H2020 Paragone Project: PARAGONE: Vaccines against animal parasites
- Type Project
- Status Filled
- Execution 2015 -2019
- Assigned Budget 8.998.559,75 €
- Scope Europeo
- Main source of financing H2020
- Project website Proyecto Paragone
Helminth and ectoparasitic infections in ruminants and poultry have a huge impact on the biological efficiency of these vital food sources. The indiscriminate use of antiparasitic drugs has generated drug resistance worldwide. The main alternative to the shortage of antiparasitic drugs is vaccines. The PARAGONE project will leverage the findings of previous EU- and other-funded projects on antiparasitic vaccine development to promote the commercialization of several promising prototypes. Partners from Europe, China, Uruguay, SMEs, and the pharmaceutical industry will directly promote prototypes against the ruminant helminths Fasciola hepatica, Cooperia spp., Ostertagia ostertagi, Teladorsagia circumcincta, and Haemonchus contortus, as well as against the ectoparasitic mites Psoroptes ovis (ruminants) and Dermanyssus gallinae (poultry).
New adjuvants or delivery systems will be used to maximize the efficacy of some of the prototypes. In addition, immunology studies will focus on pathogens that have previously proven problematic, often because they release immunosuppressive molecules that must be overcome for vaccines to work or because recombinant vaccines have failed to elicit the protection observed with native prototypes. Cutting-edge technologies will be used to interrogate host/parasite interactions to define key signatures of protection that can be used to inform delivery systems that will enhance immunity, while other studies will define polymorphism in current vaccine candidates to ensure that derived prototypes are fit for purpose at all geographical scales.
Key to this is the engagement of scientists with the pharmaceutical industry and other stakeholders (farmers, veterinarians, regulators) through various outreach activities that will be used to gather feedback on how the vaccines can be best implemented in the field. The outcome will be at least two prototypes that have reached the point of adoption by the pharmaceutical industry, government, or philanthropic agencies, and a clear path to commercialization for all the prototypes studied.
The research led to the development of the aforementioned vaccines and immunological tools. These activities were supported by demonstration objectives led by commercial partners. The academic partners fulfilled their obligation to publish their findings and updated the project website. Early career scientists had the opportunity to participate in interlaboratory visits and workshops (Next-Generation Sequencing, Immunological Tools, Veterinary Vaccinology). Numerous outreach activities ensured the project reached its impact potential; in-person stakeholder symposia and an international online survey provided insights into the future prospects for antiparasitic vaccines.
The vaccines started at various stages along the development path; from most advanced to least advanced, these were vaccines against T. circumcincta, O. ostertagi, C. oncophora, F. hepatica, P. ovis, and the poultry red mite. Linked to trials testing combinations of antigens were studies on the formulation of vaccines designed to promote protective responses. This work was linked to defining antiparasitic protective responses so that vaccines could be designed to be effective in all populations. For O. ostertagi and C. oncophora, immunological studies and assays demonstrated that antigen conformation is key in inducing protection using ASP antigens. A native ASP from C. oncophora was shown to cross-protect cattle against another isolate and other Cooperia spp. but did not protect sheep against C. curticei. Formulation of a recombinant Ostertagia ASP with SME’s novel adjuvant formulation XStalbio with MAMP modulated responses to a desired phenotype, but did not induce protection. A field trial with native Ostertagia ASP, which had induced immunity in pen trials, did not generate protection against pasture challenge. One study tested a recombinant ASP, thiol-purified in the same manner as the protective native ASP, but this did not produce a protective vaccine.
The work in T. circumcincta aimed to simplify a recombinant vaccine shown to induce protection. Here, eight antigens were successfully co-expressed in three systems. The co-expressed version did not induce immunity in lambs. The XStalbio adjuvanted formulation with MAMP was tested to examine whether responses could be enhanced by co-administration. Incorporation retained antigenicity but did not enhance the desired responses. Pen trials in Canary breeds that displayed different resistance to worms showed that in 6-month-old "resistant" ewes, resistance increased with vaccination. In "susceptible" ewes, vaccination had a negative effect on worm development. A similar effect was seen in 3-month-old "resistant" ewes. Antigen-coding sequences in worms from different regions showed low diversity in 7/8 proteins. A prototype of two proteins induced protection similar to the range of the prototype of eight proteins.
This 2-protein vaccine was retested in a study looking at the dose effect; although vaccinees had lower parasitological parameters than controls, the differences were not significant. Mathematical modeling, using previous data on the 8-protein vaccine, showed that the previously achieved efficacy levels could have a substantial effect on subsequent contamination if the vaccine was given to sheep and lambs. Recombinant F. hepatica antigens had previously been shown to provide variable protection; the partners tested these in combination to examine whether this would generate consistent protection. Significant protection was seen in a sheep trial using 4 antigens + montanide; this was not repeatable. Two cattle trials using all 4 antigens were unsuccessful. Antigen sequences in worms from different regions showed low diversity in all but one. The incorporation of MAMP into the XStalbio adjuvant formulation was tested to examine whether responses could be enhanced by co-administration. Antigenicity was maintained, particularly with MAMP. Responses were adjuvant-dependent, but no protection was obtained when sheep were challenged. Additional antigens were tested, but these did not provide protection in sheep.
Work on correlates of protection showed a role for IgG2. Epitope analysis indicated selective recognition of cathepsin L in protected cattle. Large-scale RNA analysis revealed that immune evasion pathways changed significantly in fluke infection, and a sheep pen trial showed immunomodulation in the early stages of infection. These immunomodulation results will now be used to inform further development of a F. hepatica vaccine. Work on a bovine prototype for P. ovis included a trial with recombinants that previously protected sheep. Although differences in lesion size were initially seen, no significant differences were observed overall.
RNA studies informed immune mechanisms. Antigen delivery systems (montanid, DNA, and transgenic Eimeria) were compared for a cathepsin vaccine against the poultry red mite. DNA and Eimeria showed negligible antibody responses, but the antigen-montanid combination produced prolonged responses. Hens were vaccinated with cathepsin-montanid, and an effect was observed in mites that fed on the blood of vaccinated birds. PARAGONE generated much-needed ovine cytokine arrays. Along with target product profiles and technical reviews for each vaccine, a commercialization plan for these tools was developed in collaboration with the SME Immunotools.
The EU-funded Horizon 2020 PARAGONE project addressed multicellular parasites, important pathogens of livestock. These significantly affect ruminant and poultry production, especially in intensive systems.
Currently, control depends on reducing the number of effective antiparasitics, and drug resistance among target parasites poses a threat to sustainable control. PARAGONE generated tools (vaccines and immunity monitoring resources) and knowledge to provide solutions for long-term control. The project also trained numerous early-career scientists skilled in the interdisciplinary approaches needed to ensure the global scientific community is prepared to address these difficult-to-control pathogens once the project concludes.
The academic associates strengthened ties with partners in the animal health industry to implement development programs targeting vaccines for parasites selected for their global impact: Fasciola hepatica, Ostertagia ostertagi, Cooperia oncophora, Teladorsagia circumcincta, Psoroptes ovis, and Dermanyssus gallinae. Developing effective vaccines against these complex organisms represents a significant challenge.
The project made substantial progress toward this goal by gaining and leveraging knowledge of parasite biology and host-parasite interactions. Lead/novel vaccine candidates were tested, along with studies to address variability in response, providing key information on protective factors that will inform future studies. These achievements were supported by robust training, outreach, and communication activities.
Helminth and ectoparasitic infections in ruminants and poultry have a huge impact on the biological efficiency of these vital food sources. The indiscriminate use of antiparasitic drugs has led to drug resistance worldwide.
The main alternative to the dwindling supply of antiparasitic drugs is vaccines. In this case, the PARAGONE project will leverage the results of previous EU-funded and other projects on parasite vaccine development to bring a number of promising prototypes toward commercialization. Partners from Europe, China, Uruguay, SMEs, and pharmaceutical companies will directly develop prototypes against the ruminant helminths Fasciola hepatica, Cooperia spp., Ostertagia ostertagi, Teladorsagia circumcincta, and Haemonchus contortus, and the ectoparasitic mites Psoroptes ovis (ruminants) and Dermanyssus gallinae (poultry). They will use adjuvants or novel delivery systems to maximize the efficacy of some of the prototypes.
In addition, immunology studies will focus on pathogens that have previously proven problematic, often because they release immunosuppressive molecules that must be overcome for vaccines to work, or because recombinant vaccines have failed to elicit the protection seen with native prototypes. Cutting-edge technologies will be used to interrogate host/parasite interactions to define key signatures of protection that can be used to inform delivery systems that will enhance immunity, while other studies will define polymorphism in current vaccine candidates to ensure that derived prototypes are fit for purpose at all geographical scales.
It is essential to engage scientists with pharmaceutical companies and other stakeholders (farmers, veterinarians, regulators) through numerous outreach activities that will be used to obtain feedback on how vaccines can be best implemented in the field. The outcome will be at least two prototypes ready for adoption by pharmaceutical, government, or philanthropic agencies, and a clear path to commercialization for all studied prototypes.
As livestock parasites develop drug resistance globally, EU-funded scientists are working on new vaccines and improving vaccine delivery systems against economically important parasites. Vaccines are a safer and more environmentally friendly alternative to drugs for disease control, as they do not leave residues or generate parasitic resistance. However, multicellular parasites are complex organisms compared to viruses and bacteria, so developing vaccines against them is not easy. “Parasites have evolved with their hosts for millions of years and have used all sorts of tricks to live in or on other animals without being detected by the immune system, making them difficult to detect,” says Al Nisbet, lead scientist on the EU-funded Paragone project and head of vaccines at the Moredun Research Institute in the UK, which coordinated the project.
The Paragone team worked on six existing vaccine prototypes that showed promise against the most prevalent parasites in livestock, including sheep, cattle, and poultry. Simplifying the sheep worm vaccine The team progressed with a vaccine against the brown stomach worm (Teladorsagia circumcincta) in sheep, starting with a prototype vaccine with eight different components. “Six of the recombinant proteins were produced in bacteria and two in yeast, and then formulated together to create the vaccine; therefore, while it was an effective prototype, it was complex and expensive to produce commercially,” Nisbet says. The most relevant proteins for protection against the parasite were identified. “By the end of the project, we were able to test a vaccine with only two components and generate a mathematical model to predict practical outcomes for various levels of vaccine efficacy,” Nisbet says, but adds that more work is needed before it is adopted by a commercial manufacturer.
Alternative approaches with current vaccines Trials evaluating prototype vaccines against the liver fluke (Fasciola hepatica) have shown the potential for using alternative approaches with current vaccines, as well as providing valuable insight into how the parasite evades the immune system. Previous work has shown that certain fluke proteins that stimulate or suppress the immune system provide protection as single-protein vaccines, but combined-protein vaccines do not. A vaccine against the sheep scab mite (Psoroptes ovis) demonstrated good levels of protection in sheep.
However, in cattle, where the same parasite can cause psoroptic mange, the results were not promising. Two other vaccines against gastrointestinal worms, Ostertagia ostertagi and Cooperia spp., showed high levels of cross-protection between different Cooperia species in cattle vaccinated with a "native" vaccine, while a recombinant version, which would be required for commercial use, offered no protection. A similar situation was observed in a prototype vaccine against Ostertagia ostertagi, indicating the need for further research into the reasons for these differences.
Better delivery systems Progress was made on a more efficient delivery system for a red mite (Dermanyssus gallinae) vaccine that would generate long-lasting and effective immune responses in hens. “Producers can’t keep taking hens out of the house to vaccinate. They want to vaccinate at a young age and have immunity last through the laying cycle,” says Tom McNeilly, Head of Disease Control at Moredun. Three different adjuvant delivery systems were tested for the prototype vaccine, ending with “a clear winner,” based on a novel adjuvant, says McNeilly. Like the EU-funded SAPHIR project, which developed livestock vaccines to reduce antibiotic use, Paragone made major advances in fundamental science, including characterizing the immune response to vaccines and ways to boost immune responses to vaccine antigens, which is useful beyond parasite vaccines.
A close relationship between academic and animal health industry partners ensured that the innovations resulting from the research aligned with the aspirations of marketable products. The partners completed the following requirements for each prototype: target product profile, likelihood of regulatory and technical success/technical review reports, and a commercialization plan for immunological tools. The team conducted an international survey to guide vaccine design and held meetings with stakeholders to discuss how the vaccines could be used on farms.
Progress was exemplified by new data on a two-protein vaccine, key insights into the protective mechanisms of nematode ASPs, and insights into epitope recognition of a F. hepatica candidate. Extensive postgraduate training ensured robust sustainability measures.
- MOREDUN RESEARCH INSTITUTE (MRI)
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