Penetration and uncoating - entry of the virus into the host cell. Gene Expression and replication - Translation of the viral nucleic acids into proteins. Transcription of the nucleic acid and replication of the viral nucleic acid. Assembly - Viral components are assembled in either the cytoplasm or nucleus of the cell. The virions escape the host cell to infect other hosts.
Adsorption takes place only when there are receptors on both the host cell and the virus.
This often determines the host range of a virus. An example is the polio virus. Primates have receptors for the polio virus but rodents do not. 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.