Rodent and germplasm trafficking: risks of microbial contamination in a high-tech biomedical world

Laboratory animal strain mobilities: handling with care for animal sentience and biosecurity

The global distribution of laboratory mouse strains is valued for ensuring the continuity, validity and accessibility of model organisms. Mouse strains are therefore assumed mobile and able to travel. We draw on the concept of 'animal mobilities' (Hodgetts and Lorimer 2019) to explain how attending to laboratory mice as living animal, commodity and scientific tool is shaping how they are transported through contemporary scientific infrastructures and communities. Our paper is framed around exploring how animal strains travel, rather than animals, as we show that it is only through understanding strain mobility that we can explain how and why live animal movement can be replaced by germinal products. The research is based on qualitative fieldwork in 2018 and 2019 that included 2 weeks ethnography and interviews with key informants involved in the movement of laboratory animals. The empirical analysis discusses practices that relate to managing biosecurity and animal welfare concerns when moving laboratory animal strains. In closing we reflect more broadly on the contemporary 'ethico-onto-epistemological' (Barad, 2014) entanglement that shapes who or what travels to support laboratory science data-making practices, and the intensity of care 'tinkering' practices (Mol and Law 2010) that facilitate the movement. We explain how a laboratory animal strain exceeds its value solely as a mobile and thus exchangeable commodity, illustrated in how values that relate to animal sentience and infection-risk supports its material transformation. Consequently, it is becoming increasingly common for non-sentient germinal products - embryos and gametes - to replace live sentient animals when being moved.

Basic reproduction numbers of three strains of mouse hepatitis viruses in mice

Mouse hepatitis virus (MHV) is a murine coronavirus and one of the most important pathogens in laboratory mice. Although various strains of MHV have been isolated, they are generally excreted in the feces and transmitted oronasally via aerosols and contaminated bedding. In this study, we attempted to determine the basic reproduction numbers (R₀) of three strains of MHV to improve our understanding of MHV infections in mice. Five‐week‐old female C57BL/6J mice were inoculated intranasally with either the Y, NuU, or JHM variant strain of MHV and housed with two naïve mice. After 4 weeks, the presence or absence of anti‐MHV antibody in the mice was determined by ELISA. We also examined the distribution of MHV in the organs of Y, NuU, or JHM variant‐infected mice. Our data suggest that the transmissibility of MHV is correlated with viral growth in the gastrointestinal tract of infected mice. To the best of our knowledge, this is the first report to address the basic reproduction numbers among pathogens in laboratory animals.

Importing genetically altered animals: ensuring quality

The reproducibility of research using laboratory animals requires reliable management of their quality, in particular of their genetics, health and environment, all of which contribute to their phenotypes. The point at which these biological materials are transferred between researchers is particularly sensitive, as it may result in a loss of integrity of the animals and/or their documentation. Here, we describe the various aspects of laboratory animal quality that should be confirmed when sharing rodent research models. We also discuss how repositories of biological materials support the scientific community to ensure the continuity of the quality of laboratory animals. Both the concept of quality and the role of repositories themselves extend to all exchanges of biological materials and all networks that support the sharing of these reagents.

Archiving genetically altered animals: a review of cryopreservation and recovery methods for genome edited animals

With the ever-expanding numbers of genetically altered (GA) animals created in this new age of CRISPR/Cas, tools for helping the management of this vast and valuable resource are essential. Cryopreservation of embryos and germplasm of GA animals has been a widely used tool for many years now, allowing for the archiving, distribution and colony management of stock. However, each year brings an array of advances, improving survival rates of embryos, success rates of in-vitro fertilisation and the ability to better share lines and refine the methods to preserve them. This article will focus on the mouse field, referencing the latest developments and assessing their efficacy and ease of implementation, with a brief note on other common genetically altered species (rat, zebrafish, Xenopus, avian species and non-human Primates).

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

In 1989 ILAR published a list and description of immunodeficient rodents used in research. Since then, advances in understanding of molecular mechanisms; recognition of genetic, epigenetic microbial, and other influences on immunity; and capabilities in manipulating genomes and microbiomes have increased options and opportunities for selecting mice and designing studies to answer important mechanistic and therapeutic questions. Despite numerous scientific breakthroughs that have benefitted from research in mice, there is debate about the relevance and predictive or translational value of research in mice. Reproducibility of results obtained from mice and other research models also is a well-publicized concern. This review summarizes resources to inform the selection and use of immune relevant mouse strains and stocks, aiming to improve the utility, validity, and reproducibility of research in mice. Immune sufficient genetic variations, immune relevant spontaneous mutations, immunodeficient and autoimmune phenotypes, and selected induced conditions are emphasized.

Shipment of Live Preimplantation-Stage Mouse Embryos

Sharing genetically modified mouse models is a very important part of collaboration between researchers. Shipping live animals around the world is inconvenient, expensive, and cumbersome because of the variety of international regulations and paperwork. The issue of health status differences between animal facilities is of great importance; traditionally, imported animals are quarantined to determine their health status and avoid the introduction of undesirable pathogens. The shipment of preimplantation-stage embryos for immediate transfer into pseudopregnant recipients upon arrival is a commonly used method for transportation. Time coordination on both sides is critical in this case, but the shipment can be done by any courier and the container does not need to be returned. This protocol has been used since the early 1990s to rederive dozens of mouse strains.

Lack of transmission of murine norovirus to mice via in vitro fertilization, intracytoplasmic sperm injection, and ovary transplantation

Since its discovery in 2003, murine norovirus (MNV) is still endemic in many rodent animal facilities. Our aim was to determine the risk of transmission of MNV (91% homology to MNV3) to embryo recipients and pups via assisted reproductive technologies, especially those which compromise the integrity of the zona pellucida. In vitro fertilization (IVF), assisted in vitro fertilization (AIVF) with reduced glutathione, intracytoplasmic sperm injection, and ovary transplantation were performed. Murine norovirus was detected by qualitative and quantitative reverse transcription polymerase chain reaction. After natural infection of immunocompetent C57BL/6NTacCnrm and immunodeficient athymic nude mice with MNV, the mesenteric lymph nodes, small intestine, spleen, liver, lung, brain, ovary, and testis were infected at specific intervals for more than a 1-year period. At Week 12, the number of viral genomes per milligram of gonad from both strains was 20 to 50. Murine norovirus strictly adhered to spermatozoa collected from infected mice because three washes did not remove MNV from the sperm. After using MNV-positive sperm for IVF, AIVF, and intracytoplasmic sperm injection, 27 to 30 genomes were detected in IVF (n = 100) and AIVF (n = 100) embryos from both mouse strains. Approximately 87% of MNV detected in these embryos was found in the zona pellucida. However, all embryo transfer recipients, pups, and ovary recipients were MNV-negative. The results indicate that manipulation of the germplasm through assisted reproductive technologies did not lead to transmission of MNV to mice. This may be because of the absence of an infectious dose or failure of the MNV strain to replicate effectively in developing embryos and the reproductive tract.

FELASA recommendations for the health monitoring of mouse, rat, hamster, guinea pig and rabbit colonies in breeding and experimental units

The microbiological quality of experimental animals can critically influence animal welfare and the validity and reproducibility of research data. It is therefore important for breeding and experimental facilities to establish a laboratory animal health monitoring (HM) programme as an integrated part of any quality assurance system. FELASA has published recommendations for the HM of rodent and rabbit colonies in breeding and experimental units (Nicklas et al. Laboratory Animals, 2002), with the intention of harmonizing HM programmes. As stated in the preamble, these recommendations need to be adapted periodically to meet current developments in laboratory animal medicine. Accordingly, previous recommendations have been revised and shall be replaced by the present recommendations. These recommendations are aimed at all breeders and users of laboratory mice, rats, Syrian hamsters, guinea pigs and rabbits as well as diagnostic laboratories. They describe essential aspects of HM, such as the choice of agents, selection of animals and tissues for testing, frequency of sampling, commonly used test methods, interpretation of results and HM reporting. Compared with previous recommendations, more emphasis is put on the role of a person with sufficient understanding of the principles of HM, opportunistic agents, the use of sentinel animals (particularly under conditions of cage-level containment) and the interpretation and reporting of HM results. Relevant agents, testing frequencies and literature references are updated. Supplementary information on specific agents and the number of animals to be monitored and an example of a HM programme description is provided in the appendices.

Transport of mouse lines by shipment of live embryos

Advances in techniques for the genetic manipulation of the laboratory mouse have resulted in a vast array of novel mouse lines for research. One challenge facing researchers is the ability to rapidly share genetically modified mouse lines with collaborators at other institutions. The standard method of shipping live animals has its share of problems, including the acceptability of the mice at the receiving institution based on health status, as well as the length of time that mice are maintained in quarantine at the receiving institution. Transfer of mouse lines between institutions can also be accomplished by shipment of cryopreserved embryos or sperm. This option, however, is limited by the availability of properly trained staff at the shipping institution who can prepare the cryopreserved materials, as well as staff at the receiving institution who can recover live animals from the transferred samples. Overnight shipment of live, preimplantation mouse embryos circumvents many of the issues involved with shipping live animals or cryopreserved samples. The technique described in this chapter for shipping live embryos provides a simple method for transferring mouse lines between institutions.

A device for the simple and rapid transcervical transfer of mouse embryos eliminates the need for surgery and potential post-operative complications

We describe a novel device that can be used for the transcervical transfer of embryos into pseudopregnant female mice. This nonsurgical embryo transfer (NSET) device is as efficient as standard surgical embryo transfer in the production of transgenic mice, and can also be used for the transfer of embryonic stem cell-containing chimeric blastocysts and cryopreserved embryos. In addition to the elimination of surgery, recipient females do not have to be anesthetized. The NSET device eliminates a painful surgical procedure as well as potential complications associated with anesthesia/post-operative care, reduces the technical expertise and equipment needed for surgical transfer, and represents substantial cost savings and regulatory reduction. NSET technology provides an easy and rapid alternative to surgical embryo transfer. Address correspondence to Brett Spear, Room 210, Combs Building, University of Kentucky College of Medicine, 800 Rose Street, Lexington, KY, 40536-0298, USA. email:

From bench to cageside: Risk assessment for rodent pathogen contamination of cells and biologics

Many newly developed animal models involve the transfer of cells, serum, or other tissue-derived products into live rodents. These biologics can serve as repositories for adventitious rodent pathogens that, when used in animal studies, can alter research outcomes and result in endemic outbreaks. This review includes a description of some of the biologics that have inadvertently introduced infectious agents into in vivo studies and/or resulted in endemic outbreaks. I also discuss the points of potential exposure of specific biologics to adventitious rodent pathogens as well as the importance of acquiring a complete developmental and testing history of each biologic introduced into a barrier facility. There are descriptions of specific cases of mycoplasma and lactate dehydrogenase–elevating virus (LDHV), two of the most common organisms that contaminate cells and cell byproducts. The information in this article should help investigators and animal resource program personnel to perform an appropriate risk assessment of biologics before their use in in vivo studies that involve rodents.

Old enemies, still with us after all these years

Although some previously common infections, such as Sendai virus and Mycoplasma pulmonis, have become rare in laboratory rodents in North American research facilities, others continue to plague researchers and those responsible for providing biomedical scientists with animals free of adventitious disease. Long-recognized agents that remain in research facilities in the 21st century include parvoviruses of rats and mice, mouse rotavirus, Theilers murine encephalomyelitis virus (TMEV), mouse hepatitis virus (MHV), and pinworms. The reasons for their persistence vary with the agent. The resilience of parvoviruses, for example, is due to their resistance to inactivation, their prolonged shedding, and difficulties with detection, especially in C57BL/6 mice. Rotavirus also has marked environmental resistance, but periodic reintroduction into facilities, possibly on bags of feed, bedding, or other supplies or equipment, also seems likely. TMEV is characterized by resistance to inactivation, periodic reintroduction, and relatively long shedding periods. Although MHV remains active in the environment at most a few days, currently prevalent strains are shed in massive quantities and likely transmitted by fomites. Pinworm infestations continue because of prolonged infections, inefficient diagnosis, and the survivability of eggs of some species in the environment. For all of these agents, increases in both interinstitutional shipping and the use of immunodeficient or genetically modified rodents of unknown immune status may contribute to the problem, as might incursions by wild or feral rodents. Elimination of these old enemies will require improved detection, strict adherence to protocols designed to limit the spread of infections, and comprehensive eradication programs.