Viral protein stimulates nerves in respiratory passages, could be target for treatment
SARS-CoV-2 has many ways of making people miserable, including by causing them to sneeze. Now, researchers have discovered the basis for this nose-tickling effect. One of the virus’ proteins stimulates neurons in respiratory passages, triggering the sneeze reflex. The results could spawn novel treatments to ease COVID-19 symptoms and to reduce transmission of SARS-CoV-2.
They might also apply to other sneeze-inciting viruses. “Prior to this study, nothing was known about how viruses cause sneezing,” says neuroimmunologist Isaac Chiu of Harvard Medical School, who wasn’t connected to the research. The study is the first to show that a viral protein “can be directly sensed by neurons to cause sneezing.”
Neurophysiologist Diana Bautista of the University of California, Berkeley and colleagues suspected SARS-CoV-2 might play a more direct role. Infected cells pump out large amounts of the viral protein PLpro, part of a family of enzymes called proteases that carve up other proteins. Previous research showed that other proteases made by plants, bacteria, and even humans stimulate sensory neurons, the cells that induce sneezing.
The researchers squirted PLpro into the noses of mice and found it stimulated a subgroup of sensory neurons called nociceptors that produce pain and itch sensations. The team then tested the protein’s effect on sneezing. The rodents started sneezing about 14 seconds after PLpro exposure, versus 30 seconds after getting a control mixture. Mice dosed with PLpro sneezed almost four times more than controls in the first 2 minutes, the team reported in an 11 January preprint on bioRxiv.