There are two main schemes used by viruses to enter a cell. In receptor mediated endocytosis the bound virus enters the cell by entering a clathrin coated pit and is then invaginated into the cell to be enclosed within an endosome. It is thought that a lowering of the PH then causes membrane fusion within the endosome, and final penetration of the endosomal membrane by the virus. In the case of naked viruses, there is no membrane fusion in the endosome. Instead, the naked virus punches a hole in the endosomal membrane.
Direct fusion is used by some enveloped viruses.
After binding, the viral receptor undergoes a confirmational change. A fusion peptide is created to cause fusion between the virus and the host cell membrane. All Rights Reserved.