Viruses!

http://pandemic2.org/

The girl who survived Rabies

EBOLA

Ebola Virus

Relative Size Do NOW

How Viruses Attack

• http://www.youtube.com/watch?v=Rpj0emEGShQ

• http://video.pbs.org/video/1240086878/

• 3:17 1918, Spanish Flu,

• Swine Flu, New Report

Swine Flu

Flu

VIRUSES

VirusesViruses are are particles particles containing:containing:

1. Nucleic acid1. Nucleic acid2. Protein coat 2. Protein coat (capsid) (capsid)

They can reproduce only by infecting They can reproduce only by infecting living cells.living cells.

All viruses enter living cells and use the All viruses enter living cells and use the infected cell( host) to produce more infected cell( host) to produce more viruses. viruses.

• Special proteins on the capsid Special proteins on the capsid ““tricktrick”” the host the host cell to let the virus in. The host cell then bursts cell to let the virus in. The host cell then bursts and is destroyedand is destroyed

Types of VirusesTypes of Viruses

• DNA viruses DNA viruses • More Stable less prone to mutationMore Stable less prone to mutation• Respond well to vaccinationRespond well to vaccination

•Ex: smallpox, chicken pox, herpes, HPV, Ex: smallpox, chicken pox, herpes, HPV, Hepatitis BHepatitis B

• RNA viruses RNA viruses • Mutate quicklyMutate quickly• Require frequent vaccinationsRequire frequent vaccinations

•Ex: Influenza (flu), HIV, Rabies Ex: Influenza (flu), HIV, Rabies

Different HostsDifferent HostsHost cell is very specificHost cell is very specific•Animal hosts: rabies, HIV, chicken poxAnimal hosts: rabies, HIV, chicken pox•Plant hosts: tobacco mosaic virus, Plant hosts: tobacco mosaic virus, •Bacteria: Bacteriophage Bacteria: Bacteriophage

Ex. Rabies Virus can only exist in an animal

Examples of Viral DiseaseExamples of Viral Disease• Smallpox, the common cold, Smallpox, the common cold,

chickenpox, influenza, shingles, chickenpox, influenza, shingles, herpes, polio, rabies, ebola, and HIVherpes, polio, rabies, ebola, and HIV

Small Pox

Smallpox killed over 500 million people in the 20th century!

Compared to: 320 million deaths caused by wars, the Spanish flu, and AIDS combined

Amherst bring Smallpox blanket to native Americas

Figure 1.15B: The press portrayed Roosevelt as a robust, physically strong leader.

POLIO

Lytic vs. Lysogenic

- Viruses inject their DNA or RNA and take over the host to make new viruses

- The viruses “pop” the cell to spread

Lytic Infection

A spacecraft injecting genetic material into a host cell.

The Lysogenic

Cycle (Sneaky!)

1. Virus injects its DNA into host cell1. Virus injects its DNA into host cell

2. Viral DNA 2. Viral DNA integratesintegrates into the host DNA into the host DNA

3. A host cell makes copies of the virus 3. A host cell makes copies of the virus every time it divides.every time it divides.

Lysogenic CycleLysogenic Cycle

The viral DNA embedded in the The viral DNA embedded in the hosthost’’s DNA is called a s DNA is called a prophageprophage..

Replicates in the host cell

Viral DNA can leave the host DNA and enter the lytic Cycle

RetrovirusesRetroviruses• RetrovirusesRetroviruses contain RNA. contain RNA.• Make a DNA copy FROM their RNA.Make a DNA copy FROM their RNA.• Then this DNA is inserted into the DNA of the host Then this DNA is inserted into the DNA of the host

cell.cell.

HIV (humanimmunodeficiency virus) can lead to AIDS (acquired immunodeficiency

syndrome)

http://www.livescience.com/16909-magic-johnson-hiv-aids-anniversary.html

Defense• Vaccination offers protection for uninfected Vaccination offers protection for uninfected

individuals (weakened version or partial individuals (weakened version or partial version of virus) version of virus)

• Works by stimulating immune system so Works by stimulating immune system so that the virus will be recognized if infectedthat the virus will be recognized if infected

Are Viruses Are Viruses Living or Non-living??Living or Non-living??

Ecuador/Galapagos