Some species of the parasite Trypanosoma brucei can a serious and deadly illness caused sleeping sickness. These parasites have a complex evolutionary history and life cycle, which relies on tsetse flies. The complexity of this life cycle has limited the geographic range of T. brucei to sub-Saharan Africa. However, some T. brucei parasite species have managed to simplify this process, and eliminate one stage of their life cycle so they no longer require tsetse flies. These parasites are considered a different species; but the simplification of their life cycle has allowed them to spread beyond parts of Africa into Asia South America, and Europe to cause illness in animals.
A new study in Nature Communications has reveled some of the genetic changes that have occurred as the life cycle of the parasite changed. The study also indicated that some efforts to control the tsetse flies that carry these parasites, as well as climate change, could trigger additional molecular changes in disease-causing T. brucei that may lead to illness in humans.
In this study, the researchers analyzed genetic data from over eighty different parasites, or trypanosomes, that were collected from people, cows, tsetse flies, and other animals. The investigators then created a phylogenetic tree that illustrated the genetic links among various strains of parasites.
The investigators also used the CRISPR gene-editing technology to assess the genetic changes in the parasites, and determine what mutations may be related to life cycle changes that allow the parasite to grow and spread without requiring tsetse flies. There were multiple genetic mutations that were found to play a role in the parasitic life cycle.
The study authors suggested that if we know the genes that are important to the parasitic life cycle, it may be possible to use them to identify strains of the parasite that may pose a threat to public health, when and if the parasite spreads to a new area.
"Trypanosomes have found ways to expand their geographic range by excluding the tsetse fly from their life cycle. The molecular changes they exhibit can allow us to detect the emergence of these virulent parasites that threaten both cattle and, potentially, humans," noted co-corresponding study author Professor Keith Matthews of the University of Edinburgh.
"We plan to continue this research and develop a portable diagnostic tool to facilitate detection of future outbreaks in real-time," said co-corresponding study author Dr. Guy Oldrieve of the University of Edinburgh.
Sources: University of Edinburgh, Nature Communications
