1. 9.1-13 Introduction to Viruses
Microbiology
Introduction to Viruses

2. 9.1 Overview of Viruses 1886 Adolph Meyer tobacco mosaic disease.
1892 Dmitri Ivanovski proved disease could be caused after all of the bacteria have been filtered out.
1930s Invention of the electron microscope.

3. 9.1 Viral host range
Surface receptors
Bacteriophages

4. 9.2 Viral Structure Capsid-outer geometric protein shell
Core-nucleic acid
Some have a fatty membrane with attached glycoproteins

5. 9.3 Viral classification Morphology Type of nucleic acid
Single-stranded DNA (ssDNA)
Single-stranded RNA (ssRNA)
Double-stranded DNA (dsDNA)
Double-stranded RNA (dsRNA)
Replication cycles

6. 9.3 Viral Classification Baltimore Virus Classification
Based upon genomes

7. 9.4 Culturing Viruses
Cell culture host- obligate intracellular parasites.
Inoculation of live animals.
Chicken eggs
Cell cultures

8. 9.5 Viral Replication Receptors & attachment Penetration Uncoating
Expression (replication)
Assembly
Release-Lysogenic cycle or Budding

9. 9.6 Subviral Entities Viroids-plant pathogens Satellites-helper virus
Prions-pathogenic proteins, mad-cow disease-untreatable & fatal

10. 9.7-10 Viral Diversity RNA Bacteriophages
Single-stranded DNA Bacteriophages
Double-stranded DNA Bacteriophages
Positive-strand RNA-foot & mouth disease
Negative-strand RNA-Rabies, influenza
Retroviruses-HIV

11. 9.11 DNA Viruses in Eukaryotes
Plants-rare but cause significant crop loss
Animals
Polyomaviruses-cancer
Adenoviruses-common cold
Herpesviruses-genital herpes, chicken pox, mononucleosis
Poxviruses-smallpox
Immunodeficiency

12. 9.11 Viruses in Eukaryotes Treatment
Interferons- glycoproteins produced by the immune system to prevent viral replication in infected cells.
Vaccines-1798 Edward Jenner cowpox
Treat symptoms

13. 9.12 Viruses & Cancer
15-20% of all cancers are caused by viral infection.
Human papilloma virus (HPV)- cervical, anal, vaginal, penile, mouth & throat cancer.
Epstein-Barr-lymphoma
Hepatitis B-liver cancer
Herpes virus-8-Kaposi sarcoma

14. 9.13 Viral Ecology Mutations-Genetic Drift Transformation
Antigenic Shift-avian flu, swine flu, H1N1 in humans
Metagenomics
Aquatic ecosystems
Bacteriophages