1. Viruses

2. What is a virus?
‘Infectious particle’
Genetic material
Protein coat

3. Properties of a virus
A virus is a very small, infectious, obligate intracellular parasite
Virus particles are not living
Viruses are chemicals, and by themselves cannot reproduce
A susceptible and permissive cellular host is needed for viruses to reproduce
All viruses must make mRNA that can be translated by host ribosomes

4. Basic virus structure

5. Basic virus structure
DNA
DNA OR OR
RNA
RNA

6. Basic virus structure
DNA
RNA OR
DNA + + OR
RNA

7. Basic virus structure + + DNA RNA OR DNA Capsid Protein Capsid Protein

8. Basic virus structure + + DNA RNA OR DNA Capsid Protein Capsid Protein

9. Basic virus structure
DNA
RNA OR +
Capsid
Protein
Nucleocapsid

10. Basic virus structure
DNA
RNA +
Capsid
Protein
Nucleocapsid OR

11. Basic virus structure
DNA
RNA OR +
Capsid
Protein
Nucleocapsid =

12. Basic virus structure
DNA
RNA OR +
Capsid
Protein
Nucleocapsid = +

13. Basic virus structure + + = DNA Capsid OR Protein RNA Nucleocapsid
Lipid membrane +
Glycoproteins

14. Basic virus structure + + = Enveloped virus DNA Capsid OR Protein RNA
Nucleocapsid = +
Lipid membrane
Glycoproteins
Enveloped virus

15. Capsid symmetry
Icosahedral
Helical

16. Attachment

17. Attachment: tropism
Lock and key

18. Penetration

19. Disassembly

20. Disassembly
Viral genome

21. Transcription
Viral genome
Viral enzymes
mRNA

22. Translation
Viral genome
Viral enzymes
mRNA
Viral proteins

23. Genome replication
Viral genome
mRNA
Viral proteins

24. Assembly
mRNA
Viral proteins

25. Assembly
Viral genome
mRNA
Viral proteins

26. Release

27. Retroviruses

28. Outcome of cellular infection

29. Immune response Cell mediated immunity Antibodies
Important in the recovery from viral illness
Antibodies
Important in the protection from repeat exposure