Transcript --- The Language of Biotechnology

Introduction to Virology
I. Objectives
 What
is a virus
 How
do viruses multiply
 How
are viruses classified
 (What
cause)
are some of the diseases viruses
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
 Bacteria
Virus
 Intracellular parasite
 Plasma membrane
 Binary fission
 Filterable
 Possess DNA & RNA
 ATP production
 Ribosomes
 Antibiotic sensitive
(no)
yes
yes
no
yes
yes
yes
yes
yes
no
no
yes
no
no
no
no
 2.
Growth comparison
 3.
Size comparison
 4.
Genome size comparison
IV. Nucleocapsid morphology
 A.
Helical
 B.
Polyhedral
 C.
Complex
V. How viruses multiply (13.10)
 1.
–
–
–
–
–
Basic strategy
Attachment
Penetration
Synthesis of viral proteins and nucleic acids
Maturation
Release
2. Bacterial viruses: Fig 13.12
 Lytic
vs lysogenic cycle
3. General Animal Virus
Multiplication
a.Virus Budding: Fig 13.20
4. Differences in lab culture of
viruses
 a.
bacteriophage
 b.
animal viruses
VI. Differences in multiplication due to
differences in genome organization
 A.
Genome organization
B. DNA Viruses: Life Cycle:
Fig 13.17
C. Replication of RNA viruses:
Fig 13.17
VI. Classification schemes
 A.
Formal taxonomies
 B.
Baltimore Classification
C. Nucleic acid type -->
Baltimore classification
 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)
1. Class I: dsDNA Viruses
 Bacterial
– Bacteriophage
 Plant
– Caulomoviridae
 Human
–
–
–
–
Herpesviridae
Adenoviridae
Poxviridae
Papovaviridae
» Papillomavirus
» Polyomavirus
» Vacuolating agent
– Hepadnaviridae
» After protein synthesis, DNA replicated through
RNA intermediate
2. Class II: ssDNA viruses
 Bacteria
 Plant
 Animal
3. Class III: dsRNA viruses
 Reoviridae
4. Class IV: ss (+) RNA viruses
 Picornaviridae

Togaviridae

Flaviviridae
 Coronaviridae

Calciviridae
5. Class V: ss (-) RNA viruses
 Rhabdoviridae
Filoviridae
 Paramyxoviridae
 Orthomyxoviridae
 Bunyaviridae
 Deltaviridae
 Arenaviridae

Retrovirus Life Cycle: Fig 13.19
6. Class VI: ss (+) viruses
(dsDNA intermediate)
 Retroviridae
– Oncoviruses
– Lentivirus
D. Review of Replication
Strategies
VII. Effects of Viral Infection on
Cell
VIII. Oncogenic Viruses
IX. Plant viruses
 Morphologically
similar to animal viruses
 Enter
through wounds or parasites
 Some
multiply in insects
X. Viroids
 Plant
pathogens
– infectious naked RNA
 20-25
 ss
identified so far
covalent circle
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