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.
DNA
RNA
OR
Basic virus structure
DNA
RNA
OR

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

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

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

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

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

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

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

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

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

15.
Capsid symmetry
Icosahedral Helical

16.
Attachment

17.
Attachment: tropism
Lock and key

18.
Penetration

19.
Disassembly

20.
Viral genome
Disassembly

21.
mRNA
Viral genome
Viral
enzymes
Transcription

22.
mRNA
Viral
proteins
Viral
enzymes
Viral genome
Translation

23.
mRNA
Viral
proteins
Viral
genome
Genome replication

24.
mRNA
Viral
proteins
Assembly

25.
mRNA
Viral
proteins
Viral genome
Assembly

26.
Release

27.
Retroviruses

28.
Outcome of cellular infection

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