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Report of the NIH Rat Model Repository Workshop

To facilitate and implement the establishment of standards for genetic, phenotypic, and microbiological monitoring.

This NRGRC would participate in establishing and maintaining standards of quality of rat model strains, both genetically and microbiologically. All rat strains maintained at the NRGRC would be fully characterized and documented for their genetic status and their health/infection status.

The possibility of moving pathogens into the NRGRC is a very serious threat to the mission, and, because of this, all animals that are moved to the NRGRC must be rederived by either cesarean section or embryo transfer, regardless of the supposed health status of the incoming animals. Even in clean embryo settings, Pasteurella pneumotropica and Mycoplasm sp. are potential threats, although they can be "cleaned" from the embryo by washing the zona pellucida with hyaluronidase.

Live animals should be housed in room or cage barriers and have sterile food, bedding, and water, in so-called barrier facilities. Rederivation by cesarean section or embryo transfer should be used with standard methodology. Embryos should be obtained from antibiotic-treated donors where necessary and transferred to surrogate dams of known health status. The NRGRC should have a quarantine area set up with separate rooms and different containment measures to facilitate rederivation.

Standard microbiological testing should be done using the surrogate dams from embryo transfer. These animals begin with the required health status, and, after the embryo is transferred and develops, they represent the ideal sentinel. It is recommended that the microbiological testing be done in the NRGRC. However, this decision is to be left to the discretion of the Center Director and Advisory Board.

Standardized microbiological monitoring is constantly evolving, and agencies such as the National Research Council and International Council for Laboratory Animal Science are responsible for disseminating current requirements and state-of-the-art methods. Responsible personnel from the Center should go to annual meetings, such as those sponsored by the American Association for Laboratory Animal Science, where these ideas are discussed. Full strain history, pedigree information, and a genetic profile should be submitted. The methods and strategies for genetic monitoring are established in several settings, e.g., Hannover, Germany, and the Central Institute for Experimental Animals (CIEA), Japan. Current methodology is described in "Genetic Monitoring of Inbred Strains of Rats" (H.J. Hedrich, ed.) and by Mossmann et al. (1998) in Methods in Microbiology, vol. 25. Because these methods will change with time, the NRGRC staff will have to pursue assiduously the latest methodology with the oversight of the Advisory Board.

The participants would encourage a mechanism to make available to investigators and commercial suppliers the standardized, quality-controlled reagents for culture media, freezing protectants, microbiological and virological screening, and genetic monitoring (for example, identical primer pairs or probes for screening) developed by the NRGRC.

The selection of sources of strains of rats itself establishes a standardized "reagent." Achieving a consensus on the genetic definition of a given strain will be enormously valuable to the community of investigators using rat models.

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