Community Research and Development Information Service - CORDIS

Periodic Report Summary 3 - ANTIDOTE (Anti-tick Vaccines to Prevent Tick-borne Diseases in Europe)

Project Context and Objectives:
The overall objective of ANTIDotE is to identify and characterize tick proteins involved in ‘tick immunity’ and transmission of tick-borne pathogens (TBPs) and to use this knowledge to develop anti-tick vaccines to prevent multiple human tick-borne diseases (TBDs), such as Lyme borreliosis (LB), tick-borne encephalitis virus (TBEV) infection and human babesiosis. In addition, through an integrated and multidisciplinary approach involving public health institutes, health organizations and industrial companies we will examine how to develop anti-tick vaccines and how to implement these in public health systems. Because of its design, which combines state of the art basic science with translational research, ANTIDotE will also deliver essential knowledge on the biological mechanisms involved in the pathogenesis of TBDs. The key objectives are:
First Objective: To identify I. ricinus tick salivary gland proteins (TSGPs) that play a role in the transmission of TBPs from the tick to the host, but also TSGPs that are recognized by anti-tick antibodies. Therefore, gene expression profiles will be analyzed of salivary glands (SGs) of uninfected and TBP-infected feeding I. ricinus ticks. We will also identify TSGPs that are recognized by mammalian anti-tick immune responses by an I. ricinus TSGP Yeast Surface Display (YSD).
Second Objective: Identified TSGPs (described above) will be characterized with the help of RNAi in ticks. Alongside, the functional activity of specific TSGPs (in relation to host defense mechanisms) will be investigated. As part of this objective we will provide in depth insights in the mechanisms involved in transmission of TBPs and will reveal candidates for anti-tick vaccine to prevent TBP transmission. For this objective in vivo animal models for the TBDs under study will be established and improved.
Third Objective: Aims to confirm which TSGPs induce ‘tick immunity’ in in vivo animal models and the artificial tick feeding system. Furthermore, the humoral and cellular immune responses that these TSGPs elicit will be characterized. Thus, third objective will reveal candidates for anti-tick vaccine that are capable of interfering with tick feeding.
Fourth Objective: As part of this objective we aim to deliver the proof of concept that a single anti-tick vaccine can prevent transmission of bacterial, protozoal as well as viral TBPs. Vaccine studies with promising candidates, or specific combinations of promising candidates, will be performed to identify an anti-tick vaccine that could interfere with all three TBPs under study. Both TSGPs that are crucial for the transmission of Borrelia, Babesia and TBEV from the tick to the mammalian host, and TSGPs that are of paramount importance for tick feeding, will be tested.
Fifth Objective: The objective of this part of the project is to deliver plans for exploitation and implementation of our findings and concepts to contribute to downscaling of the burden of TBDs on Central and Eastern Europe and other endemic European societies, as well as to disseminate ANTIDotE results. We will do so by attending and arranging workshops and meetings.
These key objective results in the following project objectives (OB):
OB 1.1 Identification of TSGPs involved in transmission of TBPs [M18]
OB 1.2 Identification of TSGPs recognized by anti-tick immune responses [M18]
OB 2.1 Describe the role of TSGPs in the transmission of TBPs in vivo using RNAi in ticks [M42]
OB 2.2 Describe the function of TSGPs in in vitro and ex vivo functional assay [M60]
OB 3.1 To confirm that TSGPs identified induce ‘tick immunity’ in mice [M42]
OB 3.2 To characterize humoral and cellular anti-tick immune responses [M48]
OB 3.3 To confirm that TSGPs identified induce ‘tick immunity’ in cows and to develop a robust ATFS for research on anti-tick vaccines [M48]
OB 4.1 To identify an anti-tick vaccine that protects against multiple TBDs by specifically interfering with TSGPs crucial for transmission of TBDs [M60]
OB 4.2 To identify an anti-tick vaccine that protects against multiple TBDs by interfering with tick feeding [M60]
OB 5.1 To exchange knowledge on LB, TBE, human babesiosis and innovative strategies to prevent TBDs
OB 5.2 To disseminate ANTIDotE results [M42, M60]
OB 5.3 To establish a road map for exploitation of novel anti-tick vaccines [M36]
OB 5.4 To explore ways to implement anti-tick vaccines in health systems [M60]

Project Results:
The aim of the ANTIDotE project is to find tick salivary gland proteins (TSGPs) that block pathogen transmission and/or interfere with tick feeding. Two main antigen discovery strategies were employed. Firstly, a trancriptomic approach; MACE and RNAseq were used to identify TSGPs upregulated upon infection with Borrelia, TBEV or Babesia, resulting in the identification of numerous TSGPs, of which a selection could be validated. We are currently drafting manuscripts on the transcriptomes of I. ricinus upon feeding and infection. As an additional effort we identified and validated multiple TSGPs that are consistently and highly upregulated upon tick feeding. Secondly, an immunoscreening; a yeast surface display was used to identify and validate over 30 TSGPs that are recognized by antibodies of frequently tick-exposed humans, and/or tick immune cows or rabbits. A selection of the thus identified TSGPs was further characterized in WP2/3.
We have established tick-transmission models for Borrelia afzelii (a manuscript has been submitted), TBEV and Babesia microti (WP2). RNAi infrastructure was established and used to investigate multiple TSGPs. Silencing of selected TSGPs thus far did not affect tick feeding parameters or TBEV and Borrelia transmission. Additional experiments are under way in the TBEV model. Production of TSGPs in E. coli and Drosophila has started and a selection is ready for vaccination studies. Preliminary data show that one of the identified TSGPs promotes Borrelia survival in vivo by impairing phagocytosis. We have also generated fluorescent B. afzelii strain CB43 to study TSGP-Borrelia interactions.
Vaccination of mice with TSGPs did not result in a significant anti-tick effect and we have shifted our focus to the tick-rabbit model to assess tick immunity (WP3). Also, five bovine vaccination experiments were performed, showing that (specific fractions of) tick tissue extracts resulted in a robust anti-tick immunity (a manuscript has been submitted). One cow vaccination trial is currently ongoing. The obtained cow sera were used to set-up an artificial in vitro tick feeding system, which demonstrated the need for combined cellular and humoral immune responses to induce tick immunity. Cloning, expression and purification of TSGPs is nearly completed and will be further tested in WP4. As an additional effort, we identified and/or tested tick-borne pathogen antigens (from B. microti and B. afzelii) as candidates for transmission-blocking vaccines.
The ANTIDotE partners have been disseminating knowledge on (inter)national conferences, in peer-reviewed scientific journals and through the ANTIDotE website. Importantly, an ANTIDotE partner has become a member of the WHO taskforce for the development of a roadmap on the prevention of Crimean-Congo Hemorrhagic Fever Virus, which also considers anti-tick vaccines. A technical report on preventive strategies to prevent TBDs (DL5.3) and a book chapter on the prevention of Lyme borreliosis have been published in collaboration with experts from the USA and Europe. Furthermore, a manuscript on the cost-effectiveness analyses of an anti-tick vaccine in a Central Eastern European country where Lyme borreliosis and tick-borne encephalitis are endemic has been provisionally accepted for publication. Furthermore, ANTIDotE partners actively engaged with stakeholders from medical and veterinary sciences, policy advisors, governmental institutions, patient interest groups and the pharmaceutical industry.
We have made significant progress: all initially planned discovery methods yielded vaccine candidates and we pursued multiple additional antigen discovery approaches, we have characterized and produced selected candidates, vaccination studies have been performed and are ongoing in multiple models and results and our strategy have been widely disseminated with up until now 24 related peer-reviewed manuscripts that have been submitted, accepted or published in books and scientific journals.
We have established tick-transmission models for Borrelia afzelii (a manuscript has been submitted), TBEV and Babesia microti (WP2). RNAi infrastructure was established and used to investigate multiple TSGPs. Silencing of selected TSGPs thus far did not affect tick feeding parameters or TBEV and Borrelia transmission. Additional experiments are under way in the TBEV model. Production of TSGPs in E. coli and Drosophila has started and a selection is ready for vaccination studies. Preliminary data show that one of the identified TSGPs promotes Borrelia survival in vivo by impairing phagocytosis. We have also generated fluorescent B. afzelii strain CB43 to study TSGP-Borrelia interactions.
Vaccination of mice with TSGPs did not result in a significant anti-tick effect and we have shifted our focus to the tick-rabbit model to assess tick immunity (WP3). Also, five bovine vaccination experiments were performed, showing that (specific fractions of) tick tissue extracts resulted in a robust anti-tick immunity (a manuscript has been submitted). One cow vaccination trial is currently ongoing. The obtained cow sera were used to set-up an artificial in vitro tick feeding system, which demonstrated the need for combined cellular and humoral immune responses to induce tick immunity. Cloning, expression and purification of TSGPs is nearly completed and will be further tested in WP4. As an additional effort, we identified and/or tested tick-borne pathogen antigens (from B. microti and B. afzelii) as candidates for transmission-blocking vaccines.
The ANTIDotE partners have been disseminating knowledge on (inter)national conferences, in peer-reviewed scientific journals and through the ANTIDotE website. Importantly, an ANTIDotE partner has become a member of the WHO taskforce for the development of a roadmap on the prevention of Crimean-Congo Hemorrhagic Fever Virus, which also considers anti-tick vaccines. A technical report on preventive strategies to prevent TBDs (DL5.3) and a book chapter on the prevention of Lyme borreliosis have been published in collaboration with experts from the USA and Europe. Furthermore, a manuscript on the cost-effectiveness analyses of an anti-tick vaccine in a Central Eastern European country where Lyme borreliosis and tick-borne encephalitis are endemic has been provisionally accepted for publication. Furthermore, ANTIDotE partners actively engaged with stakeholders from medical and veterinary sciences, policy advisors, governmental institutions, patient interest groups and the pharmaceutical industry.
We have made significant progress: all initially planned discovery methods yielded vaccine candidates and we pursued multiple additional antigen discovery approaches, we have characterized and produced selected candidates, vaccination studies have been performed and are ongoing in multiple models and results and our strategy have been widely disseminated with up until now 24 related peer-reviewed manuscripts that have been submitted, accepted or published in books and scientific journals.
Potential Impact:
The incidences of Lyme borreliosis (LB) and TBEV are on the rise in several European countries and diseases caused by other pathogens, such as Babesia spp. and Borrelia miyamotoi are emerging. Environmental, socio-economic and demographic factors synergistically increase the risk of acquiring tick-borne diseases (TBDs). Indeed, the European Center for Disease Prevention and Control (ECDC) has predicted that the incidence of TBDs will rise in the near future. Therefore, and also because the societal fear for ticks and TBDs seems to be ever growing, the old adage ‘prevention is better than cure’ certainly holds true for tick-borne diseases.
Currently there are no human or animal vaccines against I. ricinus available. However, anti-tick vaccines are available against other tick species for the veterinary market and there is a body of experimental evidence that anti-tick vaccines could also work for Ixodes ticks. Our project aims to show proof of concept that anti-I. ricinus vaccines can protect against multiple TBDs, which is innovative by itself. Moreover, we will provide insights into the molecular mechanisms involved in transmission of tick-borne pathogens from the tick to the host, and in the process of tick feeding. Furthermore, we will go one step further and also discuss with public health representatives and relevant industrial stakeholders how anti-I. ricinus vaccines could be exploited and implemented. This could lead to a paradigm shift in how public health institutes tackle TBDs in Europe and result in a road map for future use of anti-tick vaccines.
Expected final results:
We expect to make major contributions in the prevention of TBDs in Europe by providing:
- molecular insights into the process of tick feeding and pathogen transmission from the tick to the host.
- robust in vitro and in vivo animal models for research on transmission of Borrelia, Babesia and TBEV.
- identification of tick antigens that could serve as candidates for anti-tick vaccines preventing Lyme borreliosis, babesiosis and TBEV.
- the first proof of concept that such a vaccine works in animal models.
- plans for future product development and implementation of anti-tick vaccines in health systems in collaboration with industry, health institutes and other relevant stakeholders.
In summary, ANTIDotE aims to shed light on the mechanisms of I. ricinus tick feeding and tick-borne pathogen transmission and to identify, characterize and assess tick salivary gland proteins as candidates for anti-tick vaccines by developing and refining in vivo and in vitro models. Hereto, ANTIDotE applies state of the art and innovative technologies; these include the use of YSD technology, RNAseq, MACE and RNAi in ticks.
Potential impact/expected use:
ANTIDotE’s major contributions and concerted multidisciplinary integrated European approach will lead to a breakthrough in the field of ticks and TBDs in many ways, since these will impact a) the research community worldwide, b) health systems, societies, economies and individual patients in European countries where TBDs are endemic, and c) industrial innovation. The expected outcomes collectively contribute to a knowledge-based society and accelerate the establishment of innovative standards for prevention of TBDs by industry and health systems in Europe.
The models, technologies and approaches used within the project, enable us to achieve our ambitious objectives and will simultaneously raise the standard for research on ticks in Europe. Furthermore, ANTIDotE will provide the scientific community with new knowledge on the process of tick feeding, anti-I. ricinus immune responses and the transmission of B. burgdorferi sensu lato, Babesia and TBEV. This is of paramount importance for the understanding of the pathogenesis of these bacterial, protozoal and viral TBDs. The new ANTIDotE-derived knowledge on the processes involved in I. ricinus tick feeding and TBP transmission will impact the understanding and development of new preventive strategies against other TBDs and other tick species in Europe. It will also reveal novel insights into specific mammalian host defense mechanisms, such as innate and adaptive immune responses, fibrinolysis, inflammation and coagulation. Taken together, improved knowledge on tick feeding and tick-borne pathogen transmission and novel candidates for anti-tick vaccines that prevent multiple human TBDs, as well as plans on how to implement anti-tick vaccines in health systems and societies could have a direct health and socioeconomic impact by diminishing the number of people at risk for TBDs.

List of Websites:
http://www.ANTIDotE-fp7.org/

Related information

Reported by

Academisch Medisch Centrum bij de Universiteit van Amsterdam
Netherlands

Subjects

Life Sciences
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