Animal Biosafety Levels

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Procedures for Administering Biohazards to Animals

Researchers who wish to administer biohazards, including microorganisms, viruses, recombinant and synthetic nucleic acid molecules, to animals, must obtain approval from the IACUC and the IBC prior to initiation of this work.

Working safely with biohazards in animals requires careful coordination with staff from Laboratory Animal Resources and EHS. After approval from both the IACUC and IBC has been received, the Principal Investigator and research staff must adhere to the following:

Before initiation of research:

  • Notify Laboratory Animal Resources (LAR) in advance of administration of the biohazard. For BSL 2 agents, 10 working days is required; for BSL 1 agents, provide at least 2 days notice.
  • If requested by LAR, provide an overview of the research, with safety precautions required, to LAR staff.
  • Notify EHS prior to administration of any BSL 2 hazard to arrange for an evaluation of containment practices.

During research:

  • Conduct research in accordance with containment recommendations provided by the IBC.
  • Upon administration of a biohazard to animal, use the biohazard cage labels, provided by LAR, to, identify cages of animals that have been exposed. List the agent on the label and indicate ABSL1 or 2.
  • Verify that a biohazard sign has been posted on the animal housing room door.
  • If administering biohazards to animals in a laboratory procedure space, request a biohazard sign for procedure room door from EHS.

Conclusion of research:

  • Notify LAR when research has been concluded, so that biohazard signs can be removed and precautions can be stopped.

Animal Biosafety Levels

A set of four biosafety levels are provided for work with vertebrate animals exposed to agents which may infect humans. These Animal Biosafety Levels, ABSL 1 thru 4, provide for practices, equipment, and facilities that are comparable to the laboratory biosafety levels. However, there are unique hazards associated with infected animals that must be understood by those personnel with animal contact and addressed in the animal facility. Animal biosafety levels are designed to protect personnel from exposure to potentially infectious materials. Quarantine facilities and procedures must be utilized to prevent spread of infectious materials from animal to animal.

A good summary of the Animal Biosafety Levels can be found in the CDC/NIH Biosafety in Microbiological and Biomedical Laboratories, 5th edition.

Animal Biosafety Level 1 (ABSL-1)

ABSL-1 is appropriate for research conducted with well-characterized strains of viable microorganisms or viruses not known to cause disease in healthy adult humans.

Research at ABSL-1 can be conducted in LAR vivarium facilities and, if permitted by the IACUC and the IBC, in laboratories outside of the vivarium.


In LAR Animal Facility

Outside of LAR facilities, with permission from IACUC and IBC.


Standard PPE required by LAR to enter animal facility.

Wear safety glasses if splash hazard exists.

Laboratory coat, preferably disposable, disposable exam gloves

Wear safety glasses if splash hazard exists.


Put on appropriate PPE prior to entering animal facility or laboratory.

Wash hands after working with animals.

Eating, drinking, handling contact lenses, applying cosmetics and storing food for human consumption is not permitted.

Sharps must be disposed of directly, without recapping, into rigid impervious sharps containers.


As required by IACUC and LAR


Entrance to housing rooms must be labeled with a sign, provided by EHS, if animals have been exposed to microorganisms/ viruses.

Cages used to house animals that have been exposed to BSL 1 materials must be labeled by the researcher with the biosafety level, agent name and exposure date.

Labs where animals are exposed  to ABSL-1 agents should be labeled with a sign, provided by EHS.


EHS determines if soiled bedding should be disposed of via the regulated medical waste stream or via regular trash.

Carcasses are disposed of through the regulated medical waste stream.


Waste soiled bedding generated in the lab should be disposed of into the regulated medical waste receptacles.

Carcasses are returned to LAR, to be disposed of through the regulated medical waste stream.

Animal Biosafety Level 2 (ABSL-2)

ABSL-2 refers to practices and procedures required to conduct research with animals infected with agents that can cause disease in humans.  ABSL-2 is designed to prevent exposures to infectious material via percutaneous injury, mucous membrane splashes and accidental ingestion.  Administration of agents requiring ABSL-2 containment must be conducted in LAR vivarium facilities.

Laboratory Design

  • Directional, single pass airflow is required
  • Restricted access to authorized personnel only.


  • Change rodent cages inside of a BSC.
  • When transporting ABSL-2 animals out of the LAR vivarium facility, place cage inside of a biohazard bag.  Cages must be transported on carts.   Research staff are responsible for cleaning spills of soiled bedding that occur during transport.
  • Disinfect BSC using Virkon S or other LAR-approved disinfectant before and after work.  Allow 10 minutes of contact time prior to wiping the surface with disposable towels. Don't spray the top grill of the BSC ( this is where the filter is located.)   If placing a disposable liner on the work surface of the BSC, don't cover the front grille.  The BSC sash can be lifted momentarily if needed, but do not work with the sash lifted and the alarm silenced, as this substantially decreases the protection provided by the BSC.
  • Soiled bedding must be autoclaved prior to disposal.  Exceptions must be approved by the BSO.
  • All animal carcasses are returned to LAR for disposal.

Signs and Labels

  • Rooms signs, prepared by EHS, must be posted on the door of each ABSL-2 housing and procedure room. The signs include:
    • Universal biohazard symbol
    • Name of infectious agent
    • Personal protective equipment required to enter
    • Immunizations or medical surveillance required to enter
    • Required training
    • Principal Investigator and Laboratory Contact
    • Special husbandry precautions
  • Cages used to house animals that have been exposed to BSL-2 materials must be labeled by the researcher with the biohazard symbol, ABSL-2, name of agent and date of exposure.  Labels are provided by LAR.


  • Small animals are housed in ventilated cage racks.  Larger animals may be housed in regular caging and additional PPE may be required.
  • Work in a BSC when:
    • Opening or changing rodent cages
    • Injecting small animals with infectious agents.

Note:  Stereotactic injections can be performed on the bench top but may require additional PPE.  IBC approval will specify additional PPE, such as respiratory protection, that may be required.


  • LAR and IACUC-required training must be completed.
  • Staff must attend Intro to Biosafety and Laboratory Safety trainingBloodborne Pathogen training is required for researchers and LAR staff who conduct animal research that involves human-derived material.
  • Agent-specific training, provided by the Principal Investigator and EHS Biosafety, may be required upon introduction of an agent that has not previously been handled in a Princeton University animal facility.

Personal Protective Equipment

  • Shoe covers
  • Disposable gloves, preferably nitrile
  • Surgical mask
  • Hair bonnet
  • Disposable lab coat, fully-buttoned
  • If splash hazard exits, safety glasses may be required
  • Additional PPE may include sleeve covers and respiratory protection, if recommended by EHS.