UC scientists study tick-borne bacterium
Climate change is benefiting these parasites, as rising global temperatures allow them to remain active for longer periods of the year.
Translation by Diana Taborda
A research team of the Centre for Neuroscience and Cell Biology of the University of Coimbra (CNC-UC) has discovered how Rickettsia, a bacterium responsible for diseases such as tick fever, manages to escape our immune system. This discovery leads to the development of new therapies against infectious diseases.
Contrary to what one might think, ticks are not responsible for tick fever, but the microorganisms that may be inside them. Rickettsia is one of the bacteria that can be found in parasites such as ticks, fleas or lice and can be transmitted to humans through their bite. Currently, climate change is favourable to these parasites, as the increase in global temperature allows them to be active longer throughout the year. As a result, there is a greater geographical spread of parasites that can carry bacteria dangerous to human health.
In order to understand how these bacteria infect our body, Pedro Curto and Isaura Simões, researchers at the CNC-UC, studied a protein present on the surface of Rickettsia bacteria, the APRc. "After the bite of an infected tick, the Rickettsia enters the bloodstream where it will be exposed to all the mechanisms of our immune system. At this point, the bacteria's priority will be to protect itself and enter our cells at all costs, since its survival and infection capacity depend on it", explains Pedro Curto, first author of the study.
"Infectious microorganisms have several mechanisms to escape our immune system. We already suspected that the APRc protein, present on the surface of Rickettsia, plays an important role in the evasion of the bacterium, but in this study we found that, in addition, it also protects it, preventing the immune system from eliminating it," explains the leader of the study, Isaura Simões.
This work, already published in the journal mBio, showed that the APRc protein can bind to antibodies present in the bloodstream, preventing the immune system attack and acting as a shield. It was also found that APRc offers extra protection to the bacteria against the bactericidal activity of proteins present in the serum (part of the blood).
"This is an important step in fundamental biology and a contribution to the development of new therapies against infectious diseases, which are now unfortunately taking on an increasingly present role in today's world," add the authors of the research.
The study was funded by the European Regional Development Fund (ERDF), through the COMPETE 2020 programme - Operational Programme for Competitiveness and Internationalisation -, and by national funds, through the Portuguese Foundation for Science and Technology (FCT).
The scientific article is available at: https://journals.asm.org/doi/10.1128/mBio.03059-21.