Using a novel, high welfare in vivo feeding device for poultry red mite and its integration with other novel tools for this parasite
Lead Research Organisation:
Moredun Research Institute
Department Name: Vaccines and Diagnostics
Abstract
Infestation of hen houses with poultry red mites (PRM) is a major animal welfare and economic problem for the egg industry worldwide, irrespective of the type of laying systems employed. The two main impacts of PRM on laying hens are direct effects of the mites biting the birds and feeding on their blood which causes irritation and anaemia, and indirect effects caused by the mites transmitting diseases to the hens. Traditional methods of controlling PRM with chemical sprays in hen houses are now failing as the mites become resistant to the chemicals. Demand for novel methods of controlling PRM is therefore high and several research groups around the world are working on these new methods of control. Typically, the testing of novel control methods uses mites in laboratory-based tests initially, followed by field testing using large numbers of hens. For example, the development of vaccines to control PRM routinely uses initial laboratory-screening tests to identify potential vaccines before moving into field trials which can use up to 800 hens in each trial and last for several months. This strategy has 2 major drawbacks:
1) Results from the laboratory-based analyses are highly variable and may not accurately predict what happens in field trials;
2) Field trials involve large numbers of birds continually exposed to parasites for prolonged periods.
To address these issues we have developed an 'on-hen' mite feeding device, as an alternative to the laboratory-based tests, which allows much more accurate assessment of vaccines and other mite control methods on small numbers of hens before field studies are conducted. This strategy addresses the "Reduction" aspect of the 3Rs principles by greatly reducing the number of hens used, as it would accurately identify poorly performing vaccines or other control methods (e.g. new pesticides) before they were progressed to field trials. This on-hen system can also be used to test the effectiveness of mite control methods across prolonged periods on small numbers of hens (4 per treatment group, as opposed to 400 per treatment group in field trials) without continually exposing birds to the parasites. This therefore addresses a second 3Rs principle - "Refinement" as it allows the birds to remain free from the parasites for the vast majority of the experimental period, with parasites only accessing the birds for short (3 hour) periods every 3 weeks instead of the continual exposure encountered in field trials.
We have successfully transferred this technology to a vaccine-development group at University of Castilla-La Mancha, Spain through a COST Action mobility grant and we now wish to hold a 3-day workshop to disseminate this technology with practical demonstrations and discussions around how it intersects with other novel and emerging tools for PRM research to promote its adoption in laboratories across Europe. The proposed participants in the workshop have interests in both refinement and reduction of the use of hens in the development of novel interventions including pesticides, repellents and vaccines and in investigations of the ability of PRM to spread disease. The principal aims of this proposal are to hold a workshop at Moredun Research Institute to:
1) Demonstrate the construction and use of an optimised system for scientists to use in an accurate, mild-severity and enhanced pre-screening of new vaccines and pesticides for the control of a blood-feeding parasite before progressing to large field trials, and;
2) Demonstrate and discuss how this novel technology may be integrated with other emerging technologies in this field.
Each of the selected participants is a member of larger networks with the potential to exploit these technologies beyond the reach of this initial workshop.
1) Results from the laboratory-based analyses are highly variable and may not accurately predict what happens in field trials;
2) Field trials involve large numbers of birds continually exposed to parasites for prolonged periods.
To address these issues we have developed an 'on-hen' mite feeding device, as an alternative to the laboratory-based tests, which allows much more accurate assessment of vaccines and other mite control methods on small numbers of hens before field studies are conducted. This strategy addresses the "Reduction" aspect of the 3Rs principles by greatly reducing the number of hens used, as it would accurately identify poorly performing vaccines or other control methods (e.g. new pesticides) before they were progressed to field trials. This on-hen system can also be used to test the effectiveness of mite control methods across prolonged periods on small numbers of hens (4 per treatment group, as opposed to 400 per treatment group in field trials) without continually exposing birds to the parasites. This therefore addresses a second 3Rs principle - "Refinement" as it allows the birds to remain free from the parasites for the vast majority of the experimental period, with parasites only accessing the birds for short (3 hour) periods every 3 weeks instead of the continual exposure encountered in field trials.
We have successfully transferred this technology to a vaccine-development group at University of Castilla-La Mancha, Spain through a COST Action mobility grant and we now wish to hold a 3-day workshop to disseminate this technology with practical demonstrations and discussions around how it intersects with other novel and emerging tools for PRM research to promote its adoption in laboratories across Europe. The proposed participants in the workshop have interests in both refinement and reduction of the use of hens in the development of novel interventions including pesticides, repellents and vaccines and in investigations of the ability of PRM to spread disease. The principal aims of this proposal are to hold a workshop at Moredun Research Institute to:
1) Demonstrate the construction and use of an optimised system for scientists to use in an accurate, mild-severity and enhanced pre-screening of new vaccines and pesticides for the control of a blood-feeding parasite before progressing to large field trials, and;
2) Demonstrate and discuss how this novel technology may be integrated with other emerging technologies in this field.
Each of the selected participants is a member of larger networks with the potential to exploit these technologies beyond the reach of this initial workshop.
Technical Summary
Infestation of hen houses with poultry red mites (PRM) is a major animal welfare and economic problem for the egg industry worldwide. Demand for novel methods of controlling PRM is high and, typically, the testing of novel control methods uses mites in in vitro efficacy assays initially, followed by field testing using up to 800 hens in each trial. This strategy has 2 major drawbacks:
1) Data from the in vitro assays are highly variable and may not accurately reflect field trials;
2) Field trials involve large numbers of birds continually exposed to parasites for prolonged periods.
To address these issues we developed an 'on-hen' in vivo mite feeding device as an alternative to both the in vitro feeding assays and field studies. This system can be used to test vaccine efficacy in longitudinal studies across prolonged experimental periods on small numbers of hens (4 per treatment group, as opposed to 400 per treatment group in field trials) without continuous exposure of the birds to the parasites. We have successfully transferred this technology to a vaccine-development group at University of Castilla-La Mancha, Spain through a COST Action mobility grant and we now wish to hold a 3-day workshop to disseminate this technology with practical demonstrations and discussions around how it intersects with other novel and emerging tools for PRM research to promote its adoption in laboratories across Europe. The proposed participants in the workshop have interests in both refinement and reduction of the use of hens in the development of novel interventions including pesticides, repellents and vaccines and in investigations of the ability of PRM to spread disease. The principal aims of this proposal are to hold a workshop at Moredun Research Institute to demonstrate the construction and use of the device and discuss how this novel technology may be integrated with other emerging technologies (e.g. RNAi) in this field.
1) Data from the in vitro assays are highly variable and may not accurately reflect field trials;
2) Field trials involve large numbers of birds continually exposed to parasites for prolonged periods.
To address these issues we developed an 'on-hen' in vivo mite feeding device as an alternative to both the in vitro feeding assays and field studies. This system can be used to test vaccine efficacy in longitudinal studies across prolonged experimental periods on small numbers of hens (4 per treatment group, as opposed to 400 per treatment group in field trials) without continuous exposure of the birds to the parasites. We have successfully transferred this technology to a vaccine-development group at University of Castilla-La Mancha, Spain through a COST Action mobility grant and we now wish to hold a 3-day workshop to disseminate this technology with practical demonstrations and discussions around how it intersects with other novel and emerging tools for PRM research to promote its adoption in laboratories across Europe. The proposed participants in the workshop have interests in both refinement and reduction of the use of hens in the development of novel interventions including pesticides, repellents and vaccines and in investigations of the ability of PRM to spread disease. The principal aims of this proposal are to hold a workshop at Moredun Research Institute to demonstrate the construction and use of the device and discuss how this novel technology may be integrated with other emerging technologies (e.g. RNAi) in this field.
Planned Impact
The outcomes of the proposed work programme will demonstrate impact through the reduction in use of hens in field trials and refinement of experimental procedures on hens leading to greatly increased welfare. The animal models immediately affected will be female domestic fowl (hens) of any commercial breed - Lohmann brown hens have been used in the development of the in vivo on-hen feeding device but the device design uses a small and flexible substrate and so is suitable for any commercial layer hen breed. Hens of >18 weeks of age will be most impacted as this age of hens will be used by all groups testing novel interventions (this is the age at which hens would be entering laying houses and would be exposed to the parasite).
The knowledge exchanged in this workshop will have immediate impacts in studies which assess novel interventions for poultry red mite control, where large numbers of parasites are required throughout the tests. This is an expanding area, with 18 new papers published in the 2 years since our current NC3Rs project began and 47 papers published in the 10 years before that: Only 17 papers on the topic were published in the 40 years prior to 2007. The two largest areas of growth in the development of novel interventions for poultry red mite control have been in the development of vaccines (10 papers since 2007) and novel acaricides/novel uses for existing acaricides (33 papers since 2007). Novel interventions are typically tested first in in vitro assays prior to escalation to field trials. Field trials for novel acaricides have employed ~300 hens whereas those for vaccines employ ~800 hens. During these trials hens are continually exposed to the parasites and the in vitro efficacy of the vaccines or novel acaricides are not always directly translated to efficacy in the field. We will demonstrate the novel on-hen mite feeding system for pre-screening in vivo efficacy of products before they are advanced to field trial to the most productive and influential groups in Europe working in this area: Once the technology is transferred, 6 research labs (in addition to our own) represented by the attendees at the workshop will use this system to pre-screen vaccine or novel-intervention formulations (e.g. new acaricides, feed additives) for poor in vivo performance before embarking on field trials. This could reduce the numbers of hens used in field trials by ~800 per vaccine formulation (see attached letters of support). As an example of the potential impacts in these research groups, we recently published a list of 22 different preparations/proteins which had shown some degree of efficacy in in vitro feeding assays and a further 9 vaccine candidates have been identified by a separate academic group. To progress any of these vaccine candidates to commercial use, their efficacy in vivo will need to be demonstrated. If our optimised on-hen in vivo feeding device was able to indicate poor in vivo efficacy for 50% of these candidates, this would lead to a reduction in the number of field trials performed and the use of ~12,000 hens in those field trials.
At the workshop we will advocate the promotion of the use of the device by workshop participants through several pathways: direct discussion with poultry veterinarians and scientists involved in this research; promotion of the currently published methodology and the forthcoming F1000 article which includes a detailed description of the device design and use (including video link).
Further 3Rs and scientific impact will be delivered through the use of the device to understand vector competency of poultry red mites and scientists working on arthropod-vectored diseases will benefit as the device may be easily altered to other biting arthropod systems.
Economic impact will be delivered through the reduced use (and expense) of unproductive field trials and through the accelerated development of novel interventions for a parasite of huge economic importance.
The knowledge exchanged in this workshop will have immediate impacts in studies which assess novel interventions for poultry red mite control, where large numbers of parasites are required throughout the tests. This is an expanding area, with 18 new papers published in the 2 years since our current NC3Rs project began and 47 papers published in the 10 years before that: Only 17 papers on the topic were published in the 40 years prior to 2007. The two largest areas of growth in the development of novel interventions for poultry red mite control have been in the development of vaccines (10 papers since 2007) and novel acaricides/novel uses for existing acaricides (33 papers since 2007). Novel interventions are typically tested first in in vitro assays prior to escalation to field trials. Field trials for novel acaricides have employed ~300 hens whereas those for vaccines employ ~800 hens. During these trials hens are continually exposed to the parasites and the in vitro efficacy of the vaccines or novel acaricides are not always directly translated to efficacy in the field. We will demonstrate the novel on-hen mite feeding system for pre-screening in vivo efficacy of products before they are advanced to field trial to the most productive and influential groups in Europe working in this area: Once the technology is transferred, 6 research labs (in addition to our own) represented by the attendees at the workshop will use this system to pre-screen vaccine or novel-intervention formulations (e.g. new acaricides, feed additives) for poor in vivo performance before embarking on field trials. This could reduce the numbers of hens used in field trials by ~800 per vaccine formulation (see attached letters of support). As an example of the potential impacts in these research groups, we recently published a list of 22 different preparations/proteins which had shown some degree of efficacy in in vitro feeding assays and a further 9 vaccine candidates have been identified by a separate academic group. To progress any of these vaccine candidates to commercial use, their efficacy in vivo will need to be demonstrated. If our optimised on-hen in vivo feeding device was able to indicate poor in vivo efficacy for 50% of these candidates, this would lead to a reduction in the number of field trials performed and the use of ~12,000 hens in those field trials.
At the workshop we will advocate the promotion of the use of the device by workshop participants through several pathways: direct discussion with poultry veterinarians and scientists involved in this research; promotion of the currently published methodology and the forthcoming F1000 article which includes a detailed description of the device design and use (including video link).
Further 3Rs and scientific impact will be delivered through the use of the device to understand vector competency of poultry red mites and scientists working on arthropod-vectored diseases will benefit as the device may be easily altered to other biting arthropod systems.
Economic impact will be delivered through the reduced use (and expense) of unproductive field trials and through the accelerated development of novel interventions for a parasite of huge economic importance.
