disease caused by Echinococcus granulosus, remains a public health and socioeconomic issue worldwide, making its prevention and treatment of vital importance. The aim of this study was to investigate changes in the intestinal microbiota of mice immunized with three peptide vaccines based on the recombinant antigen of E. granulosus, P29 (rEg.P29), with the hope of providing more valuable information for the development of vaccines against CE.

METHODS

Three peptide vaccines, rEg.P29T , rEg.P29B , and rEg.P29T + B , were prepared based on rEg.P29, and a subcutaneous immunization model was established. The intestinal floras of mice in the different immunization groups were analyzed by 16 S rRNA gene sequencing.

RESULTS

The intestinal microbiota analysis at both immunization time points revealed that Firmicutes, Bacteroidota, and Verrucomicrobiota were the predominant flora at the phylum level, while at the genus level, Akkermansia, unclassified_Muribaculaceae, Lachnospiraceae_NK4A136_group, and uncultured_rumen bacterium were the dominant genera. Some probiotics in the intestines of mice were significantly increased after immunization with the peptide vaccines, such as Lactobacillus_taiwanensis, Lactobacillus_reuteri, Lachnospiraceae_NK4A136_group, Bacteroides_acidifaciens, and so forth. Meanwhile, some harmful or conditionally pathogenic bacteria were decreased, such as Turicibacter sanguinis, Desulfovibrio_fairfieldensis, Clostridium_sp, and so forth, most of which are associated with inflammatory or infectious diseases. Kyoto Encyclopaedia of Genes and Genomes enrichment analysis revealed that the differential flora were enriched in multiple metabolic pathways, primarily biological systems, human diseases, metabolism, cellular processes, and environmental information processing.

CONCLUSION

In this study, we comprehensively analyzed and compared changes in the intestinal microbiota of mice immunized with three peptide vaccines as well as their related metabolic pathways, providing a theoretical background for the development of novel vaccines against E. granulosus.

Immunogenicity of peptide-based vaccine composed of epitopes from Echinococcus granulosus rEg.P29

Echinococcus granulosus is one of the main causes of economic loss in the livestock industry because of its food-borne transmission. Cutting off the transmission route is a valid prevention method, and vaccines are the most effective means of controlling and eliminating infectious diseases. However, no human-related vaccine has been yet marketed. As a genetic engineering vaccine, recombinant protein P29 of E. granulosus (rEg.P29) could provide protection against deadly challenges. In this study, we generated peptide vaccines (rEg.P29T , rEg.P29B , and rEg.P29T+B ) based on rEg.P29 and an immunized model was established by subcutaneous immunization. Further evaluation showed that peptide vaccine immunization in mice induced T helper type 1 (Th1)-mediated cellular immune responses, leading to high levels of rEg.P29 or rEg.P29B -specific antibodies. In addition, rEg.P29T+B immunization can induce a higher antibody and cytokine production level than single-epitope vaccines, and immune memory is also longer. Collectively, these results suggest that rEg.P29T+B has the potential to be developed as an efficient subunit vaccine for use in areas where E. granulosus is endemic.

Clinical characteristics and antibodies against Echinococcus granulosus recombinant antigen P29 in patients with cystic echinococcosis in China

Objectives

Cystic echinococcosis (CE) is a neglected parasitic zoonotic disease caused by the larval stage of the tapeworm Echinococcus granulosus (E. granulosus). This study aimed to understand the clinical characteristics of human CE in Ningxia Hui Autonomous Region (NHAR) located in northwest China and to investigate the antibody profiles against the recombinant E. granulosus antigen P29 (rEg.P29) in plasma of CE patients.

Methods

A total of 37 human CE patients, along with 37 healthy donors enrolled in this study and demographic and clinical data were analyzed, including age, gender, laboratory data, symptoms, and cysts description. Plasma levels of cytokines, total IgG, and total IgE were determined by sandwich ELISA kits. Specific antibodies against rEg.P29 and hydatid cyst fluid (HCF) were assessed by indirect ELISA.

Results

The results revealed that females have a higher percentage of CE patients than males. The incidence of CE reached a peak in the 41–50 years-old group. The liver was the most frequent location, accounting for 91.9%. Based on the CT images, cysts of 34 patients who had liver involvement, were classified as 1 (2.9%) CE1, 12 (35.3%) CE2, 5 (14.7%) CE3a, 1 (2.9%) CE3b, and 15 (44.2%) CE5. Twenty-nine (78.4%) patients had a single cyst and 8 (21.6%) had at least two cysts. The most frequently reported symptom was upper abdominal pain. The plasma level of IL-6 and total IgE were significantly increased in CE patients compared with healthy donors. Additionally, IgG response to rEg.P29 in CE patients was significantly higher than in healthy donors, and the dominant IgG subclass was IgG4. Further analysis of different patient groups revealed that rEg.P29-specific IgG and IgG4 were only elevated in CE patients with CE2 type cysts.

Conclusions

This study systematically investigated the clinical characteristics of patients with CE and may provide a reference basis for the diagnosis and treatment of CE in NHAR. Furthermore, tests of specific IgG and IgG4 against rEg.P29 can be used as an assisted method for imaging techniques to identify cystic activity and determine the best therapeutic approach for CE.

Identification of B‐cell dominant epitopes in the recombinant protein P29 from Echinococcus granulosus

Introduction

Echinococcus granulosus (E. granulosus) causes a hazardous zoonotic parasitic disease. This parasite can occupy the liver and several areas of the body, causing incurable damage. Our previous studies have provided evidence that the recombinant protein P29 (rEg.P29) exhibit immune protection in sheep and mice against pathological damage induced by E. granulosus, showing its potential as candidate for vaccine development. However, information on the B‐cell epitopes of rEg.P29 has not yet been reported.

Methods

Immunological model was established in mice with rEg.P29. SDS‐PAGE and Western blot were used to identify protein. Screening for B‐cell dominant epitope peptides of rEg.P29 by enzyme‐linked immunosorbent assay (ELISA) and immune serum. Dominant epitopes were validated using ELISA and flow cytometry. Multiple sequence alignment analysis was performed using BLAST and UniProt.

Results

Immunization with rEg.P29 induced intense and persistent antibody responses, and the epitope of the dominant antigen of B cells are identified as rEg.P29_166–185 (LKNAKTAEQKAKWEAEVRKD). Anti‐rEg.P29_166–185‐specific antibodies lack epitopes against IgA, IgE, and IgG3, compared to anti‐rEg.P29‐specific antibodies. However, anti‐rEg.P29_166–185 IgG showed comparatively higher titers, as determined among those peptides by endpoint titration. In addition, rEg.P29 and rEg.P29_166–185 promote B‐cell activation and proliferation in vitro. The dominant epitopes are relatively conserved in different subtypes of the rEg.P29 sequence.

Conclusion

rEg.P29_166–185 can act as a dominant B‐cell epitope for rEg.P29 and promote cell activation and proliferation in the same way as rEg.P29.

Identification of a dominant murine T-cell epitope in recombinant protein P29 from Echinococcus granulosus

Echinococcus granulosus causes echinococcosis, an important zoonotic disease worldwide and a major public health issue. Vaccination is an economical and practical approach for controlling E. granulosus. We have previously revealed that a recombinant protein P29 (rEg.P29) is a good vaccine candidate against E. granulosus. However, T cell immunogenic epitopes have not been identified. In the present study, we use rEg.P29-immunized mice as models to screen immunogenic epitopes for the construction of a novel multi-epitope vaccine. We search for immunodominant epitopes from an overlapping peptide library to screen the peptides of rEg.P29. Our results confirm that rEg.P29 immunization in mice elicits the activation of T cells and induces cellular immune responses. Further analyses show that a T cell epitope within amino acids 86–100 of rEg.P29 elicits significant antigen-specific IFN-γ production in CD4+ and CD8+ T cells and promotes specific T-cell activation and proliferation. Collectively, these results provide a reference for the construction of a novel vaccine against broad E. granulosus genotypes based on epitopes of rEg.P29.

The Recombinant Eg.P29-Mediated miR-126a-5p Promotes the Differentiation of Mouse Naive CD4+ T Cells via DLK1-Mediated Notch1 Signal Pathway

Cystic echinococcosis (CE) is a zoonotic parasitic disease spread worldwide caused by Echinococcus granulosus (Eg), which sometimes causes serious damage; however, in many cases, people are not aware that they are infected. A number of recombinant vaccines based on Eg are used to evaluate their effectiveness against the infection. Our previous report showed that recombinant Eg.P29 (rEg.P29) has a marvelous immunoprotection and can induce Th1 immune response. Furthermore, data of miRNA microarray in mice spleen CD4⁺ T cells showed that miR-126a-5p was significantly elevated 1 week after immunization by using rEg.P29. Therefore, in this perspective, we discussed the role of miR-126a-5p in the differentiation of naive CD4⁺ T cells into Th1/Th2 under rEg.P29 immunization and determined the mechanisms associated with delta-like 1 homolog (DLK1) and Notch1 signaling pathway. One week after P29 immunization of mice, we found that miR-126a-5p was significantly increased and DLK1 expression was decreased, while Notch1 pathway activation was enhanced and Th1 response was significantly stronger. The identical conclusion was obtained by overexpression of mmu-miR-126a-5p in primary naive CD4⁺ T cells in mice. Intriguingly, mmu-miR-126a-5p was significantly raised in serum from mice infected with protoscolex in the early stages of infection and markedly declined in the late stages of infection, while has-miR-126-5p expression was dramatically reduced in serum from CE patients. Taken together, we show that miR-126a-5p functions as a positive regulator of Notch1-mediated differentiation of CD4⁺ T cells into Th1 through downregulating DLK1 in vivo and in vitro. Hsa-miR-126-5p is potentially a very promising diagnostic biomarker for CE.

The Immunization of Protoscolices P29 DNA Vaccine on Experimental Cystic Echinococosis in Balb/c Mice

PURPOSE

Cystic Echinococosis is one of the important parasitic diseases that is considered as a problem economics and health in many parts of the world. Many efforts have been performed for controlling the disease in the world. To reach a reliable vaccine against Cystic Echinococosis is one of the important duty of governments. Several antigen of hydatid cyst for vaccine candidate have been evaluated. In this study, P-29 antigen has been used for this purpose.

METHODS

E.g P29 antigen was cloned in Escherichia coli and transfected into the Chinese hamster ovary cell for antigen proliferation and used for vaccination in Balb/c mice. The recombinant antigen E.g-29 was shown using Western blot test. Two dilution of DNA vaccine (pCEgP-29) including 50 µg/100 µl and 100 µg/100 µl were prepared. Twenty four Balb/C male 6-8 week mouse were divided in 4 groups. The groups were included in 2 vaccination groups (pcEg.P29 50 µg/100 µl and 100 µg/100 µl dilution) as immunized groups and 2 groups of plasmid and PBS as control. The mice were injected intramuscularly 3 times with 2 weeks interval. After 3 weeks from last injection, all groups were challenged intraperitonealy with 2000 protoscolices. After 5 months, the mice were euthanized by ketamine/xylasine injection and number, size, and weight of cysts were recorded.

RESULTS

Immunization rate was up to 93% in vaccinated group when compared with the control group.

CONCLUSION

The results of this study showed that rEg.P29 could be considered as an effective vaccine for controlling of E. granulosus prevalence in intermediated host.

lncRNA028466 regulates Th1/Th2 cytokine expression and associates with Echinococcus granulosus antigen P29 immunity

Background

Cystic echinococcosis (CE) is a parasitic disease that is caused by Echinococcus granulosus (Eg). The recombinant Echinococcus granulosus antigen P29 (rEg.P29) was shown to confer effective immunity to sheep and mice during E. granulosus secondary infection in our previous study. In this study, we sought to investigate the ability of long noncoding RNA 028466 (lncRNA028466) as a regulator for the protective immunity mediated by rEg.P29 vaccination and to study the effects of lncRNA028466 on CD4⁺T cell differentiation in mice spleen.

Methods

Female BALB/c mice were divided into two groups and were vaccinated subcutaneously with rEg.P29 antigen and PBS as a control (12 mice each group). Following prime-boost vaccination, CD4⁺T, CD8⁺T, and B cells from the spleen were isolated by flow cytometry. Quantitative real-time PCR (qRT-PCR) was performed to measure the expression of lncRNA028466 in these three kinds of cells. Then, lncRNA028466 was overexpressed and knocked down in naive CD4⁺T cells, and Th1 and Th2 cytokine expression was detected. qRT-PCR, western blot, and ELISA were performed to evaluate the production of IFN-γ, IL-2, IL-4, and IL-10, and flow cytometry was performed to detect the differentiation of Th1 and Th2 subgroups.

Results

lncRNA028466 was significantly decreased after the second week of immunization with rEg.P29 antigen. The proportion of CD4⁺ T cells was increased after rEg.P29 immunization. Overexpression of lncRNA028466 facilitated the production of IL-4, IL-10 and suppressed the production of IFN-γ, IL-2. Furthermore, after transfection with siRNA028466, IL-2 production was facilitated and IL-10 production was suppressed in naive CD4⁺ T cells.

Conclusions

Immunization with rEg.P29 downregulated the expression of lncRNA028466, which was related to a higher Th1 immune response and a lower Th2 immune response. Our results suggest that lncRNA028466 may be involved in rEg.P29-mediated immune response by regulating cytokine expression of Th1 and Th2.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-04795-2.

Vaccination with rEGVac elicits immunoprotection against different stages of Echinococcus granulosus life cycle: A pilot study

Vaccination against dog-sheep transmission cycle is necessary to control cystic echinococcosis (CE) infection. A multi-epitope multi-antigenic recombinant vaccine was developed-comprising the three putative vaccine antigens EG95, Eg14-3-3 and EgEnolase-was cloned and expressed. In a pilot experiment, the multi-antigen vaccine was assessed in 15 dogs and 15 sheep (five experimental groups and three animals in each group) by two subcutaneous doses 28 days apart. To evaluate the efficacy of the vaccine candidate first immunological analysis were done comprising IgG and IgE antibodies and the cytokine IL-4 in sera of the immunized dogs and sheep. Serum IgG, IgE, and IL-4, in particular in the dogs, were increased after the two rounds of vaccine candidate injection, while the total number of hydatid cysts was reduced (~85.43%). This pilot trial indicated significant immune protection efficacy against E. granulosus especially in dogs, while its efficacy in sheep was not as high as dogs. The multi-antigenic candidate vaccine is proposed as a protective vaccine modality in both dogs and sheep.

Bioinformatics features and immunogenic epitopes of Echinococcus granulosus Myophilin as a promising target for vaccination against cystic echinococcosis

Cystic echinococcosis (CE) is a neglected zoonosis especially in underdeveloped countries around the world. Hence, immunization strategies are beneficial to avert the infection. The present investigation was aimed to predict the primary biochemical characteristics of the EgMyophilin and its potential B-cell and human leukocyte antigen (HLA)-binding epitopes as a promising vaccine candidate. Different web servers were used to predict physico-chemical, antigenic and allergenic profiles, transmembrane domain, subcellular localization, post-translational modification (PTM) sites, secondary and 3D structure, tertiary model refinement and validations. B-cell and HLA-binding epitopes were predicted and screened in terms antigenicity, allergenicity, solubility (B-cell) or hydrophobicity (T-cell). The 89.82 KDa protein was non-allergenic, hydrophilic, stable, with improved thermotolerance and 94 post-translational modification sites. The secondary structure included 42.94% alpha helix, 42.82% random coil and 41.23% extended strand. Based on Ramachandran plot output for refined model, 96.2%, 99.5%, and 0.45% of amino acid residues were incorporated in the favored, allowed, and outlier regions of the refined model, respectively. After epitope screening, four B-cell and five HLA-binding epitopes possessed the highest antigenic index in the protein sequence. This paper is a premise for further researches, and provides insights for the development of a suitable vaccine against CE. More empirical studies are required using the EgMyophilin alone or in combination with other antigens/epitopes in the future.

MiR-374b-5p Regulates T Cell Differentiation and Is Associated with rEg.P29 Immunity

Cystic echinococcosis (CE) is a zoonotic disease caused by Echinococcus granulosus (Eg) infection. Our previous study confirmed that recombinant Eg.P29 (rEg.P29) could protect against echinococcus granulosus secondary infection in sheep and mice. The aim of the study was to investigate the association between immunoprotection of rEg.P29 vaccine and mmu-miR-374b-5p (miR-374b-5p) and study the immunity influence of miR-374b-5p on CD4⁺ T cells in mice spleen. MiR-374b-5p level was significantly increased after the second-week and the fourth week of vaccination with rEg.P29. Overexpression of miR-374b-5p increased IFN-γ, IL-2, IL-17A mRNA levels and decreased IL-10 mRNA levels in CD4⁺ T cells. Moreover, the inhibition of miR-374b-5p decreased IFN-γ and IL-17A and increased IL-10 mRNA levels in CD4⁺ T cells; this was further confirmed by the flow cytometry. The vaccination of rEg.P29 enhanced miR-374b-5p expression that was associated with a higher Th1 and Th17 immune response, a lower IL-10 mRNA production with miR-374b-5p overexpression, a lower Th1 immune response, and a higher IL-10 mRNA levels with miR-374b-5p inhibitions. To sum up, these data suggest that miR-374b-5p may participate in rEg.P29 immunity by regulating Th1 and Th17 differentiation.

Current situation and future prospects of Echinococcus granulosus vaccine candidates: A systematic review

Cystic echinococcosis is a worldwide zoonotic disease, represents a threat for livestock and humans, manifests as a quiescent, subclinical and chronic hydatid cyst infection. The disease imposes high expenditures and economic losses in medical and veterinary. Prophylactic vaccination would be one of the effective preventive health care against echinococcosis. During the last decades, many studies have characterized the protective antigens of Echinococcus granulosus and their role in immunization of various animal host species. Herein, we aimed to systematically evaluate and represent the best antigens as possible vaccine candidates for cystic echinococcosis. Data were systematically searched from five databases including ProQuest, PubMed, Scopus, ScienceDirect and Web of Science, up to 1 February 2020. Two reviewers independently screened and assessed data extraction and quality assessment. A total of 47 articles were eligible for inclusion criteria in the current study. The most common antigens used for vaccination against E. granulosus were EG95 and antigen B. Freund's adjuvant and Quil A have been predominantly utilized. In addition, regarding the antigen delivery, animal models, measurement of immune responses and reduction in hydatid cyst have been discussed in the text. The data demonstrated that DNA vaccines with antigen B and recombinant protein vaccines based on EG95 antigen have the best results and elicited protective immune responses.

Linking murine resistance to secondary cystic echinococcosis with antibody responses targeting Echinococcus granulosus tegumental antigens

Successful establishment of a parasite infection depends partially on the host intrinsic susceptibility to the pathogen. In cystic echinococcosis (CE), a zoonotic disease caused by the cestode parasite Echinococcus granulosus, the infection outcome in the murine model of secondary CE varies according to the mouse strain used. In this regard, intrinsic differences in susceptibility to the infection were previously reported for Balb/c and C57Bl/6 mice, being C57Bl/6 animals less permissive to secondary CE. Induction of parasite-specific antibodies has been suggested to play relevant roles in such susceptibility/resistance phenomena. Here, we report an in deep comparison of antibody responses induced in both mouse strains. Firstly, only C57Bl/6 mice were shown to induce specific-antibodies with efficient anti-parasite activities during early secondary CE. Then, through ImmunoTEM and Serological Proteome Analysis (SERPA), an evaluation of specific antibody responses targeting parasite tegumental antigens was performed. Both strategies showed that infected C57Bl/6 mice -unlike Balb/c animals- narrowed their IgG recognition repertoire against tegumental antigens, targeting fewer but potentially more relevant parasite components. In this sense, tegumental antigens recognition between Balb/c and C57Bl/6 mice, either by natural and/or induced antibodies, was analyzed through SERPA and MALDI-TOF/TOF studies. A total of 13 differentially recognized proteins (DRPs) uniquely targeted by antibodies from C57Bl/6 mice were successfully identified, wherein a subset of 7 DRPs were only recognized by infection-induced antibodies, suggesting their potential as natural protective antigens. In this regard, immunoinformatic analyses showed that such DRPs exhibited higher numbers of possible T cell epitopes towards the H-2-IA^b haplotype, which is present in C57Bl/6 mice but absent in Balb/c animals. In summary, our results showed that the genetic predisposition to generate better T-dependent antibody responses against particular tegumental antigens might be a key factor influencing host susceptibility in the murine model of secondary CE.

Combining proteomics and bioinformatics to explore novel tegumental antigens as vaccine candidates against Echinococcus granulosus infection

Echinococcus granulosus is the parasite responsible for cystic echinococcosis (CE), an important worldwide-distributed zoonosis. New effective vaccines against CE could potentially have great economic and health benefits. Here, we describe an innovative vaccine design scheme starting from an antigenic fraction enriched in tegumental antigens from the protoscolex stage (termed PSEx) already known to induce protection against CE. We first used mass spectrometry to characterize the protein composition of PSEx followed by Gene Ontology analysis to study the potential Biological Processes, Molecular Functions, and Cellular Localizations of the identified proteins. Following, antigenicity predictions and determination of conservancy degree against other organisms were determined. Thus, nine novel proteins were identified as potential vaccine candidates. Furthermore, linear B cell epitopes free of posttranslational modifications were predicted in the whole PSEx proteome through colocalization of in silico predicted epitopes within peptide fragments identified by matrix-assisted laser desorption/ionization-TOF/TOF. Resulting peptides were termed "clean linear B cell epitopes," and through BLASTp scanning against all nonhelminth proteins, those with 100% identity against any other protein were discarded. Then, the secondary structure was predicted for peptides and their corresponding proteins. Peptides with highly similar secondary structure respect to their parental protein were selected, and those potentially toxic and/or allergenic were discarded. Finally, the selected clean linear B cell epitopes were mapped within their corresponding 3D-modeled protein to analyze their possible antibody accessibilities, resulting in 14 putative peptide vaccine candidates. We propose nine novel proteins and 14 peptides to be further tested as vaccine candidates against CE.

The ectodomains of the lymphocyte scavenger receptors CD5 and CD6 interact with tegumental antigens from Echinococcus granulosus sensu lato and protect mice against secondary cystic echinococcosis

Background

Scavenger Receptors (SRs) from the host’s innate immune system are known to bind multiple ligands to promote the removal of non-self or altered-self targets. CD5 and CD6 are two highly homologous class I SRs mainly expressed on all T cells and the B1a cell subset, and involved in the fine tuning of activation and differentiation signals delivered by the antigen-specific receptors (TCR and BCR, respectively), to which they physically associate. Additionally, CD5 and CD6 have been shown to interact with and sense the presence of conserved pathogen-associated structures from bacteria, fungi and/or viruses.

Methodology/Principal findings

We report herein the interaction of CD5 and CD6 lymphocyte surface receptors with Echinococcus granulosus sensu lato (s.l.). Binding studies show that both soluble and membrane-bound forms of CD5 and CD6 bind to intact viable protoscoleces from E. granulosus s.l. through recognition of metaperiodate-resistant tegumental components. Proteomic analyses allowed identification of thioredoxin peroxidase for CD5, and peptidyl-prolyl cis-trans isomerase (cyclophilin) and endophilin B1 (antigen P-29) for CD6, as their potential interactors. Further in vitro assays demonstrate that membrane-bound or soluble CD5 and CD6 forms differentially modulate the pro- and anti-inflammatory cytokine release induced following peritoneal cells exposure to E. granulosus s.l. tegumental components. Importantly, prophylactic infusion of soluble CD5 or CD6 significantly ameliorated the infection outcome in the mouse model of secondary cystic echinococcosis.

Conclusions/Significance

Taken together, the results expand the pathogen binding properties of CD5 and CD6 and provide novel evidence for their therapeutic potential in human cystic echinococcosis.

Scavenger Receptors (SRs) are constituents of host’s innate immune system able to sense and remove altered-self and/or pathogen components. Data on their interaction with helminth parasites is scarce. In this work, we describe that CD5 and CD6 -two lymphoid SRs previously reported to interact with conserved structures from bacteria, fungi and viruses- recognize tegumental components in the cestode parasite Echinococcus granulosus sensu lato (s.l.). Moreover, both receptors differentially modulate the cytokine release by host cells exposed to E. granulosus s.l. tegumental components. Importantly, the infusion of soluble forms of CD5 or CD6 improve infection outcomes in a murine model of secondary cystic echinococcosis. In summary, our results expand the pathogen binding properties of CD5 and CD6 and suggest their therapeutic potential against helminth infections.

Immunization of sheep against Echinococcus granulosus with protoscolex tegumental surface antigens

AIM

Cystic echinococcosis (CE) has potential economic effects to both animal products and human health. A vaccine to protect livestock against CE can be effective in reducing economic costs and increasing the livestock products. Protoscolex tegumental surface antigens (PSTSA) used to induce the production of specific antibodies against Echinococcus granulosus in sheep. The tegumental antigens were extracted from viable protoscolices by solubilization in sterile phosphate-buffered saline containing decanoyl-N-methylglucamine.

MATERIALS AND METHODS

Ten lambs which were infected with CE (positive control), 10 negative control, and 10 test groups of sheep were included in the study. 300 µg emulsion of purified-PSTSA was injected intramuscularly in a two-step immunization on the first and 30 days. Sera were collected immediately before immunization and 6 times with 10-day intervals until 60 days post immunization. Thereafter, the sera were tested for antibodies by indirect hemagglutination test in microtiter plate.

RESULTS

After two immunizations, all the infected animals in test group showed substantial increases in antibody titer. Statistical analysis showed a significant difference between the titer obtained in the test and negative control groups in both phases of immunization (p<0.05).

CONCLUSION

The results showed that the PSTSA is a promising immunogenic compound for immunization of sheep against CE.

Genetic diversity and phylogenetic analysis of EG95 sequences of Echinococcus granulosus: Implications for EG95 vaccine application

OBJECTIVE

To analyse the genetic variability of EG95 sequences and provide guidance for EG95 vaccine application against Echinococcus granulosus (E. granulosus).

METHODS

We analysed EG95 polymorphism by collecting total 97 different E. granulosus isolates from 12 different host species that originated from 10 different countries. Multiple sequence alignments and the homology were performed by Lasergene 1 (DNASTAR Inc., Madison, WI), and the phylogenetic analysis was performed by using MEGA5.1 (CEMI, Tempe, AZ, USA). In addition, linear and conformational epitopes were analysed, including secondary structure, NXT/S glycosylation, fibronectin type III (FnIII) domain and glycosylphosphatidylinositol anchor signal (GPI-anchor). The secondary structure was predicted by PSIPRED method.

RESULTS

Our results indicated that most isolates overall shared 72.6-100% identity in EG95 gene sequence with the published standard EG95 sequence, X90928. However, EG95 gene indeed has polymorphism in different isolates. Phylogenetic analysis showed that different isolates could be divided into three subgroups. Subgroup 1 contained 87 isolates while Subgroup 2 and Subgroup 3 consisted of 3 and 7 isolates, respectively. Four sequences cloned from oncosphere shared a high identity with the parental sequence of the current vaccine, X90928, and they belonged to Subgroup 1. However, in comparison to X90928, several amino acid mutations occurred in most isolates besides oncosphere, which potentially altered the immunodominant linear epitopes, glycosylation sites and secondary structures in EG95 genes. All these variations might change their previous antigenicity and thereby affecting the efficacy of current EG95 vaccine.

CONCLUSIONS

This study reveals the genetic variability of EG95 sequences in different E. granulosus isolates, and proposed that more vaccination trials would be needed to test the effectiveness of current EG95 vaccine against distinct isolates in different countries.

Proteomic Analysis of Excretory-Secretory Products of Mesocestoides corti Metacestodes Reveals Potential Suppressors of Dendritic Cell Functions

Accumulating evidences have assigned a central role to parasite-derived proteins in immunomodulation. Here, we report on the proteomic identification and characterization of immunomodulatory excretory-secretory (ES) products from the metacestode larva (tetrathyridium) of the tapeworm Mesocestoides corti (syn. M. vogae). We demonstrate that ES products but not larval homogenates inhibit the stimuli-driven release of the pro-inflammatory, Th1-inducing cytokine IL-12p70 by murine bone marrow-derived dendritic cells (BMDCs). Within the ES fraction, we biochemically narrowed down the immunosuppressive activity to glycoproteins since active components were lipid-free, but sensitive to heat- and carbohydrate-treatment. Finally, using bioassay-guided chromatographic analyses assisted by comparative proteomics of active and inactive fractions of the ES products, we defined a comprehensive list of candidate proteins released by M. corti tetrathyridia as potential suppressors of DC functions. Our study provides a comprehensive library of somatic and ES products and highlight some candidate parasite factors that might drive the subversion of DC functions to facilitate the persistence of M. corti tetrathyridia in their hosts.

The metacestode larval stages of life-threatening tapeworms grow within the organs of its mammalian hosts, thus causing severe and long-lasting morbidity. Immunosuppression, which mainly depends on factors that are released or leaking from the parasite, plays an important role in both survival and proliferation of the larvae. These parasite-derived molecules are potential targets for developing new anti-parasitic drugs and/or improving the effectiveness of current therapies. Moreover, an optimized use of such factors could help to minimize pathologies resulting from uncontrolled immune responses, like allergies and autoimmune diseases. The authors herein demonstrate that larvae from a parasitic cestode release factors that sufficiently support the suppression of dendritic cells, a set of innate immune cells that recognizes and initiates host immune responses against invading pathogens. Employing modern analytic proteomic tools combined with immunological bioassays, several cestode-derived candidate immunomodulators were identified. This is the first bioassay-guided comprehensive library of candidate immunomodulators from a tissue-dwelling cestode larva. This work validates the unmet value of the Mesocestoides corti system in characterizing the mechanisms of host immunomodulation by metacestodes and reveals the largest database of candidate metacestode-derived immunomodulators until date.