Mutual viral and bacterial infections after housing rats of various breeders within an experimental unit

Approved and novel strategies in diagnostics of rat bite fever and other Streptobacillus infections in humans and animals

Rat bite fever (RBF), a worldwide occurring and most likely under-diagnosed zoonosis caused by Streptobacillus moniliformis, represents the most prominent disease of Streptobacillus infections. Recently, novel members have been described, from which a reservoir in rats and other animal species and a zoonotic potential can be assumed. Despite regularly published case reports, diagnostics of RBF continues to represent a 'diagnostic dilemma', because the mostly applied 16S rRNA sequence analysis may be uncertain for proper pathogen identification. Virtually nothing is known regarding prevalence in humans and animal reservoirs. For a realistic assessment of the pathogen's spread, epidemiology and virulence traits, future studies should focus on the genomic background of Streptobacillus. Full genome sequence analyses of a representative collection of strains might facilitate to unequivocally identify and type isolates. Prevalence studies using selective enrichment mechanisms may also enable the isolation of novel strains and candidate species of this neglected group of microorganisms.

1 Management of Immunocompromised and Infected Animals

This chapter discusses the management of immunocompromized and infected animals. The microbiological quality of laboratory animals is a direct result of colony management practices, and monitoring provides an after-the-fact assessment of the adequacy of those practices. In the case of immunocompromised animals or in infection experiments, however, monitoring for a comprehensive list of micro-organisms is reasonable. The testing of animals usually starts with necropsy and blood sampling for serology, followed by microscopic examination for parasites and sampling of organs for bacteriology, pathology, and, in rare cases, virological examinations. Biological materials represent a high risk, if they originate from or have been propagated in animals. In particular, tumors, viruses, or parasites that are serially passaged in animals often pick up pathogens, and therefore a high percentage of these are contaminated. It has been shown in mice and rats that all preimplantational stages can be revitalized successfully upon freezethaw procedures. For long-term storage, eight-cell stages have been recommended in the chapter, while two-cell stages were considered to be less suitable. One embryo batch (inbred strain) derived from a single pedigree donor pair may be regarded as a prospective breeding nucleus, if one fertile breeding pair is obtained upon revitalization. Assuming an average revitalization rate of 20% (fertile breeders), one embryo batch should contain a minimum number of 10 embryos to obtain at least one breeding pair with a 50% chance of revitalization.

Efficient replication of pneumonia virus of mice (PVM) in a mouse macrophage cell line

Pneumonia virus of mice (PVM; family Paramyxoviridae, subfamily Pneumovirinae) is a natural respiratory pathogen of rodent species and an important new model for the study of severe viral bronchiolitis and pneumonia. However, despite high virus titers typically detected in infected mouse lung tissue in vivo, cell lines used routinely for virus propagation in vitro are not highly susceptible to PVM infection. We have evaluated several rodent and primate cell lines for susceptibility to PVM infection, and detected highest virus titers from infection of the mouse monocyte-macrophage RAW 264.7 cell line. Additionally, virus replication in RAW 264.7 cells induces the synthesis and secretion of proinflammatory cytokines relevant to respiratory virus disease, including tumor necrosis factor-alpha (TNF-alpha), interferon-beta (IFN-beta), macrophage inflammatory proteins 1alpha and 1beta (MIP-1alpha and MIP-1beta) and the functional homolog of human IL-8, mouse macrophage inflammatory peptide-2 (MIP-2). Identification and characterization of a rodent cell line that supports the replication of PVM and induces the synthesis of disease-related proinflammatory mediators will facilitate studies of molecular mechanisms of viral pathogenesis that will complement and expand on findings from mouse model systems.

Management of immunocompromised and infected animals

This chapter discusses the management of immunocompromised and infected animals. The microbiological quality of laboratory animals is a direct result of colony management practices and monitoring provides an after-the-fact assessment of the adequacy of those practices. Monitoring is, therefore, of greatest value in connection with the maintenance of animals in isolation systems where vigorous microbiological control is applied. In addition to constructive measures, an appropriate management system is necessary for the prevention of infections, as well as for their detection and control. It is a major task for the management of an animal facility to understand the way micro-organisms might be introduced or spread under the specific conditions given. The management of all animal facilities in an institution is best centralized. This warrants that all information dealing with the purchase of animals, the use of experimental materials and equipment and the performance of animal experiments flows through one office. This reduces the opportunity for the failures of communication. Centralized management can best establish comprehensive monitoring programs to evaluate important risk factors, such as animals and biological materials, before they are introduced into a facility.

Parasite survey in mouse and rat colonies of Brazilian laboratory animal houses kept under differents sanitary barrier conditions

A parasitological study was undertaken to determine the health status of 15 mouse and 10 rat colonies bred in 18 Brazilian laboratory animal houses maintained under different sanitary barrier conditions which supply animals for teaching, research purposes and manufacture of biological products for medical or veterinary use. Parasitological methods were used for diagnosis of mites, lices, helminthes and protozoan parasites. A questionnaire was answered by institutions with the intention to obtain information about the existence of barriers against infections and of regular sanitary monitoring program of their colonies. The questionnaire data show that the majority of the animal houses investigated do not possess an efficient sanitary barrier system able to keep animals under controlled health sanitary conditions. Ecto and endoparasite infections are widespread in the colonies and multiple infections were common in animals from most facilities investigated. The prevalences of parasites detected among the mouse and rat colonies of the laboratory animal houses investigated were: Myocoptes musculinus (46.6%), Myobia musculi (26.6%), Radfordia ensifera (13.3%), Syphacia obvelata (86.6%), Aspiculuris tetraptera (60.0%), Hymenolepis nana (53.3%), Spironucleus muris (80.0%), Tritrichomonas muris (80.0%), Giardia muris (66.0%), Entamoeba muris (20.0%), Eimeria sp. (13.3%), Hexamastix muris (26.6%), Poliplax spinulosa (30.0%), Poliplax serrata (10.0%), Radfordia ensifera (30.0%), Syphacia muris (80.0%), Hymenolepis nana (40.0%), Trichosomoides crassicauda (55.5%), Spironucleus muris (90.0%), Tritrichomonas muris (80.0%), Giardia muris (60.0%), Entamoeba muris (80.0%), Eimeria sp. (60.0%) and Hexamastix muris (60.0%).

Natural pathogens of laboratory mice, rats, and rabbits and their effects on research

Laboratory mice, rats, and rabbits may harbor a variety of viral, bacterial, parasitic, and fungal agents. Frequently, these organisms cause no overt signs of disease. However, many of the natural pathogens of these laboratory animals may alter host physiology, rendering the host unsuitable for many experimental uses. While the number and prevalence of these pathogens have declined considerably, many still turn up in laboratory animals and represent unwanted variables in research. Investigators using mice, rats, and rabbits in biomedical experimentation should be aware of the profound effects that many of these agents can have on research.