Volume 44 Supplement 1
Functional Genomics to Study Complex Diseases in Livestock Species
© The Author(s); licensee BioMed Central Ltd. 2003
Published: 31 March 2003
Many diseases in production animals display a complex interplay between host immune responses and pathogen-specific events. Indeed, many of the pathologies of diseases such as Johne's disease and mastitis result from the host immune response or immunopathology as opposed to direct effects of the pathogen. In addition, numerous factors may affect the outcome of any particular infection event. Production stresses such as heat, transport, parturition and nutrition all combine to dramatically alter the immune status of the host. With such complex interactions, it is clear that single gene approaches in highly controlled environments cannot describe or predict the outcome of most production diseases. The Center for Animal Functional Genomics at Michigan State University was created to address this shortfall by applying global gene expression profiling techniques to complex problems in livestock and companion animals. Our working hypothesis is that global gene expression profiling will divulge clues to the basic biological mechanisms underlying host immune responses and interactions with various pathogens. As a first step in testing this hypothesis, we have created a high quality normalized cDNA library from total bovine leukocytes (BOTL) and used this library to produce cDNA microarrays. The first of these arrays contained approximately 720 unique genes and appropriate controls. Subsequently, bovine sequences representing over 450 key genes encoding various chemokines, cytokines, chemotactic factors, adhesion molecules, transcription factors and other regulatory factors have been obtained. A batch primer tool was used to derive primer sequences to these genes and amplicons of the various factors added to the BOTL cDNA microarrays. In initial studies using a predictable model of immune activation, stimulation of peripheral blood mononuclear cells with concanavlin A (ConA) resulted in dramatic up regulation of over 85 genes. Interestingly no genes were down regulated following stimulation with ConA. Preliminary clustering of these genes by product function shows that many of the stimulated genes encode transcription factors, adhesion molecules and proteins involved in signal transduction or cell cycle regulation. We have begun to apply our BOTL cDNA microarrays to samples obtained from animals undergoing various forms of production stress, such as transport and parturition. In addition, these arrays have been combined with differential display reverse transcriptase PCR (DDRT-PCR) in an attempt to more fully understand the complex interactions of Mycobacteria with bovine macrophages. Our results to date suggest that various forms of production stress may result in altered immune function by hampering various signal transduction pathways and reducing expression of key factors involved in maintaining immune cell viability. We have also identified at least one gene that is normally upregulated following phagocytosis, but appears to be preferentially inhibited following uptake of pathogenic Mycobacteria by bovine macrophages. These preliminary results clearly demonstrate that global gene expression profiling offers an outstanding opportunity for animal scientists and veterinarians to gain new insights into complex production diseases.
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.