Viral multiplication

the procesess at whic virus replicate intracelllularly.

1. Viral Multiplication

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

3. Viral Multiplication Cycle Adsorption Entry Uncoating Component production Assembly release

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

5. 2)Penetration (enveloped viruses) E ither F usion with plasma membrane or E ntry via endosomes, fusion with acidic endosome membrane

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

7. 7 H+

8. 8 2)Penetration (Enveloped Viruses)

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

10. 10 H+

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

12. 12 4)Synthesis o f Viral Nucleic Acid and Protein N ucleic acid may be made in the nucleus or the cytoplasm P rotein synthesis is always in the cytoplasm Latent viruses.

13. Transcription/Translation/Synthesis: 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: T akes place in cell nucleus , cytoplasm or (with most enveloped viruses) at the plasma membrane

16. 16 6)Release Either Lysis Or B udding through plasma membrane

17. Virus replication: general

18. 1,000 – 100,000 viruses/cell, 5 – 24 hours

19. Adsorption (attachment) Entry Replication Latency Release