the procesess at whic virus replicate intracelllularly.

2. Viruses are obligate intracellular
parasites
They can only replicate in living
cells.

3. Viral Multiplication Cycle
1) Adsorption
2) Entry
3) Uncoating
4) Component production
5) Assembly
6) release

4. 1)ADSORPTION
 requires viral attachment protein
 cellular receptors
 specie specific.
 some neutralizing antibodies are specific
for the attachment proteins
4

5. 2)Penetration (enveloped viruses)
Either
• Fusion with plasma membrane
or
• Entry via endosomes, fusion with
acidic endosome membrane

6. 2)Penetration
herpes viruses, paramyxo viruses, HIV
6

7. 7

8. 2)Penetration
(Enveloped Viruses)
8

9. 2)Penetration (non enveloped)
Only via
endosomes (endocytosis or
viropexis)

10. 10

11. 3)Uncoating & eclipse
release of viral genome
Viral particle can no more be
detected.

12. 4)Synthesis of Viral Nucleic Acid
and Protein
Nucleic acid may be made in the
nucleus or the cytoplasm
Protein synthesis is always in the
cytoplasm
Latent viruses.
12

13. Transcription/Translation/Synthes
is:
DNA viruses:
• replicate their DNA in host cell
nucleus. Exception - Poxviruses
• synthesize capsid and other
proteins in cytoplasm

14. Transcription, translation and
synthesis:
RNA viruses:
 Most RNA viruses replicate in the
cytoplasm
 Few exceptions e.g. Influenza virus,
retroviruses.

15. 5)Assembly:
Takes place in cell nucleus,
cytoplasm or (with most
enveloped viruses) at the plasma
membrane

16. 6)Release
Either
Lysis
Or
Budding through plasma membrane
16

18. Virus replication: general

19. 1,000 – 100,000 viruses/cell, 5 – 24 hours

20. Adsorption (attachment)
Entry
Replication
Latency
Release