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

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!!!

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.

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.

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

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

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.

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.

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

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.

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 >>>>>

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.

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

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