Related Experiment Video
Updated: Aug 30, 2026
Operating and Biocontainment Procedures of a Facility for Laboratory Mice with a Natural Microbiome: Immunophenotyping Procedure
Published on: December 13, 2024
Assessing the risk of transmission of three infectious agents among mice housed in a negatively pressurized caging
David D Myers1, Ellen Smith, Isabelle Schweitzer
1The Jackson Laboratory, 600 Main Street, Bar Harbor, Maine 04609, USA.
Abstract:
Previous studies from our institution have shown that ventilated caging run at negative pressure to a mouse room dramatically reduced exposure of personnel to the major mouse allergen, Mus m 1. The current study was designed to determine whether negative cage ventilation posed an inordinate risk for spread of infectious agents between cages and/or racks. B6;129S-Tnfsf5(tm1Imx)/J (TNF) mice, which were naturally and persistently infected with Pneumocystis carinii, Helicobacter bilis, and Pasteurella pneumotropica, were used as the source of infections. Uninfected C3Smn.CB17-Prkdc(scid)/J (SCID) mice with severe combined immunodeficiency were used to detect transmission. The following methods were used to detect transmission of infections: polymerase chain reaction (PCR) amplification and histological examination of lungs for P. carinii; PCR of fecal specimens or cecal contents for H. bilis; and culture of oropharyngeal, tracheal, or vaginal swabs for P. pneumotropica. We determined whether transmission of the three agents occurred via direct contact (cohabitation), exposure to soiled bedding, and/or by handling naive SCID mice after handling infected TNF mice. During a 12-week period, all three infectious agents were readily transmitted to uninfected mice by cohabitation. Transmission was much less efficient and occurred later among mice exposed to contaminated bedding. Transmission did not occur as a result of handling. We then studied transmission of the three infectious agents among mice housed in individually ventilated cages run at negative pressure in a small, crowded mouse room. Transmission of P. carinii was detected at the end of the 12-month study in the densely populated room, probably because the exhaust from the changing station passed over soiled cages and caused aerosolization of particulates. Caging systems run at negative pressure effectively reduce personnel exposure to allergens and may also inhibit the transmission of infectious diseases.
Insights
Negative pressure ventilated caging reduces personnel allergen exposure and may also inhibit infectious disease transmission among mice, even in crowded conditions. This study assessed pathogen spread via cohabitation, bedding, and handling.
Area of Science:
- Laboratory Animal Science
- Infectious Disease Transmission
- Occupational Health & Safety
Background:
- Ventilated caging at negative pressure reduces personnel exposure to mouse allergens like Mus m 1.
- The potential for infectious agent transmission in such caging systems requires investigation.
Purpose of the Study:
- To determine if negative pressure cage ventilation increases the risk of infectious agent spread between mouse cages and racks.
- To evaluate transmission routes of Pneumocystis carinii, Helicobacter bilis, and Pasteurella pneumotropica.
Main Methods:
- Infected TNF mice were used as a source for three agents: P. carinii, H. bilis, and P. pneumotropica.
- Uninfected SCID mice were exposed via cohabitation, soiled bedding, or handling.
- Transmission was detected using PCR, histology, and microbial culture.
Main Results:
- All three agents transmitted efficiently via cohabitation.
- Transmission via soiled bedding was less efficient and slower.
- No transmission occurred through handling.
- P. carinii transmission was detected after 12 months in a crowded room with negative pressure ventilated cages.
Conclusions:
- Negative pressure ventilated caging effectively reduces allergen exposure.
- These systems may also inhibit infectious disease transmission, though cohabitation remains an efficient route.
- Crowded conditions and specific ventilation setups may influence transmission dynamics.
