Fish fend off invading germs with an initial response similar to the one found in people
The functional similarity between the initial responses of the zebrafish embryo and humans to infection suggests that the zebrafish embryo can be a useful model for understanding the early immune response and identification of potential therapies for infection immune disease. However, the initial response of zebrafish to infection and how it compares to the human response is not well understood.
When humans first encounter germs such as viruses or bacteria, the first stage of a two-part triggers an inflammatory response, called the innate immune response. During this first phase, the proteins are made around the site of infection to start the body’s defense system and to recruit circulating immune cells, initiating the inflammatory process. A family of proteins that are critical to instigate an immune response are the interferon (IFN), particularly IFN-γ.
Scientists now report that IFN-γ also occurs in zebrafish embryos when exposed to the bacteria that cause disease in fish. These studies are the development of zebrafish embryos, whose response to infection is isolated to the innate immune response. Because the zebrafish embryo shows only innate immunity, which allows the specific study of the effects of IFN-γ in these early events. This study demonstrates that the zebrafish and human proteins in IFN-γ function in the same way, despite having very different protein structures. In zebrafish and humans, IFN-γ triggers the production of a series of proteins that rally the defense mechanisms of the infected cell and activate the immune system. They also found that compromising the ability of zebrafish embryos to produce IFN-γ impairs the ability of fish to survive the infection. Thus, the zebrafish embryo can be a very simple model to understand the innate immune response.
Interestingly, large amounts of bacteria, resulting in septic shock – a potentially fatal condition – in humans, do not provoke the same response in zebrafish. This suggests that some key differences between the immune systems of zebrafish and humans can also provide information on harmful events associated with inflammation.
The characterization of IFN-γ function in zebrafish occurs in the research paper entitled “The role of gamma interferon in innate Inity the zebrafish embryo,” which was written by Dirk Sieger, Cornelia, David Neif and Maria Leptin University of Cologne in Germany and Astrid van der Sar at the VU University Medical Center in Amsterdam in the Netherlands.
More information: The study is published in the November/December 2009 issue of the new research journal, Disease Models & Mechanisms (DMM), http://dmm.biologists.org/, published by The Company of Biologists, a non-profit based in Cambridge, UK.
Source: The Company of Biologists (web)
Tags: embryo, human, humans, ifn, immune, immune response, infection, innate, innate immune, innate immune response, proteins, response, response to infection, zebrafish, zebrafish and humans, zebrafish embryo, zebrafish embryos