How does SARS-CoV-2 infect a human cell?

SARS-CoV-2 entry by Janet Iwasa

SARS-CoV-2 is the virus responsible for COVID-19. The surface of the virus is studded with spike proteins, coloured teal, membrane proteins, coloured yellow, and envelope proteins, coloured red. A cross-section shows the viral RNA genome in orange and the nucleocapsid protein, which protects the RNA, in grey.

An individual can be infected with SARS-CoV-2 after inhaling airborne viral particles. Upon entering the airways, the virus particles encounter respiratory ephitelium cells in the trachea and lungs.

The SARS-COV-2 spike protein recognizes a membrane-bound protein on the surface of the cells known as ACE2, shown here in purple. Once bound to ACE2, the spike protein is unable to open, close and bend freely, locking it in place. Another cell surface protein called transmembrane protease, serine 2, shown here in orange, cuts the spike protein in a specific location. These segments of the spike protein fall away and expose previously hidden parts of the spike.

The spike protein can then undergo a series of dramatic conformational changes. During the first stage, the spike protein inserts itself into the cell membrane. Once inserted, the spike protein folds back on itself, pulling the membranes of the cell and virus together so they can fuse.

After fusion, the viral RNA is deposited into the host cell, where it hijacks the cell's machinery to produce more virus particles.

This animation was created and kindly provided by the Animation Lab at the University of Utah.