Biosecurity and Gnotobiology

The management of the sanitary status of laboratory animals is essential both from an animal welfare and a scientific standpoint. Poor sanitary status may have clinical impact and lead to invalid and/or irreproducible scientific results. Most of the laboratory animals are bred for research under strict hygienic procedures in order to exclude microorganisms that can impact their health and the outcome of experimental procedures. In these circumstances, the microbiological component of the animal models is defined by an exclusion list, i.e. the animals are free of certain microorganisms. In certain fields of research, the microbiota carried by the animals (microorganisms present in the animal, at interfaces with the environment, i.e. skin, mouth, nose, respiratory tract, genital tract, digestive tract) needs to be defined, and therefore gnotobiotic animals need to be used. Indeed, the phenotype of an animal depends on both its genotype and the envirotype, and like the genome, the microbiota can be manipulated to investigate its impact on the biology of the host. In this chapter, we will answer to practical questions to understand the procedures to put in place when building a standard biosecurity program, and the specific ones that need to be implemented to produce germ-free and gnotobiotic animals. We will focus mainly on laboratory rodents, but the main principles may apply to other species used in research.