Rodent and Germplasm Trafficking: Risks of Microbial Contamination in a High-Tech Biomedical World

Abstract

High-tech biomedical advances have led to increases both in the number of mice used for research and in exchanges of mice and/or their tissues between institutions. The latter are associated with the risk of dissemination of infectious agents. Because of the lack of international standardization of health surveillance programs, health certificates for imported rodents may be informative but may not address the needs of the importing facility. Preservation of mouse germplasm is achieved by cryopreservation of spermatozoa, embryos, or ovaries, and embryonic stem cells are used for the production of genetically engineered mice. After embryo transfer, recipients and rederived pups that test negative in microbiological screening for relevant microorganisms are released into full barrier holding areas. However, current research shows that embryos may also transmit microorganisms, especially viruses, to the recipient mice. In this article, we discuss regulations and practical issues in the shipping of live mice and mouse tissues, including spermatozoa, embryos, ovaries, and embryonic stem cells, and review work on microbial contamination of these biological materials. In addition, we present ways to reduce the risk of transmission of pathogens to mice under routine conditions.

Lack of Transmission of Mouse Minute Virus (MMV) from In Vitro-Produced Embryos to Recipients and Pups Due to the Presence of Cumulus Cells During the In Vitro Fertilization Process

“…The higher risk of transmission of another parvovirus (MPV) by embryos originating from infected females compared with those from infected males has been recently documented in detail [29]. This knowledge emphasizes the fact that oocytes for IVF should be collected from pathogenfree mice, and stringent hygienic measures should be implemented, including recipients being kept in IVCs and their being screened before release of the rederived pups [36].…”

Immune Relevant and Immune Deficient Mice: Options and Opportunities in Translational Research

“…Despite the usual absence of clinical signs in parovirus-infected mice, these agents should be especially concerning in immune relevant and cancer studies. 409,[416][417][418][419][420] Although mouse herpesviruses are not expected in contemporary research colonies, mice are host to several lymphocytotropic herpesviruses that are reported in pet store and feral mice. 421,422 Mouse thymic virus infection in newborn mice causes thymic necrosis, with selective targeting of T cells, and transient immunosuppression.…”

Old Enemies, Still with Us after All These Years

“…Whereas in the past the primary risk associated with incoming rodents was from occasional contamination at a handful of major vendors, now there is a similar or greater level of risk from each of the dozens or scores of collaborators that ship rodents between institutions (Mahabir et al 2008). …”

“…As with all viruses, there is the possibility of transmission by cell lines or biologically derived reagents (Mahabir et al 2008). However, the cell tropism of enterotropic MHV strains is quite limited, suggesting their infrequent transmission by biological material.…”