Abstract
Pathogen-free sentinel mice were placed in 7 animal rooms with different housing conditions and were serologically screened for antibodies to mouse hepatitis virus (MHV), pneumonia virus of mice (PVM), Sendai virus, reovirus 3, Theiler's mouse encephalomyelitis virus (TMEV), ectromelia virus and Mycoplasma pulmonis by enzyme-linked immunosorbent assays, at intervals after introduction. The most commonly detected antibody was against MHV, which was found in mice from 4 rooms, followed by PVM antibody in mice from 3 rooms. Seroconversion to Sendai virus and TMEV was detected in mice from one room each. No seroconversion to any of the antigens was found in 2 rooms. The common criteria of these 2 rooms were that they housed pathogen-free animals from a single source and that the access to the rooms was, purposely or not, restricted to people who had no contact to other mice. The study demonstrated the importance of husbandry and hygienic regimen on the prevalence of infectious agents in laboratory mice.