Introduction to Virology

Lecture Outline u I. Objectives u II. Historical perspective u III. What is a virus –A. Characteristics –B. Comparison to bacteria u IV. Nucleocapsid morphology –A. Helical –B. Polyhedral –C. Complex

u V. How viruses multiply –A. Basic strategy –B. Bacterial viruses –C. Animal viruses –D. Culturing viruses in the lab u VI. How to classify viruses? –A. Formal taxonomies –B. Baltimore Classification –C. Which means what?

u 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 u VIII. Summary of effects of viral infection on cells u IX. Oncogenic viruses

u X. Viroids u XI. Prions

I. Objectives u What is a virus u How do viruses multiply u How are viruses classified u What are some of the diseases viruses cause

II. Historical Perspective u A. Ancient times –1. poliovirus –2. smallpox u B. More recent history – ’s »Iwanowski – ’s »Jenner

III. What is a virus? u A. Characteristics

B. Comparison to bacteria 1. overall u Bacteria Virus u Intracellular parasite (no) yes u Plasma membraneyes no u Binary fission yes no u Filterable no yes u Possess DNA & RNAyes no u ATP production yes no u Ribosomesyes no u Antibiotic sensitive yes no

u 2. Size comparison u 3. Genome size comparison

IV. Nucleocapsid morphology u A. Helical u B. Polyhedral u C. Complex

V. How viruses multiply (13.10) u A. Basic strategy –Attachment –Penetration –Synthesis of viral proteins and nucleic acids –Maturation –Release

B. Bacterial viruses: Fig u Lytic vs lysogenic cycle

C. Animal Viruses

D. Culturing viruses in the lab u 1. bacteriophage u 2. animal viruses

VI. How to classify viruses? u A. Formal taxonomies u B. Baltimore classification u 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 u Class I –ds DNA u Class II –ssDNA (positive and negative) u Class III –dsRNA u Class IV –ssRNA (positive)

u Class V –ssRNA (negative) u Class VI –ssRNA (positive, replication intermediate DNA)

Brief note on nomenclature u Family u Genus u Species u eg. Family Herpesviridae, genus Simplexvirus, human herpes virus 2

VII. Viruses and the diseases they cause u A. Class I: dsDNA Viruses –1. Bacterial –2. Plant

u 3. Human host –a. Herpesviridae –b. Adenoviridae –c. Poxviridae –d. Papovaviridae »Papillomavirus »Polyomavirus »Vacuolating agent –e. Hepadnaviridae

B. Class II: ssDNA viruses u 1. Bacteria u 2. Plant u 3. Human –A. Parvoviridae

C. Class III: dsRNA viruses u 1. Reoviridae

D. Class IV: ss (+) RNA viruses u 1. Picornaviridae u 2. Togaviridae u 3. Flaviviridae u 4. Coronaviridae u 5. Calciviridae

E. Class V: ss (-) RNA viruses u 1. Rhabdoviridae u 2. Filoviridae u 3. Paramyxoviridae u 4. Orthomyxoviridae u 5. Bunyaviridae

Retrovirus Life Cycle: Fig 13.19

F. Class VI: ss (+) viruses (dsDNA intermediate) u 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 u A. Fig u B. PrP C vs PrP Sc –Structural differences –Detergent solubility differences –Differences in susceptibility to protein degrading enzymes

Prion diseases of humans and animals