Coronavirus protein triggers pain nerves causing cough and sneeze

Biologists have identified a specific protein produced by the coronavirus that binds to pain receptors in the respiratory system. This interaction activates nerve cells responsible for sensing pain, offering an explanation for symptoms such as sneezing, coughing, and headaches experienced by patients. The findings were published in the scientific journal "Neuron."

The mechanism behind respiratory symptoms

"Coughing and sneezing are among the most common symptoms of acute viral respiratory infections, but until now we did not know how coronaviruses and other pathogens cause these specific physiological responses," the biologists stated. They demonstrated for the first time that the viral protein PLpro is capable on its own of activating pain-sensing neurons and inducing cough and sneeze reflexes.

A team of American molecular biologists led by Professor Diana Bautista from the Howard Hughes Medical Institute made this discovery while studying how various viral proteins interact with cellular systems during coronavirus replication. Many of these proteins suppress immune responses and affect body functions by destroying peptides they produce.

PLpro’s role in infection

The PLpro protein performs similar functions: it inhibits the immune response and plays a key role in forming the protein components of the coronavirus particle envelope. Given that structurally similar molecules found in plant, bacterial, and animal cells can bind to pain receptors and cause pain, researchers decided to test the effect of PLpro on neurons located in the nasopharynx and respiratory organs of mice.

Measurements revealed that very small quantities of this protein activated approximately one-third of the neurons in these organs. Most of these were TRPV1 type, a category of pain receptor. High-speed camera recordings showed that direct activation of these neurons caused the mice to sneeze and cough, in addition to experiencing pain.

Implications for viral spread

Researchers concluded that PLpro protein particles produced by other viruses, including SARS-CoV-1 and MERS, triggered similar responses in mice. This suggests that at least several viruses can interact with the host's nervous system and alter its activity in a way believed to facilitate their spread.