Rearing and breeding of germ-free mice for over 1 year in a sealed positive pressure cage system

Germ-free mice and gnotobiotic mice have long been used as models in various research areas. Historically, they were reared and used for studies of flexible film isolators, but such isolators have several operational disadvantages. To overcome these disadvantages, a new individually ventilated cage system that promises more standardized cage conditions and reduced operational costs for maintaining germ-free or gnotobiotic mice has been developed. However, in the context of this system, only short periods (2-12 weeks) of rearing and experimental use of germ-free or gnotobiotic mice have been reported. In this report, we describe the rearing and breeding of 117 germ-free mice for over 1 year using the Sentry SPP cage, a sealed positive pressure isolation cage dedicated to gnotobiology.