Transcript Introduction to Virology

Introduction to Virology
Lecture Outline
 I.
Objectives
 II. Historical perspective
 III. What is a virus
– A. Characteristics
– B. Comparison to bacteria
 IV.
Nucleocapsid morphology
– A. Helical
– B. Polyhedral
– C. Complex
 V.
–
–
–
–
How viruses multiply
A. Basic strategy
B. Bacterial viruses
C. Animal viruses
D. Culturing viruses in the lab
 VI.
How to classify viruses?
– A. Formal taxonomies
– B. Baltimore Classification
– C. Which means what?
 VII.
–
–
–
–
–
–
Viruses and the diseases they cause
A. Class I: dsDNA
B. Class II: ssDNA
C. Class III: dsRNA
D. Class IV: ss(+)RNA
E. Class V: ss(-)RNA
F. Class VI: ss(+)RNA with dsDNA
intermediate
 VIII.
Summary of effects of viral infection
on cells
 IX. Oncogenic viruses
 X.
Viroids
 XI. Prions
I. Objectives
 What
is a virus
 How
do viruses multiply
 How
are viruses classified
 What
are some of the diseases viruses cause
II. Historical Perspective
 A. Ancient
times
– 1. poliovirus
– 2. smallpox
 B.
More recent history
– 1. 1790’s
» Iwanowski
– 2. 1890’s
» Jenner
III. What is a virus?
 A.
Characteristics
B. Comparison to bacteria
1. overall

Intracellular parasite
 Plasma membrane
 Binary fission
 Filterable
 Possess DNA & RNA
 ATP production
 Ribosomes
 Antibiotic sensitive

Bacteria
(no)
yes
yes
no
yes
yes
yes
yes
Virus
yes
no
no
yes
no
no
no
no
 2.
Size comparison
 3.
Genome size comparison
IV. Nucleocapsid morphology
 A.
Helical
 B.
Polyhedral
 C.
Complex
V. How viruses multiply (13.10)
 A.
–
–
–
–
–
Basic strategy
Attachment
Penetration
Synthesis of viral proteins and nucleic acids
Maturation
Release
B. Bacterial viruses: Fig 13.12
 Lytic
vs lysogenic cycle
C. Animal Viruses
D. Culturing viruses in the lab
 1.
bacteriophage
 2.
animal viruses
VI. How to classify viruses?
 A.
Formal taxonomies
 B.
Baltimore classification
 C.
Which means what?
1. Genome organization
2. Genome organization affects
replication
3. DNA Viruses: Life Cycle:
Fig 13.17
4. Replication of RNA viruses:
Fig 13.17
5. Viral classes
 Class
I
– ds DNA
 Class
II
– ssDNA (positive and negative)
 Class
III
– dsRNA
 Class
IV
– ssRNA (positive)
 Class
V
– ssRNA (negative)
 Class
VI
– ssRNA (positive, replication intermediate
DNA)
Brief note on nomenclature
 Family

Genus

Species

eg. Family Herpesviridae, genus Simplexvirus,
human herpes virus 2
VII. Viruses and the diseases they
cause
 A.
Class I: dsDNA Viruses
– 1. Bacterial
– 2. Plant
 3.
–
–
–
–
Human host
a. Herpesviridae
b. Adenoviridae
c. Poxviridae
d. Papovaviridae
» Papillomavirus
» Polyomavirus
» Vacuolating agent
– e. Hepadnaviridae
B. Class II: ssDNA viruses
 1.
Bacteria
 2.
Plant
 3.
Human
– A. Parvoviridae
C. Class III: dsRNA viruses
 1.
Reoviridae
D. Class IV: ss (+) RNA viruses
 1.
Picornaviridae

2. Togaviridae

3. Flaviviridae
 4.

Coronaviridae
5. Calciviridae
E. Class V: ss (-) RNA viruses

1. Rhabdoviridae

2. Filoviridae

3. Paramyxoviridae

4. Orthomyxoviridae

5. Bunyaviridae
Retrovirus Life Cycle: Fig 13.19
F. Class VI: ss (+) viruses
(dsDNA intermediate)
 1.
Retroviridae
– Oncoviruses
– Lentivirus
G. Review of Replication
Strategies
VIII. Summary of effects of viral
infection on cells
IX. Oncogenic Viruses
X. Viroids
XI. Prions
 A.
Fig 13.21
 B.
PrPC vs PrPSc
– Structural differences
– Detergent solubility differences
– Differences in susceptibility to protein
degrading enzymes
Prion diseases of humans and
animals