Scientists have discovered how the coronavirus that causes COVID-19 hijacks human cells, a finding that could lead to new treatments for the disease.

The study, published in the journal Nature, found that the SARS-CoV-2 virus uses a protein called TMPRSS2 to enter human cells. TMPRSS2 is a protease, an enzyme that cuts proteins into smaller pieces. The virus uses TMPRSS2 to cut a protein on the surface of human cells, called ACE2, which allows the virus to enter the cell.

"This finding is significant because it provides a potential target for new therapies to prevent or treat COVID-19," said study co-author Dr. James Voss, a virologist at the University of North Carolina at Chapel Hill. "We could develop drugs that target TMPRSS2 and stop the virus from entering cells."

The researchers also found that the SARS-CoV-2 virus can use another protease, called furin, to enter human cells. However, furin is less efficient at cutting the ACE2 protein than TMPRSS2, which suggests that TMPRSS2 is the primary protease used by the virus to enter cells.

The study findings could also explain why some people are more susceptible to COVID-19 than others. People with higher levels of TMPRSS2 in their lungs may be more likely to become infected with SARS-CoV-2.

"This research provides important insights into the mechanisms by which SARS-CoV-2 enters human cells," said study co-author Dr. Ralph Baric, a virologist at the University of North Carolina at Chapel Hill. "These findings could lead to new therapies to prevent or treat COVID-19."

In addition to TMPRSS2, the researchers also found that the SARS-CoV-2 virus can use another protein, called cathepsin L, to enter human cells. However, cathepsin L is only expressed in certain types of cells, which suggests that it is not the primary protease used by the virus to enter cells.

The research team says that further studies are needed to confirm the role of TMPRSS2 and furin in the entry of SARS-CoV-2 into human cells. The researchers also plan to study the role of cathepsin L in the entry of SARS-CoV-2 into human cells.