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Microbiological monitoring in inbred mouse foundation stocks in Japan
Abstract:
Microbiological monitoring on 128 inbred mouse foundation stocks consisted of common 10 inbred strains and inbred strains originated from outbred dd mice was performed by cooperation of 24 organizations. A total of 881 mice were divided into 647 conventional animals from 95 colonies and 234 barrier-sustained animals from 33 colonies. Three viral, one mycoplasmal, 6 bacterial, one fungal and 3 parasitic agents selected as monitoring microbes according to the proposed selection standards. Among conventional colonies, 84.2% were positive for at least one agent. The highest detection rate was 44.2% for S. obvelata, followed by P. pneumotropica and S. muris, P. aeruginosa, G. muris, Sendai virus, M. pulmonis, MHV and E. coli O115a, c: K (B). Of these agents, only one microbe, P. aeruginosa, was detected in barrier-sustained colonies (36.4%), thus the efficacy of barrier system for the microbiological quality control of the inbred mouse foundation stocks was actually demonstrated. The positive rates of MHV (6.3%) and Sendai v. (16.8%) were significantly low compared with those in experimental mouse colonies. Positivity for parasites was rather high and they were infested together with other pathogens in many cases. Thus parasites including G. muris, S. muris and S. obvelata were regarded as useful indicators to see microbiological contaminations in conventional mice. There observed no strain difference in susceptibility to pathogens except for C57BL/6 and AKR mice which seemed to be high antibody responders to MHV.
Insights
Microbiological monitoring of inbred mouse stocks revealed high contamination rates in conventional colonies, with parasites like S. obvelata being common indicators. Barrier systems effectively controlled microbial agents in specialized mouse foundation stocks.
Area of Science:
- Laboratory animal science
- Microbiology
- Immunology
Background:
- Inbred mouse strains are crucial research models.
- Maintaining microbiological quality in foundation stocks is essential for reproducible research.
- Previous monitoring efforts lacked comprehensive data across multiple institutions.
Purpose of the Study:
- To assess the microbiological status of inbred mouse foundation stocks across multiple organizations.
- To evaluate the efficacy of barrier systems in controlling microbial contamination.
- To identify key microbial agents and potential indicators of contamination in conventional mouse colonies.
Main Methods:
- Cooperative microbiological monitoring of 881 inbred mice from 128 foundation stocks (10 inbred strains and dd mice derivatives).
- Samples analyzed from 647 conventional animals (95 colonies) and 234 barrier-sustained animals (33 colonies).
- Testing for three viral, one mycoplasmal, six bacterial, one fungal, and three parasitic agents.
Main Results:
- 84.2% of conventional colonies showed contamination with at least one agent.
- Highest detection rates in conventional mice: S. obvelata (44.2%), P. pneumotropica, S. muris, P. aeruginosa, G. muris, Sendai virus, M. pulmonis, MHV, and E. coli.
- Barrier-sustained colonies showed significantly lower contamination, with only P. aeruginosa detected (36.4%), demonstrating barrier efficacy.
- MHV and Sendai virus rates were lower in foundation stocks than in experimental colonies.
- Parasites (G. muris, S. muris, S. obvelata) were frequent and often co-occurred with other pathogens, serving as contamination indicators.
Conclusions:
- Conventional inbred mouse colonies exhibit high rates of microbial contamination.
- Barrier systems are highly effective in maintaining microbiological quality for inbred mouse foundation stocks.
- Parasitic agents can serve as valuable indicators for microbiological contamination in conventional mouse settings.
- Strain-specific susceptibility to pathogens was minimal, with C57BL/6 and AKR mice showing higher MHV antibody response.