1. Virus

2. What is a Virus? Non living disease causing agent All viruses enter living cells and use the host cell to replicate Composed of: –Genetic Material –Protein Coat (capsid) –Sometimes Lipids

3. Plant virus to plants Animal virus to animals Bacterial virus (called bacteriophages) to bacteria

5. How do they work? The capsid proteins bind to receptors on the surface of a cell and “trick” the cell into letting it inside Once inside, the virus replicates, transcribes, & translates its genetic info. Viruses are generally specific

6. Lytic Infection A virus enters a cell Virus makes copies of itself Causes the cell to burst Example-Bacteriophage T4

7. Lysogenic Infection Virus integrates its DNA into DNA of host cell Viral genetic info replicates with host cell DNA Prophage-viral DNA that is in host DNA Example- bacteriophage lambda

9. Characteristics of Living Things o Made of up of cells o They reproduce by them selves o Have nucleic acid o Grow and develop o Get and use energy o Respond to their environment o Maintain homeostasis o Change over time

11. Retro means “backward” Contain RNA & from that make DNA –Viral DNA inserted into host cell DNA Examples –Cause some cancer –Cause Acquired immune deficiency syndrome (AIDS) Retrovirus

12. Viral Disease in Humans Common cold Influenza Smallpox Warts AIDS Chickenpox Measles Hepatitis A, B, and C West Nile Polio

13. 13 Retroviruses

14. 14 Characteristics of Retroviruses Contain RNA, not DNA Family Retroviridae Contain enzyme called Reverse Transcriptase When a retrovirus infects a cell, it injects its RNA and reverse transcriptase enzyme into the cytoplasm of that cell

15. 15 ENZYME

16. 16 Retroviruses HIV, the AIDS virus, is a retrovirus Feline Leukemia Virus is also a retrovirus

17. AIDS Infected by HIV (human immunodeficiency virus) through blood or sexual contact There is no evidence sharing certain body fluids spreads HIV, but very tiny amounts of blood can transmit the virus HIV has to break past body defenses to infect a host (saliva, skin, etc…)

18. Aids Is a condition caused by HIV When you immune system gets severely damaged and can no longer fight off infections HIV becomes AIDS 18

19. 19 Adenovirus COMMON COLD

20. Common Cold Infections of the upper and lower respiratory tract. Can also lead to infections of the gastro-intestinal tract and eye (pink eye) Spread via respiratory secretions or by fecal contamination. 20

21. Polio It invades the nervous system, and can cause total paralysis in a matter of hours. Initial symptoms are fever, fatigue, headache, vomiting, stiffness in the neck and pain in the limbs. One in 200 infections leads to irreversible paralysis (usually in the legs). Amongst those paralyzed, 5%-10% die when their breathing muscles become immobilized. Although polio paralysis is the most visible sign of polio infection, fewer than 1% of polio infections ever result in paralysis

22. A virus causes Polio

23. 23 Influenza Virus

24. Influenza Spreads like the common cold Its symptoms can be similar to the cold, but usually include: –Nausea –Headache –Body Soreness/Achiness Approximately 65,000 deaths a year 24

25. Flu Influenza A and B cause epidemics of respiratory illness in humans and animals. Animal hosts include: birds, pigs, ducks, whales, horses, and seals The vaccine you received this year is for strain B, strain A is what is causing all the trouble this season.

26. 26Smallpox Edward Jenner (1796) developed a smallpox vaccine using milder cowpox viruses Deadly viruses are said to be virulent Smallpox has been eradicated in the world today

27. Small pox- Poxvirus Spread via sores, blood, respiratory secretions. It can infect by ingestion, inhalation, or incorporation in to a skin lesion. 27

28. Small Pox Causes: Outer sores Internal hemorrhaging Death 28

29. 29

30. 30 Papillomavirus – Warts!

31. A virus causes warts

32. Cancer Caused by a Virus? human papillomavirus is a STD that has the potential to cause cervical cancer in girls and oral cancer in boys Approximately 20 million people are currently infected with HPV. At least 50 percent of sexually active men and women acquire genital HPV infection at some point in their lives. By age 50, at least 80 percent of women will have acquired genital HPV infection. About 6.2 million Americans get a new genital HPV infection each year

33. HPV Most HPV infections have no signs or symptoms; therefore, most infected persons are unaware they are infected, yet they can transmit the virus to a sex partner. There is no "cure" for HPV infection, although in most women the infection goes away on its own

34. http://www.youtube.com/watch?v=kYf_Sl8 W3qYhttp://www.youtube.com/watch?v=kYf_Sl8 W3qY

35. 35 Prions Prions are “infectious proteins” They are normal body proteins that get converted into an alternate configuration by contact with other prion proteins They have no DNA or RNA The main protein involved in human and mammalian prion diseases is called “PrP”

36. 36 Prion Diseases Prions form insoluble deposits in the brainPrions form insoluble deposits in the brain Causes neurons to rapidly degeneration.Causes neurons to rapidly degeneration. Mad cow disease (bovine spongiform encephalitis: BSE) is an exampleMad cow disease (bovine spongiform encephalitis: BSE) is an example People in New Guinea used to suffer from kuru, which they got from eating the brains of their enemiesPeople in New Guinea used to suffer from kuru, which they got from eating the brains of their enemies