Administration of human or animal tissues (e.g., tumors, cell lines) or other biological materials into animals, especially rodents, is a common research practice. These tissues and biological materials may be infected with a variety of agents that may be infectious to humans or animals and potentially jeopardize the health of both. Additionally, contaminating pathogens may act as a confounding variable on research results.

Because collaborative research is the rule rather than the exception in today’s research environment, and rodents (especially mice) and biological materials (including cell lines) are shared and sent between investigators within and between institutions, ensuring pathogen-free animals and biological samples greatly facilitates collaborative research.

The BU IACUCInstitutional Animal Care and Use Committee IACUC oversee... and BU IBCInstitutional Biosafety Committee The IBC is an instituti... work together to assure human and animal health. Any biological materials of human origin require handling at the BSL-2 level (including animal housing at ABSL-2 containment) and observation of standard operating procedures for universal precautions and blood-borne pathogens. Therefore, testing cell lines of human origin for human pathogens is NOT required.


The three main reasons for testing are as follows:

  1. To protect human staff from zoonotic agents.
  2. To protect research and research animals.
    • Many rodent research models, especially those involving immunology and cancer research, are vulnerable to interference if the animal is host to an adventitious murine virus (a virus that does not result in clinical disease but nevertheless affects immune function).
  3. To identify and eliminate any sources of mouse parvovirus (MPV), which is a major confounder to animal studies.

It has been reported that approximately 1% of biological screens tested come up positive for pathogens. 70% of these consist of MPV and lactate dehydrogenase virus (LDV). The rest include polyomavirus (POLY), reovirus (REO), mouse adenovirus (MAV), and others.13 Mycoplasma is also a frequent contaminant of cell lines.










A. Murine viruses have been shown to be transmitted both by cell culture products and additives and by the cells themselves.









H. Repeat testing is required every five years.


Procedures Prior to Testing Cell Lines

Prior to testing, it is imperative to build up a cell line to anticipated volume and concentration required for the next several years. The aliquots are frozen at −80oC. One aliquot is submitted for pathogen testing and the rest, and provided this tests SPF, are thawed and used as needed.

Decontamination of Mycoplasma or Virus-Infected Cell Lines

“Cells can be treated with antibiotics to eliminate Mycoplasma, but a virus-infected cell line cannot be cured. On the other hand, transplantable cell lines (i.e., those maintained by passage in animals) can be virus-contaminated without actually being infectious. For example, lactate dehydrogenase elevating virus (LDV) has generally be shown to be the most common contaminant of tumor lines maintained by transplantation in mice (probably because LDV causes a persistent, high-level viremia). As LDV has a very narrow host range (i.e., I believe it replicates only in mouse macrophages), however, in most if not all cases the LDV-contaminated transplantable cell line would not be LDV-infected. In this situation, it may be possible to eliminate the LDV contamination by passaging the cells in vitro or in rats, which are not susceptible to LDV infection.”16




Testing Procedures



BU IACUC Approved June 2009, Revised January 2014, Reviewed July 2019

Pathogen Screening of Biological Materials Introduced into Rodents