Rederivation

The process of rederivation eliminates pathogens such as pinworm, parvovirus, and mouse hepatitis virus from infected mouse lines. Pre-implantation embryos, which are relatively resistant to such pathogenic microorganisms due to the physical barrier of the zona pellucida surrounding the embryo, are collected from infected mice and washed through several droplets of embryo culture media, then surgically transferred into specific pathogen-free pseudopregnant females. Resulting mice can then be transferred to the barrier-level vivarium in the Lurie Research Center. Rederivation allows the import of established mouse lines with either known pathogens or of unknown health status from anywhere in the world.

Information you need to provide prior to scheduling rederivation:

Note: CCM must initially approve the receipt of all animals into the vivarium

1. Submit an Animal Procurement form to CCM and they will:
   • Assess the health status of the requested animals
   • Determine whether rederivation is necessary
   • Provide options for receiving the mice
2. If opting to have the TTML rederive the line, complete and return the Rederivation Request form (Word) and we will:
   • Review the information
   • Contact CCM to schedule the shipping of the animals (Note: projects will be completed faster if 2-3 males are available)

The rederivation process:

1. Animals are received and housed in containment; males are singly housed upon arrival: tail samples will be taken and provided to verify genotype of received mice
2. Wild-type females are purchased and mated with males
3. Embryos are surgically transferred to SPF recipient mothers
4. Litters are born 19 days following surgical transfer
5. Blood for pathogen testing is collected from the mothers when pups weaned at 3 weeks of age; tissue is provided for genotyping if necessary
6. Rederived pups are transferred to your specified animal room

Expected results:

• Timeline is dependent on the number and fertility of the males received
• Males are single housed upon arrival and allowed to acclimate for a week before mating with wild-type females
• Males are mated for 2 consecutive weeks, which generally yields enough embryos for rederivation
• Blood results are usually obtain within a week

Your responsibilities following rederivation:

• Transfer of animals: once pups are weaned and pathogen testing results are received, TTML will initiate the paperwork for the transfer of these mice to your animal room and protocol

Costs and Services