Rederivation
Rederivation of mice by embryo transfer
Research is more and more international and as a consequence, a rise of animal exchanges between laboratories all around the world is observed. And because the health status is an important variable that affects the results of animal studies, shipments of mice have necessitated close attention to animal health and animal health reporting. While mice from commercial breeders are usually of high health quality, animals from universities or research institutions are more frequently colonized or infected by unwanted agents. To considerably reduce the risk of contamination between research facilities, it is important to develop strategies and technics allowing to maintain or to recover a high health status. The most important strategy to reduce this risk is the adoption of a common specific list of unwanted pathogens that cannot be found in mice housed under SPF health status (FELASA recommendations; www.felasa.eu). Rederivation by embryo transfer is another of these strategies permitting to recover a specific pathogen free health status from contaminated animals.
Sanitization or rederivation by embryo transfer implies the following sequence, and allows to recover a clean mouse line free from unwanted pathogens and of some opportunistic microorganisms. This is performed following FELASA recommendations and IETS recommendations (www.iets.org):
- Superovulation and mating of donor females;
- Collection of embryos from contaminated animals in a medium containing antibiotics;
- Sorting and washing (10 times) of the embryos;
- Surgical transfer of only zona pellucida intact embryos into SPF foster mothers;
- Housing of all implanted recipients in a quarantine room (SPF) in isocages under negative pressure;
- Confirmation of the recovery of the SPF health status after weaning (following FELASA recommendations for the health monitoring, 2014)
Mice required for rederivation can be bred at the conventional facility of the ULg or supplied at regular intervals from your facility.
