Background

Mouse Parvovirus is the third most common infectious pathogen of mice affecting one or more colonies at 30% of research institutions and trailing only pinworms and MHV in prevalence. It is clinically silent, but with an affinity for T cells and a capability of perturbing immune function. The virus causes infection in immunocompetent mice lasting up to 6 months and characterized by a 2-6 week period of intermittent fecal shedding. In mice that are immunosuppressed, infection and shedding theoretically may be lifelong. PCR of mesenteric lymph node and serology are used for diagnosis, but up to six weeks may be required for some mice to show seroconversion. Dissemination is facilitated by the hardy nature of the agent, which can persist in the environment for months or more. Exposure to infected mice, their soiled cages, or contaminated personnel, surfaces or equipment that have been in contact with infectious mice are most important for transmission from animal-to-animal. Adult, weanling and neonatal mice are highly and equally susceptible to infection. Once a colony is breached, MPV, because of the aforementioned factors, is well-suited to sustain infection in breeding colonies in barrier cages. Serologic assessment of sentinel mice in July showed Mouse Parvovirus (MPV) infection in several mouse colonies. Although sentinels detected infection only in the Rollins Building and Eye Center, all colonies should be considered to be infected until shown otherwise. This ended an era of 12 years of apparent virus-free status of Emory University mouse colonies. The conduits for entry of pathogens into our colonies are numerous and are listed in the table below:

Potential Sources of Infection in Rodent Colonies

General MPV Containment and Preventive Practices

All personnel entering mouse rooms must wear a disposable gown, hair net, surgical-type mask, shoe covers and gloves and must change such garb if moving from room-to-room. Mice should only be handled in a biosafety cabinet with gloved hands kept moist with disinfectant. DAR staff handle mice during cage changes with forceps soaked in povidone iodine disinfectant. Practices in some colonies of transferring animals from cage-to-cage by hand have been discontinued except for newborn litters. Where feasible, clean cage wash and clean cage storage areas have been secured and non-DAR staff have been excluded. Provisions of clean cages and other implements for investigator use are now kept in each mouse room. Quinticare has been replaced as the disinfectant for surfaces and gloved hands by Quatricide-PV. It is critically important to properly use the containment caging system and not open cages outside of a biosafety cabinet.

Animal Transfers

Under no circumstance may rodents be moved from other institutions, including the VAMC or Yerkes, to campus without veterinary approval. Likewise, researchers working with mice at the VAMC or Yerkes must not subsequently enter animal research facilities on campus during the same day. On campus, rodents should not be moved from room-to-room or building-to-building on the Emory campus without the knowledge and consent of the veterinary staff.

Quarantined Colonies

Quarantined colonies are listed in the table below and have been identified with signage placed on the room door. All cages from quarantined rooms are bagged and autoclaved prior to washing. Research staff should put assembled cages in orange biohazard bags on the floor next to the hood. DAR staff will process these cages and remove them on a daily basis. Bags of cages and any carts, including wheels, must be sprayed with disinfectant prior to removal from the room. Individuals entering quarantined rooms are not permitted to enter other mouse rooms. Live mice may not be removed from quarantined rooms under any circumstance. Tissues from mice in these rooms may be removed for experimental purposes in disinfected containers, but may not be inoculated into other animals. Research implements must be disinfected by wiping with chemical disinfectant or autoclaving (or equivalent) prior to removal from the room.

Health Assessment

The DAR, through regular and thorough assessment of mice and biological materials, is in the progress of localizing infection to specific colonies. It will probably take until mid-September to bring the aggressive health surveillance campaign to a conclusion. Although only sentinel mice have been shown to be infected with MPV to date, all mice should be suspected of infection and handled accordingly. The current results of the health surveillance effort are summarized in the table below:

MPV Surveillance Results

*Sentinel cohorts were mice received from the same source and at the same time as the sentinels originally shown to be MPV seropositive in July. The sentinel cohorts were used as sentinels in other colonies in Rollins, but all were removed from their respective colonies in August, isolated, tested for MPV in October, and shown to be seronegative.

Eradication Program

Once infected colonies are localized, impacted investigators will be informed and consulted regarding the disposition of infected mice. In general, infected mice will be identified and either euthanized or designated for depopulation through research attrition. Disease-free breeders will be identified and programmatically and physically isolated from potentially infected stock and continually monitored. However, no action will be taken without consultation with the involved investigators.

• 1999 National AALAS Meeting - Seminar 25 notes
• Mouse Parvovirus Update - (11/15/1999)
• MPV Quarantine Lifted - (11/15/1999)
• September 22, 1999 Update
• Mice of Black/6 Lineage and MPV
• August 27, 1999 Update
• SDAV ALERT - (2/11/2000)
• Methoxyflurane - No longer being manufactured (1/17/2000)
• Mouse Parvovirus - Quarantine Lifted (3/17/2000)
• Rat SDAV at Rollins - (5/01/2000)
• Emory Rat Pinworm Eradication Campaign - (6/14/2000)