VIRUSES

1. VIRUSES “A virus is a piece of bad news wrapped in a protein.” -Sir Peter Medawar Nobel Laureate

2. Are viruses living or non-living? • The lack the ability to reproduce on their own. • They cannot transform their own energy. • The lack cell membranes, nucleus and cell organelles. • They are dormant unless in contact with a host cell. • You make the decision!!!

3. Viruses Come In Many Shapes • All viruses have a capsid made of protein that encloses a central core of either DNA or RNA. • There are three basic groups of viruses: bacterial, plant and animal.

4. What was the first identified virus? • In 1933 Wendall Stanley of the Rockefeller Institute purified an extract of tobacco mosaic virus which caused discoloration of tobacco leaves.

5. Bacteriophages • These are viruses that infect bacteria. • They are large in size. • All are virulent and multiply within a host cell.

6. Bacteriophages • The T4 bacteriophage has a head and a tail attached to an end plate. The capsule contains DNA. • The end plate attaches to the host and the head contains the DNA

7. The Lytic Cycle - Viral Reproduction • Follow the path on the right of the diagram. • Virus attaches to host cell. • DNA is injected into the host. • DNA forms proteins needed to form new viruses. • New viruses form and then leave the cell.

8. What is a retrovirus? • Retroviruses have a core of RNA. • The RNA enters the host and forms DNA. • HIV virus is an example of a retrovirus. • They can be used to transport genes for genetic engineering and gene manipulation.

9. Viruses and Cancer • Some types of viruses can cause tumor growth in laboratory cultures. • Epstein Barr and hepatitis B viruses have been linked to cancer growth. • It is believed some viruses contain cancer genes called oncagenes. • Oncagenes in contact with certain human oncagenes and cancer causing agents can cause some types of cancer. • Ex. Some types of leukemia, some types of cervical cancer and liver cancer

10. Emerging Viruses • An existing virus can evolve and and cause disease in organisms that were one immune to it. • An existing virus can spread from one type of host to another. Humans can get viruses from other species. • An existing virus can spread from a small population to become more widespread. Hantavirus can spread from small mouse populations to the human population.

11. Your Assignment • Your assignment is to look at some viruses of note from the 20th century. • The viruses that you will select from have all been well known viruses that emerged in the 20th century. These are usually not new but have expanded their host territory. • You are to select a virus and type a one page report in Microsoft Word about the virus. The report will include >>>>>

12. What should be included? • The name of the virus you selected • A description of the virus? What is its host? • How does one get the virus? • What part of the body is affected and how might you recognize it? • When did the virus first become noticed or when was there an epidemic and where? • Three web links to information on the virus. • Try and find a picture of your virus and list the link.

13. HIV Hantavirus Ebola virus Smallpox Polio Hepatitis Dengue fever Lassa fever Rift valley fever Influenza Monkeypox Epstein-Barr virus What are some viruses that can be used?

14. Where do I start? • These are hyper-linked so all you have to do is click on them and they will go to the site. • Center for Disease Control • Outbreak • Hidden Killers • World Health Organization