To survive in the human bloodstream, the African trypanosome parasite wears a "cloak" made of proteins known as a variant surface glycoprotein (VSG). The study, published in Nature Microbiology, identifies the protein that allows the parasite to fine-tune this "cloak".
The newly discovered ESB2 protein acts as a "molecular shredder", allowing the parasite to avoid detection by destroying specific parts of its genetic instructions with surgical precision as they are being produced.
By understanding how the parasite manages to do this with such incredible precision, researchers can now identify new vulnerabilities in its life cycle. This opens the door for future treatments for Sleeping Sickness, a disease that continues to have a devastating impact on communities across sub-Saharan Africa.
Transmitted by the bite of the tsetse fly, if left untreated the parasites invade the central nervous system, causing neurological issues including severe sleep disruptions, confusion, and coma.
Dr Joana Faria, senior author of the study and leader of the research group at the University of York, said: "We've discovered that the parasite's secret to staying invisible isn't just what it prints, but what it chooses to redact. By placing a "molecular shredder" directly inside its "protein factory", the parasite can edit its genetic manual in real-time.
"This suggests a fundamental shift in how we view infection: survival for many organisms may depend less on how they issue genetic instructions and more on how they destroy them at the source."
The discovery provides an answer to a bizarre quirk in the parasite's biology that has baffled scientists for 40 years. The genetic manual for the "cloak" also contains several "helper genes" needed for survival and immune evasion. Logic suggests that when the parasite follows these genetic instructions, it should produce equal amounts of each protein. However, the parasite somehow produces a mountain of cloak proteins but only a tiny amount of helper proteins.
By identifying the ESB2 protein, the York team discovered that the parasite controls its genetic messages through destruction rather than just production.
ESB2 sits directly inside the parasite's protein factory, known as the Expression Site Body. As the genetic manual is being printed, ESB2 acts as a "molecular blade" that instantly shreds the helper sections while leaving the cloak instructions intact. This real-time redaction ensures the parasite expresses exactly what it needs to remain hidden from the host's immune system.
The breakthrough marks the first major output for Dr Faria's new laboratory at the University of York, representing a significant addition to the city's growing reputation as a global hub for life sciences.
The project was funded by a Sir Henry Dale Fellowship – a partnership between the Wellcome Trust and the Royal Society – and brought together expertise from the United Kingdom, Portugal, the Netherlands, Germany, Singapore and Brazil.
Lianne Lansink, first author of the study, said: "When we first saw the molecular shredder localised in the microscope, we knew we had found something special."
Dr Faria added: "This discovery is a real full-circle moment for me. The mystery of how this parasite manages the asymmetric expression of its genetic manual has been a cold case in the back of my mind since my days as a postdoc. To finally solve it now, as the first major output of my own lab here at York, is incredibly rewarding. It's a testament to what a fresh lab and a diverse group of scientists can achieve when they look at an old problem from a completely new angle."
