Applying the 3Rs at Pirbright
The principles of the 3Rs, Reduction (in numbers), Refinement (of procedures) and Replacement (with laboratory procedures) were developed over 50 years ago as a framework for humane animal research.
Improvements in veterinary medicines and diagnostics are the result of years of research and much of the time is spent doing research in laboratories (in-vitro). However, the sheer complexity of viral diseases and the hosts’ immune responses to them means that research with animals (in-vivo) is essential to better understand the disease and to develop new methods of control.
At The Pirbright Institute this usually entails working with the species for whose improved health the research is directed (cattle, poultry, sheep and pigs). We also use small numbers of mice and rabbits in our research.
Whilst the number of animals used at the Institute is tiny compared to the millions of animals that benefit from the Institute’s research, we strive to apply the principles of the 3Rs for the benefit of animals used in research and for the quality of the data that they yield.
Pirbright scientists researching African swine fever virus (ASFV) are committed to the 3Rs principles; they are constantly looking for new ways to reduce, refine and replace the use of animals in their research.
Before beginning any research involving animals, experimental design is carried out in collaboration with statisticians to ensure statistically relevant results are obtained. Vaccine candidates are extensively tested in cell cultures before advancing to the stage of animal experiments to reduce the number of animals needed.
The use of standardised clinical and pathology scoring facilitates comparisons between experiments and thus reduces the numbers of groups which have to be used in each experiment. Continued re-evaluation of results from experiments mean the data collected can be refined and the outcomes of experiments can be predicted based on cell culture and analysis of host responses that correlate with protection.
Cells taken from immune animals are also used to identify those ASFV proteins that are recognised by the host immune system which may be capable of inducing protection. This greatly reduces the requirement for animal experiments to obtain this information.
FMD vaccine matching
Foot and mouth disease virus (FMDV) is an extremely variable virus. Successful control involves identifying the right vaccine to use and demonstrating the efficacy of batches of the selected vaccine. This used to involve vaccination of cattle (a group of cattle for each vaccine to be assessed) which would then be challenged (inoculated) with virus. The Institute now uses serologically based methods that have greatly reduced both the number of cattle that are used and those that are challenged.
Together with mathematical modellers at Glasgow University, researchers are working towards a robust and challenge-free computational based model for the assessment of FMD vaccine efficacy.
Lumpy skin disease (LSD)
In order to improve the range of diagnostic, control and prevention tools available for lumpy skin disease (LSD), Pirbright scientists have optimised an experimental model of the disease. The 3Rs were guiding principles underpinning the research and considered throughout the model development. The group have provided serum with high titres of lumpy skin disease virus (LSDV) antibodies from the LSDV-infected cattle to the OIE Capripoxvirus Reference Laboratory, based at Pirbright, for assay validation. Tissue and fluid samples are also being provided to international colleagues to avoid them from having to duplicate the in-vivo LSD experiments. For example polymorphonuclear blood cells and sera have been provided to the H2020 project DEFEND to support development of novel diagnostic tests for LSD.
Tissues from LSD-affected animals are being made into a histology 'slide set' in collaboration with the Scottish Agricultural College. These will be used to teach trainee pathologists about LSD lesions. We hope to make these freely available in electronic form in the future.
Feeding our insect colonies
Colonies of biting midges and mosquitoes were traditionally fed using mice. The Institute has shown that the insects can be fed successfully using artifical membrane based feeding units. We now only used this for feeding our insect colonies which has replaced the requirement of thousands of mice per annum.
Animal housing and enrichment
Refinement includes environmental enrichment for animals used in experiments. Animals used in research at The Pirbright Institute are housed under strictly controlled conditions. Our NACWO's are constantly investigating new areas and types of enrichment for their animals. Enrichment is available to provide a stimulating environment in order for the animals to demonstrate their species typical behaviour and to enhance and ensure their well-being. Animals are also housed in pairs or groups where possible to allow for normal social interaction.
The Pirbright Institute provides all species with a range of enrichment items. Large animals are provided with mineral licks, brushes, treats, bedding material and/or rubber matting. Small animals are provided with red polycarbonate huts which gives them a sense of security and shelter by reducing the level of perceived light, running wheels, tubes, fruit and vegetables, nest boxes and nesting material.
Lumpy skin disease (LSD)
In their research to optimise an experimental model of lumpy skin disease (LSD), Pirbright scientists have characterised the behavioural, physiological, immunological and virological changes that occur in LSD in order to identify predictive markers that can be used to define humane end points for future studies. In addition, they have developed LSD-specific daily 'scoring charts' to clearly determine the level of pain, suffering and distress in each animal.
A surgical microbiopsy technique (a 1mm diameter skin biopsy) has been developed to measure the quantity of lumpy skin disease virus (LSDV) in the skin of cattle. This procedure is less invasive and less painful than a more traditional skin biopsy (8mm) which requires local anaesthetic and suturing. The microbiopsy is well tolerated and provides sufficient tissue for detection and assessment of the levels of LSDV in the skin.