Pre-immunization of diet-induced obese male mice with inactivated pathogens increases power in a liraglutide intervention study

Pre-immunization with inactivated antigens has been developed as an alternative to the use of 'dirty' mice, which in contrast to specific pathogen free (SPF) mice, harbour a range of pathogens. Within certain research areas, such mice are considered better models for humans than SPF mice, as they have an immune system that better mirrors human immunity. We inactivated murine adenovirus type 1 (FL), minute virus of mice, mouse hepatitis virus (A59), respirovirus muris (Sendai), Theiler's encephalomyelitis virus (GD7) and Mycoplasma pulmonis by ultraviolet irradiation. We show that pre-immunization with these inactivated pathogens combined with adjuvant prior to the dietary induction of obesity in C57BL/6NTac mice substantially reduced the group sizes needed for showing an effect of the GLP-1 receptor analogue, liraglutide. Nesting, open field and novel object behaviours of the mice were unaffected. We conclude that pre-immunization with inactivated pathogens may be a simple tool to increase power in this type of intervention study on the DIO mouse model.