• Home
• About Us
• Products
• Contact Us

Cirrus BioSystems

Products

The Research Environment

Every day, in thousands of research facilities throughout the United States and the world, animal technicians and research personnel spend hours disinfecting rodent cages with low-tech spray bottles. The process is time consuming and inefficient, yet personnel working in these facilities must adhere to strict guidelines and standard operating procedures to avoid introducing pathogens into their animal colonies.

• The SPF Environment
• Infectious Agents
• Outbreaks
• Working in an Animal Room Hood
• Placing Cages and Equipment into the Hood
• The Challenges of Manual Disinfection Methods

The Specific Pathogen Free (SPF) Environment

Specific Pathogen Free, or SPF, is a general term used to indicate that certain pathogens (disease causing microbes) have been excluded from an animal or a colony of animals. SPF facilities are designed to maintain rodents (both normal and transgenic) in an environment that is free of certain infectious organisms that are pathogenic and capable of interfering with research objectives.

Infectious Agents

Like all animals, rodents are susceptible to a variety of viruses, bacteria and parasites. Some of these agents are capable of inducing disease outright, while others may significantly alter host responses to experimental conditions without causing overt signs of disease (i.e., sub-clinical infections). For these reasons, it's important to keep these agents out of SPF vivaria.

Infectious agents excluded from SPF facilities may include:

• Mouse hepatitis virus (MHV)
• Mouse parvovirus (MPV)
• Minute virus of mice (MVM)
• Reovirus-3 (Reo-3)
• Pneumonia virus of mice (PVM)
• Epizootic diarrhea of infant mice (EDIM)
• Theiler’s murine encephalomyelitis virus (TMEV)
• Lymphocytic choriomeningitis virus (LCMV)
• Ectromelia (mouse pox)
• Sendai virus
• Sialodacryoadenitis virus (SDAV)
• Rat parvoviruses
• Mycoplasma pulmonis
• Pinworms
• Fur mites

The four basic routes of pathogen introduction are contact, fomites, airborne/aerosol, and matters of biological origin. SPF procedures are designed to prevent these entries.

Outbreaks

If a pathogen is detected, the entire room is placed under quarantine and investigators who have rodents in the room are notified. What happens next depends on the type of pathogen that was detected. In the case of a parasite like pinworms or fur mites, treatment is typically begun by Veterinary Services. Treatment is generally effective, but can be lengthy and expensive. For example, pinworm treatment takes approximately three months.

In the case of a virus like MHV, or certain bacteria for which no effective treatment exists, infected rodents are identified through testing. Usually rodents found to be infected are euthanized. If an entire line of rodents is infected however, and cannot be found at another SPF facility, then there may be other options to save the line from extinction. One option is embryo rederivation.

Once virus- or bacteria-infected rodents have been identified and removed, successive rounds of testing are conducted until it is determined that the pathogen is no longer present in the room. The frequency of this testing varies depending on the type of pathogen. Quarantine length also depends on the pathogen involved, and how well its spread was contained before anyone knew it was there.

As long as SPF procedures are rigorously followed, it is quite possible for a pathogen to be limited to one or a few cages. This is remarkable, considering the extremely contagious nature of pathogens like MHV, and demonstrates how well SPF equipment and procedures can perform when used properly and consistently.

Working in an Animal Room Hood

Specific steps must be followed closely in order to avoid contamination to the SPF environment and to research animals. Personnel must put on shoe covers as they step across the threshold of the doorway into the room. In some SPF facilities (termed Barrier SPF), one must take a shower first. Once in the room, a hair bonnet, gloves and lab coat are required. To work in a dedicated hood within the room, personnel must put on a set of sleeves to cover their forearms and a second pair of gloves so that the gloves overlap the cuff of the sleeves.

Placing Cages and Equipment into the Hood

During the transfer of an animal cage to a dedicated hood for procedural testing and/or animal husbandry (changing the bedding, water or food), care must be taken to ensure that the filter-top, or micro-isolator lid, stays securely in place as it protects the inside cage environment from any airborne pathogens that could infect the animals.

All items (cages, supply boxes, worker's gloved hands) that go into the hood must be sprayed with disinfectant prior to their entry per standard SPF operating procedures. Once the item is sprayed with disinfectant, it may enter the hood and be placed on the work surface.

The Challenges of Manual Disinfection Methods

The current and standard procedure employed worldwide for disinfecting an animal cage and other items is to manually “hard-spray” the cage with disinfectant employing a typical spray bottle. The user holds and carefully rotates a cage in one hand, while spraying disinfectant on all four sides and the bottom with the other “free” hand. Extreme caution must be used when rotating the cage as to avoid dropping the cage on the floor, which could potentially injure or kill the animal(s) inside.

A standard mouse cage measures 11½”L x 7½”W x 5”H and typically houses one to five animals while a standard rat cage measures 19”L x 10”W x 8”H and can house up to three animals. The size of these cages alone makes them extremely difficult to handle with one hand.

Once the cage has been sprayed, it is extremely slippery and even more difficult to control. The amount of time required to disinfect a single cage using the current “spray bottle method” can take up to 15 seconds or more. Rodent cages must be cleaned on a regular basis by dedicated animal care staff. They may also be handled multiple times on a daily basis by the research investigative groups performing experimental procedures.