Viruses are non-living particles that can only reproduce inside host cells. They are smaller than bacteria and contain genetic material surrounded by a protein coat. Viruses come in various shapes and sizes and cause diseases like influenza, measles, HIV/AIDS, and some cancers. Edward Jenner developed the first vaccine for smallpox using a related cowpox virus. Viruses are identified based on their morphology, genetic material, presence of an envelope, capsid shape, host cell, and more. They exist in nature as parasites and depend on host cells for reproduction through lysogenic or lytic cycles.

1. CHARACTERISTICS OF VIRUSES

2. Are Viruses Living or Non-living?Biologists consider viruses to be non-living because:Are not cellsDo not grow or respond to their surroundingsCannot make food, take in food, or produce wastesViruses do not respond to stimuli.They can only multiply if in another living cell

3. What are Viruses?Definition-Viruses are noncellular particles made up of genetic material and protein that can invade living cells.

4. 4Discovery of VirusesBeijerinck (1897) coined the Latin name “virus” meaning poison

5. 5Tobacco Mosaic VirusWendell Stanley (1935) discovered viruses were made of nucleic acid and protein

6. 6SmallpoxEdward Jenner (1796) developed a smallpox vaccine using milder cowpox virusesSmallpox has been eradicated in the world today

7. How Big is a Virus?Viruses are very small – smaller than the smallest cell.

8. 8CharacteristicsNon living structuresNon-cellularContain a protein coat called the capsidHave a nucleic acid core containing DNA or RNA (one or the other - not both)Capable of reproducing only when inside a HOST cell

9. 9CharacteristicsCAPSIDSome viruses are enclosed in an protective envelopeSome viruses may have spikes to help attach to the host cellMost viruses infect only SPECIFIC host cellsDNAENVELOPESPIKES

10. 10EBOLA VIRUSHIV VIRUSOutside of host cells, viruses are inactiveViruses cause many common illnesses/ diseases Some viruses may cause some cancers like leukemiaCharacteristicsMEASLES

11. 11CharacteristicsViruses cause many common illnesses diseases Some viruses may cause some cancers like leukemiaMEASLES

12. What do Viruses look like?Viruses are unusual and different from other things in nature.Viruses come in a variety of shapesSome may be helical shape like the Ebola virusSome may be polyhedral shapes like the influenza virusOthers have more complex shapes like bacteriophages

13. 13Types of Viruses: Helical Viruses

14. 14Polyhedral Viruses

15. 15Complex Viruses

16. 16Viral TaxonomyFamily names end in -viridaeGenus names end in -virus Viral species: A group of viruses sharing the same genetic information and ecological niche (host). Common names are used for speciesSubspecies are designated by a number

17. 17Used for Virus IdentificationMorophologyRNA or DNA VirusDo or do NOT have an envelopeCapsid shapeHOST they infect

18. 18Herpes Virus SIMPLEX I and II

19. 19Adenovirus COMMON COLD

20. 20Influenza Virus

21. 21Chickenpox Virus

22. 22Papillomavirus – Warts!

23. HOST SPECIFICITYAll kingdoms can be infected by virusesViruses are kingdom specific but they may or may not be species specificSpread is specific to the type of virus

24. PARASITISMViruses are parasites.A parasite is an organism that depends upon another living organism for its existence in such a way that it harms that organism.

25. 25Bacteriophages

26. 26CylcesLysogenic CycleViral DNAMay stay inactive in host for long periods of timeLong lasting Example Mono or chickenpoxLyticCylceShort and can be over come Example flu virus

27. Vaccine Is a weaken form of the virus To expose your immune system to the virus which will allow your body to better fight off the virus when exposed to the full blow virus.

28. Vector ControlThis is controlling the vectors that are carrying the virus. Examples:We stay home when sick, cover our mouth when we cough etc. We control the mosquito population in order to control the West Nile virus

29. 29Other DrugTreatmentsSpecific to certain viruses. They don’t cure the virus but they can slow down and inhibit the multiplication of the virus. copyright cmassengale

30. Reducing the RiskThey can’t be treated but they can be prevented! Cover mouth/nose when you sneeze of coughWash hands frequentlyAvoid contact with the body fluidsNot foolproof but reduces the risks