Zebrafish and Humans Share Similar Response to Invading Germs
Since the human response to infection is highly complex, research to
understand how people fight infection is facilitated by studying how similar
processes occur in simpler organisms. Zebrafish are becoming an important
model for human disease, since they are easily handled, maintained and
manipulated and many fundamental processes between zebrafish and humans are
conserved. In addition, the small zebrafish embryo is highly amenable to
drug screening assays. The functional similarity between the initial
responses of zebrafish embryo and humans to infection suggests that the
zebrafish embryo may be a valuable model for understanding early immune
responses and identifying potential therapeutics for infection or immune
mediated 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, like viruses or bacteria, the first stage
of a two-part inflammatory response is triggered, which is termed the innate
immune response. During this early phase, proteins are made around the site
of infection to initiate the body's defense system and to recruit
circulating immune cells, which begins the inflammatory process. A family of
proteins that are critical to instigating the immune response are the
interferons (IFN), particularly IFN-?.
Scientists now report that IFN-? is also produced in zebrafish embryos when
they are exposed to bacteria that cause disease in fish. These studies use
developing zebrafish embryos whose response to infection is isolated to the
innate immune response. Since the zebrafish embryo only demonstrates innate
immunity, it allows for specific study of the effects of IFN-? on these
early events. This study demonstrates that both zebrafish and human IFN-?
proteins function in much the same way, despite having very distinct protein
structures. In both zebrafish and humans, IFN-? triggers the production of
an array of proteins that rally the defense mechanisms of the infected cell
and activate the immune system. They also found that compromising the
ability of the zebrafish embryos to produce IFN-? impairs the fish's ability
to survive infection. Thus, the zebrafish embryo may provide a very simple
model to understand the innate immune response.
Full article available at DMM: Disease Models & Mechanisms
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