Anthrax bacterium secretes three toxins, including LF and EF, and is only known to infect mammals. Because fruit flies lack components required for toxin entry into cells, they cannot actually contract the anthrax disease. However, the study finds that fruit flies can be used to test the effects of a single virulence factor, such as the LF or EF toxins, on signaling pathways shared by flies and humans.
Guichard and her co-authors applied lethal factor toxin to fruit fly embryos and larvae and observed that a component of the expected signaling pathway was inactivated, disrupting the whole molecular system and leading to death. When applied in a more limited fashion, LF interfered with the formation of sutures in the epidermis, resulting in a hole or cleft in thoracic regions of embryos and adults. This developmental process disrupted by LF treatment is similar mechanistically to wound healing, which is mediated by the same signaling pathway in humans.
The EF toxin is also lethal when applied to fly larvae and can cause severe malformation in the wings of adult fruit flies--an effect that can also be understood as an interruption of another unrelated signaling process common to flies and humans.
"We asked the simple question of whether anthrax toxins affecting mammals could act on the fly counterparts of proteins affected in humans, and the answer is yes," said Ethan Bier, a professor of biology at UCSD who was the senior author of the study. "What this means is that similar types of analyses might identify yet unknown proteins shared by flies and humans that can be acted on by anthrax toxins. More generally, this study suggests that flies can be used as a rapid whole organism system to determine the function of a variety of bacterial and viral pathogens of unknown function. One could then test hypotheses obtained from these studies with flies in mammalian organisms such as mice."
The biologists also anticipate that toxins
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Source:University of California - San Diego