PCR Testing of Media Placed in Soiled Bedding as a Method for Mouse Colony Health Surveillance

Abstract

Rodent colony health surveillance has traditionally been accomplished by testing sentinel animals that have been exposed to soiled bedding from colony animals. Collecting samples from exhaust plenums on ventilated caging systems, followed by PCR analysis, has emerged as another promising method for health surveillance. However, environmental testing at the rack level is not effective for all ventilated rack designs. In this study, we tested whether media placed in soiled bedding is effective in detecting 3 adventitious agents: mouse norovirus (MNV), Helicobacter spp., and fur mites. Soiled bedding was collected from pathogen-positive colony mice and distributed to traditional sentinel mouse cages and mouse-free experimental cages every 1 to 2 wk for static and ventilated cages, respectively. Experimental cages contained 10 flocked swabs (‘passive swabs’) and 1 piece of filter media. After 90 d, fresh feces, pelage swabs, and blood were collected from the sentinel cages, and the passive swabs and filter media were collected from the experimental cages. Concurrently, 10 additional flocked swabs(‘active swabs’) were stirred through the cumulated soiled bedding of each experimental cage. Sentinel mice were positive for MNV and Helicobacter spp., but negative for fur mites by pelage swab PCR. All samples from experimental cages were positive for Helicobacter spp. and fur mites in both caging types. For MNV, passive swabs were most effective at detection(100%), followed by active swabs (80% to 100%) and filter media (60% to 80%). These findings suggest that testing media in pooled soiled bedding samples is more effective than traditional sentinel methods for colony health surveillance and is a viable option when sampling at the rack level is ineffective.

Microbiota and environmental health monitoring of mouse colonies by metagenomic shotgun sequencing

“…PCR on nucleic acids extracted from filters has proven to be more sensitive and effective than the use of sentinels for the detection of specific pathogens such as Murine norovirus (MNV) (Zorn et al, 2017 ), Mouse hepatitis virus (MHV) (O’Connell et al, 2021 ), Sendai virus (Compton et al, 2004b ), Murine Astrovirus (Korner et al, 2019 ), Pasteurella pneumotropica (Miller et al, 2016 ), Helicobacter spp. (Mailhiot et al, 2020 ), Lactate dehydrogenase elevating virus (LDV) (Luchins et al, 2020b ), Pneumocystis murina (Miller and Brielmeier, 2018 ), fur mites (Hanson et al, 2021 ) ( Gerwin et al, 2017 ) ( Korner et al, 2019 ) Protozoa and pinworm (Kapoor et al, 2017 ) (Dubelko et al 2018 ) (Bauer et al, 2016 ). This rodent-free approach is ethical reducing animals and animal manipulations.…”