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PARAGONE: vaccines for animal parasites

Periodic Reporting for period 3 - Paragone (PARAGONE: vaccines for animal parasites)

Okres sprawozdawczy: 2018-04-01 do 2019-03-31

The EU Horizon 2020 project, PARAGONE, addressed multicellular parasites, major livestock pathogens. These significantly impact ruminant and poultry production, especially in intensive systems. Currently, control relies on a reducing number of effective antiparasitics and drug resistance in the target parasites is a threat to sustainable control. PARAGONE generated tools (vaccines and resources to monitor immunity) and knowledge to provide solutions for long-term control. The project also trained many early career scientists, skilled in the necessary interdisciplinary approaches to ensure the global scientific community is equipped to address these intractable pathogens beyond the project lifetime.

Partner academics strengthened links with animal health industry partners to implement development programmes to address vaccines for parasites selected on global impact: Fasciola hepatica, Ostertagia ostertagi, Cooperia oncophora, Teladorsagia circumcincta, Psoroptes ovis and Dermanyssus gallinae. Making effective vaccines against these complex organisms is a major challenge. The project made substantial progress against this aim by obtaining/exploiting knowledge on parasite biology and host/parasite interactions. Lead/new vaccine candidates were tested, alongside studies to address variability in responsiveness, providing key information on correlates of protection to inform future studies. These achievements were supported by strong training, dissemination and communication activities.
Research progressed vaccines and immunological tools listed at the outset. These activities were supported by demonstration objectives led by commercial partners. Academic partners fulfilled their obligation to publish their findings and provided updates for the project website. Early career scientists were given opportunities to engage in inter-laboratory visits and workshops (Next Generation Sequencing, Immunological Tools, Veterinary Vaccinology). Many outreach activities ensured the project fulfilled its impact potential; face-to-face stakeholder symposia and an international online survey publicised future prospects for parasite vaccines.

The vaccines started at various stages in the development path; from most to least advanced these were vaccines against T. circumcincta, O. ostertagi, C. oncophora, F. hepatica, P. ovis, poultry red mite. Linked to trials that tested antigen combinations, were studies on vaccine formulation designed to promote protective responses. This work was linked to defining protective anti-parasite responses so vaccines could be designed to be effective across populations. For O. ostertagi and C. oncophora, immunology studies and trials demonstrated that antigen conformation is key in inducing protection using ASP antigens. A C. oncophora native ASP was shown to cross-protect cattle against another isolate and other Cooperia spp. but not protect sheep against C. curticei. Formulation of a recombinant Ostertagia ASP with SME XStalbio’s novel adjuvant formulation 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 engender protection against pasture challenge. A study tested a recombinant ASP, thiol-purified in the same way as protective native ASP, but this did not produce a protective vaccine. Work on T. circumcincta aimed to simplify a recombinant vaccine shown to induce protection. Here, 8 antigens were successfully co-expressed in 3 systems. The co-expressed version did not induce immunity in lambs. XStalbio’s adjuvant formulation with MAMPs was tested to examine if responses could be enhanced by co-delivery. Incorporation retained antigenicity but did not enhance desired responses. Pen trials in Canarian breeds shown to have differing worm resistance showed that in 6 month-old 'resistant' sheep, resistance was augmented by vaccination. In 'susceptible' lambs, vaccination had a negative effect on worm development. A similar effect was observed in 3-month ‘resistant’ sheep. Sequences encoding antigens in worms from different regions showed low diversity in 7/8 proteins. A 2-protein prototype induced protection similar to the range of the 8-protein prototype. This 2-protein vaccine was re-tested in a study which analysed effect of dose; although vaccinates had lower parasitological parameters than controls, the differences were not significant. Mathematical modelling, using prior data on the 8-protein vaccine, showed that efficacy levels achieved previously could have a substantial effect on downstream contamination if the vaccine was given to ewes and lambs. F. hepatica recombinant antigens were previously shown to afford variable protection; partners tested these combined to examine if this would engender consistent protection. Significant protection was observed in a sheep trial using 4 antigens+montanide; this was not repeatable. Two cattle trials using the 4 antigens were not successful. Antigen sequences in worms from different regions showed low diversity in all but one. Incorporation into XStalbio’s adjuvant formulation with MAMP was tested to examine if responses could be enhanced by co-delivery. Antigenicity was retained, particularly with MAMP. Responses were adjuvant-dependent but protection was not obtained when sheep were challenged. Additional antigens were tested, but these did not afford protection in sheep. Work on protection correlates showed a role for IgG2. Epitope analysis indicated selective recognition of cathepsin L in protected cattle. Large-scale RNA analysis revealed immune evasion pathways significantly changed in fluke infection and a sheep pen trial showed immunomodulation early in infection. These results on immunomodulation will now be used to inform further development of the F. hepatica vaccine. Work on a bovine prototype for P. ovis encompassed a trial using recombinants that protected sheep previously. Although differences in lesion size were observed initially, no significant difference was observed overall. RNA studies informed immune mechanisms. Antigen delivery systems - montanide, DNA, transgenic Eimeria - were compared for a red poultry mite cathepsin vaccine. DNA and Eimeria showed negligible antibody response, but antigen+montanide gave prolonged responses. Hens were vaccinated with cathepsin+montanide and an effect observed on mites that fed on blood from vaccinated birds.

PARAGONE generated much-needed ovine cytokine arrays. Along with Target Product Profiles and Technical Reviews for each vaccine, a Commercialisation Plan was generated for these tools in partnership with SME, Immunotools.
A cohesive relationship between academic and animal health industry partners ensured innovations coming out the research pipeline were aligned to aspirations for marketable products. Partners completed the following for each prototype; Target Product Profile, Probability of Regulatory & Technical Success/Technical Review Reports and a Commercialisation Plan for immunological tools. The team completed an international survey to inform vaccine design and stakeholder meetings to discuss how vaccines might be used on-farm. Progress was exemplified by new data on a two-protein vaccine, key data on protective mechanisms of nematode ASPs and insights into epitope recognition of a F. hepatica candidate. Extensive post-graduate training ensured strong sustainability measures.