Context

• A new study has found that an endogenous protein (one that originates within the body’s systems) prevents coronaviruses, including SARS-CoV-2, from fusing with host cells. 
• The team of researchers at the University of Georgia (UGA) in the US noted that the SARS-CoV-2 protein PLpro is essential for the replication and the ability of the virus to suppress host immune function.

Back to Basics

About the LY6e Protein

• The protein, called LY6e, is produced by the human immune system.
• LY6e was discovered in 2017, during research by virologist Stephanie Pfänder (then with the Institute of Virology and Immunology in Switzerland in order to identify genes that prevent coronavirus
• Investigations has shown that the protein exerted this inhibitory effect on all analysed coronaviruses, including.
• Tests with different cell cultures have shown that LY6e affects the ability of the virus to fuse with the host cells.
• This was validated in an animal model.
• Mice lacking Ly6e in immune cells were found highly susceptible to a normally non-lethal mouse coronavirus and succumb to infection.

About PLpro Protein

• PLpro, is produced by the human cell itself after the virus hijacks the cell mechanism. PLpro is essential for replication of the virus.
• Pharmacological inhibition of PLpro blocks virus replication and also strengthens our immune response.
• When SARS-CoV-2 infects us, the infected body cells release messenger substances known as type 1 interferons. These attract our killer cells, which kill the infected cells. SARS-CoV-2 fights back by letting the human cell produce PLpro.
• This protein suppresses the development of type 1 interferons, which would have attracted our killer cells.
• Researchers have now been able to monitor these processes in cell culture. If they blocked PLpro, virus production was inhibited, and the innate immune response of the human cells was also strengthened.