Scientists around the world are currently investigating strategies to combat the corona pandemic. The answer could lie in the immune system, researchers are now discovering. An endogenous protein must prevent Sars-CoV-2 from causing an infection. This raises hopes for new therapeutic approaches.

A protein produced by the human immune system can strongly inhibit coronaviruses, including Sars-CoV-2, the causative agent of Covid-19. An international team from Germany, Switzerland and the USA was able to prove that the LY6E protein prevents coronaviruses from causing infections. “This provides information about possible treatment strategies,” said Stephanie Pfänder from the Institute for Molecular and Medical Virology at the Ruhr University in Bochum (RUB), lead author of the study.

“We wanted to know which factors prevent animal corona viruses from jumping on people,” said Volker Thiel from the University of Bern, co-author of the study. “Now we have, so to speak, managed to find the needle in the haystack.” The study was published in the journal “Nature Microbiology”.

The LY6E protein plays a role in several diseases: Some time ago, American researchers discovered that the protein increases the infectivity of flu-causing flu viruses. The team led by Pfänder and Thiel has now found that the immune protein has the opposite effect on coronaviruses: it prevents the infection.

Tests with different cell cultures showed that LY6E affects the ability of the virus to fuse with the host cells. “If the virus cannot fuse with these cells, it cannot cause an infection,” explains Thiel Mitteilungen from the University of Bern.

Detection in mice

The researchers were able to demonstrate this in an animal model: mice without LY6E in the immune cells were very susceptible to a normal, non-fatal mouse coronavirus and died.

The scientists emphasize that the mouse coronavirus used in the experiment differs significantly from the causative agent of the current Covid 19 outbreak. For example, it does not cause severe acute respiratory syndrome, but hepatitis. However, mouse coronavirus is widely recognized as a model for understanding the basic concepts of coronavirus replication and immune responses in a live animal.

“Our study provides new insights into how important these antiviral genes are for controlling virus infection and for an adequate immune response to the virus,” the authors write. “Since LY6E is a naturally occurring human protein, we hope that this knowledge can help develop therapies that may one day be used to treat coronavirus infections.” A therapeutic approach that mimics the mechanism of action of LY6E could be a first line of defense against coronavirus infection.