Virus Replication

• Viruses are obligate parasites.
• They must live in a host cell in order to replicate.

Stages in Viral Replication

1. Attachment

2. Entry

3. Synthesis

4. Assembly

5. Release

   

6. Attachment

• The virus attaches to the host cell.

7. Entry

• The virus creates a hole in the host cell membrane.
• Viral nucleic acid is injected into the host cell.
• In bacteriophages, the protein coat remains outside the bacterial cell.
• In animal cells, the protein coat enters the cell but is digested.

8. Synthesis

• The host nucleic acid becomes inactive.
• The viral nucleic acid uses the host's organelles to produce new viral nucleic acid and proteins.

9. Assembly

• New viruses are assembled inside the host cell.

10. Release

• The host cell bursts to release the new viruses.
• This bursting of the host cell is called lysis.
• These newly formed viruses infect other cells.