Scientists are getting better at spotting some sneaky tick-borne viruses before they make people sick. In a new study published in ACS Infectious Diseases, researchers discovered how a group of dangerous viruses called nairoviruses hide from the human immune system—and that knowledge could help protect people down the road.
The team, led by Scott Pegan of the U.S. Army Reserve, found that nairoviruses survive by producing special enzymes that act like molecular scissors. These enzymes snip off two tiny proteins—called ubiquitin and ISG15—that normally act as alarm signals, telling the body to fight back against an infection. Without those alarm proteins attached, the immune system doesn't realize the virus is there, giving it time to spread.
"The Crimean-Congo hemorrhagic fever virus represents the global danger that nairoviruses can pose to the public," Pegan said. That particular virus can be deadly and threatens both civilians and military personnel in Africa, the Middle East, and Asia.
The researchers tested enzymes from four species of nairoviruses, including three newly identified ones taken from patients in Asia. One virus caught their attention: the Pacific Coast tick nairovirus, or PCTNV. Its enzyme was actually the best at removing ubiquitin and ISG15, suggesting it might evade human immune defenses more effectively than other nairoviruses. That's concerning because PCTNV is carried by a tick species already known to spread diseases like Rocky Mountain spotted fever—and that tick lives along the U.S. West Coast.
But the study isn't all worry. The team also gathered enzyme activity data from 13 different nairovirus species and used it to train computer models that can identify which viruses might be dangerous to humans. Early results show promise for a biosurveillance system—essentially an early warning network to track these viruses before they cause outbreaks.
"This study reinforces the need to be vigilant about not just tick bites but the type of ticks that an individual has been bitten by, as they may carry diseases beyond what we have been used to looking for," Pegan concluded. By understanding exactly how these viruses slip past our defenses, scientists now have a clearer target for developing new tools to detect and fight them.