Reduced tumorigenicity by addition in vitro of Sendai virus

Implications of infectious agents on results of animal experiments

Report of the Working Group on Hygiene of the Gesellschaft für Versuchstierkunde–Society for Laboratory Animal Science (GV-SOLAS)

GV-SOLAS Working Group on Hygiene: Werner Nicklas (Chairman), Felix R. Homberger, Brunhilde Illgen-Wilcke, Karin Jacobi, Volker Kraft, Ivo Kunstyr, Michael Mähler, Herbert Meyer & Gabi Pohlmeyer-Esch

Of mice and microflora: considerations for genetically engineered mice

The phenotype of genetically engineered mice is a combination of both genetic and environmental factors that include the microflora of the mouse. The impact a particular microbe has on a mouse reflects the host-microbe interaction within the context of the mouse genotype and environment. Although often considered a confounding variable, many host-microbe interactions have resulted in the generation of novel model systems and characterization of new microbial agents. Microbes associated with overt disease in mice have been the historical focus of the laboratory animal medical and pathology community and literature. The advent of genetic engineering and the complex of mouse models have revealed previously unknown or disregarded agents that now oblige the attention of the biomedical research community. The purpose of this article is to describe and illustrate how phenotypes can be affected by microflora by focusing on the infectious diseases present in genetically engineered mouse (GEM) colonies of our collective institutions and by reviewing important agents that are rarely seen in most research facilities today. The goal is to introduce the concept of the role of microflora on phenotypes and in translational research using GEM models.

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.

Potential detrimental effects of rodent viral infections on long-term experiments

Healthy animals are of paramount importance in obtaining meaningful, reliable scientific results. Viral infections of rodents often have a significant impact on various types of biomedical research. Laboratory animal specialists and researchers must be aware of the possible consequences associated with the use of infected animals. The objective of the paper is a discussion of the frequently encountered viral infections that can complicate or invalidate the interpretation of results by altering the host's response.

Increased tumorigenicity of polyploid Ehrlich variants during growth in vivo is associated with karyotypic changes

In previous studies, treatment of Ehrlich ascites tumors (EAT) with either Sendai virus, Herpes virus or neuraminidase produced variants that differed significantly from EAT in both tumorigenicity and karyotype. In this study, less tumorigenicity variants of EAT were isolated by culturing in media containing low concentrations of serum or without serum. In contrast to the relative stability of tumorigenicity in such variants cultured in vivo, the tumorigenicity of these variant clones passaged in vivo was variable, depending on the variant clone. During growth in vivo, 3 variant clones independently isolated from serum-free medium, low serum-containing medium and after neuraminidase treatment produced markedly heterogeneous tumors, and after 4 passages the tumors were about 1000 times more tumorigenic than the initial variants. In generating new tumors, the tumors always segregated chromosomes. The banded chromosome analysis of a variant clone isolated from serum-free medium and its malignant tumor showed that most of the chromosomes segregated from the clone were normal types. On the other hand, the tumorigenicity of Herpes virus-induced variants was unchanged during growth in vivo.